Rich Experiences, Physical Activity
Create Healthy Brains

An Interview with Developmental Psychologist William Greenough

Abstract: Research indicates some early life stresses can have a profound impact, resulting in changes in brain function and behavior, and even differences in the ways some genes express their particular genetic code signature. At various times during early development, different neural systems appear to have an increased sensitivity to stress and can influence long-term social behavior in a number of ways. A stable, nurturing environment is an important element in normalizing the development of a child experiencing stress.

Council Member William Greenough, Ph.D. is a professor in the University of Illinois Urbana-Champaign departments of Psychology, Psychiatry, and Cell and Structural Biology, and a full-time faculty member in the Beckman Institute NeuroTech Group. His research interests include mechanisms of brain-behavioral development, neural mechanisms of learning and memory, and plasticity of non-neuronal cells and systems of the brain.

Your research indicates that connections in the brain change dramatically when a young subject learns something new. Please tell us more.

One thing we’ve found is that animals that grow up in a challenging, experience-filled environment learn better than animals that grow up in sterile, uninteresting cages. Animals raised in richer environments exhibit more complex behaviors and perform better at solving problems (such as finding their way through a maze more rapidly). Their brains also have more connections between neurons, more cells called glia that support the functioning of neurons and their connections, and a denser network of capillaries supplying blood to the brain. It’s clear that a stimulating environment produces a richer brain.

If you take animals that have been raised in bare cages until they were adolescents and put them in a richer environment, you still get some effects, but the effects are smaller. As the animals become older and older, the effects diminish more and more. In truly elderly rats, you see very small effects. They still benefit from being placed in a rich environment, but not nearly as much. The take-home message for humans is that there is still plasticity at later ages but the early environment is critically important to the optimal development of brain architecture.

Given that the effects are greater earlier in life, how important are the right experiences, at the right time, to the development of brain architecture in the young brain?

Experiences that are well-tuned to the child’s behavior and developmental stage and that provide information about the world the child is experiencing are much more valuable than non-interactive information such as images on a television screen that don’t relate at all to the child’s behavior. Quality and quantity of interaction are both important. Children who don’t receive meaningful interaction are likely to suffer developmentally. A particularly sad example is the situation in orphanages in Romania [see Perspectives: “Deprivation and Disruption”], for instance, where the ratio of caregivers to children doesn’t allow for meaningful interaction. Children who grow up in this kind of extremely deprived environment have developmental deficiencies that are difficult to reverse later on, even with very intensive efforts at intervention.

Is rich experience important after childhood, into adulthood, for sturdy brain architecture?

Some things, such as the extra capillaries and glial cells in animals that engage in physical exercise or explore enriched environments, seem to disappear fairly quickly if you take an animal out of the environment. Others, like connections between neurons, diminish very slowly. Results like these emphasize the importance of both a highly supportive earlier environment and continuing environmental stimulation to truly optimize brain development.

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