The ‘Sports Encephalon’: Exercise, Sports, and the Brain

The 'Sports Encephalon'
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Your brain loves to exercise! Learn more about how exercise affects the
structure and function of the brain and how to protect it from injury.
Image source: http://www.crossfit650.com/wp-content/uploads/2013/01/weight-lifting-brain1.jpg

Although the importance of exercise for disease prevention and physical health are well-known, there is a growing body of evidence which suggests exercise may also have a significant effect on brain function and structure [1]. Animal models and human studies have found myriad beneficial links among exercise, sports, and the brain. For example, exercise can enhance learning and memory, delay cognitive decline associated with aging and neurodegenerative diseases, and play a therapeutic role in depression [1]. Sports participation however, comes with an increased risk of traumatic brain injury [2]. Therefore, studying sports-related concussions and brain injury is necessary to gain a more comprehensive understanding of the impact of exercise on the brain. This promising new field of neuroscience is helping demonstrate that participation in physical exercise is a vital component of achieving physical and mental wellbeing over the life course [3].

Research on the interplay of exercise, sports, and the brain has been conducted in professional athletes and amateurs alike, demonstrating diverse effects on our mental and physical wellbeing depending on the length, type, and intensity of activity involved [3]. One way to categorize the effects of exercise is to consider how the brain structure and function changes throughout the different stages of physical activity—pre-game, in-game, and post-game.

Pre-Game. Ahead of the game, long term training and exercise can modify the physiological environment of the brain, produce structural changes, and affect cognitive function. We will investigate exercise-induced neurogenesis and neuronal plasticity, and how changes in Brain Derived Neurotrophic Factor (BDNF), N-acetyl Aspartate (NAA), choline, and dopamine levels associated with exercise can influence cognition. Additionally, implications for aging and pathology will be discussed, given findings that exercise may improve learning and memory, delay the onset of neurodegenerative diseases, and prevent or treat mental illness such as depression.

In-Game. What is occurring in the brains of athletes during sports participation? We will consider short term changes in brain function and the perception of one’s body state during the act of exercise—including mood modulation, decreased pain perception, and the effect of visual input. Plastic adaptive changes in the brain circuitry of athletesversus non-athletes will also be investigated, as visualized through non-invasive neuroimaging techniques. Such changes in grey matter and brain connectivity may be responsible for the improved perception and reactivity observed in trained athletes.

Post-Game. A potential consequence of sports participation is the increased risk of injury to the brain. In this final section, we intend to explore concussions, traumatic brain injury(TBI), and chronic traumatic encephalopathy (CTE) and the evolving diagnostic procedures used to identify injury and prescribe appropriate treatment. For example, new techniques testing changes in reaction time, odor identification, and brain activation offer promising advancements in detecting concussions. TBI will be discussed in terms of microenvironment changes and how genetics may mediate susceptibility to secondary insults. Finally, the etiology of CTE and its symptoms and possible identification in living athletes will be investigated.

Bibliography
1. van Praag, H. Neurogensis and Exercise: Past and Future Directions. Neuromol Med. 2008. 10: 128-140.
2. Daneshvar, D.H., Nowinski, C. J., McKee, A.C., & Cantu R.C. The epidemiology of sport-related concussion. Clin Sports Med. 2011. Jan; 30 (1): 1-17.
3. Voss, M. W., Nagamatsu, L. S., Liu-Ambrose, T., & Kramer A. F. Exercise, brain, and cognition across the life span. J Appl Physiol. 2011. Nov; 111 (5): 1505-1513.


Brain Perception During Exercise and Sport

main article: Brain Perception During Exercise and Sport
author: Viki Nguyen

What is your brain doing during exercise?
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[Untitled cartoon of an exercising brain]. Retrieved March 26,2013 from:
http://media.tumblr.com/tumblr_lta2i1xmTU1qja0yo.jpg

The brain and its ability to perceive and react to stimuli is very important in the world of sport and exercise. Even more amazing and being highly researched is the brain's acute ability to adapt to stressful situations, in the form of sports and exercise, and alter perception. These exercise-induced modulations involve a wide range of neuronal networks such as the limbic, opioidergic, and somatosensory systems in order to change mood, pain, and exertion perception. The mechanisms behind elevated mood[1], decreased pain perception[2], and changes in perceived exertion[3]are being deciphered and its details are hotly pursued. Perhaps more relatable to the general public is the effect of one of the most accessible and commonly used drugs on these exercise-induced mechanisms, caffeine. During exercise and sport, it is the careful balance of these perceptions and manipulations of these perceptions that can differentiate between a successful athlete and non-professional exercisers.

Bibliography
1. Boecker, H., Sprenger, T., Spilker, M., Henrikson, G., Koppenhoefer, M., Wagner, K., et al. (2008). The runner's high: opioidergic mechanisms in the human brain.. Cereb Cortex, 11(18), 2523-2531.
2. Scheef, L., Jankowski, J., Schild, H., Zimmer, A., Boecker, H., Daamen, M., et al. (2012). An fMRI study on the acute effects of exercise on pain processing in trained athletes.. Pain, 8(153), 1702-1714.
3. Parry, D., Chinnasamy, C., & Micklewright, D. (2012). Optic flow influences perceived exertion during cycling. J Sport Exerc Psychol., 4(34), 444-456.


Chronic Traumatic Encephalopathy

main article: Chronic Traumatic Encephalopathy
author: Pavel Tselichtchev

Chronic Traumatic Encephalopathy
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A comparison of a healthy brain to that of a brain diagnosed with CTE. [Bibliography item example27 not found.]

Chronic Traumatic Encephalopathy(CTE) is a neurodegenerative disease that is believed to be caused from repeated blows to the head[1]. CTE has recently gained prominence due to big name athletes such as Junior Seau dying as a result of it and the media attention it has received recently [2]. The disease has been found to affect numerous areas of the brain including: frontal and temporal cortices, medial temporal lobe, basal ganglia, diencephalon, and the brainstem [3]. The symptoms of CTE include memory loss, impaired cognition, unstable emotional state, and depression and typically start to appear many years after the athlete has retired [4]. Many modern sports feature varying degrees of head contact during action. The most notable being: football, boxing, and hockey. However even sports such as soccer and skiing have been found to result in concussions and can run the risk of developing CTE down the road [3]. CTE is an important illness to study as many athletes and even non-athletes can succumb to head injuries and as a result can possibly develop the illness. Recently, it’s been shown that CTE can be identified in living human brain tissue whereas before this was not possible[5]. However as of yet, there are no cures for CTE so it is important to investigate the onset of this disease on a molecular level and potentially look for ways to hinder the progression of the symptoms.

Bibliography
1. Gavett, B. Stern, R., McKee, A. (2011). Chronic Traumatic Encephalopathy: “A Potential Late Effect of Sport-Related Concussive and Subconcussive Head Trauma”. Clinical Journal of Sports Medicine, 30(1): 179-xi.
2. Samson, K. (2013) “NIH: NFL’s Junior Seau had Chronic Traumatic Encephalopathy”. Neurology Today, 13(4): 12-15
3. McKee, A., Cantu, R., Nowinski, C., Hedley-Whyte, T., Gavett, B., Budson, A., Santini, V., Lee, H., Kubilus, C., Stern, R. (2009).” Chronic Traumatic Encephalopathy in Athletes: Progressive Tauopathy following Repetitive Head Injury”. Journal of Neuropathology and Experimental Neurology, 68(7): 709–735.
4. Yi, J., Padalino, D., Chin, L., Montenegro, P., Cantu, R. (2013) “Chronic Traumatic Encephalopathy”. Current Sports Medicine Reports, 12(1): 28-32.
5. Small, G. Kepe, V. Siddarth, P. Ercoli, L. Merrill, D. Donoghue, N. Bookheimer, S. Martinez, J. Omalu, B. Bailes, J. Barrio, J. (2013). “PET Scanning of Brain Tau in Retired National Football League Players: Preliminary Findings”. American Journal of Geriatric Psychiatry, 21(2):138-144.


Exercise and Cognition

main article: Exercise and Cognition
author: Ariana De Almeida

Figure 1. Exercise!
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Image obtained from http://macnavs.ca/ultimate_frisbee.jpg

Exercise has benefits, not only for cardiovascular and general physical health, but it also plays a role in brain health.[1] On top of regular aging, which generally brings a cascade of health problems - including decline of cognitive function, but there are also multiple brain disorders which impair cognition. [3] Long term training and regular aerobic exercise, result in improvements of the cognitive function of healthy individuals, as well as that of older people whose cognitive function is declining or impaired.[2] The mechanisms through which exercise affects cognition are not yet well understood, and are currently still being investigated. Improvements can be observed in various aspects of cognition, therefore, physiological changes must be taking place at the different brain substrates responsible for those functions. Thus, emphasis has been placed in the role that neurotrophins may play in bringing about these effects, since they have brain wide interactions, play a role in dendritic growth and long term potentiation, and their levels fluctuate in response to exercise. [3]


Video neatly outlining the extensive benefits of exercise for health in general.

Bibliography
1. K. Kamijo, Y. Takeda. 2010. Regular physical activity improves executive function during task switching in young adults. International Journal of Psychophysiology 75, 304–311
2. Li G, Peskind ER, Millard SP, Chi P, Sokal I, et al (2009). Cerebrospinal Fluid Concentration of Brain-Derived Neurotrophic Factor and Cognitive Function in Non-Demented Subjects. PLoS ONE, 4(5).
3. I. Barbosa, B. Diniz, A. Kummer, A. Teixeira. (2010). Circulating levels of brain-derived neurotrophic factor: correlation with mood, cognition and motor function. Biomarkers in Medicine, 4(6), 871+.


Exercise-Induced Hippocampal Neurogenesis

main article: Exercise-Induced Hippocampal Neurogenesis
author: Galina Gheihman

Figure 1. Exercise promotes neurogenesis in the adult hippocampus
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Photomicrographs in (a, b) show running animals have significantly
more dividing cells (BrdU+) than controls. Immunofluorescent confocal
microscopy (c, d) can be used to identify the newly born neurons,
where double-labeling for proliferation (BrdU+) and a neuronal phenotype
(NeuN+) appears orange. Adapted from Figure 2 in [6].

It is now widely recognized that neurogenesis—the birth, differentiation, and long term survival of new neurons—continues to occur in select regions of the adult mammalian brain throughout the lifespan [1]. This proliferation occurs primarily in the sub-ventricular zone and the dentate gyrus of the hippocampus and may be influenced by numerous endogenous and exogenous factors [2].

One important promoter of hippocampal neurogenesis in rodents and humans alike is aerobic exercise (Figure 1). Several molecular mechanisms have been proposed to underlie this effect, including the stimulation of growth factors, changes in angiogenesis, or activation of neurotransmitter systems following exercise [1].

Physical activity has been shown to act as an effective treatment in major depressive disorder [3]. In parallel, certain commonly-prescribed antidepressants have been shown to promote hippocampal neurogenesis. Taken together, these findings suggest hippocampal neurogenesis may serve as a common therapeutic mechanism for exercise and pharmacological interventions in depression [4].

Thus, mounting evidence continues to reveal the significant and relevant effects of exercise on the brain [5], and in particular, how the structural and functional changes associated with exercise-induced neurogenesis may have implications for cognition, mood, and overall psychological wellbeing.

Bibliography
1. van Praag H. Neurogenesis and Exercise: Past and Future Directions. Neuromol Med. (2008) 10: 128-140.
2. Aimone JB, Deng W, Gage FH. Adult neurogenesis: integrating theories and separating functions. Trends Cogn Sci. (2010) 14 (7): 325-337.
3. Fabel K, Kempermann G. Physical activity and the regulation of neurogenesis in the adult and aging brain. Neuromolecular Med. (2008) 10 (2): 59-66.
4. Huang GJ, Ben-David E, Tort Piella A, Edwards A, Flint J, Shifman S. Neurogenomic evidence for a shared mechanism of the antidepressant effects of exercise and chronic fluoxetine in mice. PLoS ONE. (2012) 7 (4): e35901.
5. Voss MW, Nagamatsu LS, Liu-Ambrose T, Kramer AF. Exercise, brain, and cognition across the life span. J Appl Physiol. (2011) Nov; 111 (5): 1505-1513.
6. Lazarov, O. Mattson MP, Peterson DA, Pimplikar SW, van Praag H. When Neurogenesis Encounters Aging and Disease. Trends Neurosci. (2010) 33(12): 569-579.


Methods in Concussion Detection and Assessment

main article: Methods in Concussion Detection and Assessment
author: TimothyLam
A concussion is a form of traumatic brain injury resulting from forceful contact to the head.[1] Although concussions can be sustained by many individuals, such as car accident victims and combat soldiers, concussions in athletes are especially common due to the vast amount of physical contact during the game.[1] If an athlete receives forceful contact to the head and subsequently loses consciousness, it is very likely the athlete has sustained a concussion and assessment is just for confirmation.[1] However, there may be instances in which forceful contact was exerted on the head, but the aforementioned symptom was not shown by the athlete.[1] This does not necessarily mean the athlete escaped from the contact concussion-free, rather these situations illustrate the difficulty in detecting a concussion as both the athlete and team physician are likely unaware of a concussion. To complicate the problem of detection, concussions do not appear to show any structural abnormalities and thus, use of X-ray computed tomography (CT scan) would not aid in the assessment process.[2] However, the athlete may experience balance problems and changes in reaction times and behaviour.[2] Acknowledgement of these symptoms has led to the creation of assessment tools that allow medical professionals to detect differences in these variables, among other symptoms, from the athlete’s baselines. The Sport Concussion Assessment Tool (SCAT2), which tests a variety of domains including cognition, balance, and memory, has been the most widely used test in determining the presence of a concussion.[2] Although SCAT2 is a comprehensive assessment, current research has sought to improve SCAT2 through the development of assessment tools yielding quicker and more accurate results.
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This Neurowiki is dedicated to the research involving both “traditional” and novel methods in concussion detection. Physical contact during gameplay may lead to concussions. The greatest challenge facing medical professionals currently is to determine the best techniques for accurate detection of unnoticed concussions. This Neurowiki will discuss methods including (from left to right) on-field assessments and neuroimaging, among others. (Adapted from (from left to right): http://www.atlantichealth.org/neuroscience/our+services/diagnostics+and+treatments/magnetoencephalography; http://www.fijirugby.com/pages.cfm/fru-news?newsid=irb-opts-further-concusssion-trials)

Bibliography
1. Khurana, V.G. & Kaye, A.H. An overview of concussion in sport. J Clin Neurosci. 19, 1-11 (2012).
2. McCrory, P. et al. Consensus Statement on Concussion in Sport: The 3rd International Conference on Concussion in Sport Held in Zurich, November 2008. J Athl Train. 44, 434–448 (2009).


Plasticity in the Athletic Brain

main article: Plasticity in the Athletic Brain
author: sannecchiarico

Animation of an MRI
Animation from:http://en.wikipedia.org/wiki/Magnetic_resonance_imaging

Athletes are known to be quicker, stronger, more agile and more accurate when compared to non-athletes. There is something different happening in the brains of these athletes. Plastic changes are occurring in their brains, where the neuronal circuits in their brains are either being rewired or enforced. Plasticity has replaced the view that our brains are static, but our brains are changing throughout our entire life [1]. Plasticity has already been shown in many studies with piano players, where the more they practiced playing the piano, the more their brains (motor cortex) had changed [2]. This same concept can be applied to athletes as well, but on a broader spectrum as many athletes use many parts of their body at once, so multiple areas as well as other changes may be occurring.

Bibliography
1. Nielsen , J., & Cohen, L. (2008). The olympic brain. does corticospinal plasticity play a role in acquisition of skills required for high-performance sports?.Journal of Physiology, 586(1), 65-70.
2. Pascual-Leone, A., Nguyet, D., Cohen, L., Brasil-Neto, J., Cammarota, A., & Hallett, M. (1995). Modulation of muscle responses evoked by transcranial magnetic stimulation during the acquisition of new fine motor skills. J Neurophysiology, 3(74), 1037-45.


Traumatic Brain Injury

main article: Traumatic Brain Injury
author: twaynepereira

Traumatic Brain Injury
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Primary traumatic brain injury, resulting from a direct blow to the head

Traumatic brain injury (TBI) has profound effects on the brain and is a major concern to health care worldwide. TBI can arise from pressure applied to the brain in the form of a direct blow to the head or objects being lodged in the skull[1]. The major causes of TBI are vehicle accidents and sports injuries; the latter possibly affecting developing brains. Understanding the outcomes of TBI in sports injuries may aid: the diagnosis process and the development of treatment options.

Depending on the severity of the head injury acute responses such as inflammation and microenvironment modifications have been reported[1]. To further understand the cortical changes that occur shortly after TBI, cellular processes that lead to vascular changes and upregulation of toxic molecules have been closely monitored. These alterations within the neocortex may also be driven by gene expression; therefore possible treatments to mitigate the consequences of TBI could target gene expression via pharmacokinetics or stem cell therapy.

Bibliography
1. Kan E.M, Ling E.A, Lu J (2012). Microenvironment changes in mild traumatic brain injury. Brain Research Bulletin (87): 359-372.



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