TMS modulation of visual and auditory processing in the posterior parietal cortex.
Audio-visual stimuli typically yield faster responses than isolated modality-specific ones. This crossmodal speed advantage depends upon efficient multisensory integration mechanisms in the brain. Here, we used repetitive transcranial magnetic stimulation (rTMS) to address the role of the posterior parietal cortex, in particular of the inferior parietal lobule (IPL), in speeding up responses to crossmodal stimuli. The results show that rTMS over IPL impairs the response to contralateral modality-specific visual and auditory targets without affecting the response speed advantage following audio-visual targets. Furthermore, this speed advantage is subserved by a neural coactivation mechanism suggesting a summation in a given neural site. Control rTMS over V1 impaired only contralateral visual responses without affecting the response to auditory or audio-visual targets. These results suggest that the response speed advantage for crossmodal targets is maintained in spite of the IPL interference that impairs modality-specific responses. The possible role of alternative sites for the audio-visual advantage, such as the superior colliculus, is discussed.
Department of Psychology, University of Milano-Bicocca, Milan, Italy. nadia.bolognini@unimib.it
Nadia
N
Bolognini
Carlo
C
Miniussi
Silvia
S
Savazzi
Emanuela
E
Bricolo
Angelo
A
Maravita
D000161:Acoustic Stimulation; D000328:Adult; D001306:Auditory Pathways / Q000502:physiology / Q000528:radiation effects; D001307:Auditory Perception / Q000502:physiology* / Q000528:radiation effects; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology* / Q000528:radiation effects; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011827:Radiation; D011930:Reaction Time / Q000502:physiology* / Q000528:radiation effects; D013028:Space Perception / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology / Q000528:radiation effects; D014795:Visual Pathways / Q000502:physiology / Q000528:radiation effects; D014796:Visual Perception / Q000502:physiology* / Q000528:radiation effects; D055815:Young Adult