Tag Archives: vestibular system

The Equilibrium System: Our Malleable Mental Module

Greg Downey conducts research on the physiological, perceptual, and phenomenological impact of physical exercise. He is particularly interested in the effects of skill acquisition on cognitive and sensory learning, in the context of sports and dance. Downey believes that human variation stems from patterns of enculturation of the body and the brain. He is the author of the chapter titled, “Balancing Between Cultures: Equilibrium in Capoeira,” found in the 2012 book, “The Encultured Brain: An Introduction to Neuroanthropology”. Downey coauthored this book and also wrote a book in 2005 titled, “Learning Capoeira: Lessons in Cunning from an Afro-Brazilian Art”. Downey currently works in the department of anthropology at Macquarie University in Australia and teaches a variety of topics including human rights, ethnographic research methods, economic anthropology, and global poverty. He conducts fieldwork in Brazil, the United States, and the Pacific and studies practices such as mixed martial arts, echolocation in the blind, cognitive skills in sports, and metabolic changes in free divers.

Downey’s chapter narrows in on the neurological enculturation of the human sensory systems; specifically, those associated with equilibrium. By contrasting Afro-Brazilian capoeira practices with gymnastics techniques, Downey depicts the pliability of the human equilibrium system. Through this comparison he demonstrates how cultural patterns are responsible for differences in physical balancing skills. Proprioception is a multisensory system that functions in our periphery without conscious monitoring, until something goes wrong and our sense of balance is disturbed. The vestibular system is located in the inner ear where the semicircular canals and the otoliths (tiny ear bones) reside. These bones detect linear motion while the semicircular canals detect angular motion. Downey explains how this complex multisensory system consists of a feedback loop that allows individuals to detect their body positioning, correct for error, and anticipate future adjustments in order to maintain balance. While this function was previously thought of as a fixed neurological system, research shows that it is highly flexible and able to be refined via conditioning and training.

Gymnastics, ballet, martial arts, figure skating, and space travel are a few instances in which this vestibular system may be trained to perform in distinct ways. Superb balance after spinning in circles and the ability to mitigate motion sickness are a couple of examples of the plasticity of this system and how with practice, humans are able to acquire these unique abilities. Downey explains how differences in training and practice between gymnasts and capoeira practitioners allow for the strengthening of specific, but divergent vestibular skills. For example, gymnasts maintain a forward-facing gaze during hand stands while capoeira practitioners are not permitted to even look at the floor. Furthermore, gymnast movements are tightly controlled while capoeira movements are dynamic and mobile. Downey’s purpose in this comparison highlights how different cultural practices subsequently elicit and strengthen different neurological proprioceptive and motor skill sets.

This chapter reminds me of almost everything we’ve read in this class and the ongoing discussion about the bidirectional feedback loop and dynamic interaction between biology and culture. I am starting to associate the term “neuroanthropology” with the phrase “nature – nurture”. If we break down the term into “neuro” and “anthropology,” we are easily able to associate “neuro” with “nature” or “biology” and “anthropology” with “nurture” or “culture”.

I thoroughly enjoyed this reading. I enjoyed the organization of Downey’s thoughts and how not only did he strategically unfold his argument, but in order to further ones understanding of this phenomenon, he used examples from two disciplines that utilize the same sensory system in different ways and explained how this utilization yields diverse outcomes. I do wish, however, that a more neuroscientific explanation was provided for this phenomenon. As I was reading, I wondered specifically what mechanisms do scientists think are responsible for this mental modulation?

This chapter reminds me of the chapter titled, “Memory and Medicine,” by M. Cameron Hay. Similar to how memory systems can be reinforced by specific memorization practices found in different cultures, the equilibrium system may also be scaffolded and strengthened in a particular way. I see it as such: specific memorization techniques (culture/nurture) lead to the strengthening of specific neural pathways associated with memorization (biology/nature), which in turn, lead to specific memorization behaviors during memory recollection (culture/nurture/the individual). Analogous to this explanation is the following: specific balancing techniques (culture/nurture) lead to the strengthening of specific neural pathways associated with balance (biology/nature), which in turn lead to specific balancing behaviors during balancing practices (culture/nurture/the individual).

This chapter also reminded me that not only can sensation be culturally patterned but so can perception. Individuals living in different cultures may be culturally patterned to select, organize, process, and interpret information in different ways. Studies conducted by Segall, Campbell, and Herskovits (1963), using the Muller-Lyer Illusion test, reveal that there are cultural effects on the visual perception of optical illusions. Furthermore, another study conducted in 2009 by Ishi, et. al., researchers showed Japanese and American students images of familiar objects as wholes and as fragmented parts to determine if there are differences in analytical versus holistic perception. Findings show that American students were better able to identify the objects in the fragmented conditions when compared to the Japanese students. Researchers believe that this may be a reflection of American “individualistic” culture versus Japanese “holistic” or “collective” culture. These findings also coincide with what Downey presented in this chapter. It is important to acknowledge that visual perception is not natural, but rather cultural. Similarly, proprioception is also culturally mediated.

Questions to Ponder:

  1. Can you think of anything that is completely void of culture or not modulated by culture?
  2. What are some other examples of biological systems that were previously thought to be devoid of cultural influence?
  3. Can you think of a neurological study we can conduct to determine neurological similarities and differences between different culture’s vestibular dispositions?
  4. While understanding how culture impacts nature and vice versa, what dangers could we face when we begin to place cultural emphasis on differences?
  5. Can viewing biological systems in light of cultural influence cause for an increase in the categorization of people into groups, thereby creating harmful cultural constructions like race?

 

Further Reading:

Hay, M. Cameron. “Memory and Medicine.” In The Encultured Brain, D. Lende and G.   Downey, eds. (2012): 141-168. Cambridge: MIT.

Ishii, Keiko, Takafumi Tsukasaki, and Shinobu Kitayama. “Culture and visual perception: Does perceptual inference depend on  culture?” Japanese Psychological Research 51,2 (2009): 103-109.

Segall, Marshall H., Donald T. Campbell, and Melville J. Herskovits. “Cultural differences in the perception of geometric illusions.” Science 139,3556 (1963): 769-771.