This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link AbstractObjects are said to automatically "afford" various actions depending upon the motor repertoire of the actor. Such affordances play a part in how we prepare to handle or manipulate tools and other objects. Evidence obtained through fMRI, EEG and TMS has proven that this is the case but, as yet, the temporal evolution of affordances has not been fully investigated. The aim here was to further explore the timing of evoked motor activity using visual stimuli tailored to drive the motor system. Therefore, we presented three kinds of stimuli in stereoscopic depth; whole hand grasp objects which afforded a power-grip, pinch-grip objects which afforded a thumb and forefinger precision-grip and an empty desk, affording no action. In order to vary functional motor priming while keeping visual stimulation identical, participants between the participants' posture and the object category they viewed. These results indicate strong affordance-related activity around 300ms after stimulus presentation, particularly when the dominant hand can easily reach an object.

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link AbstractMany 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 categorised 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 localisation 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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