Mental weightlifting

"Of course it works. Didn't you ever do pushups before heading out to the beach?" I was listening to a well-known cognitive neuroscientist and fMRI guru explaining the close relationship between neuronal activity and blood flow that is the basic of functional neuroimaging of the brain. He wasn't talking to me, I was helping to explain the technique but I didn't get his example right away, so I had to inquire, "um, what?" He explained that pushups caused more blood to flow to the muscles of your arms, beefing them up and enhancing one's physique in anticipation of attracting hotties on the beach.

"Oh, well ok, then." Unlike this particular quite famous cognitive neuroscientist, I don't think my physique was ever within any reasonable number of pushups from attracting any positive attention at the beach. It's still a memorable example, though, and it certainly works in brain imaging: neurons doing "pushups" (e.g., firing electrical potentials) draw additional blood to active areas and blood flow changes can be picked up in MRI scanners to track changes in neural activity.

But how far can we push the analogy? Can we build up and strengthen our neural functions by targeted programs of mental exercise? Practically, of course the answer is "yes." If we study chess, mathematics, music, or physical skills like sports we get better at them. That means we're learning and learning means there are physical changes in our brains reflecting this. But can we bulk up mentally?

If you accepted the idea that we don't grow new neurons as adults, you'd be inclined to say "no." You might even be tempted to make a disparaging remark about the thoroughly discredited 19th-century study of phrenology. Phrenology is a famous example of pseudo-science based on trying to assess mental abilities by measuring bumps on your head. The shred of scientific idea behind it was that your relatively more effective mental functions were bigger and this would show up as larger bulges in your skull. That turns out to be as silly as it sounds, but there's an important idea hiding in it, namely that cognitive functions in the brain are physically localized. That turns out to be true in many cases and was not well appreciated until much later.

It also turns out that we do grow new neurons in the brain. Rusty Gage and colleagues and subsequently many other neuroscientists have studied adult neurogenesis and found there is some addition of new neurons in the adult brain. And even better, it can be enhanced by rich environments with lots of mental stimulation. Most of that basic neuroscience is examined in animals, but Eleanor Maguire has reported some intriguing results about changes in the size of specific brain structures in London cabbies. That sounds odd, but London is a particularly difficult city to navigate within and Dr. Maguire has observed that cabbies with many years of experience appear to have relative increases in the size of a brain region associated with spatial memory. Don't chalk this one up as a vindication for phrenology, though, the region of the brain increasing in size is essentially in the part of the cortex furthest from the skull. You need an MRI to see it, not just looking for bumps on the skull.

There have been other reports of systematic differences in the size of specific brain regions like auditory cortex for musicians. Those results quickly lead one back to a nature/nuture style debate. Did the brain differences occur based largely on genes and lead those people to become musicians? Or did the differences in size occur due to extensive music practice?

An intriguing result along these lines was recently reported by Erickson and colleagues about learning rates in videogame play. Larger volume in the dorsal part of the striatum (a central and subcortical brain region) predicted faster learning of Space Fortress, a fairly simple video game. The nature/nurture question is intriguing here, too. Were the fast learners genetically advantaged by a larger part of the brain involved in learning this game? Or had they developed that part of the brain as a muscle by extensive prior experience with games?

Either account is very interesting (and they aren't mutually exclusive), but the brain-as-muscle possibility is particularly compelling. If we can strengthen the brain as a muscle, we have even more reason to believe in the "use it or lose it" hypothesis of mental activity being effective to hold off cognitive decline associated with aging. There's a decent accumulation of evidence that mentally active people age well, but it's also the case that aging well lets you stay mentally active.

Intervention studies have been fairly promising. A huge, multi-center study of more than 2k older adults found that providing just 10 hours of training in memory, attention or decision making produced gains and the gains lasted 5 years. On the downside, training in one area didn't help the other two abilities. Nor was there any evidence of slower overall decline, so "using it" may not generally prevent you from still "losing it." It might give you more to lose, so to speak, so you function better for longer.

So those "brain training" sites on the internet that offer to provide some mental weightlifting might actually be helpful. And you might not just have to work out like in a gym, another recent report by Chandramallika Basak (working with Arthur Kramer of Univ Illinois, who was also a contributor to the Erickson report above) found that "training" by playing Rise of Nations for 20 hours led to improvements in "executive control functions" like decision making, working memory and task switching in a group of older participants. Notably, those cognitive functions tend to be at least partly supported by the same region that was larger in the better Space Fortress learners.

So maybe you can grow your brain by mental weightlifting. And maybe you can even do mental weightlifting with video games. That'd be cool.

[Self-editing note: this essay doesn't have the cites or links to the background research, although they are all pretty easy to find on google scholar. Nor is it really written in a tight, accessible style you'd like to see in a media-oriented article on science. It seems natural to write in a semi-formal rambling style, but I wonder if it's useful.]