How Enriched Environments Benefit The Brain (page 4)

By — John Wiley & Sons, Inc.
Updated on Jan 12, 2011

Increased Neurogenesis and Growth Factors

Recent studies show that adult lab animals (and humans) generate new brain cells (neurogenesis) and that enrichment efforts can accelerate this process. In elderly mice exposed to an environmentally complex housing condition, the quantity of new brain cells generated was not 10, 20, or 50 percent higher, but a whopping 500 percent higher than for the nonenriched control group.41 As early as 1998, researcher Gerd Kempermann discovered that rats grew brand new brain cells every day. By use of an ingenious staining technique, involving a green fluorescent protein extracted from jellyfish, his team was able to identify and photograph newly dividing neurons. And in a later study, Kempermann, a Swede working with San Diegan Fred Gage at the Salk Institute in La Jolla, California, got permission to inject the same dye into the brains of elderly Swedish patients with inoperable cancer. When the patients eventually died from cancer in the following months, Kempermann and Gage were able to autopsy the brains and verify that humans can and do grow new brain cells.42 Additional groundbreaking research has shown not only that humans do grow new neurons but that the rate of growth can be increased by enrichment efforts.43

Growth factors are critical chemicals that regulate and support the growth and survival of brain cells and have been linked to increased rates of cognition.44 Research has shown an increase in gene expression for brain-derived neurotrophic factors in songbirds after exposure to an enriching environment, and an increase in an insulin-like growth factor was also found in enriched rats.45 These growth factors are linked to the proliferation, survival, and functionality of new neurons. Rats in enriching environments had significantly higher survival rates (85 percent) of new neurons compared with the control and other experimental conditions, in which rates ranged from 42 percent to 56 percent.46 What does all this lead to? It seems to be the daily positive environmental influences on the subject over the long haul that are critical for enrichment, not just the one-time burst of activity.

Figure 3.6 summarizes the current understanding about a key role for neurogenesis. The production of new neurons is partly genetic and partly modifiable by human experience. We not only can alter our behaviors to produce more new neurons (which are correlated with learning, mood, and memory) but can enhance their survival changes with behavioral modifications using enrichment protocols.

Recovery from Trauma and System Disorders

Many animal studies suggest that enrichment effects can influence recovery from genetic disorders, trauma, and brain impairments. Mice bred for slower learning (variety 129/SvJ) are known to do worse on maze tasks, and they have lower neuronal production than do their genetically bred typical counterparts.47 But they improved dramatically in an enhanced environment in two ways: neurogenesis and learning performance.48

In rodents with neonatal binge alcohol exposure, enrichment efforts improved learning dramatically.49 Early environmental neglect causes profound neural and behavioral effects. Animals reared in isolation show increased anxiety and poorer performance in learning and spatial memory tasks. But later enrichment efforts reverse some or all of the deficits induced by isolation rearing.50 In addition, environmental enrichment leads to a functional reversal of the effects of maternal separation through the development of neural compensation.51 The negative effects of a stressful social experience can affect us even at the micro level of our cells.

Recovery from Trauma and System Disorders

At Duke University, experimenters showed that an enriching environment could override even a genetic mutation in mice that caused obesity.52 One advantage of these types of animal studies is that a disability can be induced, and the animal can be placed in study to determine if an enhanced environment can help in rehabilitation. That's been done quite often. Humans suffer a variety of challenging brain insults. But the good news is that some of these problems have been induced and repaired with enrichment in mice models.

Enrichment benefits have been found when there's exposure to environmental lead, debilitating head injuries, alcoholism, stroke, and toxic exposure.53 Studies with contrasting environments show that those in an enriched condition have more protective strengths and recover faster from exposure to injury.54 These results are found in the enriched condition as compared with those in the standard or control condition. These studies collectively suggest that we may be able to facilitate learning-underperforming and special needs learners with an enrichment program.

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