Grip Force Is Part of the Semantic Representation of Manual Action Verbs

Victor Frak,Henri Cohen,Tatjana Nazir,Michel Goyette,Marc Jeannerod,Paul L Gribble

doi:10.1371/journal.pone.0009728

Abstract

Motor actions and action verbs activate similar cortical brain regions. A functional interference can be taken as evidence that there is a parallel treatment of these two types of information and would argue for the biological grounding of language in action. A novel approach examining the relationship between language and grip force is presented. With eyes closed and arm extended, subjects listened to words relating (verbs) or not relating (nouns) to a manual action while holding a cylinder with an integrated force sensor. There was a change in grip force when subjects heard verbs that related to manual action. Grip force increased from about 100 ms following the verb presentation, peaked at 380 ms and fell abruptly after 400 ms, signalling a possible inhibition of the motor simulation evoked by these words. These observations reveal the intimate relationship that exists between language and grasp and show that it is possible to elucidate online new aspects of sensorimotor interaction.

Highlights

The consequence of lesions and the functional overlap between language and motor action strongly suggest that aspects of language and action are intimately linked
There was a change in grip force when the target word was a verb, but not when it was a noun An increase in force was observed at about 100 ms following the verb display, deviated significantly from the noun curve at approximately 260 ms and fell abruptly after reaching a peak at 380 ms
Analyses of non-target verbs and nouns showed no significant difference in grip force

Summary

Introduction

The consequence of lesions and the functional overlap between language and motor action strongly suggest that aspects of language and action are intimately linked. In early writings on apraxia, Liepmann [1] described patients unable to carry out voluntary and skillful movements following verbal requests with their left body parts following lesions to the forebrain. In the case of articulatory dyspraxia, with difficulties in speaking or pronunciation, the question remains as to whether it is a disorder of motor control or an expression of aphasia constrained by syntactic categories. Broca [3], in his original presentation of patient Tan, already presented evidence of articulatory disturbance in speech (aphemia) as a result of frontal cerebral damage

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