Walking | NBB in Paris

Google Map directions of the 5-minute walk from the ACCENT center to Pause Café.

“It’s a 20-minute walk,” sighed my American friends, complaining that it was “too long.” It was our first week in Paris on our study abroad program, and we were planning on going to a café. After Google maps indicated that the metro stop was far from the original café, we ended up going to Pause Café. It was on the corner of the street near the ACCENT center, where our daily classes are held.

Image of Pause Café.

I was shocked by the lack of energy that we had. Looking around us, Parisians were walking from place to place without breaking a sweat. Walking for twenty minutes, even thirty, was typical for a Parisian. This got me thinking, how different would my life be if I lived in Paris. In Atlanta, shops and restaurants were far apart, sidewalks were narrow, and the city was difficult to explore without a car. But in Paris, everything was nearby, and sidewalks were wide. If I were to walk this much every day for the rest of my life, how would that impact my health?

Exercise is known to have many health benefits. A fact that has been ingrained in my mind since elementary school. What I knew was that exercise could prevent heart attacks and diseases, but not its effect on the brain.

Researchers show that exercise improves memory, specifically our memory of certain places and events (Cassilhas et al., 2016). The anterior hippocampus provides us with the ability to imagine our house and move around our neighborhood (Zeidman and Maguire, 2016). As we get older the hippocampus decreases in volume resulting in increased forgetfulness (Raz et al.,2005). However, there may be a way to halt those effects and possibly reverse them.

Erickson et al. (2011), reveal in their study that physical exercise improves our long-term memory, specifically our navigational memory. By exercising 3 times a week for one-year, participants had an increase in the volume of their anterior hippocampus. However, participants who did not exercise had a decreased anterior hippocampal volume. Overall, the study showed that only the decreased volume in the anterior hippocampus can be reversed with exercise, but not other parts of the hippocampus. This is a well-designed experiment because 120 participants were involved in the study, which makes the results more applicable to the general public by representing different types of people in the population. The differences in the size of the anterior hippocampus can be better observed and statistically tested with this large number of participants. Further, by testing participants prior to the exercise protocol, after 6 months, and after one year, we can look at the effects of exercise on the anterior hippocampal volume both in the short-term and long-term.

Graphs of the increase in the volume of the anterior hippocampus for the exercise group (blue line) compared to the decrease in the volume of the anterior hippocampus for the control (red line), evident in both the left hemisphere and the right hemisphere of the hippocampus.

Writing this now, I regret missing that 20-minute walk because I now know that a little exercise every day goes a long way in improving my memory. This leaves me wondering, is there a certain time frame when I should be exercising after learning new material?

Researchers performed a study to test whether there is an appropriate time to exercise after learning to improve memory recall (Van Dongen et al., 2016). Participants were assigned into three groups; those who exercised immediately, those who exercised after 4 hours and those who did not exercise. They learned to associate a certain object with a location (refer to image below).The researchers then asked the participants to recall that association. The results showed that exercising 4 hours after learning instead of immediately after enhanced participant’s ability to remember those associations compared to those who did not exercise. Hence, properly timed exercise can enhance long-term memory. The researchers strengthen their conclusion by controlling for problems that could affect the results.Such as having half the participants perform the task at 9AM, while the other half perform it at 12PM. This accounts for the differences in performance at different times of the day, which ensures that improvement in memory recall is occurring due to exercise.

Image of task protocol: associating an object with a location. The orange box represents the study phase, while the blue box represents the testing phase.

So, my elementary school teacher was right after all. Exercise is important for a healthy heart and, as it turns out, a healthy memory. Not only does this motivate me to exercise more often, but also, these studies give me hope for new intervention methods for patients with memory recall deficits. An example would be Alzheimer patients, who struggle with navigating the world (Weller et al., 2018). Another would be patients with major depressive disorder, who have memory impairments in encoding and recalling information (Gourgouvelis et al., 2017). It is cases like these that highlight the importance of understanding the impact of exercise on memory.

Now, when my friends and I have the option between using the metro or walking for 20-minutes, we choose the latter. Living in Paris for 4 weeks today, I have assimilated with the Parisian way of life. I am now able to walk in Paris for hours without the slightest soreness in my legs. It has become my new way of life.

References:

Cassilhas, R. C., Tufik, S., & de Mello, M. T. (2016). Physical exercise, neuroplasticity, spatial learning and memory. Cellular and Molecular Life Sciences, 73(5), 975-983.

Erickson, K. I., Voss, M. W., Prakash, R. S., Basak, C., Szabo, A., Chaddock, L., … & Wojcicki, T. R. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017-3022.

Gourgouvelis, J., Yielder, P., & Murphy, B. (2017). Exercise promotes neuroplasticity in both healthy and depressed brains: an fMRI pilot study. Neural plasticity, 2017.

Raz, N., Lindenberger, U., Rodrigue, K. M., Kennedy, K. M., Head, D., Williamson, A., … & Acker, J. D. (2005). Regional brain changes in aging healthy adults: general trends, individual differences and modifiers. Cerebral cortex, 15(11), 1676-1689.

Van Dongen, E. V., Kersten, I. H., Wagner, I. C., Morris, R. G., & Fernández, G. (2016). Physical exercise performed four hours after learning improves memory retention and increases hippocampal pattern similarity during retrieval. Current Biology, 26(13), 1722-1727.

Weller, J., & Budson, A. (2018). Current understanding of Alzheimer’s disease diagnosis and treatment. F1000Research, 7.

Zeidman, P., & Maguire, E. A. (2016). Anterior hippocampus: the anatomy of perception, imagination and episodic memory. Nature Reviews Neuroscience, 17(3), 173.

When I came to Paris, I thought I was prepared for everything: the bakeries, the museums, the landmarks, the culture — but nothing could have prepared me for the walking I was about to do. Unlike the suburban areas around Emory or my hometown of Topeka, Kansas, where a car is considered necessary for most outings, the streets of Paris are easily traversable by foot, and public transportation is much more accessible. And in a city so beautiful, I had a hard time refusing the ease of foot travel. Still, with the recent muggy weather, walking hasn’t felt quite as pleasant. People always say “no pain, no gain,” and I began to wonder what all my walking was doing for me brain-wise.

My steps before and after I came to Paris. As one can see, my steps significantly increased after I came to Paris, May 22th.

Turns out, there’s a lot to be gained from regular aerobic exercise. Consistent research has pointed to the role of physical activity in cognitive function and has grown in volume over the past decade (Soga et al., 2015). General movement has been suggested to contribute to brain plasticity, which in turn facilitates interaction between cognitive and motor functioning (Doyon and Benali, 2005). Furthermore, research has also linked physical activity to academic performance (Castelli et al., 2007). While these results doesn’t necessarily mean that taking up routine walking or running will guarantee better grades or memory, the two do seem to be invariably related.

Amidst this burgeoning research, Colcombe and colleagues decided to research the cortical mechanisms beneath cardiovascular fitness-related changes in cognitive function (Colcombe et al., 2004). Functional magnetic resonance imaging (fMRI) was used to study how changes in fitness might affect the brain. Researchers particularly focused on the anterior circular cingulate (ACC), an area of the limbic system linked to brain structures responsible for sensory, motor, emotional, and cognitive information (Bush et al., 2000).

The study took place in 2 segments, with Study 1 involving high-fit (HF) older adults, and Study 2 involving adults randomly assigned to either a cardiovascular fitness training (CFT) group or a stretching and toning group (control) (Colcombe et al., 2004). All participants in both groups underwent a flanker task in which they filtered and identified incongruent cues (Colcombe et al., 2004). The flanker test allowed researchers to study participants’ ability to filter and respond to relevant information (Colcombe et al., 2004). Researchers then compared cortical mechanisms triggered by incongruent clues to those triggered by congruent ones, to see whether HF adults would demonstrate higher activation in attention- and control-related regions (Colcombe et al., 2004).

fMRI scans of the ACC illustrate activation of different cortical areas in the task-related activity (Colcombe et al., 2004).

Sure enough, fMRI scans supported the study’s hypothesis that older adults with high levels of measured cardiovascular fitness would demonstrate significantly more activation in cortical regions linked with attention selection and control (Colcombe et al., 2004). These cortical regions include the medial frontal gyrus (MFG), superior frontal gyrus (SFG), and superior parietal lobe (SPL) (Colcombe et al., 2004). Significantly less activation was observed in the ACC, which is linked with behavioral conflict and adaptation of attentional control (Colcombe et al., 2004).

One weakness of the study by Colcombe and colleagues is the cross-sectional approach taken in Study 1. Being observational, cross-sectional studies are vulnerable to non-response bias, which can lead to a participant pool unrepresentative of the population (Sedgwick, 2014). Furthermore, data can only be collected during one set period of time, leaving researchers unable to create long-term representations of cause and effect (Sedgwick, 2014). However, it is important to note that longitudinal studies might also be difficult to complete with older participants, due to possible interference from disease or other age-related complications (Sedgwick, 2014). Ultimately, the research by Colcombe and colleagues was important at the time of its publication because it expanded upon existing research regarding the underlying cortical mechanisms of cardiovascular fitness.

More recent research by Brockett and colleagues suggests that physical exercise may contribute to extensive plasticity and increased cognitive functioning (Brockett et al., 2015). Rats who ran for moderate durations of 12 days were able to better discriminate than control rats in a task testing medial prefrontal cortex (mPFC) function, though little difference was seen between both groups in a task testing perirhinal cortex (PRC) function (Brockett et al., 2015). In a second experiment, runner rats took less trials and errors than control sedentary rats to reach criteria for simple discrimination, reversal, extradimensional shift (Brockett et al., 2015). Researchers also tested whether running influences astrocytes, non-neural brain cells that communicate with neurons and suggest links to synaptic plasticity, learning, and memory (Brockett et al., 2015). Co-labelling of astrocytes with visual markers revealed increase in astrocytes cell body area in the hippocampus, mPFC, and OFC (Brockett et al., 2015). These results aligned with data from the behavioral tests, suggesting that physical exercise can enhance cognitive performance in tasks that activate the hippocampus, mPFC, and OFC (Brockett et al., 2015). The lack of significant change to the PRC suggests that routine running lacks observable relation to the PRC. Ultimately, results suggest greater cognitive performance in tasks reliant on the prefrontal cortex, as well as enhanced synaptic, dendritic, and astrocytic measures in several regions. This evidence supports the hypothesis that physical exercise contributes positively to plasticity and cognitive functioning. Together, both papers by Colcombe, Brockett, and their colleagues have contributed to the growing understanding that exercise generally promotes greater cognitive functioning.

Brockett and colleagues’ research has made me wonder how much I would have to run to achieve the human equivalent of a rat’s 12-day regimen. As a student, it’s incredibly easy to get sucked into the grind and become deskbound. But the grind is exactly why brain power is important for the students, and optimizing my brain power in exchange for a few minutes and some physical effort has started to sound like a much better idea than the old me would have thought.

References

Brockett AT, LaMarca EA, Gould E (2015) Physical exercise enhances cognitive flexibility as well as astrocytic and synaptic markers in the medial prefrontal cortex. Public Library of Science ONE 10(5): e0124859. https://doi.org/10.1371/journal.pone.0124859.

Bush G, Luu P, Posner MI (2000) Cognitive and emotional influences in anterior cingulate cortex. Trends in Cognitive Sciences. 4(6):215-222. https://doi.org/10.1016/S1364 6613(00)01483-2.

Castelli DM, Hillman CH, Buck SM, Erwin HE (2007) Physical fitness and academic achievement in third- and fifth-grade students. Journal of Sport and Exercise Psychology 29(2):239-252. https://doi.org/10.1123/jsep.29.2.239.

Colcombe SJ, Kramer AF, Erickson KI, Scalf P, McAuley E, Cohen NJ, Webb A, Jerome GJ, Marquez DX, Elavsky S (2004) Cardiovascular fitness, cortical plasticity, and aging. Proceedings of the National Academy of Sciences of the United States of America 101(9):3316-3321. https://doi.org/10.1073/pnas.0400266101.

Doyon J, Benali H (2005) Reorganization and plasticity in the adult brain during learning of motor skills. Current Opinion in Neurobiology 15(2):161-167. https://doi.org/10.1016/j.conb.2005.03.004.

Sedgwick P (2014) Cross sectional studies: Advantages and disadvantages. BMJ 348. https://doi.org/10.1136/bmj.g2276.

Soga K, Shishido T, Nagatomi R (2015) Executive function during and after acute moderate aerobic exercise in adolescents. Psychology of Sport and Exercise 16:7-17. https://doi.org/10.1016/j.psychsport.2014.08.010.

Image 1 taken by myself.

Image 2 from Colcombe et al., 2004.

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