title: Modulation of right motor cortex excitability without awareness following presentation of masked self-images.
abstract: The neural substrates of self-awareness have been studied with a variety of neurophysiological and behavioral tools. In the present study, unconscious modulation of corticospinal excitability following presentation of self-images was probed with transcranial magnetic stimulation (TMS). TMS-induced motor evoked potentials (MEP) were collected from the contralateral first dorsal interosseus (FDI) muscle while subjects viewed masked pictures of their own face. MEP amplitudes were compared to those obtained when pictures of strangers were masked. Masked self-images induced a relative increase in corticospinal excitability when TMS was applied to the right primary motor cortex. These results demonstrate the utility of TMS to probe unconscious processing and support the notion of hemispheric asymmetry in the processing of self-images.
authors.affiliation: Laboratory for Magnetic Brain Stimulation, Behavioral Neurology Unit, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA. hugo.theoret@umontreal.ca
authors.forename: Hugo
authors.initials: H
authors.lastname: Théoret
authors.forename: Masahito
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Lotfi
authors.initials: L
authors.lastname: Merabet
authors.forename: Tim
authors.initials: T
authors.lastname: Wagner
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Tormos
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
mesh_terms: D000328:Adult; D004574:Electromagnetic Fields; D005145:Face; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D012649:Self Concept