Such a hot topic! And probably not going away anytime soon. Likewise in hotness is neurogenesis, the adult brain’s capacity to grow new brain cells, known as neurons. These two phenomena collide in a wonderful way to suggest that exercising is great for our brains and our memory!
Neurogenesis has been noted in several brain regions but of particular interest to me (and other behavioural neuroscientists) is that there is a hot bed of new neuron growth in the hippocampus, an area that of the brain that has a very important role in memory. Typically, things that increase neurogenesis tend to correlate with increased memory and those that decrease neurogenesis tends to have a negative effect on memory. There are a few exceptions to this, which I hope to discuss in an upcoming post on hyper-plastic brains, but for now, a simple way of noting the relationship between neurogenesis and memory is that increase equals increase and vice versa.
Yesterday, I went to a session by Dr. Henriette van Praag, a well-established neurogenesis researcher, who was presenting years of her work looking at the effects of exercise on neurogenesis. Generally, exercise increases both the rate of cell growth (i.e., proliferation) and the production of new neurons (neurogenesis). Furthermore, when mice are tested on a pattern-separation task (one of many tasks that require a functioning hippocampus and therefore memory), rats that exercised do better.
A human equivalent for such a pattern-separation task would be something like learning to remember where your gender’s washroom is compared to the other gender’s. It’s easy when one is in the south building and one is in the north building but it gets harder when they are right beside each other. Our ability to discriminate is tougher than just remember when they are farther apart. What van Praag showed was that when mice exercise, they are able to remember the difference between both scenarios quite easily, whereas the mice that did not exercise can’t do the more difficult task and that this effect was correlated with the amount of neurogenesis.
These tests may seem rather trivial to the non-neuroscientist but when these studies are considered along with several studies that show similar results across many different tasks, it becomes clear that exercise-induced neurogenesis is having a significant cognitive benefit, one that many of us could make use of. You may not need to science to realize this is true for you. While sitting around having a beer the other night with several of my neuroscience colleagues, we too claimed that going for a run inevitably promoted clear-mindedness and productivity in the work we did that followed our exercise.
But that’s not all that’s interesting about exercise and neurogenesis. In fact, much of what I have just said is fairly common knowledge to neurogenesis researchers and some exercise researchers. What was particularly interesting from what van Praag discussed had to do with the mechanisms by which exercise exerts it’s effects on the brain and behavior. What she had shown was that a factor important for muscle physiology and that contributes to physical endurance (AMP-activated protein kinase: AMPK), is also responsible for enhanced memory function. Van Praag and her colleagues hypothesized that signals from the muscles might be making their way to the brain to stimulate neurogenesis and the cognitive benefits. Indeed, they determined this to be the case by stimulating AMPK itself, rather than relying on exercise to do so. When they found that this worked, they applied the same paradigm to aged mice, as a way of seeing if they could increase neurogenesis and reduce cognitive decline normally associated with aging. Again, they were able to do just that and show that AMPK both increased neurogenesis and enhanced memory.
So, without a doubt exercise (and the physiological factors associated with it) is having a positive effect on our mind, body, and brain, and can continue to do so even as we age. Now, if that’s not enough, I also found out that our Canadian winters might place some of us at a particular advantage when it comes to getting an extra boost of neurogenesis when we exercise outside. I also spoke with Mark Maynard, Graduate Student at the University of Houston, at his poster earlier this week about an interesting set of studies he was doing in attempts to help boost the effects of exercising in space. The problem, according to NASA, is that Astronauts are forced to spend about 3 hours a day exercising in order to minimize muscle atrophy while living in space. Although some of us would appreciate having to exercise on the job, the problem is that it takes away from valuable time needed to spend doing science and technology stuff you can only do in space! So Mark was trying to fiddle with factors that could reduce the amount of time spent exercising while maintaining the equivalent benefits. His first set of studies seem promising because when he ran rats in hypothermic conditions (4 degrees Celsius). That relatively simple modification boosted the number of brain cells being born, the number of cells that survived, and the number of those cells that finally matured into neurons, (tagged respectively with Ki67, BrdU, and DCX for those who need to know the neurolingo). Kinda makes me happy to think of all of those years I spent playing hockey in those cold arenas!
Well, there you have it. A quickie update on some ways in which exercise changes our brain in a way that might prove to be quite helpful for us now, as we age, as winter approaches and if we go into space.
To read more posts inspired by the Society for Neuroscience Meeting return here:
Scientific Study References:
AMPK agonist AICAR improves cognition and motor coordination in young and aged mice.
Kobilo T, Guerrieri D, Zhang Y, Collica SC, Becker KG, van Praag H. (2014).
Endurance factors improve hippocampal neurogenesis and spatial memory in mice
Tali Kobilo, Chunyan Yuan, and Henriette van Praag (2011)