Neural encoding of actual and imagined touch within human posterior parietal cortex.

Srinivas Chivukula,Nader Pouratian,Kelsie Pejsa,Richard A Andersen,Tyson Aflalo,Carey Y Zhang,Matiar Jafari

doi:10.7554/elife.61646

Abstract

In the human posterior parietal cortex (PPC), single units encode high-dimensional information with partially mixed representations that enable small populations of neurons to encode many variables relevant to movement planning, execution, cognition, and perception. Here, we test whether a PPC neuronal population previously demonstrated to encode visual and motor information is similarly engaged in the somatosensory domain. We recorded neurons within the PPC of a human clinical trial participant during actual touch presentation and during a tactile imagery task. Neurons encoded actual touch at short latency with bilateral receptive fields, organized by body part, and covered all tested regions. The tactile imagery task evoked body part-specific responses that shared a neural substrate with actual touch. Our results are the first neuron-level evidence of touch encoding in human PPC and its cognitive engagement during a tactile imagery task, which may reflect semantic processing, attention, sensory anticipation, or imagined touch.

Highlights

Touch is a complex, multisensory perceptual process (de Haan and Dijkerman, 2020; de Lafuente and Romo, 2006; Graziano and Gross, 1993)
We referred to the implant area as the anterior intraparietal cortex, a region functionally defined in non-human primates (NHPs) (Aflalo et al, 2020, Aflalo et al, 2015; Rutishauser et al, 2018; Zhang et al, 2017; Zhang et al, 2020; Andersen et al, 2019; Sakellaridi et al, 2019)
Single neurons discriminated the location of actual touch: Of the 263 responsive units shown in Figure 1A, we found that 257 discriminated touch location (ANOVA, FDR corrected for multiple comparisons)

Summary

Introduction

Multisensory perceptual process (de Haan and Dijkerman, 2020; de Lafuente and Romo, 2006; Graziano and Gross, 1993). Recent human neuroimaging studies suggest that the PPC is recruited during touch cognition in the absence of actual tactile input (e.g., seen touch or imagined touch), supporting a notion that both higherlevel touch processing and tactile cognition share a neural substrate (Chan and Baker, 2015; Lucas et al, 2015). To date, such a link has not been established at the single neuron level. This richness of representation is made possible through a partially mixed encoding in which single neurons represent multiple variables, allowing a relatively small neuronal population

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Discussion

Conclusion