1. 1 Psychology 304: Brain and Behaviour Lecture 21

2. 2 Development of the Nervous System 1. What developmental changes are observed in the nervous system after birth? 2. How does early experience influence neuro- development? 3. Is the adult brain capable of change?

3. 3 By the end of today’s class, you should be able to: 1. discuss neurodevelopment in infancy through to adolescence. 2. define the term “sensitive period.” 3. generate examples to illustrate the impact of early experience on neurodevelopment. 4. review evidence of neuroplasticity in adulthood.

4. 4 Self-Test Complete the following list of the chronological stages of neurodevelopment. 1.Induction of the neural ____________. 2.Formation of the ____________ tube. 3.Cell ____________. 4.Cell ____________. 5.Growth of ____________. 6.Formation of ____________. 7.Neuron ____________ and synapse ____________.

5. 5 What developmental changes are observed in the nervous system after birth? With two exceptions, all of the neurons that will compose the adult human brain develop by the 7 th month of pregnancy. Nevertheless, the brain grows substantially after birth. Postnatal brain growth results from synaptogenesis, myelination of axons, and increased branching of dendrites.

6. 6 The rates of postnatal synaptogenesis and myelination vary across brain regions. Once maximum postnatal synaptic density is achieved, synaptic loss often occurs. The overproduction of synapses early in life is thought to underlie the greater plasticity of the child’s brain.

7. 7 The prefrontal cortex does not “mature” until late adolescence. The relatively late maturation of this brain region is thought to contribute to the impulsivity observed in early adolescence.

8. 8 The effects of experience on neurodevelopment are often time-dependent. How does early experience influence neurodevelopment? Sensitive period: A period during which an organism is highly responsive to environmental influences; a “window of opportunity” for experience to influence development.

9. 9 Research on the effects of experience on neurodevelopment has largely focused on the impact of sensory deprivation and enrichment. Examples:  Monocular and binocular deprivation in cats  Rats reared in enriched environments.  Children exposed to early music training.  Children with cataracts.

10. 10 Is the adult brain capable of change? Neuroplasticity was thought to be restricted to early development. However, recent research has demonstrated that mature brains are capable of substantial reorganization. Among the research findings that have demonstrated the neuroplasticity of the mature brain are:

11. 11 1. Neurogenesis in the adult brain  A number of studies have demonstrated that new neurons are constantly created in the olfactory bulb and hippocampus.  Exposure to enriched environments and regular exercise contribute to neurogenesis in the adult brain.

12. 12 Neurogenesis in the Adult Brain

13. 13 Development of the Nervous System 1. What developmental changes are observed in the nervous system after birth? 2. How does early experience influence neuro- development? 3. Is the adult brain capable of change?