Neural Activity during Voluntary Movements in Each Body Representation of the Intracortical Microstimulation-Derived Map in the Macaque Motor Cortex

PLoS One. 2016 Aug 5;11(8):e0160720. doi: 10.1371/journal.pone.0160720. eCollection 2016.

Abstract

In order to accurately interpret experimental data using the topographic body map identified by conventional intracortical microstimulation (ICMS), it is important to know how neurons in each division of the map respond during voluntary movements. Here we systematically investigated neuronal responses in each body representation of the ICMS map during a reach-grasp-retrieval task that involves the movements of multiple body parts. The topographic body map in the primary motor cortex (M1) generally corresponds to functional divisions of voluntary movements; neurons at the recording sites in each body representation with movement thresholds of 10 μA or less were differentially activated during the task, and the timing of responses was consistent with the movements of the body part represented. Moreover, neurons in the digit representation responded differently for the different types of grasping. In addition, the present study showed that neural activity depends on the ICMS current threshold required to elicit body movements and the location of the recording on the cortical surface. In the ventral premotor cortex (PMv), no correlation was found between the response properties of neurons and the body representation in the ICMS map. Neural responses specific to forelimb movements were often observed in the rostral part of PMv, including the lateral bank of the lower arcuate limb, in which ICMS up to 100 μA evoked no detectable movement. These results indicate that the physiological significance of the ICMS-derived maps is different between, and even within, areas M1 and PMv.

MeSH terms

  • Animals
  • Body Image*
  • Brain Mapping / methods*
  • Electric Stimulation
  • Macaca
  • Motor Cortex / physiology*
  • Movement / physiology*
  • Neurons / physiology*

Grant support

This study was supported by Grants-in-Aid for Scientific Research (Grant Number 16K01489) from Japan Society for the Promotion of Science (JSPS; http://www.jsps.go.jp/english/e-grants/index.html) and Precursory Research for Embryonic Science and Technology (PRESTO) program from the Japan Science and Technology Agency (JST; http://www.jst.go.jp/EN/index.html) to NH. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.