Chapter 14. Environment and the Brain

Learning Objectives

cortex

outermost layers on the surface of the brain, where most cognitive processing occurs

maturation

process of growth and development guided by an individual’s genetic plan

dendrites

the parts of a neuron specialized for receiving signals from other neurons; dendrites often resemble the branches of a tree

neuron

a single nerve cell, forming the basic unit of the nervous system

Environment and the Brain

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Learning Objectives:

Understand the role of environmental experience in brain development.

Describe the relevant evidence about brain development from experiments on rat environments.

Review

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1. Although brain development is guided by maturation based on genetic inheritance, early experiences also influence brain development.

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2. Early experience helps develop our brain's neural connections for processing information from our senses, for moving our body effectively, and for higher-level thinking and problem solving.

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There are two cages. The first cage contains a rat, food, and water. This cage represents an impoverished environment. The second cage has four rats, a ball, a running wheel, food, and water. This cage represents an enriched environment.

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3. One of the best examples of the impact of early experience on brain development comes from experiments by Mark Rosenzweig and his collaborators. They raised some young rats in a solitary, "impoverished" environment and other rats in a communal playground considered an "enriched" environment.

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Simple but humorous cartoon-type drawing representing a “smart” rat

4. When their brains were later analyzed, the rats raised in the enriched environment had developed a heavier and thicker brain cortex with extra dendrites, allowing more connections between neurons—presumably giving these rats a higher level of rat intelligence.

Practice: Simulating the Rosenzweig Experiment

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Practice: Simulating the Rosenzweig Experiment

How do early experiences leave their "marks" in the brain? To find out, we're going to simulate one of the famous experiments by Mark Rosenzweig and David Krech (Rosenzweig, 1984), using young rats from the same litter (so they have similar genetic traits).

Instructions: Select one rat to go into this individual cage. The rest will be placed in a different cage for comparison.

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Quiz 1

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Quiz 1

Drag each label to the area that best matches that information. When all the labels have been placed, select the CHECK ANSWER button.

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Perhaps you should go back to review brain responses to different environments.

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Thinner cortex, fewer neural connections

Thicker cortex, more neural connections

Enriched environment

Impoverished environment

Environment

Neurons

Brain development

Environment

Neurons

Brain development

Quiz 2

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Quiz 2

Select the best answer for the question below. Then, press the CHECK ANSWER button.

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Try to answer the question again.

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The rats raised in the enriched environment showed:

more aggressive behavior

more interconnections between brain cells

smaller, lighter brains

Conclusion

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