Neurogenesis

For a long time, we believed that the brain never makes new cells. Every organ in your body is constantly recycling, regenerating, and growing, except for neurons, which never divide for your entire life. Sounds pretty implausible, doesn't it? And yet it has been ingrained as a paradigm of neuroscience.

Luckily, some recent researchers have begun to see differently. The concept of neurogenesis-- making new neurons-- is gaining ground from a series of detailed experiments. This article delves into the details of how the paradigm is being shifted, chiefly by Professor Elizabeth Gould of Princeton.

Please persevere through the whole article, or you might get the wrong impression. The old paradigm is one of genetic determinism: You are stuck with the brain you are born with. The beginning of the article replaces this notion with equally oppressive environmental determinism.

First we learn that Gould discovered that neurogenesis actually does occur. Hallelujah! We aren't stuck with the brain we were born with. But hope is immediately dashed by environmental determinism:

Gould’s insight was that understanding how stress damages the brain could illuminate the general mechanisms — especially neurogenesis — by which the brain is affected by its environ-mental conditions. For the last several years, she and her post-doc, Mirescu, have been depriving newborn rats of their mother for either 15 minutes or three hours a day. For an infant rat, there is nothing more stressful.[...]

Gould and Mirescu’s disruption led to a dramatic decrease in neurogenesis in their rats’ adult brains. The temporary trauma of childhood lingered on as a permanent reduction in the number of new cells in the hippocampus. The rat might have forgotten its pain, but its brain never did.

So, if we are allowed to extrapolate from rats to humans, it could be concluded that a traumatic or deprived childhood cannot be recovered from. The brain has been permanently damaged.

But wait. That's not actually a statement Gould would agree with. Luckily she didn't stop after the rat experiments, but went on to uncover more of the truth.

Neurogenesis is an optimistic idea. Though Gould’s lab has thoroughly demonstrated the long-term consequences of deprivation and stress, the brain, like skin, can heal itself, as Gould is now beginning to document, finding hopeful antidotes to neurogenesis-inhibiting injuries. “My hunch is that a lot of these abnormalities [caused by stress] can be fixed in adulthood,” she says. “I think that there’s a lot of evidence for the resiliency of the brain.”

[...]

The mind is like a muscle: it swells with exercise. Gould’s and Kozorovitskiy’s work reminds us not only how easy it is to hurt a brain, but how little it takes for that brain to heal.

Yes.

The mind is incredibly plastic. It can change in dramatic ways that you yourself have a hand in shaping. We are self-organizing creatures in ways beyond what the conscious mind can comprehend. (Gould doesn't say this; I'm adding my own views here).

I noticed also that there is some irony in Gould's own lifestyle. She has proven that chronic stress increases the chances of debilitating mental states while decreasing creativity, and yet...

Four days after giving birth to her third child, Gould was back at work, lecturing to a room full of undergraduates. She has always worked long hours, and expects nothing less of her employees. (Saturdays in the Gould lab are indistinguishable from Mondays.)

Nope. No chronic stress there!

And now, off to create some more neurons...