Human development concepts and applications

Diamond

Marian Diamond addressed the nature vs. nurture issue so long debated by researchers and scientists by actually observing the effects of living in different environments on young rats. The beginnings of her research with Donald Head occurred in the 1960's, a time when the brain was not viewed as plastic. When presenting the results of their early research demonstrating a small but significant thicker cerebral cortex in rats raised in enriched environments vs. rats raised in impoverished environments she was actually told, "Young lady, that brain cannot change" (Diamond and Hobson, 1998-page 8). Nonetheless, Diamond believed the neurological basis that the environment provided for brain enrichment is the spreading of dendritic spines in the neuron as a result of environmental stimulation (Diamond and Hobson, 1998-page 25). In fact, research from her lab along with other researchers found that even honey bees' brains responded to environmental stimulation. Based on the work of Richard Coss it has been shown that bees making a single trip out of the hive had significantly different dendritic brain changes than those bees who remained in the hive. Other research matching the dendritic patterns in the brains of jellyfish and mynah birds exposed to enriched or deprived environments have shown similar results (Diamond and Hobson, 1998-page 27). The obvious parallel here is that if the brains of lower species demonstrate this environmental response, why should not the brains of humans since the human brain is much more complex and humans display little species specific behaviors?

The specific component of change as a result of environmental stimulation (or lack of stimulation) occurs in the nerve cells of the brain, the neuron (Diamond and Hobson, 1998-page 26). Neurons communicated with one another via a chemical process (for the most part) by means of the release of neurotransmitters. Environmental stimulation leads to neuronal stimulation. Neurons, stimulated by the environment, send an electric impulse down their axons (the action potential) resulting in the release of neurotransmitters in the synaptic space (a small area between sending and receiving neurons). The neurotransmitters lock onto the dendrites of the receiving neuron and stimulate the same process in them, and so forth. The stimulation provided by this process of neural communication results in the growth of dendritic spines in every neuron involved in this process. The more stimulation the organism receives the more dendritic growth occurs. The greater the dendritic growth the more efficient the process and the thicker that area of the brain becomes. Thus, certain types of stimulation might affect more specific areas of the brain (e.g., visual stimulation would be expected to lead to massive effects in the occipital lobes). An enriched environment with many different inputs would be expected to stimulate multiple areas in parallel (Diamond and Hobson, 1998-page 29). Diamond discusses the effects of a controlled experiment on rats with three conditions of environmental enrichment. The results support the notion that more environmental stimulation (input) leads to thicker cerebral cortices while impoverished environmental result in the opposite affect (Diamond and Hobson, 1998-page 30).