Neuroplasticity: Can We Direct Our Brains to Fix What's Broken?
One word: neuroplasticity. The term is brain science for hope. We begin with London taxi drivers "
In a famous experiment published in PNAS in 2000, Eleanor Maguire of the University of London performed brain scans on 16 London cabbies. The scans revealed that a particular region of the brain - the posterior hippocampus, which plays a major role in memory - was larger than that of the control subjects in the study. The growth was at the expense of the front part of the hippocampus. Senior cabbies had the most impressive memory muscles.
These results aligned with earlier studies performed on scrub jays and squirrels, who cache their food and dig it up later. Such a feat requires a prodigious memory, which means - you guessed it - a much larger than normal hippocampus.
London taxi drivers must memorize a tangle of 25,000 streets within a six-mile radius of Charing Cross Station. To obtain their license, they spend three to four years driving on mopeds and enduring a series of grueling exams. The success rate is only fifty percent.
In a follow-up study published in Current Biology in 2011, Dr Maguire took before-and-after brain scans of 79 aspiring cabbies and a control group over a four-year period. The results revealed that the posterior hippocampi in the successful trainees had grown over time while those of the unsuccessful candidates and control group had not.
Significantly, the hippocampus is one of two areas in the brain (the other being the olfactory bulb) with the capacity to grow new neurons (neurogenesis). This particular region of the brain has received considerable attention from those who research mood disorders, but we're jumping ahead.
Until the later part of the twentieth century, it was thought that we were stuck with the brains we were born with. Heaven help if yours came equipped with a faulty mood regulator - you were broken for life.
But then scientists started questioning why stroke victims, for instance, often recovered lost brain function over time. Could it be that the brain was engaged in its own rebuilding projects?
In a study published in 1984, Michael Merzenich of UCSF and colleagues amputated the third digit of an owl monkey's hand (yes, I know). Two months later, brain scans revealed that the monkey's brain had "remapped" itself - the area in the brain formerly occupied by the third digit had been taken over and merged by the areas corresponding to the second and fourth digits.
We now know the brain performs similar feats in responding to external stimuli and in learning new skills. This may involve the brain laying down new neural circuits or strengthening old ones.
In 2009, I heard Dr Merzenich speak at the International Conference on Schizophrenia, held in San Diego. ""Basically," he told his audience, "we create ourselves." He added that the brain is born stupid, then evolves and becomes "massively optimized to fit into your world."
Dr Merzenich is the brains behind Posit Science, which markets computer exercises under the name BrainHQ . According to the product's website:
Our programs harness the brain's inherent plasticity - its ongoing remodeling throughout life - and direct it in ways that enhance overall performance.
Brain HQ and its competitor Lumosity are aimed at the general public, but it doesn't take a brain scientist to see a clinical application. (See an earlier piece here.) Dr Merzenich was speaking at a session entitled, "Optimizing Cognitive Training Approaches in Schizophrenia." His fellow panelist, Sophia Vinogradov, also of UCSF, reported encouraging results on this particular population. "We are seeing enduring changes in the cognitive performance of patients six months later."
Hey, I might want some of that, too. If you're like me, your brain is entirely too efficient in reacting to your environment. Once stress kicks in, even routine thinking and social interactions pose enormous challenges. Brain scan studies reveal that we work our bipolar brains a lot harder simply trying to cope. (See this previous post.)
And we all know how that story plays out. We become overwhelmed. We flip out or shut down.
Recall those London cabbies with enlarged hippocampi. Well, it appears that in response to stress, the hippocampus shrinks. Meanwhile, the amygdala - which triggers fight-or-flight and has neural connections to the hippocampus - becomes over-active. Suppose, in the bipolar brain, our amygdala works entirely too well to begin with - too big, too muscular, too assertive - overwhelming the other regions of the brain.
So here is the million-dollar question: What if we could do for our amygdalae and our response to stress what London cabbies did for their hippocampi and capacity to memorize?
Of course, when I posed a version of this question - citing Merzenich's work and its application to schizophrenia - to a panel of experts two years later at The International Conference on Bipolar Disorders in Pittsburgh, no one knew what I was talking about.
Fortunately, four years later, attitudes are shifting to the point where it's safe to say that sometime soon we may be devoting a portion of our day to remapping our brains. There are no guarantees, but think about it: Our brains may not be as broken as we think. And maybe, instead of cursing our fate, we can start taking charge.
Let's end on that high note.
More to come "