Motor‐evoked potentials reveal a motor‐cortical readout of evidence accumulation for sensorimotor decisions |
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Authors: | Aviad A. Hadar Paula Rowe Steven Di Costa Alexander Jones Kielan Yarrow |
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Affiliation: | 1. Department of Psychology, City University London, London, UK;2. Department of Life Science, Ben‐Gurion University, Be'er Sheva, Israel;3. Institute of Cognitive Neuroscience & Department of Psychology, University College London, London, UK;4. Department of Psychology, Middlesex University, London, UK |
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Abstract: | Many everyday activities require time‐pressured sensorimotor decision making. Traditionally, perception, decision, and action processes were considered to occur in series, but this idea has been successfully challenged, particularly by neurophysiological work in animals. However, the generality of parallel processing requires further elucidation. Here, we investigate whether the accumulation of a decision can be observed intrahemispherically within human motor cortex. Participants categorized faces as male or female, with task difficulty manipulated using morphed stimuli. Transcranial magnetic stimulation, applied during the reaction‐time interval, produced motor‐evoked potentials (MEPs) in two hand muscles that were the major contributors when generating the required pinch/grip movements. Smoothing MEPs using a Gaussian kernel allowed us to recover a continuous time‐varying MEP average, comparable to an EEG component, permitting precise localization of the time at which the motor plan for the responding muscle became dominant. We demonstrate decision‐related activity in the motor cortex during this perceptual discrimination task, suggesting ongoing evidence accumulation within the motor system even for two independent actions represented within one hemisphere. |
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Keywords: | MEP Motor control Decision making TMS Face processing Accumulation‐to‐bound models |
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