1. Chapter Five-Module 1 Development of the Brain Chapter Fourteen-Module 1 Lateralization & Function

2. Development of the Brain- Growth and Differentiation of the Vertebrate Brain *Early Beginnings  CNS begins to form at two weeks gestation  Development of the neural tube (figure 5.2)  At birth, brain weighs 350g, at one year 1,000g (figure 5.3) *Growth and Development of Neurons  Proliferation-production of new cells  Migration-move toward final destination  Differentiation-form axons and dendrites  Myelination-addition of insulating sheath

3. Figure 5.2 Early development of the human central nervous system The brain and spinal cord begin as folding lips surrounding a fluid-filled canal. The stages shown occur at approximately age 2 to 3 weeks.

4. Figure 5.3 Human brain at five stages of development The brain already shows an adult structure at birth, although it continues to grow during the first year or so. Video

5. Development of the Brain- Neuronal Survival X Determinants of Neuron Survival *Must make correct connections *Must receive support from nerve growth factor  neurotrophins act in several ways –early in development cause cells to survive and grow –increase the branching of incoming axons –decrease pain and increase regrowth of damaged axons *apoptosis-programmed cell death that occurs when connections are not reinforced X Competition Among Axons as a General Principle *We produce redundant synapses *the most successful axons and combinations survive

6. Development of the Brain Pathfinding Axons X Pathfinding by Axons *Chemical Pathfinding by Axons  Example: Weiss and the grafted salamander leg *Specificity of Axon Connections  Example: Sperry and the rotated eye of newt (figure) *Chemical Gradients  cell surface molecule  chemical attractants (e.g. TOP DV )  Neurotrophins

7. Figure 5.7 Summary of Sperry’s experiment on nerve connections in newts After he cut the optic nerve and inverted the eye, the optic nerve axons grew back to their original targets, not to the targets corresponding to the eye’s current position.

8. Development of the Brain Fine-Tuning by Experience X Fine-Tuning by Experience *Genetic Instruction are “only approximate” *Effects of Experience on Dendritic Branching  Enriched environments increase dendritic branching (figure 5.10) & dendritic spine growth (5.11) thus a thicker cortex  What is an enriched human environment? Effects? *Generation of New Neurons  Can the adult brain generate new neurons?  Olfactory cells must…. Why?  stem cells in the interior of the brain  scientists have observed new cells in hippocampus and cerebral cortex in monkeys of ages.  Possible meaning of new neural development?

9. Development of the Brain Effects of Experience on Human Brain Structures X Example: music training on temporal lobe development *identifying “absolute pitch” and temporal cortex growth X Example: somatosensory cortex (post-central gyrus) in violin players *MEG: D5 dipole strength, age of first playing, and control groups (figure 5.13b) X Combinations of Chemical and Experiential Effects *not always a clear 2-stage process of chemical pathfinding and experiential strengthening  e.g., the identification by lateral geniculate cells of activating retinal neurons (spontaneous embryonic firing)

10. Development of the Brain The Vulnerable Developing Brain X Fetal Alcohol Syndrome *decreased alertness, hyperactivity, varying degrees of mental retardation, motor problems, heart defects, and facial abnormalities X Fetal Nicotine Exposure *low birthweight, SIDS, decreased intelligence, hyperactivity X Fetal Cocaine Exposure *decrease in IQ and language skills X Module 1 Conclusions

11. Chapter Fourteen- Module 1 Lateralization

12. Lateralization of Function X Some Definitions *Lateralization-Division of labor between the two hemispheres *Commissures-Cross-over points of information in the brain  Corpus Callosum  Anterior Commissure  Hippocampal Commissure

13. Figure 14.1 Two views of the corpus callosum The corpus callosum is a large set of axons conveying information between the two hemispheres. (a) A sagittal section through the human brain. (b) A dissection (viewed from above) in which gray matter has been removed to expose the corpus callosum.

14. Figure 14.4 The anterior commissure and hippocampal commissures These commissures allow for the exchange of information between the two hemispheres, as does the larger corpus callosum.

15. Visual Connections to the Hemispheres X Visual Field-what is visible at any moment *Right visual field-->left half of each retina-->left hemisphere *Left visual field-->right half of each retina-->right hemisphere X Cutting the Corpus Callosum *Sometimes done to treat severe epilepsy *Behavior is abnormal only when sensory stimuli are limited to one side of the body

16. Figure 14.2 Connections from the eyes to the human brain Route of visual input to the two hemispheres of the brain. Note that the left hemisphere is connected to the left half of each retina and thus gets visual input from the right half of the world; the opposite is true of the right hemisphere.

17. Split Hemispheres X Competition *Soon after surgery you may see competition between activities on the two sides of the body X Hemispheric Specialization *Left  Speech  Happiness  Detail-oriented *Right  Emotional content of speech  Recognizes emotions in others  Expresses fear and anger  Spatial Relationships  Music perception Animation