The document summarizes developmental reorganization of the human cerebral cortex based on three criteria: 1) presence of transient cellular zones, 2) intensity of specific neurodevelopmental events, and 3) patterns of functional organization. During the first half of gestation, proliferation and migration are dominant, while the second half sees growth of major axonal pathways through transient zones. Initial synaptogenesis begins in the third month and relates to endogenous circuitry. In early preterm infants, thalamic fibers relocate from transient zones and evoked potentials can be recorded, showing coexistence of endogenous and sensory-driven circuitry. In neonates, synaptogenesis is dominant and transient zones disappear gradually.
This document summarizes recent findings on the mechanisms that govern neuronal migration during development. It discusses:
1) Neuronal migration involves leading process dynamics and somal translocation that allow neurons to move through the brain. Different neuron types adjust this process depending on their migratory pathway.
2) Real-time imaging has revealed distinct leading process morphologies in different neuron types that influence their directional guidance. Tangentially migrating neurons display more elaborate branching than radially migrating pyramidal cells.
3) Guidance cues influence the branching and orientation of leading processes to allow rapid changes in migratory direction without reorienting existing branches. This is a different mechanism than growth cone steering in axon guidance
The foetal brain develops within few weeks from a thin cell layer to a gigantic and complex network with billions of neurons and trillions of connections. This process is influenced by environmental factors (e.g. maternal stress) from the beginning. Understanding of the developmental processes is the basis of prenatal medicine and psychology.
Five steps can be related to fairly defined time periods: (1) From 7 to 22 weeks of gestation 20 billion neurons are produced and migrate to their final locations in the brain. (2) From 20 to 35 weeks the transient subplate structure lays the foundation of the cortex. (3) The organization of the neural network (nerve fibre and synapse formation) starts at 24 weeks gestation and continues throughout life. (4) Individual adjustment of the neural network by elimination of more than 50% of the neurons and circuits also starts at 24 weeks, and shapes the brain in three waves. (5) Myelination of axons begins during the last weeks of
gestation and continues for decades.
New neurons are generated from neural stem cells located in the subventricular zone and subgranular zone of the adult brain. These stem cells differentiate into precursor cells, then neuroblasts, and finally mature neurons. Neuroblasts migrate through glial tubes made by astrocytes, with those from the subventricular zone traveling to the olfactory bulb along the rostral migratory stream. BrdU and tritiated thymidine are used to track the generation of new neurons by labeling cells during DNA synthesis. Adult neurogenesis is regulated by various environmental factors that can increase or decrease the proliferation and survival of new neurons.
This document summarizes recent research showing interactions between circadian rhythms and memory formation. It discusses how:
1) Studies in animals have found time-of-day effects on neurophysiology and memory, suggesting common mechanisms underlie circadian rhythms and long-term memory.
2) Mutations in circadian "clock genes" like period disrupt both circadian locomotor rhythms and memory formation in fruit flies.
3) Conserved molecular pathways involving proteins like PER, CREB, and MAPK regulate both circadian rhythms and memory processes in flies and mammals.
This document presents a case study of a 10-year-old male patient with mental subnormality and Lennox-Gastaut syndrome. MRI findings showed lissencephaly with cerebellar hypoplasia. Radiological findings included vertically oriented folia in the cerebellum instead of the normal horizontal pattern. The diagnosis was determined to be cortical/cerebellar dysplasia. The discussion describes abnormalities that can occur in cerebellar development, including defective foliation patterns and irregular gray/white matter junctions, which were present in this patient.
1) The document is an orientation for a class on brain structure and origins taught at MIT in 2005.
2) It introduces the goals of learning vertebrate neuroanatomy through studies of development, evolution, and function.
3) The first topics to be covered are neural terminology, the evolution and study of neurons, and an overview of the central nervous system.
This presentation summarizes some of the most popular neural differentiation protocols. It also contains some of the most recent developments in these protocols including small molecule based methods.
This document summarizes the development of neural stem cells in the cerebral cortex. It discusses:
1) Neural stem cells in the developing neuroepithelium give rise to neurons and glial cells of the central nervous system. The main types of neural stem cells are neuroepithelial cells and radial glial cells, which reside in the apical surface of the ventricular zone.
2) As development proceeds, neural stem cells transition between different division modes - from symmetric proliferative divisions to produce more stem cells, to asymmetric divisions to produce one stem cell and one progenitor cell, and eventually symmetric neurogenic divisions to produce neurons directly.
3) The cerebral cortex is formed from the telencephalon.
This document summarizes recent findings on the mechanisms that govern neuronal migration during development. It discusses:
1) Neuronal migration involves leading process dynamics and somal translocation that allow neurons to move through the brain. Different neuron types adjust this process depending on their migratory pathway.
2) Real-time imaging has revealed distinct leading process morphologies in different neuron types that influence their directional guidance. Tangentially migrating neurons display more elaborate branching than radially migrating pyramidal cells.
3) Guidance cues influence the branching and orientation of leading processes to allow rapid changes in migratory direction without reorienting existing branches. This is a different mechanism than growth cone steering in axon guidance
The foetal brain develops within few weeks from a thin cell layer to a gigantic and complex network with billions of neurons and trillions of connections. This process is influenced by environmental factors (e.g. maternal stress) from the beginning. Understanding of the developmental processes is the basis of prenatal medicine and psychology.
Five steps can be related to fairly defined time periods: (1) From 7 to 22 weeks of gestation 20 billion neurons are produced and migrate to their final locations in the brain. (2) From 20 to 35 weeks the transient subplate structure lays the foundation of the cortex. (3) The organization of the neural network (nerve fibre and synapse formation) starts at 24 weeks gestation and continues throughout life. (4) Individual adjustment of the neural network by elimination of more than 50% of the neurons and circuits also starts at 24 weeks, and shapes the brain in three waves. (5) Myelination of axons begins during the last weeks of
gestation and continues for decades.
New neurons are generated from neural stem cells located in the subventricular zone and subgranular zone of the adult brain. These stem cells differentiate into precursor cells, then neuroblasts, and finally mature neurons. Neuroblasts migrate through glial tubes made by astrocytes, with those from the subventricular zone traveling to the olfactory bulb along the rostral migratory stream. BrdU and tritiated thymidine are used to track the generation of new neurons by labeling cells during DNA synthesis. Adult neurogenesis is regulated by various environmental factors that can increase or decrease the proliferation and survival of new neurons.
This document summarizes recent research showing interactions between circadian rhythms and memory formation. It discusses how:
1) Studies in animals have found time-of-day effects on neurophysiology and memory, suggesting common mechanisms underlie circadian rhythms and long-term memory.
2) Mutations in circadian "clock genes" like period disrupt both circadian locomotor rhythms and memory formation in fruit flies.
3) Conserved molecular pathways involving proteins like PER, CREB, and MAPK regulate both circadian rhythms and memory processes in flies and mammals.
This document presents a case study of a 10-year-old male patient with mental subnormality and Lennox-Gastaut syndrome. MRI findings showed lissencephaly with cerebellar hypoplasia. Radiological findings included vertically oriented folia in the cerebellum instead of the normal horizontal pattern. The diagnosis was determined to be cortical/cerebellar dysplasia. The discussion describes abnormalities that can occur in cerebellar development, including defective foliation patterns and irregular gray/white matter junctions, which were present in this patient.
1) The document is an orientation for a class on brain structure and origins taught at MIT in 2005.
2) It introduces the goals of learning vertebrate neuroanatomy through studies of development, evolution, and function.
3) The first topics to be covered are neural terminology, the evolution and study of neurons, and an overview of the central nervous system.
This presentation summarizes some of the most popular neural differentiation protocols. It also contains some of the most recent developments in these protocols including small molecule based methods.
This document summarizes the development of neural stem cells in the cerebral cortex. It discusses:
1) Neural stem cells in the developing neuroepithelium give rise to neurons and glial cells of the central nervous system. The main types of neural stem cells are neuroepithelial cells and radial glial cells, which reside in the apical surface of the ventricular zone.
2) As development proceeds, neural stem cells transition between different division modes - from symmetric proliferative divisions to produce more stem cells, to asymmetric divisions to produce one stem cell and one progenitor cell, and eventually symmetric neurogenic divisions to produce neurons directly.
3) The cerebral cortex is formed from the telencephalon.
An update of wallace´s zoogeographic regions of the worldCarlos Sáenz
This document reports on a study that mapped global zoogeographic regions by integrating data on the distributions and phylogenetic relationships of over 21,000 amphibian, bird, and mammal species. The study identified 20 distinct zoogeographic regions grouped into 11 larger realms. Key findings include:
1) Support was lacking for several regions previously defined based solely on distributional data.
2) Spatial turnover in phylogenetic composition was higher in the Southern Hemisphere than the Northern Hemisphere.
3) Incorporating phylogenetic information provided insight on historical relationships among regions and identified evolutionarily unique regions.
A Neurovascular Niche for Neurogenesis after Strokejohnohab
Stroke causes cell death but also birth and migration of new neurons within sites of ischemic damage. The cellular environment that induces neuronal regeneration and migration after stroke has not been defined. We have used a model of long-distance migration of newly born neurons from the subventricular zone to cortex after stroke to define the cellular cues that induce neuronal regeneration after CNS injury. Mitotic, genetic, and viral labeling and chemokine/growth factor gain- and loss-of-function studies show that stroke induces neurogenesis from a GFAP-expressing progenitor cell in the subventricular zone and migration of newly born neurons into a unique
neurovascular niche in peri-infarct cortex. Within this neurovascular niche, newly born, immature neurons closely associate with the remodeling vasculature. Neurogenesis and angiogenesis are causally linked through vascular production of stromal-derived factor 1 (SDF1) and angiopoietin 1 (Ang1). Furthermore, SDF1 and Ang1 promote post-stroke neuroblast migration and behavioral recovery. These experiments define a novel brain environment for neuronal regeneration after stroke and identify molecular mechanisms that are shared between angiogenesis and neurogenesis during functional recovery from brain injury.
This document summarizes the molecular mechanisms underlying neuromuscular junction (NMJ) formation. It discusses how agrin, Lrp4, and Musk signaling pathways induce acetylcholine receptor clustering at the post-synaptic membrane. Wnt signaling is also involved in pre-patterning of acetylcholine receptors before nerve terminal arrival. NMJ formation involves precise interactions between motor neurons, muscle fibers, and glial cells. Defects in these molecular pathways can lead to myasthenia gravis or congenital myasthenia syndrome.
1. The article discusses the development of pain responses from preterm infants through childhood.
2. It notes that while pain pathways are immature early in development, nociceptors and basic pain responses exist even in the youngest preterm infants.
3. The article reviews the maturation of peripheral and central pain pathways from fetal stages through early postnatal life, finding that pathways are functional but immature neonatally and continue developing into childhood.
The Louisville Twin Study followed nearly 500 twin pairs from infancy through adolescence to examine developmental synchronies in behavior. The study found that individual differences in intelligence stabilized by school age, with each child following a unique pattern of cognitive growth spurts and lags. Identical twins became increasingly similar in their development over time, more so than fraternal twins or siblings, showing the strong influence of genes. However, qualitative aspects of the home environment also significantly predicted children's IQ, indicating genes and environment both shape development. The results support a developmental model where genetic programs guide behavior in dynamic interaction with experiences over time.
The Role Of The Cytoskeleton During Neuronal PolarizationDalí Mb
This document summarizes recent advances in understanding the intracellular mechanisms underlying neuronal polarization, with a focus on the role of the cytoskeleton. It discusses how local actin instability in the future axonal growth cone allows microtubule protrusion and formation of multiple axons. Key regulators of this process include Rho-GTPases and their downstream targets, which influence actin dynamics. The Ena/VASP family of proteins also promotes neurite formation by antagonizing actin capping and facilitating bundling. Recent studies further reveal microtubule stabilization as another mechanism in neuronal polarization, complementing actin dynamics.
Cortical dysplasia is a malformation of cortical development caused by abnormal neuronal migration or organization during brain development. It can cause intractable epilepsy and neurodevelopmental disorders like autism. The lecture discusses normal brain development and corticogenesis. It then covers specific malformations including focal cortical dysplasia, describing their histopathology and clinical correlates. Recent research suggests focal disruptions of cortical layering found in children with autism may represent early cortical dysplasia, providing insight into a potential cause of autism.
Sleep slow oscillation as traveling wave massimini tononi jns2004Bernard Baars
1) The study used high-density EEG recordings in humans to show that each cycle of the slow oscillation during NREM sleep is a traveling wave that originates at a specific site in the brain and propagates across the scalp.
2) Waves most frequently originated in prefrontal-orbitofrontal regions and propagated in an anteroposterior direction.
3) The rate of occurrence of these waves increased progressively during NREM sleep, reaching almost once per second as sleep deepened.
1) The article proposes that the primary function of consciousness is to integrate competing demands from specialized systems in the nervous system that influence skeletal muscle plans.
2) These "supramodular systems" operate in parallel to control actions like breathing, pain response, elimination, but can only collectively influence action through consciousness.
3) During a "supramodular conflict", when different systems demand opposing skeletal muscle actions, consciousness is necessary to integrate the systems and determine the appropriate response.
This document appears to be a collection of 11 unfiled note pages with no other context or information provided. The pages are unlabeled and contain no discernible main topics, key details, or overall narrative to summarize.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against developing mental illness and improve symptoms for those who already suffer from conditions like anxiety and depression.
This document discusses fetal pain and the development of the human brain prior to birth. It summarizes that the human brain is more developed than once thought by around 2 months before birth, comparable to a newborn macaque. Neurons in the subplate zone of the fetal brain form functional networks and influence cortical development. While cortical neurons were once thought necessary for conscious pain perception, immaturity alone does not preclude fetal pain, as subcortical structures are also involved in consciousness.
This document examines the possibility of fetal pain based on anatomical and psychological evidence. It finds that:
1) The basic anatomy for pain processing, including free nerve endings and connections from the spinal cord to the thalamus, develop by 7 weeks gestation. However, the nervous system is still immature at this stage without laminar brain structures or cortical development.
2) More advanced connections from the thalamus to the cortex begin to form between 12-16 weeks, but these connections initially target the transient subplate zone and not the cortical plate.
3) For pain to be experienced, unique in utero neuroinhibitors that maintain unconsciousness must be overcome, and the psychological elements of experience
This document discusses anesthesia considerations for fetal surgery procedures. It describes how open fetal surgery requires general anesthesia but minimal invasive procedures can be done with local or regional anesthesia. Ex-utero intrapartum treatment procedures are open fetal surgeries but can be done with regional anesthesia if uterine relaxation can be achieved without volatile anesthetics using intravenous nitroglycerin. Both maternal and fetal factors must be considered during fetal anesthesia as the fetus is at risk from hypothermia, hypoperfusion and hypoxia during surgery due to its immature organ systems.
This bill seeks to ensure that women seeking abortions after 20 weeks of fertilization are informed about evidence that unborn children at this stage of development can experience pain during certain abortion procedures. The bill cites several findings regarding the capacity for unborn children to feel pain after 20 weeks of development, as well as existing laws and regulations that aim to protect animals and fetuses from unnecessary pain and discomfort. If passed, it would add a new title to the Public Health Service Act requiring abortion providers to inform women of the pain the unborn child could experience during the procedure.
1. Using clonal lineage tracing in the adult mouse dentate gyrus, the study found that neuronal precursors of glutamatergic granule neurons exhibit significant tangential migration along blood vessels, followed by limited radial migration.
2. Genetic birthdating and morphological/molecular analyses identified the neuroblast stage as the main developmental window when tangential migration occurs.
3. Observations of a dense plexus of capillaries associated specifically with neuroblasts provided insight into the role of blood vessels as a substrate for neuronal migration in the adult mammalian brain.
This document provides an overview of cerebellar development in mice. It discusses how signaling centers establish the cerebellar territory and define its boundaries. Two primary progenitor zones give rise to cerebellar cells - the ventricular zone and rhombic lip. The rhombic lip generates glutamatergic neurons, including granule neuron progenitors that form the external granule layer and drive cerebellar growth. The ventricular zone produces GABAergic neurons and interneurons. Finally, it notes that while mouse studies provide insights into human cerebellar development and disease, direct study of human fetal cerebella remains important due to species differences.
Akhtar and Breunig-2015-Frontiers in Cellular Neuroscience - Barriers to post...Aslam Akhtar, MS
This document summarizes barriers to postnatal neurogenesis in the cerebral cortex. It describes how the cortex develops prenatally through tightly regulated neurogenesis along radial glial scaffolds. After birth, radial glia are depleted and the "gliogenic switch" stops neurogenesis in favor of gliogenesis. As a result, the adult cortex has very little ability to replace neurons lost to injury or disease. Strategies to promote postnatal neurogenesis, such as interneuron transplantation and glial reprogramming, aim to circumvent the developmental barriers normally preventing regeneration in the adult brain.
This document summarizes recent research on the development of nociceptive (pain-sensing) circuits in infants. It discusses how:
1) Nociceptive neurons are specified early in development through molecular pathways involving tyrosine kinase receptors and neurotrophic factors.
2) Functional synapses and neural circuits in the dorsal horn develop over the first postnatal weeks through changes in excitatory and inhibitory synaptic transmission.
3) Sensory activity, both non-nociceptive and excessive nociceptive inputs, can influence the development of pain processing circuits in early life.
This document reviews various techniques that have been used to study neural crest cell migration, including:
1. Classic ablation experiments, which remove neural folds to observe structure development but have interpretive issues.
2. Explantation experiments, which culture neural crest cells but their potential varies depending on location.
3. Cell marking techniques like radioactive labeling but the label is diluted over generations.
4. The quail-chick chimera technique, which grafts quail neural tissue into chicks to track migration based on nuclear differences.
5. Cell lineage studies using fluorescent dyes to label and track single cells and their descendants.
6. Cell lineage studies using retroviruses to incorporate genetic markers into mouse
This document summarizes research on neural stem cells in the human subventricular zone (SVZ). It finds that the SVZ contains multipotent neural stem cells that can self-renew and generate neurons, astrocytes and oligodendrocytes. These stem cells express markers common to astrocytes. The human SVZ has a unique structure compared to other mammals, containing four layers lining the lateral ventricles. Trophic factors are found to strongly regulate the proliferation, differentiation and migration of neural stem cells in the SVZ.
An update of wallace´s zoogeographic regions of the worldCarlos Sáenz
This document reports on a study that mapped global zoogeographic regions by integrating data on the distributions and phylogenetic relationships of over 21,000 amphibian, bird, and mammal species. The study identified 20 distinct zoogeographic regions grouped into 11 larger realms. Key findings include:
1) Support was lacking for several regions previously defined based solely on distributional data.
2) Spatial turnover in phylogenetic composition was higher in the Southern Hemisphere than the Northern Hemisphere.
3) Incorporating phylogenetic information provided insight on historical relationships among regions and identified evolutionarily unique regions.
A Neurovascular Niche for Neurogenesis after Strokejohnohab
Stroke causes cell death but also birth and migration of new neurons within sites of ischemic damage. The cellular environment that induces neuronal regeneration and migration after stroke has not been defined. We have used a model of long-distance migration of newly born neurons from the subventricular zone to cortex after stroke to define the cellular cues that induce neuronal regeneration after CNS injury. Mitotic, genetic, and viral labeling and chemokine/growth factor gain- and loss-of-function studies show that stroke induces neurogenesis from a GFAP-expressing progenitor cell in the subventricular zone and migration of newly born neurons into a unique
neurovascular niche in peri-infarct cortex. Within this neurovascular niche, newly born, immature neurons closely associate with the remodeling vasculature. Neurogenesis and angiogenesis are causally linked through vascular production of stromal-derived factor 1 (SDF1) and angiopoietin 1 (Ang1). Furthermore, SDF1 and Ang1 promote post-stroke neuroblast migration and behavioral recovery. These experiments define a novel brain environment for neuronal regeneration after stroke and identify molecular mechanisms that are shared between angiogenesis and neurogenesis during functional recovery from brain injury.
This document summarizes the molecular mechanisms underlying neuromuscular junction (NMJ) formation. It discusses how agrin, Lrp4, and Musk signaling pathways induce acetylcholine receptor clustering at the post-synaptic membrane. Wnt signaling is also involved in pre-patterning of acetylcholine receptors before nerve terminal arrival. NMJ formation involves precise interactions between motor neurons, muscle fibers, and glial cells. Defects in these molecular pathways can lead to myasthenia gravis or congenital myasthenia syndrome.
1. The article discusses the development of pain responses from preterm infants through childhood.
2. It notes that while pain pathways are immature early in development, nociceptors and basic pain responses exist even in the youngest preterm infants.
3. The article reviews the maturation of peripheral and central pain pathways from fetal stages through early postnatal life, finding that pathways are functional but immature neonatally and continue developing into childhood.
The Louisville Twin Study followed nearly 500 twin pairs from infancy through adolescence to examine developmental synchronies in behavior. The study found that individual differences in intelligence stabilized by school age, with each child following a unique pattern of cognitive growth spurts and lags. Identical twins became increasingly similar in their development over time, more so than fraternal twins or siblings, showing the strong influence of genes. However, qualitative aspects of the home environment also significantly predicted children's IQ, indicating genes and environment both shape development. The results support a developmental model where genetic programs guide behavior in dynamic interaction with experiences over time.
The Role Of The Cytoskeleton During Neuronal PolarizationDalí Mb
This document summarizes recent advances in understanding the intracellular mechanisms underlying neuronal polarization, with a focus on the role of the cytoskeleton. It discusses how local actin instability in the future axonal growth cone allows microtubule protrusion and formation of multiple axons. Key regulators of this process include Rho-GTPases and their downstream targets, which influence actin dynamics. The Ena/VASP family of proteins also promotes neurite formation by antagonizing actin capping and facilitating bundling. Recent studies further reveal microtubule stabilization as another mechanism in neuronal polarization, complementing actin dynamics.
Cortical dysplasia is a malformation of cortical development caused by abnormal neuronal migration or organization during brain development. It can cause intractable epilepsy and neurodevelopmental disorders like autism. The lecture discusses normal brain development and corticogenesis. It then covers specific malformations including focal cortical dysplasia, describing their histopathology and clinical correlates. Recent research suggests focal disruptions of cortical layering found in children with autism may represent early cortical dysplasia, providing insight into a potential cause of autism.
Sleep slow oscillation as traveling wave massimini tononi jns2004Bernard Baars
1) The study used high-density EEG recordings in humans to show that each cycle of the slow oscillation during NREM sleep is a traveling wave that originates at a specific site in the brain and propagates across the scalp.
2) Waves most frequently originated in prefrontal-orbitofrontal regions and propagated in an anteroposterior direction.
3) The rate of occurrence of these waves increased progressively during NREM sleep, reaching almost once per second as sleep deepened.
1) The article proposes that the primary function of consciousness is to integrate competing demands from specialized systems in the nervous system that influence skeletal muscle plans.
2) These "supramodular systems" operate in parallel to control actions like breathing, pain response, elimination, but can only collectively influence action through consciousness.
3) During a "supramodular conflict", when different systems demand opposing skeletal muscle actions, consciousness is necessary to integrate the systems and determine the appropriate response.
This document appears to be a collection of 11 unfiled note pages with no other context or information provided. The pages are unlabeled and contain no discernible main topics, key details, or overall narrative to summarize.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against developing mental illness and improve symptoms for those who already suffer from conditions like anxiety and depression.
This document discusses fetal pain and the development of the human brain prior to birth. It summarizes that the human brain is more developed than once thought by around 2 months before birth, comparable to a newborn macaque. Neurons in the subplate zone of the fetal brain form functional networks and influence cortical development. While cortical neurons were once thought necessary for conscious pain perception, immaturity alone does not preclude fetal pain, as subcortical structures are also involved in consciousness.
This document examines the possibility of fetal pain based on anatomical and psychological evidence. It finds that:
1) The basic anatomy for pain processing, including free nerve endings and connections from the spinal cord to the thalamus, develop by 7 weeks gestation. However, the nervous system is still immature at this stage without laminar brain structures or cortical development.
2) More advanced connections from the thalamus to the cortex begin to form between 12-16 weeks, but these connections initially target the transient subplate zone and not the cortical plate.
3) For pain to be experienced, unique in utero neuroinhibitors that maintain unconsciousness must be overcome, and the psychological elements of experience
This document discusses anesthesia considerations for fetal surgery procedures. It describes how open fetal surgery requires general anesthesia but minimal invasive procedures can be done with local or regional anesthesia. Ex-utero intrapartum treatment procedures are open fetal surgeries but can be done with regional anesthesia if uterine relaxation can be achieved without volatile anesthetics using intravenous nitroglycerin. Both maternal and fetal factors must be considered during fetal anesthesia as the fetus is at risk from hypothermia, hypoperfusion and hypoxia during surgery due to its immature organ systems.
This bill seeks to ensure that women seeking abortions after 20 weeks of fertilization are informed about evidence that unborn children at this stage of development can experience pain during certain abortion procedures. The bill cites several findings regarding the capacity for unborn children to feel pain after 20 weeks of development, as well as existing laws and regulations that aim to protect animals and fetuses from unnecessary pain and discomfort. If passed, it would add a new title to the Public Health Service Act requiring abortion providers to inform women of the pain the unborn child could experience during the procedure.
1. Using clonal lineage tracing in the adult mouse dentate gyrus, the study found that neuronal precursors of glutamatergic granule neurons exhibit significant tangential migration along blood vessels, followed by limited radial migration.
2. Genetic birthdating and morphological/molecular analyses identified the neuroblast stage as the main developmental window when tangential migration occurs.
3. Observations of a dense plexus of capillaries associated specifically with neuroblasts provided insight into the role of blood vessels as a substrate for neuronal migration in the adult mammalian brain.
This document provides an overview of cerebellar development in mice. It discusses how signaling centers establish the cerebellar territory and define its boundaries. Two primary progenitor zones give rise to cerebellar cells - the ventricular zone and rhombic lip. The rhombic lip generates glutamatergic neurons, including granule neuron progenitors that form the external granule layer and drive cerebellar growth. The ventricular zone produces GABAergic neurons and interneurons. Finally, it notes that while mouse studies provide insights into human cerebellar development and disease, direct study of human fetal cerebella remains important due to species differences.
Akhtar and Breunig-2015-Frontiers in Cellular Neuroscience - Barriers to post...Aslam Akhtar, MS
This document summarizes barriers to postnatal neurogenesis in the cerebral cortex. It describes how the cortex develops prenatally through tightly regulated neurogenesis along radial glial scaffolds. After birth, radial glia are depleted and the "gliogenic switch" stops neurogenesis in favor of gliogenesis. As a result, the adult cortex has very little ability to replace neurons lost to injury or disease. Strategies to promote postnatal neurogenesis, such as interneuron transplantation and glial reprogramming, aim to circumvent the developmental barriers normally preventing regeneration in the adult brain.
This document summarizes recent research on the development of nociceptive (pain-sensing) circuits in infants. It discusses how:
1) Nociceptive neurons are specified early in development through molecular pathways involving tyrosine kinase receptors and neurotrophic factors.
2) Functional synapses and neural circuits in the dorsal horn develop over the first postnatal weeks through changes in excitatory and inhibitory synaptic transmission.
3) Sensory activity, both non-nociceptive and excessive nociceptive inputs, can influence the development of pain processing circuits in early life.
This document reviews various techniques that have been used to study neural crest cell migration, including:
1. Classic ablation experiments, which remove neural folds to observe structure development but have interpretive issues.
2. Explantation experiments, which culture neural crest cells but their potential varies depending on location.
3. Cell marking techniques like radioactive labeling but the label is diluted over generations.
4. The quail-chick chimera technique, which grafts quail neural tissue into chicks to track migration based on nuclear differences.
5. Cell lineage studies using fluorescent dyes to label and track single cells and their descendants.
6. Cell lineage studies using retroviruses to incorporate genetic markers into mouse
This document summarizes research on neural stem cells in the human subventricular zone (SVZ). It finds that the SVZ contains multipotent neural stem cells that can self-renew and generate neurons, astrocytes and oligodendrocytes. These stem cells express markers common to astrocytes. The human SVZ has a unique structure compared to other mammals, containing four layers lining the lateral ventricles. Trophic factors are found to strongly regulate the proliferation, differentiation and migration of neural stem cells in the SVZ.
This document summarizes a study examining the effects of delivering human umbilical cord blood cells to an animal model of stroke. The key findings are:
1) Delivery of CD34+ umbilical cord blood cells within 48 hours of inducing a stroke in mice led to functional recovery, increased cortical thickness, angiogenesis near the injury site, and some neurogenesis.
2) The cord blood cells may have stimulated angiogenesis and lifted suppression of neurogenesis, contributing to recovery, though their direct incorporation was limited.
3) While the study provides promising evidence that cord blood cells may enhance post-stroke recovery, further research is needed to fully understand the mechanisms involved and determine the precise role of neurogenesis
Adult Neurogenesis and it's Role in Alzheimer'sAbhishek Das
This document summarizes adult neurogenesis and its role in brain disorders such as Alzheimer's disease. It describes how new neurons are generated from neural stem cells in the subventricular zone and hippocampus of the adult brain. Alterations in neurogenesis are linked to neurological conditions like Alzheimer's, where neurofibrillary tangles and amyloid plaques accumulate and neurons die, affecting areas like the hippocampus early on. Efforts are underway to understand how neurogenesis contributes to disease and potentially harness neural stem cells to help repair symptoms.
Abhishek Das_20131056_BIO334_Adult Neurogenesis_RevisedAbhishek Das
This document summarizes adult neurogenesis and its role in brain disorders such as Alzheimer's disease. It describes how new neurons are generated from neural stem cells in the subventricular zone and hippocampus of the adult brain. Alterations in neurogenesis are linked to neurological conditions - decreased neurogenesis is associated with Alzheimer's disease, where neurofibrillary tangles and amyloid plaques accumulate and cause neuronal death. Efforts are being made to understand how neurogenesis contributes to disease and potentially harness neural stem cells to help repair symptoms.
1. The document discusses a lecture on human brain anatomy. It covers divisions of the nervous system including the central nervous system (CNS) which contains the brain and spinal cord, and the peripheral nervous system (PNS) which includes the somatic and autonomic nervous systems.
2. The lecture discusses different ways to divide up and understand the brain including gross morphology of lobes and gyri, microanatomy of cells and connections, and functional anatomy mapping brain regions to their functions.
3. Key areas discussed include the motor cortex, somatosensory cortex, primary visual, auditory and association cortices, limbic system structures, basal ganglia, thalamus and cerebellum.
Glial cells - Neurobiology and Clinical AspectsRahul Kumar
Glial cells outnumber neurons in the central nervous system and provide support and protection for neurons. There are several types of glial cells - astrocytes, oligodendrocytes, microglia, and ependymal cells. In disease states, glial cells can become reactive or activated and contribute to conditions like stroke, cerebral edema, Alzheimer's disease, neuropathic pain, epilepsy, and glioma. The document provides an overview of glial cell types, functions, pathophysiology, and their involvement in specific nervous system diseases and conditions.
Handbook of the cerebellum and cerebellar disordersSpringer
This document summarizes the cell types and molecular mechanisms involved in specifying neurons in the cerebellum and precerebellar systems. It describes:
1) The cerebellum contains GABAergic inhibitory neurons and glutamatergic excitatory neurons that are derived from two regions - the rhombic lip (RL) expressing Atoh1 produces glutamatergic neurons, while the ventricular zone (VZ) expressing Ptf1a produces GABAergic neurons.
2) Two precerebellar systems project to the cerebellum - the mossy fiber system from various brainstem nuclei and the climbing fiber system exclusively from the inferior olivary nucleus.
3) Recent studies have identified the transcription
FUBP1 is a tumor suppressor gene that encodes a protein which regulates the expression of the c-MYC gene by binding to its promoter region. As a transcriptional regulator, FUBP1 plays an important role in controlling cell proliferation. Mutations or deletions of the FUBP1 gene have been associated with several types of brain tumors, including oligodendrogliomas and astrocytomas.
The Collaborative Mind: Neuroplasticity and Cybernetic Social CognitionMicah Allen
“With the advent of multi-level findings demonstrating neuroplasticity in the adult brain, neuroscience is currently undergoing a decisive paradigm change. Although Ramón y Cajal, the father of the neuron doctrine, first speculated that synaptic neuroplasticity might be the fundamental mechanism of learning, neurogenesis has remained a controversial hypothesis. Recent multi-method research has overturned this dogma, finding dramatic plasticity at cellular, cognitive, developmental, and axonal levels. I review these findings, arguing that neuroplasticity challenges traditional understandings of the mind and cognition while presenting an upcoming fMRI project investigating social-media, cognitive augmentation, and neuroplasticity.”
Pten Deletion in Adult Neural Stem/Progenitor Cells Enhances Constitutive Neu...johnohab
Here we show that conditional deletion of Pten in a subpopulation of adult neural stem cells in the subependymal zone (SEZ) leads to persistently enhanced neural stem cell self-renewal without sign of exhaustion. These Pten null SEZ-born neural stem cells and progenies can follow the endogenous migration, differentiation, and integration pathways and contribute to constitutive neurogenesis in the olfactory bulb. As a result, Pten deleted animals have increased olfactory bulb mass and enhanced olfactory function. Pten null cells in the olfactory bulb can establish normal connections with peripheral olfactory epithelium and help olfactory bulb recovery from acute damage. Following a focal stroke, Pten null progenitors give rise to greater numbers of neuroblasts that migrate to peri-infarct cortex. However, in contrast to the olfactory bulb, no significant long-term survival and integration can be observed, indicating that additional factors are necessary for long-term survival of newly born neurons after stroke. These data suggest that manipulating PTEN-controlled signaling pathways may be a useful step in facilitating endogenous neural stem/progenitor expansion for the treatment of disorders or lesions in regions associated with constitutive neurogenesis.
Here are the key functions of the structures in abnormal psychology based on the information provided:
Amygdala: Responsible for how one perceives emotions like anger, fear, and sadness. Also controls emotions like aggression. Helps store memories of events and emotions.
Hypothalamus: Regulates basic bodily functions like hunger, thirst, sleep, temperature, and heart rate. Releases hormones that control these functions.
Thalamus: Sorts and distributes sensory data to different areas of the cortex. Sorts information as visual, tactile, auditory, or gustatory and sends it to the appropriate cortical region for processing. Sends visual information to the occipital lobe.
Neurons migrate long distances during development from glial-produced attractants or repellents. Migration occurs in three stages: leading edge extension, nuclear translocation through centrosome positioning and nuclear movement, and trailing process retraction. Defects in proteins involved in these processes, such as Lis1, doublecortin, and Reelin, can cause neuronal migration disorders and neurodevelopmental conditions like lissencephaly.
This document summarizes evidence that some synaptic contacts become "silent" during postnatal synapse elimination in muscle, retaining the ability to release acetylcholine. The authors investigated whether blocking certain molecular pathways could induce the functional recruitment of these silent synapses. They found that blocking muscarinic acetylcholine autoreceptors, calcium channels, or protein kinase C, or applying brain-derived neurotrophic factor, increased the number of functional inputs per neuromuscular junction. This suggests silent synapses may be recruited through these molecular mechanisms before being eliminated. The balance between trkB and muscarinic signaling pathways may regulate synaptic suppression during development.
The document discusses various regions of the brain, including the cerebrum, cerebellum, Broca's area, parietal lobe, somatosensory cortex, occipital lobe, and temporal lobe. It describes the functions of each region, such as the cerebrum having control over every organ, the cerebellum providing smooth body movement, Broca's area producing language, and the somatosensory cortex processing sensory input from the body. The document also examines neurological structures and concepts like pyramidal cells, inhibitory control, and disinhibition circuits in the brain.
Similar to Developmental reorganization of the human cerebral cortex (20)
The document discusses evidence related to whether a fetus can experience pain. It summarizes the development of anatomical structures and pathways involved in pain perception in a fetus from 8 weeks gestation onwards. It also discusses physiological evidence from preterm infants that suggests nociceptive pathways are functional from 24-26 weeks gestation. The document considers arguments that a fetus may experience pain in a primitive way without requiring consciousness, self-consciousness, or previous experience. It notes evidence that early painful experiences can have long-term effects on stress responses and sensitivity to pain.
An unborn child has the capacity to feel pain by 20 weeks gestation according to scientific evidence. By this point in development, the neural pathways, nerve tracts, thalamus, and cortex necessary to feel pain are all present. Studies show the unborn child responds to touch as early as 6 weeks and releases stress hormones when injected with a needle at 18 weeks, similar to the stress response in adults feeling pain. While abortion methods do not provide anesthesia to the unborn child, commercial livestock must be rendered insensible to pain before slaughter according to federal law.
This document discusses two approaches to understanding associative learning: the propositional approach and the dual-system approach. The propositional approach argues that associative learning results from controlled reasoning processes, while the dual-system approach argues it results from both controlled reasoning and the automatic formation of links between mental representations. The authors review evidence from past research and conclude that there is little support for the automatic link-formation mechanism proposed by the dual-system approach. Instead, they argue learning is better understood as resulting from propositional reasoning processes.
This document discusses the concept of fetal pain and whether a fetus is capable of perceiving pain. It explores definitions of pain, the anatomical and neurophysiological development of the fetal nervous system, and behavioral responses to stimuli. While connections from the spinal cord to the thalamus develop by 20 weeks, and thalamocortical connections are present from around 26 weeks, the document notes debate around whether these are necessary for pain perception. It concludes that while the very young fetus is likely incapable of feeling pain, the capacity for pain perception likely develops before full term birth.
The document reviews the development of the fetal pain system and debates whether a fetus can feel pain. It finds that:
1) While reflex reactions to noxious stimuli can occur very early in development, cortical processing required for the emotional experience of pain likely only emerges after 26 weeks of gestation with the development of thalamo-cortical connections.
2) Before the cortex is involved, noxious stimuli can still trigger stress responses that affect development.
3) Rather than speculate on fetal pain, the clinically relevant aim is to avoid noxious stimuli to prevent their potential adverse effects on development.
This document summarizes a research article about the mental capacities of newborn infants. It argues that while newborns appear helpless, research shows they have an integrated consciousness and can engage in synchronized interactions with caregivers. This suggests newborns have intersubjective minds, emotions, and motives for social engagement. The study of infant cognition required moving beyond theories of the mind as developing through experience and language alone, to recognize innate capacities for shared intentionality and cultural learning from birth.
This commentary agrees with Shanahan's view that language acquisition has an emotional basis. It provides a supplementary neuroscience perspective, arguing that:
1) Primary-process emotional systems in subcortical brain regions like the central amygdala generate affective intensity, not just secondary cognitive processes.
2) Social-emotional systems like separation distress, nurturance, play, and lust motivated the development of inter-subjective communication between mothers and infants, which may have promoted linguistic prosody.
3) Early affective communication through melodic "motherese" engages infants more than cognitive thought, and music is tightly linked to language in brain and development. Language may have evolved from our emotional nature through
The study recorded EEG signals simultaneously from the scalp and thalamus of 7 patients undergoing deep brain stimulation for essential tremor. The patients performed a go/no-go task where they had to either execute or withhold a cued finger movement based on subsequent go or no-go cues. Event-related potentials differentiated between go and no-go conditions earlier at thalamic recording sites compared to scalp sites, suggesting the thalamus is involved in early classification of go and no-go instructions. Correlations between thalamic and frontal scalp responses were stronger for no-go activities, indicating the thalamus provides information to frontal areas involved in inhibiting prepared actions. The findings support a role for the thalamus
The document discusses whether a fetus can feel pain and at what gestational age. It examines the anatomical, physiological, and behavioral evidence. While the fetus's experience of pain cannot be directly measured, the neural pathways for pain are developed by 20 weeks gestation. The fetus shows stress responses to invasive procedures from 16 weeks onward. Therefore, it is possible the fetus can feel pain from 20 weeks of gestation. More research is needed to fully understand fetal pain and how to provide appropriate analgesia during invasive prenatal procedures.
This randomized, double-blind study compared remifentanil and diazepam for fetal immobilization and maternal sedation during fetoscopic surgery. The study found that remifentanil produced better fetal immobilization with mild maternal respiratory depression, allowing for shorter surgeries, while diazepam resulted in greater maternal sedation but less fetal immobilization and longer surgeries. Remifentanil may thus be superior to diazepam for fetal immobilization during fetoscopic procedures.
The article discusses pain and stress responses in the human fetus. It notes that fetuses likely develop the physiological capacity to feel pain between 20-26 weeks gestation as the connections between the thalamus and cortex develop during this period. The article references evidence that fetuses as young as 18 weeks can experience rises in stress hormones in response to noxious stimuli like invasive medical procedures. While cortical involvement is thought necessary for a conscious pain experience, the fetus may experience pain prior to full cortical development due to subplate zone connections between 20-26 weeks gestation.
This summary provides the key details from the document in 3 sentences:
The document discusses an experimental drug that has shown promise in stopping the hepatitis C virus from replicating and reducing virus levels in test subjects by over 1000 times. It also mentions that surveys found some tanning bed users exhibited behaviors indicating addiction to tanning, and interventions are needed to address addiction and anxiety regarding skin cancer risks. Additionally, it briefly outlines the debate around a new Nebraska law restricting abortion claiming fetuses can feel pain at 20 weeks, which is contradicted by experts saying the structures and ability to feel pain do not exist until later in development.
This document discusses disagreements between Lisa Feldman Barrett's view of emotions and Jaak Panksepp's theory of basic emotions. Panksepp argues that Barrett does not adequately consider evidence from animal studies of how stimulating specific brain regions produces distinct emotional states. He believes multiple basic emotional systems exist in the brain beyond just positive and negative affect. Panksepp claims human brain imaging and physiology are not robust enough on their own to determine basic vs complex emotions. He advocates considering causal evidence from animal models to better understand the neural bases of human emotion.
More from South Dakota Pain Capable Unborn Child Protection Act (20)
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Communicating effectively and consistently with students can help them feel at ease during their learning experience and provide the instructor with a communication trail to track the course's progress. This workshop will take you through constructing an engaging course container to facilitate effective communication.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
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Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Developmental reorganization of the human cerebral cortex
1. Paediatr Croat 2007; 51 (Supl 1): 93-98 Pregled
Review
DEVELOPMENTAL REORGANIZATION OF THE HUMAN CEREBRAL CORTEX
IVICA KOSTOVIĆ1, ZDRAVKO PETANJEK1, 2
This paper reveals data on developmental reorganization of the human cortex. Three criteria were used to determine reorga-
nization: (1) presence of transient cellular zones: ventricular (VZ), subventricular (SVZ), intermediate (IZ) zone, subplate (SP),
cortical plate (CP) and marginal zone (MZ); (2) intensity of specific neurodevelopmental cellular events: proliferation, migration,
differentiation, growth of axon and synaptogenesis; (3) pattern of functional organization: (a) endogenous, transient circuitry and
(b) permanent, sensory driven circuitry. First half of gestation is characterized by proliferation and migration. During the second
half of gestation major axonal pathways grow through the intermediate zone and "wait" in the subplate. Initial synaptogenesis
begins during third month of gestation and is related to the endogenous, spontaneous circuitry. In early preterm thalamocortical
fibers relocate from the subplate (after 24th postconceptional weeks) and first evoked potentials may be recorded. The fundamental
pattern is coexistence of endogenous and permanent, sensory driven circuitry. In neonatal brain synaptogenesis is main neuroge-
netic event and there is gradual disappearance of transient endogenous circuitry and transient cellular zones. The review support
ideas of developmental "windows", selective vulnerability of specific transient cellular zones (subplate) and increased vulnerability
of the human fetal and neonatal brain.
Descriptors: PREMATURUS, KORTIKALNE VEZE, TALAMOKORTIKALNA VLAKNA, SINAPTOGENEZA, HISTOGENEZA
Acknowledgements: This work was ● presence of transient circuitry and ● Functional patterns in developing
supported by grants 108-1081870-1876 transient functions (1). brain might be (a) endogenous (spon-
(I.K.) and 108-1081870-1932 (Z.P.) from taneous), transient circuitry, mostly
the Croatian Ministry of Science, Educa- In this review we will discuss reor- characterized with oscillatory prop-
tion & Sport. ganization of developing brain based on erties and (b) sensory driven, perma-
these three basic patterns of organiza- nent circuitry (2, 3).
Introduction tion. Our focus will be on fetal, early pre-
term, late preterm and neonatal period. Transient patterns and their reorganization during
Fetal cortex differs from the neona-
In order to describe each of this periods prenatal and perinatal developmental "windows"
tal in three different aspects of organiza-
of development it is necessarily to define
tion:
transient zones, neurogenetic events and
Fetal period
● presence of transient cell zones in types of transient functional patterns.
which cellular events takes place; Fetal period is dominated by two
● Transient zones (Figure 1) in which
neurodevelopment events, proliferation
● intensity of specific neurodevelop- neurodevelopmental events take
and migration (4, 5). It is also a period
mental cellular events; places are ventricular zone (VZ),
when synaptogenesis begins and axonal
subventricular zone (SVZ), interme-
pathways (projections) establish. Prolif-
1
Department of Neuroscience diate zone (IZ), subplate (SP), cor-
Croatian Institute for Brain Research eration: Neurons are generated in ven-
tical plate (CP) and marginal zone
School of Medicine, University of Zagreb tricular and subventricular zone from
(MZ).
2
Department of Anatomy the neuronal stem cells by asymmetric
School of Medicine, University of Zagreb and symmetric divisions. The period of
● The neurodevelopmental cellular
Address: events which will be considered in proliferation of neurons is between 4th
Zdravko Petanjek, MD, PhD, Professor of this review are proliferation, migra- and 28th postconceptional week (Rakic
Anatomy & Neuroscience 2006, Cerebral Cortex). According to re-
Department of Neuroscience
tion and differentiation of neurons,
Croatian Institute for Brain Research axonal growth and synaptogenesis. cent evidence radial glia cells also serve
School of Medicine, University of Zagreb Myelinization and cell death will be as neural stem cell and might produce
10000 Zagreb, Šalata 12, Croatia not discussed in this review. pyramidal neurons (Rakic 2006). The
E-mail: zpetanjek@net.hr GABA-ergic (inhibitory interneurons) in
93
2. I. Kostović et al. Developmental reorganization... Paediatr Croat 2007; 51 (Supl 1): 93-98
Migration: Newly generated neu- Pattern of functional organization:
rons migrate along radial glia cells In the fetal cortex there is no sensory
through intermediate zone and form em- driven activity. However, synapse seems
bryonic column (4). The disturbances of to be very active (3). This type of oscilla-
proliferation and migration might result tory activity was described as spontane-
in so called migratory disorders, which ous activity (2, 3, 5, 17). Early thalamic
are frequently associated with epilepsy input to subplate might participate in this
and mental retardation. Transient lami- circuitry, as a transient input. Subplate
nar pattern: After 13 postconceptional neurons have also efferent projection to
week a new lamina develops below cor- thalamus and subcortical centers and
tical plate and became very soon thickest this presumably glutamatergic output
lamina of the telencephalon. This lamina might contribute to generation of fetal
is subplate zone which can be seen on general movements (18). In conclusion,
both Nissl preparations and magnetic early fetal circuitry is transient and it is
resonance images in vivo and in vitro (6, related to transient pattern of structural
7). Prominent subplate zone is the main organization. This concept is accepted
characteristic of fetal pattern of laminar by most modern neurophysiologist and it
organization. It is easy to distinguish the is in contrast with some classical opin-
following layers (from ventricle to pia): ions about reflex type generation of fetal
VZ, SVZ, IZ, SP, CP and MZ (Figure 1). motility.
The subplate zone is site of early syn-
aptogenesis, endogenous neural activity Early preterm period
and neuronal differentiation.
Figure 1 During early preterm period several
Transient laminar organization of the Growth of axonal pathways: The reorganizational events take place. This
telencephalic wall:
Cresyl violet (Nissl) staining of the earliest pathways which arrive in fe- period is characterized by development
telencephalic wall in the human fetus during tal cortex are monoaminergic afferents of primary gyri and sulci (19-21). Tran-
midgestation; transient zones in which from brain stem tegmentum and cholin- sient laminar organization: For the first
neurodevelopmental events take place are ergic afferents from the basal nucleus time there is initial lamination in corti-
ventricular zone (VZ), subventricular zone
(SVZ), intermediate zone (IZ), subplate (SP), of Maynert (8-10). Next afferents in se- cal plate, which coexists with extremely
cortical plate (CP) and marginal zone (MZ) quentional growth are massive pathways prominent subplate zone. This is a spe-
Slika 1. originating in thalamus. Thalamic fibers cial feature of preterm cortex and mix-
Prolazna laminarna organizacija stjenke originate not only from sensory tha- ture of fetal and permanent patterns (2,
telencefalona: lamic nuclei, but also from associative 14). Neurogenetic events: Intensity of
Krezil violet (Nisslovo) bojanje stjenke proliferation and migration during pre-
thalamic nuclei (2, 5, 11-13). This most
telencefalona u fetusa čovjeka tijekom srednje
trećine trudnoće: prolazni stanični slojevi koji massive input grows throughout subplate term period decreased significantly. Ven-
su mjesto specifičnih neurorazvojnih događaja zone during prolonged period of axonal tricular zone become thinner and neural
su: ventrikularni (VZ), subventrikularni pathfinding (14). At the end of fetal pe- stem cells gradually stop producing neu-
(SVZ), intermedijarni (IZ) sloj (zona), sloj rons and continue to produce glia cell
riod that is between 21-23 postconcep-
ispod ploče (subplate-SP), kortikalna ploča
(CP) i marginalni sloj (zona) (MZ) tional weeks, thalamocortical afferents lines (proolygodendrocites, astrocytes).
accumulate in the superficial part of the Migration decreases in intensity and late
subplate zone (5, 13). These fibers are de- born neurons only might be found to mi-
humans originate in the pallial (cortical)
scribed as "waiting" fibers. grate through intermediate zone.
ventricular zone, while in rodent brain
main source of GABA-ergic neurons is Synaptogenesis: Early synapses de- Axonal growth: The crucial event in
in another germinal structure called gan- velop above and below cortical plate. axonal growth is relocation of thalamic
glionic eminence. Several distinct fea- Below cortical plate is plexiform pre- afferents from subplate zone and their
tures distinguish human brain from other subplate layer and above cortical plate is ingrowth into cortical plate. That event
species, especially rodents (4). This is on marginal zone. This early fetal pattern of occurs almost simultaneously in primary
the first place increased number of mitot- synaptic distribution might be described and associative cortex (11-13). Parallel to
ic cycles (35 in human compared to 11 in as period of two synaptic strata (15, 16). the thalamo-cortical ingrowth there is
the rodents). Second, there is local gen- The early postsynaptic elements are pre- rapid areal differentiation (14, 22). Syn-
eration of the GABA-ergic interneurons plate and marginal zone neurons, as well aptogenesis: In the early preterm infant
(as stated above). Third, ganglionic emi- as branches of cortical plate neurons synapses are formed, for the first time,
nence which is the basal enlargement of which are distributed in marginal zone within deep part of the cortical plate (15,
the basal telencephalic ventricular zone and preplate (15). 16). This intracortical synaptogenesis is
generates also neurons for thalamus (4). related to development of thalamo-corti-
cal circuitry (12-14).
94
3. I. Kostović et al. Developmental reorganization... Paediatr Croat 2007; 51 (Supl 1): 93-98
Functional pattern of organization: still waiting in subplate, and majority as it was show by Burkhalter et al. (42).
Development of thalamocortical connec- of "permanent" axons are already in the Functional pattern: The main character-
tivity explains early evoked potential in cortical plate. istic of neonatal period is establishment
preterm infant (23-27). The early devel- of sensory driven activity. This is par-
opment of evoked potential in preterm Synaptogenesis and neuronal differ- ticularly important for development of
infant together with transient circuitry in entiation: Synaptogenesis is proceeding columnar organization in sensory corti-
subplate shows that there are interactions very fast in superficial part of cortical ces (3). Also, there is synchronization in
between endogenous circuitry of the sub- plate paralleled with accelerated devel- EEG and sleep pattern, transient general
plate zone, and thalamic sensory driven opment of dendrites pyramidal neurons movements still persist in the neonatal
circuitry (2, 3). Same thalamic terminals (35, 36). Functional pattern: Due to the period indicating immaturity of cortical
might activate cell in the cortical plate fast synaptogenesis in superficial cortex, and subcortical circuitry (18).
and form synapses in subplate. This co- cortical electrical dipole changes and
existence with transient endogens and surface negative response dominates in
electrical recordings. There is gradual Discussion
permanent driven circuitry might exist
in the human preterm for a prolonged disappearance of giant potentials and
In this review we have presented
time (2). This combined circuitry seems synchronization of EEG (23, 37).
evidence that fetal and preterm cortex
to be essential feature of the preterm in- shows transient pattern of organiza-
fant and underlie transient electrophysi- Neonatal period tion and permanent developmental re-
ological and behavioral phenomena (23, organization. These phenomena were
28-30). Establishment of thalamo-corti- During neonatal period fetal and also observed using different structural
cal connection with somatosensory cor- preterm patterns are reorganized dra- approaches and physiological record-
tex attracted recently a great attention matically. This reorganization from tran- ings (1, 4). Neurodevelopmental cellu-
among anesthesiologists, due to the fact sitional patterns to final organization is lar event occur with different intensity
that this pathway may represent anatom- crucial for understanding physiological throughout development. The periods of
ical substrate for pain input to cortex in and behavioral phenomena in neonatal increased cellular activity might also be
early preterm infants (7, 14, 16, 31, 32). period. Laminar organization: Neocor- described as developmental "windows".
The final prove that pain stimuli can tex develops into typical six layered pat- Throughout each developmental window
reach human cortex in early preterm in- tern. However, layer IV (granular layer) transient zones display characteristic
fants comes from study of M. Fitcgerald is still present in motor cortex (in adult structural and chemical properties. In
showing changes in cortical blood flow motor cortex is agranular) (14). Second, our review we have emphasized out that
detected by infrared monitoring after subplate zone is not different cytoarchi- transient zones are essential spatial pa-
pain peripheral stimuli (33). tectonic layer due to the full development rameters for cellular events (4, 6). Using
of white matter in cortical gyri. Howev- imaging techniques it is possible to visu-
er, subplate neurons remain as the inter- alize all transient cellular zones (7). Ex-
Late preterm face between layer VI and white matter. ception is marginal zone which is visible
Transient laminar pattern: In the In the associative cortex neurons of the in the hippocampal cortex only, while in
late preterm transient laminar pattern subplate might exist as a distinct popula- neocortical areas is beyond resolution of
gradually disappear and six layer Brod- tion as long as 6 months (38). Some of 1.5 T imaging.
mann grundtypus appeared (1, 14). De- the cells die by naturally occurring cell
velopmental events: There is no produc- death (4, 15). The demonstration of transient cel-
tion of neurons, except in hippocampal lular zones is important for in-vivo as-
Neurogenetic events: Two neuro- sessment of structural and functional
cellular formation and olfactory region. genetic events dominate early postna-
All neurons are in final position and mi- development and reorganization of the
tal development. First this is explosive human fetal and preterm brain (5). In ad-
gratory processes stopped. Radial glial development of synapses and second
cells which were main guides for radial dition, magnetic resonance imaging of
is the extensive production of postsyn- transient patterns of organization is im-
migratory neurons undergone transfor- aptic spines (39, 40). Axons: The major
mation in atrocities (4). Axonal growth: portant for contemporary diagnostic pro-
reorganization during neonatal period cedures (20, 21, 43-45). We believe that
Callosal fibers show overgrowth phe- is related to exuberant callosal axons.
nomena (exuberance) and the number of abnormalities of transient cellular zones
The newborn monkey shows three times might be objectively analyzed in differ-
axons in corpus callosum is higher then grater number of axons than adult mon-
in adult brain. The overgrowth of corpus ent genetic and epigenetic pathologies.
key (34). The same phenomena have The knowledge about reorganization of
callosum was proven by counting axons been described in the human brain (41).
on the midsagital sections (34). Within developing cortex is of great significance
However, the exact time of axon reduc- of our understanding of structural plas-
the hemisphere there are three major tion in man is not known, but is expected
patterns of callosal distribution. Some ticity and vulnerability of the human
to occur during early postnatal time (41). brain. For example, thalamocortical af-
axons are distributed within the white During neonatal period there is continua-
matter around ventricles, other axons are ferents are in "waiting" position in the
tion of short corticocortical fiber growth
95
4. I. Kostović et al. Developmental reorganization... Paediatr Croat 2007; 51 (Supl 1): 93-98
poxia-ischemia (44, 49). It was proposed growing axons and subplate zone, pos-
that subplate neural elements might be sibilities of neuroprotection and their vi-
partially involved in diffuse periven- sualization with modern magnetic reso-
tricular "lesion", so called DEHSI (5, 44, nance imaging techniques, is the most
48, 50). It was found using diffusion ten- challenging task in modern developmen-
sor imaging that DEHSI is the most fre- tal neurology. The role of transient neu-
quent finding in preterm infants (51-53). ronal circuitry and plasticity opens new
Searching for structural correlates and visitas for the treatment of the children
pathogenesis of this important MR find- with perinatal brain injury.
ing remains the most challenging task in
the contemporary perinatal medicine. LITERATURE
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Conclusion organization of the human prefrontal cortex
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sequentional analysis of transient cellu- transient and permanent circuitry elements in
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Figure 2 48: 388-93.
tional pattern. All cellular zones in the
Fiber "rerouting" after lesion:
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Sažetak
RAZVOJNA REORGANIZACIJA KORE MOZGA ČOVJEKA
I. Kostović, Z. Petanjek
U ovom preglednom članku osvrnuli smo se na razvojnu reorganizaciju ljudskog mozga. Tri kriterija korištena su u svrhu
određivanja reorganizacije: (1) prisutnost prolaznih staničnih slojeva: ventrikularni (VZ), subventrikularni (SVZ), intermedijarni
(IZ) sloj (zona), sloj ispod ploče (subplate-SP), kortikalna ploča (CP) i marginalni sloj (zona) (MZ); (2) intenzitet specifičnih neu-
rorazvojnih staničnih događaja: proliferacija, migracija, diferencijacija, izrastanje aksona i sinaptogeneza; (3) obrazac unutarnje
funkcionalne organizacije: (a) prolazni, endogeni neuralni krugovi, te (b) trajni, osjetno stimulirani neuralni krugovi. Prva polovi-
ca trudnoće obilježena je proliferacijom i migracijom. Tijekom druge polovice trudnoće glavni aksonski putovi urastaju kroz inter-
medijarni sloj i "čekaju" u sloju pod pločom. Prve sinapse vidljive su tijekom trećeg mjeseca trudnoće i povezane su s unutarnjim,
spontanim neuralnim krugovima. U ranog prematurusa (nakon 24. postkoncepcijskog tjedna) talamokortikalna vlakna premještaju
se iz sloja pod pločom i urastaju u kortikalnu ploču, te se mogu po prvi puta zapaziti evocirani potencijali. Osnovno obilježje je
istodobna prisutnost unutarnjih i trajnih, osjetno stimuliranih neuralnih krugova. U mozgu novorođenčeta sinaptogeneza je glavno
neurorazvojno događanje, a također dolazi i do postupnog nestanka prolaznih unutarnjih neuralnih krugova i prolaznih staničnih
slojeva. Ovaj pregledni rad podupire hipotezu o razvojnim "prozorima", selektivnoj vulnerabilnosti i specifičnim, prolaznim fetal-
nim slojevima (subplate), te povećanoj vulnerabilnosti mozga fetusa i novorođenčeta čovjeka.
Deskriptori: PRETERM INFANT, CEREBRAL PATHWAYS, THALAMOCORTICAL AFFERENTS, SYNAPTOGENESIS, HISTOGENESIS
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