Lateral prefrontal ‘gaze’ signals encode future head and hand motion during visually guided reach.

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Veronica Nacher Carda¹ (vnacherc@yorku.ca), Parisa Abedi-Khoozani¹, Harbandhan Arora¹, Vishal Bharmauria¹, Xiaogang Yan¹, Hongying Wang¹, John Douglas Crawford¹; ¹York University

Lateral prefrontal cortex (LPFC) is associated with executive function, working memory and response selection. There is evidence that posterior LPFC is concerned with the high-level selection of specific motor repertoires, but it is not known if the LPFC is involved in the planning and coordination of the motion of specific effectors. Could LPFC encode context-dependent, coordinated, effector-specific motor strategies? We investigated this question by recording from the posterior lateral prefrontal cortex (pLPFC; spanning Brodman areas 45, 46, & 8a) while two Rhesus monkeys performed head-unrestrained reaches toward visual targets. Many (208 / 499) task-related neurons showed time-locked gaze- (and later reach) related responses, but surprisingly these ‘gaze’ responses disappeared (35 / 84 neurons) or diminished during gaze shifts toward the same targets without reach. Further, an in-depth spatial analysis (based on model fits to neural response fields) confirmed that these ‘gaze’ responses were not what they appeared to be. In direct contrast to the saccade system, gaze displacement models provided the worst fits to the data. Instead, pLPFC ‘gaze’ neurons preferentially coded skeletomotor motion, either future head (49%) or hand (33%) motion, with reach codes predominating later in the task. This is an important demonstration that signal timing does not always reflect spatial tuning in the same neurons. We conclude that many pLPFC ‘gaze’ responses are not involved in gaze control, but rather reflect gaze inputs that trigger complex head-hand repertoires: in other words, a high-level neural mechanism for eye-head-hand coordination.

Topic Area: PERCEPTION & ACTION: Vision