During the morning session of #SfN14 today, I was able to survey some of the posters in the “sensorimotor learning” poster session. One poster that grabbed my attention was presented by Peter Butcher, who works for Jordan Taylor at Princeton University. Their work was exploring what kinds of sensory feedback are actually associated with sensorimotor adaptation.
“Sensorimotor adaptation” refers to how we accustom ourselves to changes in the environment. This is often probed using experiments that mess with sensory feedback or that apply unusual forces to subjects as they attempt to accomplish tasks. One of the most common paradigms for sensorimotor adaptation experiments is the “curl-field” paradigm. In these paradigms, subjects hold a robotic arm during reaching tasks, but the arm is programmed to apply a velocity-dependent force perpendicular to the direction of movement, and subjects have to compensate for this force to accomplish their tasks.
In the experiment Peter was talking about in his poster, subjects were required to move a cursor into a target. Two types of feedback were given: either end-of-movement visual feedback was given, or an integer value was given such that a score of 100 means you’re in the target. Only the case with visual feedback displayed adaptation; reward feedback does not cause the aftereffect you typically see when you return to full visual feedback. So the researchers asked: what is it about visual feedback that induces adaptation? They were able to determine that getting feedback about what direction the target is relative to your current position(without distance information) drives adaptation, while the converse (distance information without directional feedback) does not seem to cause adaptation. (Of course, having both kinds of feedback together gave the best adaptation results.)
What does this mean about how we learn? From a rehab perspective, understanding which aspects drive learning and adaptation can help shape the way we train and retrain movements.