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. 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.
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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?
The principle is called neuroplasticity. A simple example is learning a musical passage. The formation of new memories involves physical changes in our neural circuitry. New studies are suggesting that repeated effort can accomplish a lot more.
So forget for now everything you may have read about “chemical imbalance.” If we are going to talk about any kind of imbalance, maybe we need to consider what happens when that 90-pound weakling of a hippocampus is forced to compete with a bulked-up amygdala. I’ve never had my brain scanned, but I am pretty sure what a picture of mine would look like.
Now imagine if you could direct your brain to physically restore balance, and, for good measure, enhance some of the gray matter in your cortical regions. Sound too good to be true? Read on …
Sara Lazar is a neuroscientist at Harvard. In a TEDx Talk delivered in 2011, she related how she took up yoga strictly as an exercise regimen. As a scientist, Dr Lazar admitted to rolling her eyes in response to her instructor’s New Age claims about yoga increasing compassion and opening up the heart and all the rest.
Funny thing, though: “After a couple of weeks, I started noticing some of these changes.” She observed that she was calmer and in better shape to handle difficult situations. Not only that, she felt more compassionate toward others. Curious, she discovered a substantial body of research linking yoga and meditation to reduced depression, anxiety, pain, and insomnia, plus enhanced ability to pay attention and improved quality of life.
She also pulled up a study that showed three months of juggling changed the parts of the brain responsible for detecting visual motion. What about mediation? she wondered.
In her first study, she recruited a group of people who practiced meditation for 30 to 40 minutes a day and compared their brain scans to a matched group of non-meditators. The results showed thicker cortical grey matter in the meditators. As we age, grey matter is expected to become thinner, but the older meditators’ brains were indistinguishable from those half their age.
A follow up study performed before-and-after scans on a group of non-meditators receiving an eight-week meditation course. You guessed it - massive increase in the hippocampus. There was also an increase in the temporal parietal junction, associated with, among other things, empathy and compassion. And, last but not least, a decrease in the amygdala. Not only that, the greater the reduction the subjects reported in their stress the smaller the amygdala.
The smaller amygdala finding paralleled in reverse findings of studies done on rodents. You can’t exactly teach rats and mice to meditate, but you can subject them to stress. Lo and behold - at the end of ten days, these on-edge critters had larger amygdalae. After being left alone for three weeks, the researchers found the rodents’ amygdalae remained large, and that they stayed stressed.
Back to the humans, Dr Lazar pointed out that nothing had changed in their environment. They still had their same stressful jobs. The economy still sucked. Yet their amygdalae got smaller and they reported less stress. As Dr Lazar concluded: “So the idea I would like to share with you today is that meditation can literally change your brain.”
Pause a second to contemplate the significance of Dr Lazar's findings. We have known for years about the benefits of meditation and yoga and related activities, but the assumption has always been that these effects were transient. You got your "feel good" boost, the equivalent of "runner's high," where endorphins kicked in, not to mention hormones such as PEA, oxytocin, and vassopressin, plus a release of dopamine to the brain's pleasure and reward centers. But a repeat dose always implied a repeat workout. The assumption was that, no matter how far along in our practice, our brains would always remain the same.
The discovery back in the late nineties that we could grow new brain cells and that exercise contributed to this growth and helped relieve depression lends support to Dr Lazar. Doing what is good for you, in effect, builds a better brain. Boggles the mind, doesn't it?
Neuroplasticity: Make it your mantra.
Brain science and recovery go hand-in-hand. For a lot of the same issues from a recovery angle, check out Meditation, Yoga, Breath.
First published as two blogs 2015, reworked into an article Jan 3, 2017.
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