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The Brain


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The Brain

  1. 1. THE BRAIN Prenatal, Infancy, Childhood, Adolescence, Early Adulthood Development
  2. 2. WHAT MAKES UP THE BRAIN <ul><li>Forebrain, Midbrain, Hindbrain </li></ul><ul><li>Cerebral cortex </li></ul><ul><ul><li>Prefrontal cortex </li></ul></ul><ul><li>Hemispheres </li></ul><ul><ul><li>Right Hemisphere/Left Hemisphere </li></ul></ul><ul><ul><li>Lateralization </li></ul></ul><ul><li>The Lobes </li></ul><ul><ul><li>Frontal, Parietal, Occipital, Temporal </li></ul></ul><ul><li>The Inner Brain (Limbic System) </li></ul>
  3. 3. WHAT MAKES UP THE BRAIN FOREBRAIN, MIDBRAIN, HINDBRAIN <ul><li>FOREBRAIN </li></ul><ul><ul><li>the largest and most highly developed part </li></ul></ul><ul><ul><ul><li>consists of the cerebrum & the structures beneath </li></ul></ul></ul><ul><li>MIDBRAIN </li></ul><ul><ul><li>uppermost part of the brainstem </li></ul></ul><ul><ul><ul><li>controls reflex actions, voluntary movements (eye movement) </li></ul></ul></ul><ul><li>HINDBRAIN </li></ul><ul><ul><li>upper part of the spinal cord </li></ul></ul><ul><ul><li>the cerebellum </li></ul></ul><ul><ul><ul><li>controls body’s vital functions (respiration & heart rate) </li></ul></ul></ul><ul><ul><ul><li>coordinates movement (hitting a tennis ball) </li></ul></ul></ul>
  5. 5. WHAT MAKES UP THE BRAIN CEREBRAL CORTEX <ul><li>Layer of tissue that covers the forebrain like a wrinkled cap </li></ul><ul><li>Two halves, or hemispheres </li></ul><ul><li>PREFRONTAL CORTEX </li></ul><ul><ul><li>higher-level thinking and self-regulation occur </li></ul></ul><ul><ul><li>most prolonged development of any brain region </li></ul></ul>
  6. 6. WHAT MAKES UP THE BRAIN HEMISPHERES <ul><li>Right Hemisphere </li></ul><ul><ul><li>specializes in humor and the use of metaphors, abstract reasoning skills, spatial reasoning, facial recognition, nonverbal memory </li></ul></ul><ul><li>Left Hemisphere </li></ul><ul><ul><li>specializes in speech and grammar, arithmetic, writing, complex motor functions, short-term verbal recall </li></ul></ul><ul><li>Lateralization </li></ul><ul><ul><li>specialization of function in one hemisphere of the cerebral cortex or the other </li></ul></ul><ul><ul><li>complex functions such as reading or performing music use both hemispheres </li></ul></ul>
  7. 7. WHAT MAKES UP THE BRAIN THE LOBES <ul><li>Frontal Lobe </li></ul><ul><ul><li>voluntary movement, thinking, personality, and intentionality </li></ul></ul><ul><li>Parietal Lobe </li></ul><ul><ul><li>registering spatial location, speech, language development, attention, sensation, and motor control </li></ul></ul><ul><li>Occipital Lobe </li></ul><ul><ul><li>vision </li></ul></ul><ul><li>Temporal Lobe </li></ul><ul><ul><li>hearing, language and memory processing </li></ul></ul>
  8. 8. WHAT MAKES UP THE BRAIN THE INNER BRAIN (LIMBIC SYSTEM) <ul><li>Hypothalamus </li></ul><ul><ul><li>internal alarm clock, controls adrenaline flow, other emotions(exhilaration/sadness) </li></ul></ul><ul><li>Thalamus </li></ul><ul><ul><li>controls information going to and from the spinal cord and the cerebrum </li></ul></ul><ul><li>Hippocampus </li></ul><ul><ul><li>sends memories out for long-term storage and retrieves them when necessary </li></ul></ul><ul><li>Amygdala </li></ul><ul><ul><li>controls emotion (anger/fear), arousal, hormonal secretions </li></ul></ul>
  9. 9. WHAT GOES ON INSIDE THE BRAIN? NEURONS <ul><li>Nerve cells </li></ul><ul><ul><li>runs on own programming that follows genetic code </li></ul></ul><ul><ul><li>handles information processing at the cellular level </li></ul></ul><ul><ul><li>sends electrical and chemical signals to communicate with each other </li></ul></ul>
  10. 10. WHAT GOES ON INSIDE THE BRAIN? DENDRITES & AXONS <ul><li>Dendrites - receive information from other neurons, muscles, or glands through the axon </li></ul><ul><li>Axons - transmit information away from the cell body </li></ul>
  11. 11. WHAT GOES ON INSIDE THE BRAIN? MYELINATION <ul><li>Myelination </li></ul><ul><ul><li>the process of encasing axons with fat cells </li></ul></ul><ul><ul><li>occurs prenatally through adolescence </li></ul></ul><ul><li>Myelin sheath </li></ul><ul><ul><li>covers most axons </li></ul></ul><ul><ul><li>speeds information transmission </li></ul></ul>
  12. 12. WHAT GOES ON INSIDE THE BRAIN? BUTTONS, NEUROTRANSMITTERS, SYNAPSES & RECEPTORS <ul><li>Terminal Buttons </li></ul><ul><ul><li>releases chemicals called neurotransmitters into synapses </li></ul></ul><ul><li>Neurotransmitters </li></ul><ul><ul><li>Chemicals (i.e. inhibitory neurotransmitters such as serotonin, dopamine) </li></ul></ul><ul><li>Synapses - tiny gaps between neurons’ fibers </li></ul><ul><ul><li>Synaptogenesis - the formation of synapses </li></ul></ul><ul><li>Receptors </li></ul><ul><ul><li>molecular structure that binds with substances </li></ul></ul>
  13. 14. WHAT GOES ON INSIDE THE BRAIN? “BLOOMING & PRUNING” <ul><li>connections that are used become strengthened and survive, while the unused ones are replaced by other pathways or disappear </li></ul>
  14. 15. BRAIN DEVELOPMENT EVOLUTION OF THE BRAIN <ul><li>Evolutionary psychology </li></ul><ul><ul><li>emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in shaping behavior </li></ul></ul><ul><li>Original assumption was that size of brain meant more intelligence – not true </li></ul><ul><li>More reasonable approach was to compare evolution of brain regions </li></ul><ul><ul><li>Cerebrum (learning, perception, motivation) </li></ul></ul><ul><ul><li>Brainstem (reflex activities) </li></ul></ul>
  15. 16. BRAIN DEVELOPMENT EVOLUTION OF THE BRAIN <ul><ul><li>Three important points: </li></ul></ul><ul><ul><ul><li>The brain has increased in size </li></ul></ul></ul><ul><ul><ul><li>Most of the increase in size has occurred in the cerebrum </li></ul></ul></ul><ul><ul><ul><li>There is an increase in the number of convolutions (folds in cerebral surface). Increases the volume of the cerebral cortex </li></ul></ul></ul><ul><li>An extended childhood period </li></ul><ul><ul><li>humans require time to develop a large brain and learn the complexity of human societies </li></ul></ul>
  16. 17. BRAIN DEVELOPMENT PRENATAL (CONCEPTION – 9 MONTHS) <ul><li>Neural Tube </li></ul><ul><ul><li>Neurulation – process of forming neural tube </li></ul></ul><ul><ul><li>Starts to form at 2-3 weeks </li></ul></ul><ul><ul><li>Closes at the top and bottom 24 days after conception </li></ul></ul><ul><ul><li>Top of tube will form the brain </li></ul></ul><ul><ul><li>Bottom of tube will form the spinal column </li></ul></ul><ul><ul><li>Neurons will travel from neural tube to the brain </li></ul></ul>
  17. 18. BRAIN DEVELOPMENT PRENATAL (CONCEPTION – 9 MONTHS) <ul><li>Neurogenesis (5 th week) </li></ul><ul><ul><li>the generation of new neurons </li></ul></ul><ul><ul><li>200-500,000 neurons are being generated every minute </li></ul></ul><ul><li>Neuronal migration (through 6 – 24 th week) </li></ul><ul><ul><li>neurons move to specific locations to await instructions </li></ul></ul><ul><ul><ul><li>Travel along glia fibers </li></ul></ul></ul><ul><ul><li>connections between neurons begin (23 rd week) </li></ul></ul><ul><ul><li>genes direct wiring patterns </li></ul></ul>
  18. 19. BRAIN DEVELOPMENT PRENATAL (CONCEPTION – 9 MONTHS) <ul><li>Neuronal migration </li></ul><ul><li>Neuron Traveling on glia fiber </li></ul><ul><li>Neuron Migration </li></ul><ul><li>Myelination </li></ul><ul><ul><li>Begins in spinal cord proceeds through subcortical regions (beneath the cortex) </li></ul></ul><ul><ul><li>Cortical regions myelinate at different times – moves from posterior regions to anterior regions </li></ul></ul><ul><ul><ul><li>Frontal & Parietal Lobes are completed last </li></ul></ul></ul>
  19. 21. BRAIN DEVELOPMENT INFANCY (BIRTH – 2 YEARS OLD) <ul><li>At Birth </li></ul><ul><li>Contains approximately 100 billion+ neurons </li></ul><ul><li>25% of its adult weight </li></ul><ul><ul><li>360 grams in females (approx. 12.7 oz.) </li></ul></ul><ul><ul><li>380 grams in males (approx. 13.4 oz.) </li></ul></ul><ul><li>Rapid growth begins in all areas </li></ul><ul><ul><li>Frontal lobes are immature </li></ul></ul><ul><ul><li>Occipital & Temporal Lobe progression </li></ul></ul><ul><ul><li>Sensory areas of Parietal Lobe mature </li></ul></ul>
  20. 22. BRAIN DEVELOPMENT INFANCY (BIRTH – 2 YEARS OLD) <ul><li>Birth – 1 year old </li></ul><ul><li>Weighs about 1000 grams at 1 year (approx. 2 lbs) </li></ul><ul><ul><li>970 grams in males </li></ul></ul><ul><ul><li>940 grams in females </li></ul></ul><ul><li>Prefrontal cortex develops massively between 7-12 months </li></ul><ul><li>Myelination – increase in brain’s weight </li></ul><ul><ul><li>3-6 months - visual pathways complete </li></ul></ul>
  21. 23. BRAIN DEVELOPMENT INFANCY (BIRTH – 2 YEARS OLD) <ul><li>Occipital Lobe (Vision) </li></ul><ul><li>NEWBORN </li></ul><ul><li>Occipital Lobe (Vision) </li></ul><ul><li>1 MONTH OLD </li></ul>
  22. 24. BRAIN DEVELOPMENT INFANCY (BIRTH – 2 YEARS OLD) <ul><li>Occipital Lobe (Vision) </li></ul><ul><li>2 MONTHS OLD </li></ul><ul><li>Occipital Lobe (Vision) </li></ul><ul><li>3 MONTHS OLD </li></ul>
  23. 25. BRAIN DEVELOPMENT INFANCY (BIRTH – 2 YEARS OLD) <ul><li>Occipital Lobe (Vision) </li></ul><ul><li>6 MONTHS OLD </li></ul>
  24. 26. BRAIN DEVELOPMENT INFANCY (BIRTH – 2 YEARS OLD) <ul><li>Temporal Lobe </li></ul><ul><ul><li>4 months: responds to every sound produced in all the languages </li></ul></ul><ul><ul><li>10 months: distinguish and produce the sounds of their own language </li></ul></ul><ul><ul><ul><li>no longer pays attention to the sounds of foreign languages </li></ul></ul></ul><ul><li>Lateralization </li></ul><ul><ul><li>Show greater electrical brain activity in the left hemisphere when listening to speech/sounds </li></ul></ul><ul><li>Amygdala - matures over the course of the first 8 months </li></ul><ul><li>Dendrite connections </li></ul><ul><ul><li>Experiences determine how connections are made </li></ul></ul><ul><ul><li>8 to 9 months: form specific memories from their experiences </li></ul></ul><ul><li>“ Blooming and Pruning” </li></ul><ul><ul><li>the more babies engage in physical activity or use language, more pathways will be strengthened </li></ul></ul><ul><li>2 years old </li></ul><ul><ul><li>75% of its adult weight </li></ul></ul><ul><ul><ul><li>1,120 grams in males (2.5 lbs) </li></ul></ul></ul><ul><ul><ul><li>1,040 grams in females (2.3 lbs) </li></ul></ul></ul>
  25. 27. BRAIN DEVELOPMENT EARLY CHILDHOOD (3 – 5 YEARS) <ul><li>Rapid, distinct spurts of growth (not as rapid as during infancy) </li></ul><ul><li>Continuous increases in dendrite connections and myelination </li></ul><ul><li>“ Blooming and Pruning” </li></ul><ul><ul><li>‘ Experience is the sculptor’ </li></ul></ul>
  26. 28. BRAIN DEVELOPMENT EARLY CHILDHOOD (3 – 5 YEARS) <ul><li>3 years old </li></ul><ul><ul><li>Brain is ¾ of adult size </li></ul></ul><ul><ul><li>Brain weight: </li></ul></ul><ul><ul><ul><li>1,270 grams in males (approx. 2.8 lbs) </li></ul></ul></ul><ul><ul><ul><li>1,090 grams in females (approx. 2.4 lbs) </li></ul></ul></ul><ul><li>4 years old </li></ul><ul><ul><li>Parietal Lobe - Hand-eye coordination myelination is complete (gross/fine motor skills) </li></ul></ul><ul><ul><li>Temporal Lobe - Auditory myelination is complete </li></ul></ul><ul><li>5 years old </li></ul><ul><ul><li>95% of its adult size </li></ul></ul><ul><ul><li>Occipital Lobe - Acuity reaches adult levels </li></ul></ul>
  28. 30. BRAIN DEVELOPMENT EARLY CHILDHOOD (3 – 5 YEARS) <ul><li>Effects of Neglect and/or Abuse </li></ul><ul><ul><li>the frontal lobe develops improperly when deprived of affection and positive emotional experiences </li></ul></ul><ul><ul><li>the lack of stimulation causes neurons in the brain to die off </li></ul></ul>
  29. 31. BRAIN DEVELOPMENT MIDDLE/LATE CHILDHOOD (6 – 11 YEARS) <ul><li>Brain volume stabilizes </li></ul><ul><li>Brain weight: Age 10 -11 </li></ul><ul><ul><li>1,440 grams in males (3.2 lbs) </li></ul></ul><ul><ul><li>1,260 grams in females (2.7 lbs) </li></ul></ul><ul><ul><ul><li>Age 6-7: maturation of occipital lobe </li></ul></ul></ul><ul><ul><ul><ul><ul><li>contrast sensitivity and peripheral vision reach adult levels </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Age 8: maturation of temporal lobe </li></ul></ul></ul><ul><li>  </li></ul><ul><li>Cerebral Cortex - thickens in the temporal and frontal lobe areas </li></ul><ul><ul><ul><li>improved language abilities such as reading </li></ul></ul></ul><ul><li>Prefrontal Cortex - pathways and circuitry increases </li></ul><ul><ul><ul><li>improved attention, reasoning, and cognitive control </li></ul></ul></ul><ul><li>“ Blooming & Pruning” </li></ul><ul><ul><li>some brain areas increase in use while others decrease </li></ul></ul><ul><ul><li>moves from broader areas to more focal, smaller areas </li></ul></ul>
  30. 32. BRAIN DEVELOPMENT ADOLESCENCE (12 – 19 YEARS) <ul><li>Brain undergoes structural changes </li></ul><ul><li>Age 12 - Parietal Lobe mature </li></ul><ul><li>Corpus callosum </li></ul><ul><ul><li>nerve fibers connect the brain’s left and right hemispheres </li></ul></ul><ul><ul><li>thickens, improves adolescents’ ability to process information </li></ul></ul><ul><li>Amygdala - matures earlier than the prefrontal cortex </li></ul><ul><li>Synapses – at adult density </li></ul><ul><li>18 – 25 years: Frontal Lobe/ Prefrontal cortex matures </li></ul>
  31. 33. BRAIN DEVELOPMENT EARLY ADULTHOOD (20 – 30 YEARS) <ul><li>Anatomically, physiologically, functionally mature </li></ul><ul><li>Brain weight: </li></ul><ul><ul><li>1,450 grams in males (3.2 lbs) </li></ul></ul><ul><ul><li>1,310 grams in females (2.9 lbs) </li></ul></ul><ul><li>Brain continues to develop connections throughout adulthood </li></ul><ul><li>Synapse formation is much slower than in childhood </li></ul><ul><ul><li>Synapses are formed based only on specific experiences in the adult's life </li></ul></ul>
  32. 34. BRAIN DEVELOPMENT MATURATION <ul><li>Brain Maturation (top) </li></ul><ul><li>Brain Maturation (side) </li></ul>
  33. 35. BRAIN DEVELOPMENT GENDER DIFFERENCES <ul><li>Areas involved in spatial memory mature about four years earlier in males than females </li></ul><ul><li>Areas involved in language and fine motor skills mature about six years early in females than in males </li></ul><ul><li>At birth, the average brain of males is between 12-20% larger than females </li></ul><ul><li>In adults, the average brain weight in men is about 11-12% more than the average brain weight in women </li></ul><ul><li>Space between cell bodies, which contains synapses, dendrites and axons, and allows for communication among neurons is more developed in women </li></ul><ul><li>An average male brain has approximately 4% more cells and 100 grams more brain tissue than an average female brain </li></ul><ul><li>Pre-optic Area of the Hypothalamus (sexually dimorphic nucleus) - involved in mating behavior - is 2.2 times larger in men than in women </li></ul><ul><li>Some research reports that the corpus callosum is bigger and more developed in women than in men. Some reports claim there is no difference </li></ul><ul><li>Broca and Wernicke areas - related to language, are larger in women </li></ul><ul><li>MALE BRAINS vs. FEMALE BRAINS </li></ul>