103.6 Saturday, Jan. 7 Kinematic and state representations by neuron population activity in MI orofacial cortex BROWN, Kevin A*; IRIARTE-DIAZ, Jose; TAKAHASHI, Kazutaka; HATSOPOULOS, Nicholas G.; ROSS, Callum F; University of Chicago; University of Chicago; University of Chicago; University of Chicago; University of Chicago firstname.lastname@example.org
The role of cortex in sensorimotor transformations during repeated iterations of voluntary arm and hand movements has been well studied, but its role in controlling ethologically relevant complex movement sequences is still poorly understood. The primate feeding system is well-suited to address this question, because feeding sequences include a rich combination of voluntary, semiautomatic, and reflexive jaw and tongue movements in response to continuously changing sensory feedback from food material properties. To investigate the role of motor cortex in regulating this complex convergence of information, we recorded activity from MIo neurons in three macaque subjects using Utah microarrays implanted in the orofacial region of primary motor cortex (MIo) while measuring tongue and jaw kinematics using videofluoroscopy and 3-d jaw tracking. Here we report that MIo neurons modulate their activity in response to natural categories of movement (ingestion, food manipulation, rhythmic chewing, swallowing), as well as continuous kinematic parameters. In particular, we show that both single neuron and population representations of movement include a nontrivial interplay between kinematic parameters and categorical state information. Using the generalized linear model framework in combination with dimensionality reduction techniques, we uncover aspects of this representation, including dynamic changes in network state as a function of movement context.