Acute exercise and brain changes

Research in the acute physical activity-cognition field has over the past 50 years investigated the relationship between cognitive function and acute physical activity (McMorris, 2016; Pesce & Audiffren, 2011). Cotman et al (2007) proposed several structural and functional changes in the brain with the use of physical activity. The most prominent area of the brain that has been researched and documented when it comes to physical activity and cognition interactions is the hippocampus (Ratey & Loehr, 2011) which according to Cotman et al (2007) is the major structure for learning and memory (Cotman, Berchtold & Christie, 2007). However, recent research has identified that the cerebellum, a region of the brain specialised in building predictive models has a strong relationship with the Hippocampus (Wolpert and Ghahramani, 2012). In the classical view, the cerebellum learns predictive internal models on the motor domain (Wolpert et al, 1998), this is standard with the large body of research that highlights that cerebellar dysfunction causes motor learning deficits (Locke et al, 2018). However, research has strongly indicated that cerebellar dysfunction has been associated with cognitive associative learning and working memory (Raymond and Medina, 2018). According to Wagner and Lu (2020) research suggests that the cerebellum learns internal models for both motor and non-motor function indicating a proposed universal functional role of the cerebellum across the brain, including the cerebral cortex. In conjunction with the cerebellum-cerebral cortex, the connection is the physical activity-cognition interactions that have been suggested to occur at the molecular and cellular levels (Ratey & Loehr, 2011). Regarding the cellular level, physical activity has been documented to increase brain activity, brain volume and blood flow, especially in the regions of the Hippocampus and prefrontal cortex that impacts attention and memory. It has been mentioned that this occurs through the process of synaptic plasticity, neurogenesis and angiogenesis (Trejo et al, 21001), This increases blood flow in the prefrontal cortex. (Bahmani et al, 2021). Within the molecular level, physical activity has been researched, with suggestions that it impacts upon, neurotrophins like Brain-derived neurotrophic factor (BDNF) which is a molecule, most often found in the hippocampus, which is again vital for learning and memory through synaptic and increase of the number of new neurons in the adult hippocampus (Cotman et al., 2007; Ratey & Loehr, 2011). How do these Physical Activity-Cognition Interactions come about? One theory is the transient hypefrontality hypothesis. This theory suggests that there is a neurochemical explanation of physical activity cognition (Dietrich, 2006) that increases the blood flow and local cerebral glucose utilization through the prefrontal cortex which spreads across the brain structures. According to Dietrich, (2006), the increment of blood flow and local cerebral glucose improves the functions in grey matter neurons, which are associated with the structures of autonomic, sensory and motor regions of the brain. In relation, McMorris (2009) also suggested a neuroendocrinological model for an interaction between physical activity and cognition. This model highlights an interaction between the sympathoadrenal system (SAS), which is a part of the autonomic nervous system (ANS) and HPA, and that during physical activity, there is a synthesis and secretion of various catecholamines like dopamine, noradrenalin, adrenalin serotonin and cortisol (McMorris (2009). However, in opposition to the hyperfrontality and neuroendocrinological model, the transient hypofrontality hypothesis, suggest that though physical activity has an impact on cognition there is limited capacity and processing ability of the brain (Vissing et al, 1996). Considering this limited capacity and processing ability of the brain, the transient hypofrontality hypothesis emphasizes that the activation of structures involved in physical activity must come at the expense of other structures involved in higher-cognitive abilities in the prefrontal cortex (Dietrich and Sparling ,2004). Originally the transient decrease in prefrontal regions has been explained by Dietrich (2006) as not directly being essential to the maintenance of physical activity with the brain then downregulating regions that are not crucially involved in the current behavior. Vissing et al, (1996) also suggested that the transient hypofrontality hypothesis predicts decreased performance on cognitive tasks that relies on the prefrontal cortex during physical activity and task that doesn’t depend heavily on prefrontal structures not being affected during physical activity. Finally, in relationship with the functional and structural changes within the brain that occurs through physical activity, several authors who have proposed a theoretical explanation for the effect of exercise intensity on cognitive performance have suggested that acute aerobic exercise is an arousing stressor (Audiffren, 2009) and as such the theoretical explanations have been anchored in unidimensional theories of arousal including the inverted-U theory (Brisswalter et al, 2002). In correlation with physical activity, the inverted-U theory is a suggestion that when the intensity of physical activity is too low, there is a lack of stimulation of the cellular and molecule changes occurring in the brain that are required for increased attention and memory performance (Pribram and McGuinness, 1975). Concerning low stress and arousal when the intensity of the physical activity there will also be a reduction of the blood flow and glucose update seen with hyperfrontality as well as the cerebellum-cerebral cortex connection (Iwańczuk and Guźniczak, 2015). In contrast, it has been suggested moderate levels of exercise increased physiological arousal and facilitated cognition, however, when physiological arousal approached a maximal level, the cognitive performance began to deteriorate (McMorris and Graydon, 2000). Interestingly research has suggested that brain changes and cognitive performance during physical activity occur as little as 6 min of activity (McMorris et al., 2008). The inverted u theory and its relationship to stress and arousal is something that has been spoken about in the catecholamines hypothesis (Cooper, 1973). The catecholamines hypothesis, in association with the acute exercise-cognition interaction effect, suggests that the increased peripheral concentrations of catecholamines do not readily cross the blood-brain barrier, if circulating concentrations were high, the blood-brain barrier would be compromised (Amemoria and Sawaguchi, 2006). Cooper (1973) also mentioned that catecholamines crossing the blood-brain barrier would lead to increases in concentrations in the reticular formation and hence an increase in arousal, which would benefit cognition at moderate concentrations (Arnsten, 2009) but will have a negative effect when concentrations levels are too high (McMorris, 2016). Yours in movement Stephen Braybrook, The Movement Man Movement Expert . Musings with The Movement Podcast Host . Author . Creator of Brain-Move Websites: brainmoveeducation.com or themovementman.com Facebook: brainmoveeducation or movementman Twitter: braybrooksj Instagram: brain_move_uk