Overview

Using Brain Stimulation and Imaging Techniques to Study Human Movement

Josh Rieskamp, Centre College, Class of 2015

Structural MRI of my brain!

= significantly stronger in

skilled imagers

= no difference

= seed region

I participated in the Summer Research in Brain and Cognitive Science Program at the University of South Carolina where I conducted research using transcranial direct current stimulation (tDCS) and functional magnetic resonance imaging (fMRI). These exciting technologies are used to study the brain and its role in human thought and behavior. I worked with a graduate student to investigate whether tDCS can improve performance on tasks of fine motor control. If effective, tDCS could potentially supplement physical therapy in recovering stroke patients. I used fMRI to investigate how the brain functions during imagined movements. In particular, I was interested in whether variations in ability to imagine movement were related to differences in brain function. I found that relative to poor imagers, skilled imagers had different intrinsic activity in brain areas related to movement. This is important because some stroke patients benefit from mental training therapies in which they imagine movements; however, only those patients who are skilled at imagining movement benefit. Potentially, fMRI could be used to determine which stroke patients would benefit from mental training.

fMRIStronger Intrinsic Functional

Connectivity in Skilled Imagers

tDCS

Blood transports oxygen to neurons. In areas where neurons are very active,

blood contains higher oxygen concentrations.

(A) and (B) Participant engages in a cognitive task. (C) Neurons in the brain become more active and consume more oxygen. Which neurons become more active depends on the nature of the task. (D) and (E) By measuring blood oxygen levels (BOLD signal) fMRI produces images indicating which areas of the brain are more active during the task. Presumably, these active areas of the brain are important for carrying out that task.

Linking Intrinsic Brain Activity to Motor Imagery Ability

Conclusions

A) A tDCS unit with two sponge electrodes. By sending weak electrical currents through the skull, tDCS stimulates the surface of the brain and shows promise for improving cognitive and motor abilities. B) The primary motor cortex contains a “map” of the body. Stimulating the “hand” part of the cortex makes hand movements more likely. C) The Jebsen-Taylor Hand Function Test is used to test fine motor skills in healthy and clinical populations. Can brain stimulation speed the recovery of fine motor function in stroke patients?

(A) (B) (C) (A) (B)

I investigated whether skilled and poor imagers exhibit differences in intrinsic functional connectivity between brain regions associated with motor imagery. (A) Brain regions suspected to be involved in motor imagery, labeled by Brodmann’s Area. (B) The simple arm movement that participants were asked to visualize. Participants reported the ease with which they imagined the movement, and were separated into skilled and poor imager groups. While in the fMRI scanner, participants were instructed not to think of anything in particular, but to let their mind wander. HypothesisI hypothesized that skilled imagers would have stronger intrinsic functional connectivity between brain regions associated with motor imagery.

•Results were consistent with the hypothesis that skilled imagers have stronger intrinsic functional connectivity than poor imagers in brain regions related to motor imagery.

•These differences in intrinsic brain activity might underlie differences in the cognitive strategies adopted by skilled and poor imagers during imagined movement.

•fMRI can differentiate between skilled and poor imagers. This could be used to determine who would benefit from motor imagery training.

•My overall experience this summer has solidified my decision to pursue a Ph.D. in neuroscience.