Motor-evoked potentials reveal a motor-cortical readout of evidence accumulation for sensorimotor decisions

Aviad A. Hadar, Paula Rowe, Steven Di Costa, Alexander Jones, Kielan Yarrow

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


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.

Original languageEnglish
Pages (from-to)1721-1731
Number of pages11
Issue number11
StatePublished - 1 Nov 2016


  • Accumulation-to-bound models
  • Decision making
  • Face processing
  • MEP
  • Motor control
  • TMS

ASJC Scopus subject areas

  • General Neuroscience
  • Neuropsychology and Physiological Psychology
  • Experimental and Cognitive Psychology
  • Neurology
  • Endocrine and Autonomic Systems
  • Developmental Neuroscience
  • Cognitive Neuroscience
  • Biological Psychiatry


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