Dysmelia

 

People born without arms and hands learn to perform all everyday tasks with their feet or mouth. In addition to finding this beautiful, I think they are a fascinating model for how the brain can change to respond to different sensory and motor experience.

 

Many parts of the brain show preferential responses to hands – viewing them, acting with them and feeling through them. What do these brain regions do in a person who has never had hands? How does your experience in using objects with your feet rather than your hands affect the perception of tools?

We have recently showed that despite having no experience in using their hands to manipulate tools, dysmelic people have typical responses for viewing hands and tools, and brain these regions overlap and connect to action networks similarly to what is found in typically developed people.

This shows that the connection between hands and tools is deeply ingrained in brain organization, and doesn’t depend on our own experience in using the two together ourselves.

In another study, we showed how action observation areas abstract beyond the body part used in the viewed action, such that they can represent actions a person cannot execute.

 

Another study showed that the early sensory and motor cortices (S1, M1) hand areas do not change their preference based on compensatory use, in that they don’t prefer the feet, used by the study participants to perform daily actions. In contrast, an association area, the anterior IPS, showed effector-based plasticity and did prefer the feet.

 

Together, these studies show that association areas dedicated to the hands are not limited in their preference for a specific body part. Instead, their organization depends on the computation performed (e.g. “tool manipulation”), which can therefore be adapted towards other body parts used for the same functions, in this case the feet.

This mirrors the metamodal, task-based organization in the visual cortex of the blind, extending it to the motor domain.

The early cortices preference, in contrast, is dictated by topographic, body-part specific representations. I currently continue studying this balance between action-type preference and body-part preference across the sensorimotor hierarchy.

 

I will be starting my lab at Georgetown University in September 2019 (SAMP Lab; Sensory and motor plasticity lab).

The lab will explore the balance between innate brain organization and experience-dependent plasticity by studying models of sensory and motor deprivation using behavioral and fMRI state of the art analytical techniques.

I am currently looking for a passionate and dedicated postdoctoral researcher to work on a project on plasticity in action execution with this population.