Neural Mechanism underlying Unique Balance Strategies

Imagine you were walking along a curb, just like what you did when you were a kid. You were trying hard to be on the edge as long as possible without falling off. However, it was hard to maintain your balance all the time, and sometimes your center of gravity would be slightly off the curb. To regain the balance, what would you do?

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What strategies do you use to maintain balance when walking along a curb?

The automatic response to this scenario is moving the pelvis, where the center of gravity is located, to make the center of gravity fall right over the curb. However, this is not the strategy of regaining balance for everyone. In Balancing between Cultures: Equilibrium in Capoeira, Greg Downey demonstrated how gymnasts and capoeira practitioners inhibit this hip-based automatic response and develop different strategies to preserve balance. For gymnasts on the balance beam, the automatic hip-based response to steady themselves is too obvious that they will get marked down. Therefore, they develop an ankle-based righting strategy. Different from gymnasts and untrained people, capoeira practitioners develop an entirely different strategy to cope with imbalance. Capoeira emphasizes a dynamic equilibrium system that practitioners don’t have to have a fixed position to remain balance. The video below demonstrated what capoeira is like and how practitioners are in constant movement. Due to the dynamic property of capoeira, when balance is lost in one position, capoeira practitioners often transit to a new position to reestablish balance smoothly. For example, experienced practitioners will transit smoothly to headstand to reestablish balance when handstand fails, whereas novice practitioners tend to fall toward their back when they lost balance during handstand, which is the automatic response (Downey, 2012).

 

In both examples of gymnasts and capoeira practitioners, the hip-based automatic response seen in untrained people for regaining balance is inhibited that only specific strategies developed accordingly to meet the requirement of cultural environment are used. The inhibition of automatic reflex seen in the two examples, argued by Downey, provided evidence that new skills can only be developed when automatic reflex is inhibited. Downey drew his theory from the ethnographic data of balance strategies seen in different professions, but his theory is well supported by neuroscience research as well. Though no brain research has been done on difference in balance strategies, research has been done on a cognitive task requiring the same skills of inhibiting automatic reflex and reinforcing a new response by allocating attention, which is the Stroop task.

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Stroop Task

The Stroop task is a color-naming task that participants are required to name the ink color of a word rather than read the word. The Condition B of the illustration placed above the paragraph demonstrated the process of Stroop task well. When the word “GREEN” is presented, participants are required to speak out the color name, which is “RED”, rather than read the word “GREEN”. It takes longer for participants to react when the color doesn’t match the meaning of the word, because naming the color instead of reading the word produces competitive information processing demands. Therefore, participants need to actively direct their attention to the name of the color and suppress the automatic reflexes of reading the word. The conflict between one well-learned or automatic behavior (reading) and a decision rule that requires this behavior to be inhibited is a accurate replicate of the cognitive demand of developing unique balance strategies in gymnasts and capoeira practitioners.

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Where the cingulate gyrus is located?

Several studies have done to examine the neural mechanism of the Stroop task. In Peterson et al. (1999), participants were asked to conduct the Stroop task while having fMRI scan. The study found that anterior cingulate, coupled with several other brain areas is activated throughout the process. The authors postulated that the anterior cingulate is in charge of coordinating attention networks to help people actively attend to the unfamiliar color-naming task, which is different from the automatic reflexes. Other studies have found that area 45 and 44 are also activated throughout the process, which may engage in suppressing the automatic behavior of reading the words (Jonides et al., 1998). The insula, premotor, and inferior frontal regions were also found to be actively involved in the task, though the exact function is not clear (Leung, Skudlarski, Gatenby, Peterson, & Gore, 2000). The authors argued that it is possible that the Stroop effect is not caused by individual brain parts, but caused by a collaborative network of different brain parts. Since the findings are Stroop specific that motor behavior suppression has not been studied, the unique learning process of gymnasts and capoeira practitioners is not fully understood. However, the Stroop research points out the possible important role of the anterior cingulate in the unique development of the balance system in gymnasts and capoeira practitioners.

The balance strategies seen in gymnasts and capoeira practitioners are not fully explained due to the gap between ethnographic observation and lab data. But I bet the efforts of bridging the gap between the qualitative data of neuroanthropology and the quantitative data of neuroscience lab research will be the next trend in neuroscience. What do you think?

 

References

Jonides, J., Smith, E. E., Marshuetz, C., Koeppe, R. A., & Reuter-Lorenz, P. A. (1998). Inhibition in verbal working memory revealed by brain activation.Proceedings of the National Academy of Sciences, 95(14), 8410-8413.

Leung, H.-C., Skudlarski, P., Gatenby, J. C., Peterson, B. S., & Gore, J. C. (2000). An event-related functional MRI study of the Stroop color word interference task. Cerebral cortex, 10(6), 552-560.

Peterson, B. S., Skudlarski, P., Gatenby, J. C., Zhang, H., Anderson, A. W., & Gore, J. C. (1999). An fMRI study of Stroop word-color interference: evidence for cingulate subregions subserving multiple distributed attentional systems. Biological psychiatry, 45(10), 1237-1258.

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