Inhibitory impact of subliminal electrical finger stimulation on SI representation and perceptual sensitivity of an adjacent finger.
Simultaneous stimulation of two adjacent fingers above sensory perception threshold (supraliminal stimulation) leads to an inhibitory interaction effect on responses in primary somatosensory cortex (SI). Moreover, during electrical finger stimulation closely below threshold for conscious perception (subliminal stimulation) inhibitory interneurons in cortical layer 4 are assumed to be activated preferentially as compared to excitatory interneurons. Using fMRI in humans, here we show that interspersed subliminal electrical stimulation of an adjacent finger reduces the response to target finger stimulation in contralateral SI. This effect was shown in a complementary study to be associated behaviorally with a diminished detectability of test pulses on the target finger. We propose the mechanism underlying this lateral inhibitory effect to be related to a representational overlap of inhibitory interneurons in SI based on the divergence of thalamocortical feedforward projections, or to intracortical lateral inhibitory projections targeting juxtaposed receptive fields, or both.
Taskin
Birol
B
Neurologische Klinik und Poliklinik, Charité-Universitätsmedizin Berlin, Campus Charité Mitte, Berlin NeuroImaging Center, Charitéplatz 1, 10117 Berlin, Germany. birol.taskin@charite.de
Holtze
Susanne
S
Krause
Thomas
T
Villringer
Arno
A
D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation; D005260:Female; D005385:Fingers / Q000294:innervation* / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology; D011601:Psychophysics; D013003:Somatosensory Cortex / Q000502:physiology*; D013360:Subliminal Stimulation