This review discusses the development of fetal pain pathways and consciousness. It summarizes that:
1) The anatomical pathways necessary for nociception are in place by 24 weeks gestation, including connections from peripheral receptors to the spinal cord and thalamus.
2) The subplate zone, which is involved in pain processing, is well-developed between 22-26 weeks and can be influenced by external stimuli via thalamic pathways.
3) Physiological evidence shows somatosensory potentials can be elicited in the fetus from 24 weeks gestation, suggesting nociceptive pathways are functionally developed.
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 discusses brain development from infancy through adolescence. It notes that connections in the brain are strengthened through use and pruned away if not used. The brain grows rapidly in the first few years of life as connections are formed and then pruned away. Environmental influences shape brain development, with the earliest years seeing the most change as experiences bombard the developing brain. Brain growth continues through childhood and adolescence as different areas mature at different rates.
The document discusses neurodevelopmental disorders from a neonatal perspective. It covers several topics:
- Child and adolescent development is not linear, occurring in rapid periods interspersed with quiet periods, influenced by genes and environment.
- Several theorists are discussed that proposed stages of development, including Freud, Erikson, Piaget, and Bowlby/Ainsworth and their theories related to psychosexual, psychosocial, cognitive and attachment development.
- Proper neurodevelopmental follow-up of at-risk newborns is important to understand if intervention is needed, plan support, and inform public health programs. Development occurs across multiple interconnected domains.
There are multiple characteristics to examine during fetal brain growth and development. Cortical surface area and cerebral volume are closely correlated with gestational age. Grey matter and white matter volume increase dramatically during the last few weeks of the third trimester. At the cellular and molecular levels, diffused white matter is involved with mylelination, cytostructural support, and communication. Myelination is closely related to the quality of neuronal connectivity.
This document discusses brain development from early embryonic stages through childhood. It outlines major developmental events such as induction, segmentation, proliferation, migration, differentiation and organization. It describes disturbances that can occur during these stages, including primary and secondary malformations. Key neurodevelopmental disorders are also summarized.
The document discusses brain and nervous system development from the early stages of embryogenesis through childhood. It covers the formation of the neural tube and differentiation of the central nervous system into the brain and spinal cord. Key topics include neural cell formation and migration, myelination, and the importance of neural activity and connectivity for proper development. Factors that can disrupt development, such as genetic defects and fetal alcohol syndrome, are also outlined.
1) A study of fetal anatomy shows that by 20 weeks gestation, the brain structures necessary for consciousness (thalamus and related areas) are developed and accompanied by coordinated EEG rhythms, suggesting consciousness is possible by this point.
2) If a more stringent threshold of continuous EEG is required, consciousness would be possible by 30 weeks gestation.
3) If consciousness is possible beginning at 20-30 weeks gestation, it is also possible that fetuses could experience something like "pain" beginning at this point. The possibility of consciousness and pain would require appropriate anesthesia and analgesia for fetal surgery.
This document summarizes a report by the Royal College of Obstetricians and Gynaecologists on fetal awareness. The report was prompted by a review of the RCOG's 1997 report on fetal awareness by the UK House of Commons Science and Technology Committee. The new report completely rewrites the 1997 report to incorporate recent scientific literature and evidence presented to Parliament. It reviews neuroanatomical and physiological evidence in fetuses to determine at what points in development fetuses may experience pain and sensory perceptions.
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 discusses brain development from infancy through adolescence. It notes that connections in the brain are strengthened through use and pruned away if not used. The brain grows rapidly in the first few years of life as connections are formed and then pruned away. Environmental influences shape brain development, with the earliest years seeing the most change as experiences bombard the developing brain. Brain growth continues through childhood and adolescence as different areas mature at different rates.
The document discusses neurodevelopmental disorders from a neonatal perspective. It covers several topics:
- Child and adolescent development is not linear, occurring in rapid periods interspersed with quiet periods, influenced by genes and environment.
- Several theorists are discussed that proposed stages of development, including Freud, Erikson, Piaget, and Bowlby/Ainsworth and their theories related to psychosexual, psychosocial, cognitive and attachment development.
- Proper neurodevelopmental follow-up of at-risk newborns is important to understand if intervention is needed, plan support, and inform public health programs. Development occurs across multiple interconnected domains.
There are multiple characteristics to examine during fetal brain growth and development. Cortical surface area and cerebral volume are closely correlated with gestational age. Grey matter and white matter volume increase dramatically during the last few weeks of the third trimester. At the cellular and molecular levels, diffused white matter is involved with mylelination, cytostructural support, and communication. Myelination is closely related to the quality of neuronal connectivity.
This document discusses brain development from early embryonic stages through childhood. It outlines major developmental events such as induction, segmentation, proliferation, migration, differentiation and organization. It describes disturbances that can occur during these stages, including primary and secondary malformations. Key neurodevelopmental disorders are also summarized.
The document discusses brain and nervous system development from the early stages of embryogenesis through childhood. It covers the formation of the neural tube and differentiation of the central nervous system into the brain and spinal cord. Key topics include neural cell formation and migration, myelination, and the importance of neural activity and connectivity for proper development. Factors that can disrupt development, such as genetic defects and fetal alcohol syndrome, are also outlined.
1) A study of fetal anatomy shows that by 20 weeks gestation, the brain structures necessary for consciousness (thalamus and related areas) are developed and accompanied by coordinated EEG rhythms, suggesting consciousness is possible by this point.
2) If a more stringent threshold of continuous EEG is required, consciousness would be possible by 30 weeks gestation.
3) If consciousness is possible beginning at 20-30 weeks gestation, it is also possible that fetuses could experience something like "pain" beginning at this point. The possibility of consciousness and pain would require appropriate anesthesia and analgesia for fetal surgery.
This document summarizes a report by the Royal College of Obstetricians and Gynaecologists on fetal awareness. The report was prompted by a review of the RCOG's 1997 report on fetal awareness by the UK House of Commons Science and Technology Committee. The new report completely rewrites the 1997 report to incorporate recent scientific literature and evidence presented to Parliament. It reviews neuroanatomical and physiological evidence in fetuses to determine at what points in development fetuses may experience pain and sensory perceptions.
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.
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
This article discusses the presence of consciousness in children born with hydranencephaly, a rare condition where the cerebral hemispheres are absent or severely compromised. While it is widely believed that these children lack consciousness, the article reviews evidence that some hydranencephalic children exhibit behaviors indicating basic levels of consciousness, such as recognizing faces, responding preferentially to familiar people/stimuli, and learning associations. However, whether they experience reflective consciousness remains controversial. The article concludes the evidence for some level of consciousness in these children is more convincing than arguments against it.
This document discusses anesthesia considerations for fetal surgery. Fetal surgery presents unique challenges as two patients, the mother and fetus, must be anesthetized. Physiologically, pregnancy increases the mother's sensitivity to anesthetic agents and affects her respiratory, cardiovascular and gastrointestinal systems. The fetus depends on intact uteroplacental blood flow. Many anesthetic agents readily cross the placenta. Providing anesthesia requires integrating obstetric and pediatric practices while minimizing risk to both patients with little margin for error. Optimal anesthetic techniques for fetal surgery continue to be studied.
This document contains the testimony of Dr. Jean Wright before Congress regarding fetal pain. Some key points:
1) Dr. Wright discusses how medical practices have changed over the past 25 years based on new evidence showing premature infants feel pain. Procedures are now done with pain management to improve outcomes.
2) Observation of premature infants in NICUs provides clear evidence they experience pain from procedures like heel sticks. Hospitals now take many steps to minimize pain and stress.
3) While medical practices incorporating pain management advanced for premature infants, the same evidence was not applied to abortions until discussions around partial birth abortion in the mid-1990s.
4) As a doctor and mother, Dr.
1) The document discusses the development of the fetal pain pathway and whether the fetus can feel pain from invasive procedures.
2) It notes that the necessary neuroanatomical structures for pain perception, like intact thalamocortical connections, do not develop until 26 weeks of gestation.
3) While the fetus reacts to stimuli through stress responses, there is no evidence these reactions involve conscious awareness or feeling of pain. However, providing fetal analgesia can reduce the stress response caused by invasive procedures.
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.
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 document discusses evidence for fetal pain from an evolutionary perspective. It argues that since fish feel pain, and early fetal development resembles the fish stage, fetuses may experience pain from an early stage. Studies showing that fish exhibit wariness after painful stimuli and can remember pain provide support. Further evidence discussed includes fetal learning abilities before birth, functional brain and sensory development by 20 weeks, and lack of self-harm suggesting sensation and memory. While some research has questioned fetal pain capabilities, the overall document makes a case that fetuses may experience some levels of consciousness, sensation and pain beginning fairly early in development.
The document discusses the evolution of pain perception and evidence that fetal pain perception may develop earlier than previously thought. It notes that by the third month of development, the fetal nervous system is developed enough to experience pain, as evidenced by studies showing fish and other early evolutionary stages can feel pain. Additional studies on fetal learning and responses to stimuli in the womb provide evidence for a level of consciousness and pain perception before the third trimester. While some research disputes these findings, the document argues that the ability to perceive and avoid harm is necessary for survival and is thus an evolved trait present early in development.
The document discusses whether there is sufficient evidence to support the concept that a fetus can experience pain. It outlines key developments in fetal neurobiology and the anatomical pathways involved in pain processing. While certain pathways are intact by 7 weeks gestation, the brain is not fully developed and lacks key features, such as cortical lamination, until later in gestation. The document concludes that the neurological systems necessary for pain experience are not fully intact and functional until around 26 weeks gestation.
The document discusses the history and current state of research on fetal pain. It summarizes that in the 1970s, the prevailing view was that fetuses and newborns could not feel pain. However, research in the 1980s by the author and colleagues established the biological structures and functions necessary to feel pain were present from early in fetal development, including nociceptors, nerves, and brain structures like the thalamus processing pain signals. The document provides extensive evidence from various studies that fetuses show physiological and behavioral responses to painful stimuli from as early as 13 weeks gestation, indicating they are capable of experiencing pain.
The document discusses the history and current state of research on fetal pain. It describes how in the 1970s, the prevailing view was that fetuses and newborns could not feel pain. However, research beginning in the 1980s found that fetuses have fully developed pain receptor pathways by 8 weeks gestation. It provides extensive evidence that fetuses can feel pain, including the presence of pain-sensing structures, neurotransmitters, hormonal and physiological responses to painful stimuli, and efforts to reduce fetal pain through anesthesia. The document rebuts common arguments against fetal pain such as lack of cortex, myelination, communication or memory.
This document discusses whether a fetus can experience consciousness or pain. It explores the development of fetal neurology and the minimal requirements for consciousness. While fetuses develop stress responses to stimuli early in gestation, consciousness requires integrated processing and coordination between brain structures and rhythms. The fetal brain structures and electrical rhythms involved in consciousness in newborns are present in utero by the third trimester, suggesting fetuses could potentially experience a rudimentary form of consciousness late in development. However, more research is needed to fully understand fetal neurology and experience.
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
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 brain plasticity and development. It begins with a review of concepts from the previous class, including that neural stem cells can give rise to both neurons and glial cells. It then discusses mechanisms of cortical development from the inside out via neuronal migration. The document reviews findings from longitudinal MRI studies showing cortical thinning from childhood to adolescence reflects pruning of synapses and myelination. It also summarizes studies finding brain differences at 6 months in infants who later develop autism versus those who do not. Finally, it discusses forms of learning in newborns including classical and operant conditioning, and how sleep facilitates memory and brain development in infants.
Which of the following receptors is most likely to exhibit tonic adap.pdfarhamnighty
Which of the following receptors is most likely to exhibit tonic adaptation? olfactory
nociceptors thermoreceptors pacinian gustatory True or False - Otoliths can only detect
rotational acceleration, they cannot provide information about the relative position of the head in
space True False Which membrane is responsible for our ability to detect pitch due to its
structure of being narrow and stiff on one end and wide and flexible on the other? basilar
membrane tympanic membrane tutorial membrane vestibular membrane The Insane Clown
Posse Why do humans begin needing reading glasses around the age of 45? the zonular fibers
attached to the lens lose their elasticity and can no longer flatten the lens as needed cone cells
within the fovea begin dying off and cannot be replaced the lens becomes inflexible and can no
longer get as spherical as needed to focus on nearby objects the lens becomes cloudy and no
longer allows the proper amount of light through it parents just really want to embarrass their
kids when they are ordering food in a public restaurant A person born with a mutation which
prevented their body from making retinal would likely experience which of the following? they
would suffer from myopia and only be able to see objects that were very to them they would not
be able to transition from bright rooms to dark rooms as well as person with functional retinal
would be able to they would have enhanced night vision because their retina would be unable to
absorb excess light their photoreceptors would respond as if there were in constant bright light
their photoreceptors would respond as if they were in constant darkness
Solution
16. Tonic receptors adapt slowly to a stimulus and continue to produce action potentials over the
duration of the stimulus. In this way it conveys information about the duration of the stimulus.
In contrast, phasic receptors adapt rapidly to a stimulus. The response of the cell diminishes very
quickly and then stops. It does not provide information on the duration of the stimulus.
An example of a tonic receptor is pain receptor. Therefore option (b) nociceptors is most likely
to exhibit tonic adaptation. Once it gets stimulated, it sends a signal along the nerves to the brain
as long as the pain stimulus continues.
Odor, touch, temperature, taste all are examples of phasic receptors. Pacinian corpuscles are
sensitive to vibration and pressure and an example of phasic receptors.
17. The Vestibular system is the sensory system in mammals that provides the contribution to the
sense of balance and spatial orientation for the purpose of balance and coordinated movement.
The \"Otolithic organs\" in the human ear are the utricle and saccule.
The Otolith organs sense gravity and linear acceleration such as from due to initiation of
movement in a straight line. Persons or animals without otolith organs or defective otoliths have
poorer abilities to sense motion as well as orientation to gravity.
The Otolith membrane serves.
- The fetal period from 9 weeks of gestation until birth is the most eventful for growth and development. The fetus is not just a passive recipient of genes but actively responds to environmental cues.
- The germinal, embryonic, and fetal periods each involve major developmental milestones as organs form and the fetus grows. The brain and senses develop throughout pregnancy, allowing the fetus to learn, respond to stimuli, and be influenced by the intrauterine environment.
- Research increasingly shows the importance of the prenatal environment and suggests experiences in the womb can impact later health, behavior, learning, and potentially the intergenerational transmission of traits. Both nature and nurture play a role in fetal development.
- The fetal period from 9 weeks of gestation until birth is the most eventful for growth and development. The fetus is not just a passive recipient of genes but actively responds to environmental cues.
- The germinal, embryonic, and fetal periods each involve major developmental milestones as organs form and the fetus grows. The brain and senses develop throughout pregnancy, allowing the fetus to learn, respond to stimuli, and be influenced by the intrauterine environment.
- Research increasingly shows the importance of the prenatal environment and suggests experiences in the womb can impact later health, behavior, learning, and disease risk through effects on neurological and physiological development. Both nature and nurture shape fetal and child 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.
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
This article discusses the presence of consciousness in children born with hydranencephaly, a rare condition where the cerebral hemispheres are absent or severely compromised. While it is widely believed that these children lack consciousness, the article reviews evidence that some hydranencephalic children exhibit behaviors indicating basic levels of consciousness, such as recognizing faces, responding preferentially to familiar people/stimuli, and learning associations. However, whether they experience reflective consciousness remains controversial. The article concludes the evidence for some level of consciousness in these children is more convincing than arguments against it.
This document discusses anesthesia considerations for fetal surgery. Fetal surgery presents unique challenges as two patients, the mother and fetus, must be anesthetized. Physiologically, pregnancy increases the mother's sensitivity to anesthetic agents and affects her respiratory, cardiovascular and gastrointestinal systems. The fetus depends on intact uteroplacental blood flow. Many anesthetic agents readily cross the placenta. Providing anesthesia requires integrating obstetric and pediatric practices while minimizing risk to both patients with little margin for error. Optimal anesthetic techniques for fetal surgery continue to be studied.
This document contains the testimony of Dr. Jean Wright before Congress regarding fetal pain. Some key points:
1) Dr. Wright discusses how medical practices have changed over the past 25 years based on new evidence showing premature infants feel pain. Procedures are now done with pain management to improve outcomes.
2) Observation of premature infants in NICUs provides clear evidence they experience pain from procedures like heel sticks. Hospitals now take many steps to minimize pain and stress.
3) While medical practices incorporating pain management advanced for premature infants, the same evidence was not applied to abortions until discussions around partial birth abortion in the mid-1990s.
4) As a doctor and mother, Dr.
1) The document discusses the development of the fetal pain pathway and whether the fetus can feel pain from invasive procedures.
2) It notes that the necessary neuroanatomical structures for pain perception, like intact thalamocortical connections, do not develop until 26 weeks of gestation.
3) While the fetus reacts to stimuli through stress responses, there is no evidence these reactions involve conscious awareness or feeling of pain. However, providing fetal analgesia can reduce the stress response caused by invasive procedures.
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.
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 document discusses evidence for fetal pain from an evolutionary perspective. It argues that since fish feel pain, and early fetal development resembles the fish stage, fetuses may experience pain from an early stage. Studies showing that fish exhibit wariness after painful stimuli and can remember pain provide support. Further evidence discussed includes fetal learning abilities before birth, functional brain and sensory development by 20 weeks, and lack of self-harm suggesting sensation and memory. While some research has questioned fetal pain capabilities, the overall document makes a case that fetuses may experience some levels of consciousness, sensation and pain beginning fairly early in development.
The document discusses the evolution of pain perception and evidence that fetal pain perception may develop earlier than previously thought. It notes that by the third month of development, the fetal nervous system is developed enough to experience pain, as evidenced by studies showing fish and other early evolutionary stages can feel pain. Additional studies on fetal learning and responses to stimuli in the womb provide evidence for a level of consciousness and pain perception before the third trimester. While some research disputes these findings, the document argues that the ability to perceive and avoid harm is necessary for survival and is thus an evolved trait present early in development.
The document discusses whether there is sufficient evidence to support the concept that a fetus can experience pain. It outlines key developments in fetal neurobiology and the anatomical pathways involved in pain processing. While certain pathways are intact by 7 weeks gestation, the brain is not fully developed and lacks key features, such as cortical lamination, until later in gestation. The document concludes that the neurological systems necessary for pain experience are not fully intact and functional until around 26 weeks gestation.
The document discusses the history and current state of research on fetal pain. It summarizes that in the 1970s, the prevailing view was that fetuses and newborns could not feel pain. However, research in the 1980s by the author and colleagues established the biological structures and functions necessary to feel pain were present from early in fetal development, including nociceptors, nerves, and brain structures like the thalamus processing pain signals. The document provides extensive evidence from various studies that fetuses show physiological and behavioral responses to painful stimuli from as early as 13 weeks gestation, indicating they are capable of experiencing pain.
The document discusses the history and current state of research on fetal pain. It describes how in the 1970s, the prevailing view was that fetuses and newborns could not feel pain. However, research beginning in the 1980s found that fetuses have fully developed pain receptor pathways by 8 weeks gestation. It provides extensive evidence that fetuses can feel pain, including the presence of pain-sensing structures, neurotransmitters, hormonal and physiological responses to painful stimuli, and efforts to reduce fetal pain through anesthesia. The document rebuts common arguments against fetal pain such as lack of cortex, myelination, communication or memory.
This document discusses whether a fetus can experience consciousness or pain. It explores the development of fetal neurology and the minimal requirements for consciousness. While fetuses develop stress responses to stimuli early in gestation, consciousness requires integrated processing and coordination between brain structures and rhythms. The fetal brain structures and electrical rhythms involved in consciousness in newborns are present in utero by the third trimester, suggesting fetuses could potentially experience a rudimentary form of consciousness late in development. However, more research is needed to fully understand fetal neurology and experience.
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
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 brain plasticity and development. It begins with a review of concepts from the previous class, including that neural stem cells can give rise to both neurons and glial cells. It then discusses mechanisms of cortical development from the inside out via neuronal migration. The document reviews findings from longitudinal MRI studies showing cortical thinning from childhood to adolescence reflects pruning of synapses and myelination. It also summarizes studies finding brain differences at 6 months in infants who later develop autism versus those who do not. Finally, it discusses forms of learning in newborns including classical and operant conditioning, and how sleep facilitates memory and brain development in infants.
Which of the following receptors is most likely to exhibit tonic adap.pdfarhamnighty
Which of the following receptors is most likely to exhibit tonic adaptation? olfactory
nociceptors thermoreceptors pacinian gustatory True or False - Otoliths can only detect
rotational acceleration, they cannot provide information about the relative position of the head in
space True False Which membrane is responsible for our ability to detect pitch due to its
structure of being narrow and stiff on one end and wide and flexible on the other? basilar
membrane tympanic membrane tutorial membrane vestibular membrane The Insane Clown
Posse Why do humans begin needing reading glasses around the age of 45? the zonular fibers
attached to the lens lose their elasticity and can no longer flatten the lens as needed cone cells
within the fovea begin dying off and cannot be replaced the lens becomes inflexible and can no
longer get as spherical as needed to focus on nearby objects the lens becomes cloudy and no
longer allows the proper amount of light through it parents just really want to embarrass their
kids when they are ordering food in a public restaurant A person born with a mutation which
prevented their body from making retinal would likely experience which of the following? they
would suffer from myopia and only be able to see objects that were very to them they would not
be able to transition from bright rooms to dark rooms as well as person with functional retinal
would be able to they would have enhanced night vision because their retina would be unable to
absorb excess light their photoreceptors would respond as if there were in constant bright light
their photoreceptors would respond as if they were in constant darkness
Solution
16. Tonic receptors adapt slowly to a stimulus and continue to produce action potentials over the
duration of the stimulus. In this way it conveys information about the duration of the stimulus.
In contrast, phasic receptors adapt rapidly to a stimulus. The response of the cell diminishes very
quickly and then stops. It does not provide information on the duration of the stimulus.
An example of a tonic receptor is pain receptor. Therefore option (b) nociceptors is most likely
to exhibit tonic adaptation. Once it gets stimulated, it sends a signal along the nerves to the brain
as long as the pain stimulus continues.
Odor, touch, temperature, taste all are examples of phasic receptors. Pacinian corpuscles are
sensitive to vibration and pressure and an example of phasic receptors.
17. The Vestibular system is the sensory system in mammals that provides the contribution to the
sense of balance and spatial orientation for the purpose of balance and coordinated movement.
The \"Otolithic organs\" in the human ear are the utricle and saccule.
The Otolith organs sense gravity and linear acceleration such as from due to initiation of
movement in a straight line. Persons or animals without otolith organs or defective otoliths have
poorer abilities to sense motion as well as orientation to gravity.
The Otolith membrane serves.
- The fetal period from 9 weeks of gestation until birth is the most eventful for growth and development. The fetus is not just a passive recipient of genes but actively responds to environmental cues.
- The germinal, embryonic, and fetal periods each involve major developmental milestones as organs form and the fetus grows. The brain and senses develop throughout pregnancy, allowing the fetus to learn, respond to stimuli, and be influenced by the intrauterine environment.
- Research increasingly shows the importance of the prenatal environment and suggests experiences in the womb can impact later health, behavior, learning, and potentially the intergenerational transmission of traits. Both nature and nurture play a role in fetal development.
- The fetal period from 9 weeks of gestation until birth is the most eventful for growth and development. The fetus is not just a passive recipient of genes but actively responds to environmental cues.
- The germinal, embryonic, and fetal periods each involve major developmental milestones as organs form and the fetus grows. The brain and senses develop throughout pregnancy, allowing the fetus to learn, respond to stimuli, and be influenced by the intrauterine environment.
- Research increasingly shows the importance of the prenatal environment and suggests experiences in the womb can impact later health, behavior, learning, and disease risk through effects on neurological and physiological development. Both nature and nurture shape fetal and child development.
The document discusses evidence that fetal memory exists and what functions it may serve. It reviews studies showing that fetuses are capable of classical conditioning, habituation, and exposure learning, indicating they have a memory. Possible functions of fetal memory discussed include practice for skills after birth, recognition of and attachment to the mother to promote breastfeeding, and aids in language acquisition. While more research is still needed, the evidence suggests fetuses possess a rudimentary memory beginning in the third trimester that allows for basic learning and may serve important developmental functions.
The document summarizes evidence that unborn children can feel pain by 20 weeks after fertilization based on 11 points. It notes that by 8 weeks the unborn child reacts to touch, and after 20 weeks reacts to stimuli that would be painful for an adult such as recoiling. Application of painful stimuli is associated with stress hormone increases in the unborn child, indicating a stress response.
The document discusses fetal pain and the neural pathways involved in the experience of pain. It summarizes that while there is general agreement that the neural pathways necessary for pain are present by 24 weeks gestation, debates remain about the possibility of fetal pain before or after this point. Some argue fetal pain is possible earlier due to sub-cortical structures, while others argue it is not possible at any stage due to lack of development and sedation in the womb. The document also notes increasing interest in fetal pain from legislation and more invasive fetal surgeries and medical procedures.
The document summarizes key aspects of neuroplasticity in children. It discusses how the brain develops in an orderly sequence from neurogenesis to synaptogenesis. Critical periods of plasticity allow maximum effects of experiences. The Hebb rule and long term potentiation explain how neurons that fire together wire together through strengthening of synapses. Experience alters gene expression, neurotrophin release, and neurotransmitters to influence development. While plasticity is highest in early life, the brain remains plastic throughout life. Adaptive and impaired plasticity, as well as excessive plasticity that causes vulnerability, are types of plasticity in children.
Similar to Fetal pain implications for research and practice (20)
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.
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.
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.
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 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 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 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 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.
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1. British Journal of Obstetrics and Gynaecology
September 1999, Vol106, pp. 881-886
RE VIEW
Fetal pain: implications for research and practice
Pain is a subjective experience. The fetus cannot tell us sive and ascending process, with the cerebral cortex the
what it is feeling, and there is no objective method for last region to develop.
the direct measurement of pain. To address the question Connections from the periphery to the spinal cord are
of pain in the fetus, one must use indirect evidence from formed early, at about eight weeks; C fibres begin to
a variety of sources, and then make an informed guess. grow into the human fetal spinal cord at about 10
This approach is similar to that which we use with ani- weeks4. The substantia gelatinosa in the dorsal horn is
mals. We cannot ask animals how they feel, but infer the spinal cord region of interneurones which is thought
from a variety of indirect approaches including study of to play a major part in the modulation of noxious inputs;
their behaviour, anatomy, and physiology. by 30 weeks of gestation it has most features of the
adult4. The cerebral cortex starts to form at 10 weeks,
although at that stage it is isolated from the rest of the
Does the fetus feel pain? brain5. Cortical development involves the structural dif-
ferentiation and maturation of cortical neurones, fibres,
Consciousness
glia and blood vessels, and this starts only at about 17
To feel pain, or suffer discomfort, one needs to be con- weeks of gestation with layers VI and V, but continues
scious, to be aware. We do not know when, if at all, con- until long after birth. From 15 weeks, the cortex is
sciousness starts in the fetus. The biological basis of underlain by the subplate zone, a layer of neurones
consciousness is little understood although at least in below the cortex that is specific to the fetus. Synapses
adult humans, the evidence suggests that it is in some appear within the cortical plate from mid-gestation. The
way associated with electrical activity in the cerebral subplate zone expands considerably between 17 and 20
cortex. Crick' has suggested that one is conscious of weeks, while from about 17 weeks, there is a shifting
something when there is electrical activity in specific population of connections from the thalamus to this
large neural cortical networks, particularly in layers IV region6. Thalamic fibres penetrate the cortical plate
to VI of the cerebral cortex2. from 24 to 28 weeks'~~, at this stage the full anatom-
and
Greenfield has emphasised that one should not think ical pathways necessary for nociception are in place.
of consciousness as an all or none phenomenon, rather I. Kostovic, who has been involved in many of the
that it may come on like a dimmer switch. This concept fundamental human fetal neuroanatomical studiesG9,
of evolving consciousnesscould apply to the developing has written in a personal communication: Between 22
fetus, in whom experience is most unlikely to be the and 26 weeks of gestation the subplate zone contains an
same as that of an adult. Furthermore, the fetus may not abundant mixture of cholinergic, thalamo-cortical and
have the same physical basis for conscious experience corticocortical waiting neurones, and there are tran-
as the older human. Frogs, for example, do not have a sient fetal synaptic circuits between the subplate and
developed cerebral cortex, lacking layers IV to VI. If cortical plate neurones. It seems probable that extrinsic
they are conscious at all, their experience must be asso- influences (via the thalamocortical pathways at least)
ciated with activity in a less complex neuronal network, could change the activity of the neocortical alange at
possibly more analogous to the fetal subplate zone3. that stage, and possibly even earlier e.g. in a 20 week
fetus when thalamocortical and cholinergic afSerents
already have synapses with upper subplate neurones,
Anatomical evidence
and these neurones very probably send axons into the
The most important evidence is anatomical. For the cortical plate. At least from mid-gestation onwards it
fetus to feel pain, it is necessary for the requisite noci- seems that extrinsic influences (via thalamo-cortical
ceptive pathways to be developed. This involves neural pathways) can act through demonstrable synapses,
connections between peripheral receptors and the spinal which, ifphysiologically active, may be involved in the
cord, upward transmission via the spinal cord to the tha- modulation of the activity of thefetal neocortex.
lamus, and from there to the outer cerebral layers. The Assuming that activity in the cerebral cortex or sub-
development of the human nervous system is a progres- plate zone is necessary for consciousness, then for the
0 RCOG 1999 British Jounzal of Obstetrics and Gynaecology 881
2. 882 REVIEW
fetus to be conscious of an external experience, these sound, over the next few weeksi6. It can respond to
regions need to be connected with incoming nervous sound from 20 weeks and discriminate between differ-
activity. Most incoming pathways, including nocicep- ent tones from 28 weeks17.
tive ones, are routed through the thalamus and, as stated With the preterm baby, who now can be kept alive
above, penetrate the subplate zone from about 17 weeks. from 23 weeks, one can observe behavioural responses
However, the earliest cortical links with the external to various clinical interventions. Such babies show a
world are formed even earlier than this; these comprise distinct pattern of behaviour to painful stimuli, such as a
the catecholamine pathways of noradrenergic and heel prick. This includes a wide range of facial expres-
dopaminergic neurones, and do not pass through the tha- sions and behaviours, including screwing up the eyes,
lamus. These monoamine fibres start to invade the sub- opening the mouth, as well as clenching the hands and
plate zone at 13 weeks and reach the cortex at about 16 limb withdrawal, which an older baby would also show,
weeks6,'o.''.This puts an early limit on when it is likely if in paini8. Most nurses and mothers looking after
that the fetus might be aware of anything that is going preterm babies are convinced that they are both sentient
on in its body or elsewhere. and feel pain. This type of evidence is similar to that
The last pathways in the nociceptive system to be from animals. Most people believe that their cat feels
formed are the inhibitory descending serotonin neu- pain if someone treads on its tail.
rones, which can block the ascending pathways. These
do not form until after birth4,raising the possibility that
the fetus may actually be more sensitive to noxious Theoretical considerations
stimuli than the older child, and may explain why the
Does one need previous experience to feel pain?
newborn shows exaggerated behavioural responses to
sensory provocation4. It has been argued that the fetus cannot feel pain,
because pain is a complex phenomenon affected by
previous e x p e r i e n ~ e ' ~It ~is . generally agreed that
- ~
Physiological evidence
stimulation of a particular nociceptive pathway in the
There is some evidence for a primitive electroen- adult can be associated with various types of conscious
cephalogram from 19 to 20 weeks, and sustained elec- experience, even in the same individual. Such varia-
troencephalogram from 22 weeks; these have been tion may depend on previous experience, or on other
obtained from very preterm infantsy.'*. Electroen- simultaneous occurrences. It is well known, for exam-
cephalic patterns are clearly measurable in older ple, that a soldier wounded in battle often feels nothing
preterm babies and have been well characterised from at the time. It is also possible to sensitise the experi-
28 weeks to termg. Studies of evoked responses in ence: people who are depressed often feel more pain
preterm babies show that both visual and somatosensory than at other times. This complexity of the experience
potentials can be elicited from as early as 24 weeks and of pain in adults is not controversial. However, the fact
are well developed by 27 weeks". The fact that a primi- that the suffering associated with nociceptive stimula-
tive somatosensory potential can be evoked at 24 weeks tion in adults can be affected by activity in other parts
suggests that the nociceptive pathways from the periph- of the brain, does not prove that in a ndve being, such
ery to the cortex are functional from that timei4. The as the fetus, there can be no experience of pain. The
flexor reflex, a measure of nociceptive function in the fact that the sensation of pain can be affected by previ-
central nervous system, is also present in preterm infants ous experience, does not entail the conclusion that pre-
tested from 26 weeks4.This evidence thus suggests that vious experience is necessary to feel pain. Such an
the nociceptive system is functional from at least 24-26 argument would suggest that a newborn baby could not
weeks, but gives little information concerning earlier feel pain either. The view that to experience pain it is
gestations. necessary to have experienced pain previously is self
defeating: there could never be a first experience of
pain.
Behavioural responses
One has to be cautious about interpreting behavioural
Is self consciousness needed?
responses in terms of conscious experience, for some, at
least, could be purely reflex. It is well known that decor- It has also been suggested that consciousness implies
ticate experimental animals show a wide range of self consciousness, and as the fetus is not self conscious
behavioural responses to noxious stimuli. it cannot be conscious eithe9'. However, consciousness
The fetus starts to make movements in response to does not necessarily imply self consciousness in the
being touched from eight weeks15, and more complex adult sense. All that is needed for the fetus to feel pain, is
movements build up, as detected by real-time ultra- that it has a simple awareness of what is going on in
0 RCOG 1999 Br J Obstet Gynaecol 106,881-886
3. itself. It does not need the more complex understanding ovine, fetus is capable of an acute brain sparing
that it itself is different from the outside world. response.
What then is the use of measuring stress responses? In
considering stress responses in relation to the question
Stress responses of fetal pain, the ‘null hypothesis’ is of relevance: if
Recent research has concentrated on the stress responses there were no change in stress hormone level, it would
of the fetus to various interventions, just as neonatal be very unlikely that the fetus was experiencing pain.
research did in the previous It is important to Stress responses can also be used to give some sort of
clarify the relevance of this work to a discussion of pain. index, though imperfect, of the degree of trauma
Stress responses, defined as an activation of specific involved, and further determine the effect of analgesia
hormonal and neurotransmitter systems, do not provide or anaesthesia. Finally, high levels of stress hormones
a direct index of pain. Although stress hormones are may have long term consequences, as discussed
usually increased when a subject is experiencing pain, below”.
there are many other situations which are not painful, It was the demonstration of stress responses in the
such as exercise, which also can increase their levels. newborn during surgery, that precipitated the change in
Furthermore, production and release of stress hormones attitude in the medical and nursing care of newborn
such as cortisol can be mediated by the hypothalamus, infants. It must be emphasised, however, with both the
without involvement of the cortex or other higher brain fetus and the newborn, that a stress response in itself
regions involved in sentience. does not tell us directly what the baby is feeling.
There is now evidence that the human fetus can
mount substantial stress responsesz4.These have been
Long term implications
shown both by examining stress hormone levels in the
blood before and after invasive procedure^^^^*^ and by There is evidence to suggest that a single early painful
examining the redistribution of blood flow within the or stressful experience can have long term effects, and
fetus27.We have shown that after intrauterine transfu- sensitise the child to pain and stress later. A recent
sions carried out at the placental cord insertion, which is prospective study showed that male babies who had
not innervated, there is little or no change in any of these been circumcised at five days or less, four to six months
variables. However, after procedures through the intra- later cried more, and showed more often other forms of
hepatic vein, that involve piercing the fetal abdomen, pain behaviour in response to their vaccination jab, than
which is innervated, there are major changes. Cortisol, those who had not been circumcised”. It has also been
j3-endorphin and noradrenaline rise substantially after shown that repeated insults, such as heel lancing, may
blood transfusions, a slow procedure that takes at least induce a state of hypersenitivity in the response to
10 minutes. With shorter interventions, such as fetal pain32.Reynolds and F i t ~ g e r a l d ~ ~ shown in a rat
have
blood sampling without transfusion, cortisol and j3- model that in the neonatal period there can be long last-
endorphin remained constant after procedures at either ing sensory nerve sprouting at the site of a wound; this
site. There is, however, evidence of a more rapid could be one mechanism for long term hypersensitivity
increase in noradrenaline, with procedures that involve to pain.
piercing the fetal abdomen, from at least 18 weeks of Animal studies suggest that brief fetal or neonatal
gestation, although this response seems variablez6. stress can have long term effects. The developing ner-
With Doppler ultrasound, our group has also shown vous system appears to be at a very plastic stage and
that with invasive procedures there is a significant fall in vulnerable to insult. In rats born at a stage equivalent to
the pulsatility index in the middle cerebral artery, con- the late fetus in man early postnatal handling perma-
sistent with a redistribution of blood flow to the brain nently increases both the density of glucocorticoid
(‘brain sparing’). It has been found after procedures that receptors in the hippocampu~~~, the behavioural
and
involve piercing the fetal trunk, and occurs rapidly, as responses to stress throughout life. Handled rats
early as 70 s after the These include fetal secreted less corticosterone and showed a faster return
blood sampling, tissue and urine sampling, body cavity to basal levels in a stressful situation. Handling in the
aspirations, and insertion of feto-amniotic shunts. These first postpartum week had greater long term effects, than
responses have been found at all gestations studied from handling in the subsequent two weeks35.
as early as 16 weeks. It has been well established that Fuji et u Z . ~showed that exposure of pregnant rats to
~
this cerebral redistribution response occurs in the human hydrocortisone for only three days, affected the long
fetus during the chronic stress associated with intrauter- term development and behaviour of the offspring. A sin-
ine growth restriction and hypoxaemia, and in response gle dose of dexamethasone administered to the rhesus
to the acute stresses of haemorrhage or hypoxaemia in macaque was sufficient to damage fetal hippocampal
animal modelsz9.It thus appears that the human, like the formation, especially the CA3 region37.Prenatal stress
Q RCOG 1999 Br J Obstet Gynaecol 106,881-886
4. 884 REVIEW
of pregnant rhesus monkeys has also been shown to 20 and 24 weeks and only a very few after that. Late ter-
have long term effects on the offspring, especially aug- minations may cause pain to the fetus if they involve an
menting their hormonal and behavioural responses to invasive procedure, such as surgical dismemberment.
new stress or^^^.^^. This may, at least in part, be due to the Modification of the technique, such as preparatory
direct transfer of some maternal cortisol across the pla- occlusion of the umbilical cord, may be ap~ropriate~~.
centaN. Whether potassium-induced termination of pregnancy
Whether fetal experience of pain or the activation of at a viable gestation or the hypoxaemia caused by uter-
major stress responses, either in utero or at birth, has ine contractions in terminations induced by prosta-
any long term effects in humans is not known. These glandins cause pain or discomfort is hard to assess.
animal experiments suggest that it may be possible and
that this is an important area for future research.
Childbirth
The experience of the baby during birth is not usually
Clinical implications
considered. It is generally assumed that as birth is a nat-
The fetus is currently treated as though it feels nothing, ural phenomenon, undergone for thousands of years
and is given no analgesia or anaesthesia for potentially without pain relief, that it is painless for the baby. This
painful interventions.This is similar to the way in which may not be the case.
newborn babies used to be treated, until the major Noradrenaline levels in umbilical cord blood after
change of practice which arose out of the work of Ayns- spontaneous vaginal delivery are 10 to 20 times those
ley Green, Anand and colleague^^^*^^*^'. They compared before labouP, and several times higher than contem-
newborn infants undergoing cardiac surgery who poraneous maternal levels. Babies born by elective cae-
received deep anaesthesia with sufentanil with those sarean section have smaller rises in cortisol,
given a lighter regimen of halothane and morphine. The noradrenaline, met-enkephalin and P-endorphin than
sufentanil group, in whom the responses of cortisol and those born by vaginal delivery4749.Vaginal delivery
noradrenaline were reduced to the baseline, had a much seems advantageous for transitional respiratory adapta-
better post-operative outcome in terms of sepsis and tion at birth, and catecholamines are known to facilitate
mortality, than the latter, in whom the stress hormone resorption of pulmonary fluidSo. Thus a degree of stress
response was not reduced to the same extent4*.Now at birth assists the baby's adaptation to the external
such pain relief is routinely given to babies not just for world. The rise in stress hormones, however, can be
open surgery, but for more minor procedure^^^. How- considerably greater in assisted than in normal vaginal
ever, it is possible that opiate drugs may themselves deliveries". Elevation of fetal catecholamines in the
have long term adverse effects, and research is needed umbilical cord are associated with p02 and pH levels
to determine their risk-benefit ratio for different inter- suggestive of h y p ~ x i aIt ~ . likely that the mechanical
~ is
ventions, both in the fetus and in the neonate. effects of instrumental delivery may add to this stress,
and it may be that in the future obstetricians will con-
sider giving analgesia before, or immediately after, such
Znvasive procedures
deliveries.
There are several areas where it is appropriate to con-
sider pain relief or anaesthesia in the fetusu. Firstly,
Analgesia for the fetus
therapeutic interventions, such as shunt insertions or
blood transfusions which are carried out for the benefit Failure to provide adequate analgesia for preterm babies
of the fetus. Many of these procedures are carried out in is now considered substandard and unethical practice52.
the third trimester at gestational ages comparable to There have been similar calls for fetuses to be given
preterm infants, who would be given analgesia. Sec- analgesia during invasive procedure^^^*^^, even though
ondly, there are diagnostic sampling or aspiration proce- there is no current evidence that analgesia blunts noci-
dures in the fetus which are only of concern in this ceptive responses in utero, or how analgesia may be
context if the procedure transgresses the fetal body; this safely and effectively administered.
will not be the case with needle insertion of the placenta, The opioid agonists, such as fentanyl, are the drugs
amniotic fluid or umbilical cord. most widely used for sedation and analgesia in neona-
tology. Fentanyl has been given directly intravenously
to fetuses before open fetal surgery, without apparent
Termination of pregnancy
adverse effect, but also without any proof that it workP.
The majority of terminations of pregnancy are camed Direct administration requires intravenous injection to
out before 13 weeks of gestation, but 10% are per- the fetus, and this is known to have risks. These could be
formed between 13and 19 weeks, less than 1%between reduced but not abolished by direct fetal intramuscular
0 RCOG 1999 Br J Obstet Gynaecol 106,881486
5. REVIEW 885
administration, the stress of which is likely to be rela- available anatomical and physiological evidence. The
tively minor, but would prolong the procedure in order physical system for nociception is present and func-
to await absorption. Intra-amniotic injections of lipid tional by 26 weeks and it seems likely that the fetus is
soluble opiods results in sub-therapeutic levels in the capable of feeling pain from this stage. The first neu-
fetuss6. rones to link the cortex with the rest of the brain are
Intravenous administration of fentanyl in the mother monoamine pathways, and reach the cortex from about
is unsatisfactory since the rate of transfer across the pla- 16 weeks of gestation. Their activation could be associ-
centa is slow: 10 minutes after administration of 1 pgkg ated with unpleasant conscious experience, even if not
the average fetal:maternal ratio was 0.31”. Larger doses pain. Thalamic fibres first penetrate the subplate zone at
may cause respiratory depression in the mother. Intra- about 17 weeks of gestation, and the cortex at 20 weeks.
venous benzodiazepines cross freely into the fetal circu- These anatomical and physiological considerations are
lation, with fetomaternal equilibrium occurring within important, not only because of immediate suffering, but
5-10 minute^^^.^^. However, not only do they cause also because of possible long term adverse effects of this
sedation, they may also have adverse behavioural early experience. Research in these areas is urgently
effects if delivery soon follows, impairing fetal respon- required.
siveness. General anesthesia has significant risks in The eighteenth century philosopher, Jeremy Ben-
pregnancy. The potential benefits of analgesia in the tham, wrote of animals The question is not Can they rea-
fetus need to be balanced against the risk of additional son?, noc Can they talk?, but Can they suffer?. This
procedures, and the potential for adverse long term drug caused a change in attitude towards animals and their
effects.Administration of safe and effective analgesia to treatment that is continuing to day, such that in the UK,
the fetus, without adverse effects in the mother, is a con- even frogs and fishes are required by Act of Parliament
siderable challenge. to be protected by anaesthesia from possible suffering
due to invasive procedures. Why not human beings?
Medical versus scientific caution
Acknowledgements
There is clearly is not enough evidence to be certain if
and when the fetus starts to feel pain. By 26 weeks the The authors would like to thank Dr M. Marin-Padilla
full anatomical system for nociception has been formed, and Dr I. Kostovic for helpful information on fetal neu-
the electroencephalogramshows activity in the cerebral roanatomy. Our work in this area is funded by WellBe-
cortex, and the preterm baby of the same gestational ing, The Henry Smith Charity, and the Children
age, if delivered, shows a complex range of pain Nationwide Medical Research Fund.
behaviour. Some have concluded that it is not possible
for the fetus to be aware of events before 26 weeks of Vivette Glover, Reader & Nicholas M. Fisk, Professor
gestation20.60, not to feel pain until considerably later
and Division of Paediatrics, Obstetrics and Gynaecology,
than that6’. This seems unduly certain, given the avail- Imperial College School of Medicine, Queen
able evidence. Before 26 weeks, too little is known Charlotte’s and Chelsea Hospital, London
about the physical basis of consciousness in the fetus,
the function of the subplate zone, the function of tran- References
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