Hariri Institute Distinguished Lecture - Jason Ritt

Starts:
3:00 pm on Wednesday, March 20, 2013
Ends:
5:00 pm on Wednesday, March 20, 2013
Location:
MCS 180
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.