No increase in corticospinal excitability during motor simulation provides a platform to explore the neurophysiology of aphantasia
Esselaar, M., Holmes, P. S., Scott, M. W., & Wright, D. J. (2024). No increase in corticospinal excitability during motor simulation provides a platform to explore the neurophysiology of aphantasia. Brain Communications, 6(2). doi:10.1093/braincomms/fcae084
Abstract
This scientific commentary refers to ‘Explicit and implicit motor simulations are impaired in individuals with aphantasia’, by Dupont et al. (https://doi.org/10.1093/braincomms/fcae072) in Brain Communications
Authors
- Maaike Esselaar2
- Paul S Holmes2
- Matthew W Scott2
- David J Wright2
What This Study Is About
Researchers wanted to know if aphantasia—the inability to "see" pictures in your mind—also affects how the brain prepares for movement. They looked at whether people with aphantasia can mentally "rehearse" an action in the same way people with typical mental imagery do.
How They Studied It
The researchers compared a group of people with aphantasia to a group with typical mental imagery (the ability to picture things in your mind).
Participants were asked to do two things:
1. Watch a video of someone pinching their fingers together.
2. Imagine the feeling of pinching their own fingers together.
While they did this, the researchers used a technique called TMS (a magnetic coil held over the head) to measure how "excited" the brain’s movement center was. Think of it like checking if a car engine is revving even while the car is in park.
What They Found
In most people, simply watching or imagining a movement "revs the engine" of the brain’s motor system, making it ready to act. However, in the aphantasia group, this didn't happen. Their brain activity didn't increase at all while watching or imagining the pinch. This suggests that for people with aphantasia, the brain doesn't "simulate" actions automatically the way it does for others.
What This Might Mean
This study suggests that aphantasia isn't just about a "blind mind's eye"—it might involve a broader difference in how the brain simulates all kinds of experiences, including touch and movement.
However, we have to be careful. This was a commentary on a specific study, and the authors noted a few "hiccups." For example, the researchers might have timed their measurements poorly. Because people with aphantasia often struggle to hold onto a mental image for long, the researchers might have checked the "engine" after it had already stopped revving. More research is needed to see if different timing would change the results.
One Interesting Detail
Aphantasia is a spectrum! While some people only lack visual images, about 24% of people with aphantasia have a "total" version where they also cannot imagine sounds, smells, or the physical feeling of a movement.
This summary was generated by AI and may contain errors. Always refer to the original paper for accuracy.