Hand specific representations in language comprehension.

Claire Moody-Triantis,Silvia P Gennari,Gina F Humphreys

doi:10.3389/fnhum.2014.00360

Claire Moody-Triantis, Silvia P Gennari + Show 1 more

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https://doi.org/10.3389/fnhum.2014.00360

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Abstract

Theories of embodied cognition argue that language comprehension involves sensory-motor re-enactments of the actions described. However, the degree of specificity of these re-enactments as well as the relationship between action and language remains a matter of debate. Here we investigate these issues by examining how hand-specific information (left or right hand) is recruited in language comprehension and action execution. An fMRI study tested self-reported right-handed participants in two separate tasks that were designed to be as similar as possible to increase sensitivity of the comparison across task: an action execution go/no-go task where participants performed right or left hand actions, and a language task where participants read sentences describing the same left or right handed actions as in the execution task. We found that language-induced activity did not match the hand-specific patterns of activity found for action execution in primary somatosensory and motor cortex, but it overlapped with pre-motor and parietal regions associated with action planning. Within these pre-motor regions, both right hand actions and sentences elicited stronger activity than left hand actions and sentences—a dominant hand effect. Importantly, both dorsal and ventral sections of the left pre-central gyrus were recruited by both tasks, suggesting different action features being recruited. These results suggest that (a) language comprehension elicits motor representations that are hand-specific and akin to multimodal action plans, rather than full action re-enactments; and (b) language comprehension and action execution share schematic hand-specific representations that are richer for the dominant hand, and thus linked to previous motor experience.

Highlights

Theories of embodied cognition argue that language understanding implies partially simulating or re-enacting the actions being described and involves brain regions that are recruited in the execution of those actions (Jeannerod, 2001; Glenberg and Kaschak, 2002; Barsalou et al, 2003; Gallese and Lakoff, 2005; Barsalou, 2008)
The nature of the representations that are shared between action and language remains unclear, in particular, their level of specificity, i.e., to what extent do we re-enact the execution of an action described by language? both primary motor and pre-motor regions have been associated with language comprehension and these contrasting findings imply different levels of specificity in the representations elicited by language: if primary motor regions are recruited during language comprehension, comprehenders can be thought to more closely re-enact the action described as if they were performing it, because these regions are directly connected to the spinal cord and musculature (Dum and Strick, 1996)
The view that language may involve highly specific action representations is consistent with fMRI language studies that have reported the recruitment of primary motor regions (Hauk et al, 2004; Rüschemeyer et al, 2007; Kemmerer et al, 2008; Kemmerer and Gonzalez-Castillo, 2010) and with TMS studies showing that stimulation of primary motor cortex during language comprehension modulates body-part specific motor evoked potentials (Oliveri et al, 2004; Buccino et al, 2005; Candidi et al, 2010)

Summary

Introduction

Theories of embodied cognition argue that language understanding implies partially simulating or re-enacting the actions being described and involves brain regions that are recruited in the execution of those actions (Jeannerod, 2001; Glenberg and Kaschak, 2002; Barsalou et al, 2003; Gallese and Lakoff, 2005; Barsalou, 2008). Both primary motor and pre-motor regions have been associated with language comprehension and these contrasting findings imply different levels of specificity in the representations elicited by language: if primary motor regions are recruited during language comprehension, comprehenders can be thought to more closely re-enact the action described as if they were performing it, because these regions are directly connected to the spinal cord and musculature (Dum and Strick, 1996). The view that language involves more schematic action representations is supported by many language studies showing the recruitment of planning-related pre-motor and parietal regions, rather than primary motor regions (Noppeney et al, 2005; Aziz-Zadeh et al, 2006; Moody and Gennari, 2010; Willems et al, 2010; Meteyard et al, 2012)

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