Time in the motor cortex: Motor evoked potentials track foreperiod duration without concurrent movement

•TMS is a widespread technique for investigating motor cortex dynamics.•We show that motor evoked potentials track duration, without a prepared response.•Cortical silent period did not vary with the duration of a strial.•These findings indicate a need for considering ‘when’ TMS is applied in a trial. Transcranial magnetic stimulation (TMS) allows for the monitoring of motor cortex dynamics in preparation for response. Using this method, it has previously been shown that motor evoked potentials (MEPs) are suppressed as a response approaches. In the current article, we applied TMS while participants either relaxed or contracted their first dorsal interosseous muscle. We varied the time at which TMS was applied, however, unlike previous studies, no participant response was required. Using this method, we provide evidence that MEPs systematically decrease with the duration of the trial, while inhibition is not similarly affected. Further, we found some evidence that MEPs are inversely proportional to the duration of the prior trial. These findings have ramifications for other research interested in the application of TMS, especially when used across multiple possible points in a trial. Further, this finding shows a role for the motor cortex in timing more broadly.