“You Never Forget How to Ride a Bike”… Because of No Plasticity?

 

The complexity of learning is something that is unique to humans. Speaking solely about physical actions, the majority of learned behaviors require at least some continual thought and processing even after the behavior has been absorbed. For example, I have played the piano for ten years and have memorized a couple of songs. Even though I have performed each song a countless number of times and am certainly more efficient at playing because of the number of repetitions, performing by memory still requires some conscious processing of each note and measure. Some learned behaviors though may become so rehearsed that they require minimal thought at all. One classic example is riding a bike.

The saying “you never forget how to ride a bike” is common in the US. Although the average person won’t typically consider this phrase in the context of neural plasticity, a significant component of learning any behavior is the strengthening of existing neural connections. As the behavior is repeatedly practiced, connections are reinforced via myelination, subsequently leading to an increase in cognitive function and development of motor skills (Fields 2005; Wendelken et al., 2015). This strengthening occurs over many other areas in the brain as well, depending on the specific environmental factor. For example, neurons can strengthen connections in the visual cortex related to depth perception as well as in the associative regions related to any existing knowledge (Dubuc, n.d.). However, the key component of learning a new behavior is the formation of new, stronger connections coupled with a decrease in the myelination of the old neural networks (Beckman, 2004). The maxim though suggests that the pathways involved are not plastic and will not deteriorate or be overwritten. So, is it possible to never forget how to ride a bike? Apparently, it’s not…

The reason it’s not possible is because Destin (the engineer from the video) never truly forgets how to ride a normal bike. Principally, the old behavior is very resistant to being overshadowed by the new bike. The first instance of this is when he is on the verge of being able to successfully ride. Between minute 3:45 and 4:01, Destin describes how he is able to ride the opposite-steering bike by not paying close enough attention to the urge to resort back to the old behavior. However, the moment he is distracted buy another stimuli (such as by a cellphone ringing), his mind reverts back to the original pathway. The fact that his mind will so easily return to its originally programed behavior illustrates the behavior’s resistance to being surpassed by a new pathway.

Destin also experiences a quick “unlearning” of the new behavior when he travels to Amsterdam at minute 4:54 of the video. When he attempts to ride a normal bike, Destin appears to struggle just as he did when he first started to learn to ride the backwards bike, or as all the people he brought on stage at his talks did in the beginning of the video. Despite his initial trouble, and although it took him eight months to learn to ride the new bike, he is able to relearn to ride the conventional bike in roughly twenty minutes. Destin explains this as an example of the brain’s biases, but it also exemplifies how resilient the original pathway is to significant changes. If the brain will revert back to its original pathway for this behavior, clearly the original pathway is resistant to change.

These behaviors though are different than genetically autonomic processes. Breathing, for example, is purely automatic in that it occurs continuously without thought; regardless of what we are doing, our diaphragm and lungs unceasingly contract and expand. For example, when someone sees a bear, his or her respiratory rate is going to increase as a result of the somatic nervous system. If there were no bear, the respiratory rate would remain constant. Thus, this is a pure reactionary process that does not require any thought and will continuously occur. Riding a bike though is a learned behavior with minimal (if any) genetic relation. Learned behaviors generally rely on plasticity whereby some pathways are strengthened while others are weakened. However, riding a bike may be a unique situation where the pathway does not undergo plasticity and the behavior cannot be unlearned or surpassed.

Questions for further discussion

  • Is the neural pathway of riding a bike only resistant to change in adulthood?
    • For example, Destin discovers that his son is able to learn to ride the new bike to the same extent he could but in roughly one-sixteenth the amount of time (two weeks instead of eight months). Combing this with the fact that children typically have more neural plasticity than adults (Georgieff, Brunette, & Tran, 2015), would a child be able to master both bikes and not have as resistant a pathway?
  • What other behaviors might experience the same resistance to unlearning?
    • Personal example: one behavior that I continually struggle with is spacing after periods. In elementary school, I was taught to add two spaces after periods when typing. As this is not the conventional behavior, I have tried to learn to just add one space. However, I frequently find myself adding two and having to backspace. Thus, for me, spacing after periods seems to be an “unforgettable behavior”.

References

Beckman, M. (2004). Crime, culpability, and the adolescent brain. Science, 305(5684), 596-599. doi:10.1126/science.305.5684.596

Dubuc, B. (n.d.). Plasticity in neural networks. The Brain from Top to Bottom. Retrieved from http://thebrain.mcgill.ca/flash/d/d_07/d_07_cl/d_07_cl_tra/d_07_cl_tra.html

Fields, R. (2005). Myelination: an overlooked mechanism of synaptic plasticity?. The Neuroscientist, 11(6), 528-531.

Georgieff, M., Brunette, K., & Tran, P. (2015). Early life nutrition and neural plasticity. Development and Psychopathology, 27(2), 411-423. doi:10.1017/S0954579415000061

Smarter Every Day. (2015, April 24). The backwards brain bicycle- Smarter every day 133 [Video file]. Retrieved from https://www.youtube.com/watch?v=MFzDaBzBlL0

Wendelken, C., Lee, J., Pospisil, J., Sastre, M., Ross, J., Bunge, S., & Ghetti, S. (2015). White matter tracts connected to the medial temporal lobe support the development of mnemonic control. Cerebral Cortex, 25(9), 2574-2583. doi:10.1093/cercor/bhu059

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