Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (UMR5287)

Aquitaine Institute for Cognitive and Integrative Neuroscience

Université de Bordeaux

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33076 Bordeaux cedex


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CNRS Ecole Pratique des Hautes Etudes Université de Bordeaux

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Competition, Conflict and Change of Mind: A Role of GABAergic Inhibition in the Primary Motor Cortex

by Loïc Grattier - published on , updated on

Bastien Ribot1, Aymar de Rugy2, Nicolas Langbour3, Anne Duron4, Michel Goillandeau1 and Thomas Michelet2*

1 CNRS, IMN, UMR 5293, University of Bordeaux, Bordeaux, France
2 CNRS, EPHE, INCIA, UMR 5287, University of Bordeaux, Bordeaux, France
3 Unité de Recherche Clinique Intersectorielle en Psychiatrie à Vocation Régionale du Centre Hospitalier Henri Laborit, Poitiers, France
4 Faculté de Médecine, Université de Paris, Paris, France

Front. Hum. Neurosci., 04 January 2022 |

Deciding between different voluntary movements implies a continuous control of the
competition between potential actions. Many theories postulate a leading role of
prefrontal cortices in this executive function, but strong evidence exists that a motor
region like the primary motor cortex (M1) is also involved, possibly via inhibitory
mechanisms. This was already shown during the pre-movement decision period,
but not after movement onset. For this pilot experiment we designed a new task
compatible with the dynamics of post-onset control to study the silent period (SP)
duration, a pause in electromyographic activity after single-pulse transcranial magnetic
stimulation that reflects inhibitory mechanisms. A careful analysis of the SP during the
ongoing movement indicates a gradual increase in inhibitory mechanisms with the level of competition, consistent with an increase in mutual inhibition between alternative movement options.
However, we also observed a decreased SP duration for highcompetition trials associated with change-of-mind inflections in their trajectories. Our results suggest a new post-onset adaptive process that consists in a transient reduction of GABAergic inhibition within M1 for highly conflicting situations. We propose that this reduced inhibition softens the competition between concurrent motor options, thereby favoring response vacillation, an adaptive strategy that proved successful at improving behavioral performance.

: decision, executive control, behavioral adaptation, reaching movement, transcranial magnetic stimulation, silent period, inhibition, primary motor cortex (M1)