Use it or lose it...

is now use it and grow some more.

We used to think is that what you got (in the way of neurons or nerve cells) was all you'd ever have. In fact, during the process of brain development in early of life, not only do millions of neurons migrate but also many die in the process of forming mature circuitry. Recent research, however, confirms that the process of neurogenesis or production of new nerve cells is alive and well in fully formed adult brains. The more we stimulate neural pathways, the more we spur on new growth in areas critical to cognition and memory.

One of our best features as successful actors in a challenging world is our ability to adapt to and learn from new experiences. Known as neural plasticity, this process involves both the generation of new neurons as well as novel hook-ups between the new and old cells in order to generate pathways capable of change and new behavior.

Scientists at the Institute for Cell Engineering at Johns Hopkins University have identified one step on the road to new brain cell development (albeit in mice)(1). Through an epigenetic process(2), they observed that nerve cells stimulated by brain activity--say the little mice were put in new environments which set their little mousy brains awhirl (Hmm, new stuff to climb, new things to sniff and eat, a brand new exercise wheel...)-- produced growth factors, thus stimulating the production of new neurons in the activated region.

One study that illustrates how this principle works in people as well as rodents was done by German scientists working with students learning to juggle. They performed magnetic resonance imaging (MRI) scans on new jugglers three months into their studies and noted a 3% increase in brain matter in certain juggling-related areas of the brain. When the students quit their juggling lessons (perhaps out of frustration, or too much to do, or just persuaded by the researchers to watch TV instead of throwing balls around), those juggling-amplified gray matter regions shrank back to pre-juggling levels.

So carry on with those Thursday, Friday, and Saturday New York Times crossword puzzles, or acrostics, or your Saturday a.m. Spanish language lessons. All those sparks flying about your aging brain are generating new cells and new circuitry even in your later years.
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1)Dengke, KM et al. Neuronal Activity-Induced Gadd45b Promotes Epigenetic DNA Demethylation and Adult Neurogenesis. Science Feb. 20, 2009, Vol 323 pp 1074-1077.

2)Epigenetics refers to changes in gene expression without change in underlying DNA. In this study, electrical activation of mature neurons induced a gene called Gadd45b to produce growth factors which trickled out into the immediately surrounding brain tissue causing local generation of new neurons.

Another example of epigenetics is the misguided series of events that occurs due to overeating of the wrong sort of food coupled with undermoving in a couch potato sort of way resulting in the metabolic syndrome and ultimately diabetes.