Your brain on change

This post, by Mike Giangrasso of Tulane University, is part of an occasional series written by undergraduate neuroscience students. If you are an undergraduate interested in writing about neuroscience for the Dana blog, or a professor who might have interested students, please contact Andrew Kahn at for more information.

In the past two months, my younger sister has started college in the Appalachian mountains, my cousin (and close friend) has inaugurated his well-earned career as an English teacher at a small private school in upstate New York, and my grandmother, who has lived with my family for eight years, has moved south, to Maryland.

It has been a busy time for my family, and we have all seen a lot of change. “Too much change,” my cousin remarked in conversation, and I absently agreed with him. Of course I agreed with him—it is almost a cliché to say that to be human is to fear change. But the same could be said for any other species with a nervous system or something close to it; to be feline is to fear change just as to be cnidarian is to fear change. This distaste for change encourages organisms to seek stability, which often involves responding immediately and appropriately to environmental fluctuation.

This external fluctuation is the reason that many organisms have been endowed with innervation. At its most basic and generalized best, the nervous system of any organism exists to allow that organism to respond to changes in its environment on a time scale much smaller than that which is permitted by evolution. A sea anemone whose nerve net allows it to retract when stimulated is far better equipped to respond to a wide variety of threats than one relying solely on its evolved ability to sting, for example.

Why, then, are some organisms equipped with tremendously complex networks of highly specialized neurons, while others maintain comparatively simple nervous systems? The answer lies in the environment: a greater degree of environmental complexity tends to correlate with a greater degree of neural complexity—and this not only applies to species in general, but also to individuals. Rats maintained in a stimulating environment, for example, have been shown to develop brains with detectable structural differences, such as enlarged cortical neurons and a proliferation of dendrites, in response to their demanding environment. Conversely, when exposed to an impoverished environment, rats’ brains become observably smaller and less complex.

As humans, we are immersed in a socially augmented environment whose changes are much more rapid and considerably less transparent than those faced by rats – while a rat’s relationships with other rats may impact its wellbeing in small ways, social graces are not high on its priority list. But social approval or disapproval can open (or close) a human being’s doors to sex, comfort, safety, and shelter. And this critical social world can change dramatically at the speed of conversation, a variable which, it should be noted, is rapidly increasing with the advent of technologies such as text messaging and the Internet; a nerve net will not suffice!

The implications of our hyper-social environment are far-reaching. In The Mating Mind, evolutionary psychologist Geoffrey Miiller argues that our brains’ incredible capacity for such cultural phenomena as art and music developed as a result of sexual selection because of the reproductive advantages early artists experienced over their social rivals.

So the next time you find it difficult to keep up with life’s rapid pace, take heart: Change is responsible for all of the richness of life that a human brain affords. 

–Mike Giangrasso, Tulane University, Class of 2013

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