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.

Neural connections or pathways in the brain
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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.

On the left side of the screen is a neuron with many branches off of it, with nearly twice as many dendrites extending from the neuron cell body as the neuron on the right side of the screen. The environment and type of brain development that describes each neuron should be selected from the following four choices: thinner cortex with fewer neural connections; thicker cortex with more neural connections; enriched environment; and impoverished environment. This page contains a matching activity. Choose the description using TAB button. Then enter one of the following numbers to select the corresponding label.
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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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