[Jason Ritt] Pinky and the Brain

3:00 PM Wednesday, March 20, 2013

Pinky and the Brain: Action and Actuation in the Sense of Touch

Jason Ritt

Assistant Professor of Biomedical Engineering
Hariri Institute Junior Faculty Fellow

Abstract: Stimulation neurotechnology encompasses an expanding range of applications, from deep brain stimulation to sensory prosthetics. I will discuss our recent efforts in applying neurocontrol to understand and manipulate biological active touch. By active, we mean that neural activity depends not only on feedforward stimuli, but also on rapid information-driven feedback to sensing behaviors. The presence of this closed loop motivates sensory prosthetic designs as dynamical control devices, and not simple encoders of fixed neural activity patterns. To investigate active sensing, we use real time neurofeedback to alter cortical activity in freely exploring mice, a key model system for the study of touch. Mice explore objects of interest through rhythmic 5-20 Hz whisker motions, with rapidly changing whisking in response to object contacts. We express the light sensitive ion channel Channelrhodopsin-2 (ChR2) in populations of neurons in primary somatosensory cortex (SI), allowing optogenetic stimulation. Using custom chronic implants, we perform multi-electrode cortical recording and optogenetic stimulation in SI, with bilateral facial electromyograms (EMG) and high speed video to track volitional whisker movement. Expanding on previous reports in head-fixed mice with randomly timed SI activation, we find that locking stimulation to volitional motions can strengthen and regularize whisking, loosely consistent with palpations of virtual objects. I will discuss our ongoing efforts to embed the stimulation paradigm into psychophysical tasks and neurocontrol theory. Of particular interest to computational scientists are theoretical challenges to finding neurocontrol strategies appropriate to the “underactuated” context of current stimulation technology. These initial results are a step toward developing control systems for use in studies of neural coding during active sensing, and potential sensory prosthetic devices.

Bio: Professor Jason Ritt joined the Department of Biomedical Engineering in 2010. His current research concentrates on how organisms gather and use information from their environment, through active sensing and sensory decision-making. For example, Prof. Ritt and his students are studying the ways in which mice explore environments using their whiskers, employing a combination of computational analysis of high-speed video, electrophysiological recordings, and neurocontrol methods implemented by a real-time feedback system built on a digital signal processing architecture. He received his Ph.D. in neuroscience and a Masters in mathematics from Boston University.