Tonight I went to the presentation by Dr. Peter J. Clark entitled “Exercising the brain: A potential role for new hippocampal neurons generated from running in improving cognitive performance.” Because I love exercising, I am glad I went to this talk and I would like to briefly discuss it here.
Mice with the option of exercising on a running wheel exhibit hippocampal neurogenesis in the inside layer of the dentate gyrus. Because this area of the brain is involved in memory, Dr. Clark and his colleagues wanted to see if running mice perform better on cognitive tests than their sedentary counterparts. In order to investigate the impact of hippocampal neurogenesis on memory, they used irradiation to kill new neurons in the hippocampus. If irradiated running and sedentary mice performed comparably on cognitive tests, the researchers could conclude that hippocampal neurogenesis does indeed enhance memory.
To me, one of the most interesting experiments was the Morris water maze. Four categories of mice were tested: sedentary, runners, irradiated sedentary, and irradiated runners. Essentially, the mice were placed in a murky water bath with a small hidden platform. They recorded the path length that the mice traveled as they searched for this platform. Compared to sedentary mice, runners could more effectively use spatial cues in the room around them to remember where the hidden platform was located. However, irradiated runners did not outperform irradiated sedentary mice in this task. Dr. Clark therefore suggests that the exercise-induced formation of new neurons in the hippocampus augments certain kinds of memory (such as declarative and special memory).
The mechanism behind this phenomenon is still under investigation. However, increased blood flow and serotonin secretion in the hippocampus during aerobic exercise may play a role. My major question is how applicable is this study to humans? It is well known that exercise buffers the negative repercussions of stress, but how much can it enhance cognitive function?
Clark, P.J., Brzezinska, W.J., Puchalski, E.K., Krone, D.A., & Rhodes, J.S. (2009). Functional Analysis of Neurovascular Adaptations to Exercise in the Dentate Gyrus of Young Adult Mice Associated With Cognitive Gain. Hippocampus, 19(10), 937-950.
My brother has been writing a paper on a very similar topic and listening to him I have found several applications of this idea of running and memory. There seems to have been a observational study of runners and how much better they do than their human sedentary counterparts and similar results have been found. An important application to remember in this is also that running specifically has this memory enhancement. Other forms of exercise do not have this positive effect on memory like running does. I don’t know if this is due to the fact that running is a natural defense so our memories work better because we are trying to defend ourselves or if it is due to another reason. This research is very interesting and will most likely lead to people being healthier and having better memories.
ReplyDeleteI was also at this talk by Dr. Peter Clark, and the association of exercise with neuronal cells in the hippocampus was extremely intriguing. I am not going to lie, I have gained a little different view with exercising, and it has been a bit of the motivating factor for me to exercise!
ReplyDeleteI was wondering if other studies have been done regarding this type of analysis. I was unable to find any human neuronal cell (or memory) association with exercise research, but I found an article that was done before Dr. Clark’s paper, “Long-term regular exercise promotes memory and learning in young but not in older rats.” It was found that memory and learning increased as a result of regular exercise in younger rats. As the rats grew older, it was found that exercise did not have an effect on learning but still helped with memory improvement. It was explained that exercise “practiced behavior that activates molecular and cellular cascades that support and maintain brain plasticity.” It was also suggested that a molecular approach of studying the hippocampus to explore the findings within the paper, which Dr. Clark had later investigated.
It is apparent that large amounts of time and work have gone into seeing the effects of exercise on an individual’s life. It has shown that it increases insulin release in type 1 diabetes patients. It has shown a decrease in cardiovascular disease, and in this case shows an increase in learning and memory capabilities. Why is it that with so many good things branching from that simple 30+ minute walk, bike ride, run, or hike, that our population is so sedentary?
Asl, N.A., Sheikhzade, F., Torchi, M., Roshangar, L., & Khamnei, S. (2008). Long-term regular exercise promotes memory and learning in young but not in older rats. Pathophysiology, 15, 9-12.
Unfortunately, I was not able to attend Dr. Clark’s presentation on exercise and its associated benefits for memory. But as a former aerobic athlete, I know this probably is true however it was difficult to personally observe such memory benefits because I was often too physically exhausted to concentrate and learn many times. It might be interesting to study the effects of intense aerobic exercise on the brain’s ability to concentrate and learn. However when considering the blog, research done by investigators in Brazil on the benefits of aerobic exercise on memory in aging mice probably sheds some light upon the mechanism by which this hippocampal protection and neurogenesis occurs. Aging mice probably exhibit many similar degenerative effects in the hippocampal regions that are similar to Dr. Clark’s irradiated mice. In this study in Brazil, cognitive-enhancing properties were attributed to activation of a certain serine/threonine protein kinase (AKT) and cAMP response element binding signaling which results in an increase of BDNF (brain-derived neurotrophic factor) mRNA expression and subsequent BDNF protein expression. This resulted in increases synaptic plasticity and improved cognition. Interestingly this study performed the similar water maze method to test the spatial learning in the aging mice. These studies illustrate an important lesson for students today as sedentary lifestyle becomes extremely pervasive. Ultimately studies such as these will show the exercise is extremely important for cognitive strength and stamina.
ReplyDeleteAderbal S. Aguiar Jr., Adalberto A. Castro, Eduardo L. Moreira, Viviane Glaser, Adair R.S. Santos, Carla I. Tasca, Alexandra Latini, Rui D.S. Prediger, Short bouts of mild-intensity physical exercise improve spatial learning and memory in aging rats: Involvement of hippocampal plasticity via AKT, CREB and BDNF signaling, Mechanisms of Ageing and Development, Available online 1 October 2011, ISSN 0047-6374, 10.1016/j.mad.2011.09.005.
Exercise, has multiple benefits that have been already shown, from losing weight, improving physical appearance, and also helping in the fast recovery of patients with mild depression and to help maintaining a good mental health as people age. Exercise increases concentrations of neurotransmitters like serotonin and norepinephrine by stimulating the sympathetic nervous system. New neurons are created in the hippocampus, which is the center of learning and memory in the brain, however the mechanism behind is still being explored. At a cellular level, it is possible that exercise stimulates an influx of calcium, which activates transcription factors in existing hippocampus neurons. There are also transcription factors that initiate the expression of the Brain-Derived Neurotrophic Factor (BDNF). BDNF acts not only to generate new neurons, but also to protect existing neurons and to promote synaptic plasticity, the efficiency of signal transmission across the synaptic cleft between neurons, generally considered the basis of learning and memory (1). In addition, exercise has a reciprocal relationship with BDNF production directly; there is a reinforcement of the serotonin-BDNF loop, which indicates that exercise can act as a potential mood-enhancer. I found and read another research article, in which the study was very consistent and has different age groups, children, young adults and older adults. The study showed that physical activity and aerobic fitness help to generate a network of structures, including the frontal lobe, the anterior cingulated cortex and the parietal cortex, which are the main structures involved with cognitive tasks, including stimulus processes and memory. The findings of this study were very consistent and the results indicate that the greater amount of physical activity or aerobic activity are beneficial to cognitive process, specially to the process that are related to allocation of attention and faster cognitive processing, the results were backed up by MRI imaging (2). However, more studies need to be done to test the benefits in school performance from children that participated in physical activities at school.
ReplyDelete1.http://www.ohsu.edu/news/2003/092603bdnf.html
2.The effect of physical activity on the brain derived neurotrophic factor: from animal to human studies.(eng) By Zoladz JA, Pilc A, Journal Of Physiology And Pharmacology: An Official Journal Of The Polish Physiological Society [J Physiol Pharmacol], ISSN: 1899-1505, 2010 Oct; Vol. 61 (5), pp. 533-41; PMID: 21081796