Evidence of dynamic top-down influences in the parieto-motor network during visuomotor behavior

It has been hypothesized that feedback connections originating from motor areas exert top-down influences on the posterior parietal cortex during visuomotor behavior. However, a comprehensive understanding of the dynamic reciprocal flow of information within the fronto-parietal network is still lacking. This study aims to investigate whether fronto-parietal communication can be modulated by cognitive components of motor preparation such as anticipation of the appearance of a visual target. To this end, two rhesus macaques were trained in a visuomotor sequential reaching task. Critically, the sequences were designed so that the predictability of the target’s location increased within the sequence. Analysis of the hand movement direction and the reaction times revealed that the animals started planning the upcoming movement earlier as the predictability of the next target location increased. Neural recordings were acquired by multi-electrode Utah arrays implanted in the dorsal premotor cortex (PMd) and the parietal area 7A. To identify the latent dimensions that maximize the preparatory tuning to different movement directions, we applied a Principal Component Analysis on the multiunit activity during the planning phase. The neural trajectories diverged from each other earlier as the predictability of the upcoming movement direction increased, coherent with our behavioral results. Directed functional connectivity analyses between the single-trial projections of PMd and 7A revealed the existence of significant top-down motor-parietal influences during movement planning, but unmodulated by target anticipation. Ongoing work aims to elaborate on the functional relevance of this interaction for the upcoming hand movement.