Sensory feedback-dependent coding of arm position in local field potentials of the posterior parietal cortex

Abstract

Although multisensory integration is crucial for sensorimotor function, it is still unclear how sensory cues provided by the visual and proprioceptive systems are combined in the brain during motor behaviors. Here we characterized the effects of multisensory interactions on local field potential (LFP) activity obtained from the superior parietal lobule (SPL) as non-human primates performed an arm position maintenance task with either unimodal (proprioceptive) or bimodal (visual-proprioceptive) sensory feedback. Based on previous analyses of spiking activity, and observations that LFP and spikes are highly correlated in some cortical areas, we hypothesized that evoked LFP responses would be tuned to arm location but would be suppressed on bimodal trials, relative to unimodal trials. We also expected to see a substantial number of recording sites with enhanced beta band spectral power for only one set of feedback conditions, as was previously observed for spiking activity. We found that evoked activity and beta band power were tuned to arm location at many individual sites, though this tuning often differed between unimodal and bimodal trials. At the population level, both evoked and beta band activity were consistent with feedback-dependent tuning to arm location, while beta band activity also showed evidence of suppression on bimodal trials. The results suggest that multisensory interactions can alter the tuning and gain of arm position-related LFP activity in the SPL and that this activity can be used to decode the arms location under varying sensory conditions.