Somatosensory Cortical Neurons Decode Tactile Input Patterns and Location from Both Dominant and Non-dominant Digits

Jonas M.D Enander,Henrik Jörntell

doi:10.1016/j.celrep.2019.02.099

Abstract

For neurons of the primary somatosensory cortex, the anatomy of the thalamocortical connections supports a digit-wise specialization, whereas the intracortical connections suggest cross-digit integration. To evaluate the digit-wise specialization in individual somatosensory neurons, we explored the decoding of eight spatiotemporally complex tactile input patterns delivered to two non-adjacent digits in the anaesthetized rat. A striking finding was a good decoding performance for the eight input patterns to the non-dominant digit of the neuron, which in some cases was even better than for the same inputs to the dominant digit. Moreover, individual neurons decoded not only the pattern received but also to which digit it was delivered. These neuronal decoding properties were uniform throughout the cortical layers. Our results indicate that non-trivial tactile inputs to a single digit engage a wide processing circuitry throughout the digit region and suggest a low impact for somatotopy on the organization of the information processing.

Highlights

The mapping of receptive fields of individual neurons has been and still is a cornerstone in many neurophysiological studies of the brain (Kaas et al, 1979; Mountcastle, 1957; Penfield and Boldrey, 1937; Woolsey et al, 1942)
Individual thalamocortical axons, even in the distinctly organized barrel cortex (Petersen, 2007), have rich branching patterns and cortical terminations well outside their primary cortical representations (Arnold et al, 2001; Oberlaender et al, 2011). These findings indicate that individual neurons in the somatosensory cortex, provided with a dominant thalamocortical input from single digits or whiskers, are provided with synapses representing information from non-dominant input
We find that individual neurons can decode tactile input patterns to a non-adjacent, non-dominant digit at a comparable or even a higher level than for inputs to the dominant digit while decoding which digit the input originated from

Summary

Introduction

The mapping of receptive fields of individual neurons has been and still is a cornerstone in many neurophysiological studies of the brain (Kaas et al, 1979; Mountcastle, 1957; Penfield and Boldrey, 1937; Woolsey et al, 1942). Individual thalamocortical axons, even in the distinctly organized barrel cortex (Petersen, 2007), have rich branching patterns and cortical terminations well outside their primary cortical representations (Arnold et al, 2001; Oberlaender et al, 2011). These findings indicate that individual neurons in the somatosensory cortex, provided with a dominant thalamocortical input from single digits or whiskers, are provided with synapses representing information from non-dominant input

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