Critical Period and Development

1. Critical Period and Development

2. Journal Entry #8: (p. 225-227)a) Critical Periods and Brain Development • What is a critical period? • What is imprinting? • In figure 7-27, why are the baby geese following the man? • What 2 characteristics of imprinting suggest that the brain makes a rapid, structural change during this time? • What changes in the brains of chicks during imprinting?

3. b) Abnormal Experience and Brain Development • Summarize Hebb’s study of the development of dogs in a restricted environment • How is the visual system impacted when an animal is raised in the dark? How does this relate to the structure of neurons? • What happens to infant monkeys raised without parental contact? • How does stress impact the developing brain?

4. c) Clinical Focus: Romanian Orphans • Developmentally, how do Romanian orphans differ from age- matched children? • Why did some orphans improve after being adopted whereas others didn’t? • What can we conclude from studies done on the Romanian orphans?

5. Journal Entry #8: (p. 225-227)Critical Periods and Brain Development • What is a critical period? • Developmental ‘window’ during which some event has a long-lasting influence on the brain; often referred to as a ‘sensitive period’ • What is imprinting? • Process that predisposes an animal to form an attachment to objects or animals • In figure 7-27, why are the baby geese following the man? • these goslings have imprinted on Lorenz, because he was the first person they saw after birth. This is an instance of imprinting gone wrong.

6. Figure 7.27Strength of imprinting

7. What 2 characteristics of imprinting suggest that the brain makes a rapid, structural change during this time? • rapid acquisition (learned fast) • permanent behavioral consequence • What changes in the brains of chicks during imprinting? • synapses in a region of the forebrain enlarge

8. b) Abnormal Experience and Brain Development • Summarize Hebb’s study of the development of dogs in a restricted environment • dogs raised in the dark with little stimulation showed: • no reaction to people or other dogs • lost their sensation of pain • performed poorly on intelligence test • How is the visual system impacted when an animal is raised in the dark? How does this relate to the structure of neurons? • The animals will be blind, even though their eyes still work. • Dendrites atrophy (shrink)

9. What happens to infant monkeys raised without parental contact? • they have grossly abnormal intellectual and social behaviors in adulthood. • How does stress impact the developing brain? • stress alters the expression of some genes related to serotonin reuptake, this in turn alters how the brain responds to stressful experiences later in life.

10. c) Clinical Focus: Romanian Orphans • Developmentally, how do Romanian orphans differ from age- matched children? • 2 standard deviations below for weight, height, head circumference • retarded motor and cognitive development • Why did some orphans improve after being adopted whereas others didn’t? • children adopted before 6 months did better • What can we conclude from studies done on the Romanian orphans? • the developing brain requires stimulation for normal development • severe deprivation results in a smaller than normal brain and associated behavioral abnormalities in cognitive and social skills.

11. Abnormal Experience and Brain Development • Early deprivation of sensory experience (e.g., being placed in dark) has the opposite effect of cognitively stimulating environments: atrophy of dendrites • Early deprivation of social experience (e.g., raised without maternal contact) has a profoundly negative effect on later intellectual and social behaviors