Unconscious modulation of motor cortex excitability revealed with transcranial magnetic stimulation.
Hugo Théoret, Erin Halligan, Masahito Kobayashi, Lotfi Merabet, Álvaro Pascual-Leone
Experimental Brain Research March 2004 DOI: 10.1007/s00221-003-1820-y (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Healthy volunteers |
| Interventions | Transcranial magnetic stimulation (TMS) masked semantic priming task |
| Measures | Motor evoked potentials (MEPs), event-related potentials |
| Key findings | The amplitude of TMS-induced motor evoked potentials from the first dorsal interosseus muscle was modulated by a masked, unseen semantic prime, consistent with temporal patterns revealed by event-related potentials. The authors state these data confirm previous reports of specific motor neural responses to an unseen visual stimulus and establish TMS as a valuable tool for studying the neural correlates of consciousness. |
Abstract
The neuronal effects of sensory events that do not enter conscious awareness have been reported in numerous pathological conditions and in normal subjects. In the present study, unconscious modulation of corticospinal excitability was probed in healthy volunteers with transcranial magnetic stimulation (TMS). TMS-induced motor evoked potentials (MEPs) were collected from the first dorsal interosseus muscle while subjects performed a masked semantic priming task that has been shown to elicit covert motor cortex activations. Our data show that the amplitude of the MEPs is modulated by an unseen prime, in line with temporal patterns revealed with event related potentials. These data confirm previous reports showing specific motor neural responses associated with an unseen visual stimulus and establish TMS as a valuable tool in the study of the neural correlates of consciousness.