engleski

Attentional modulation of the M50 cortical network underlying the auditory gating out phenomenon

Spatio-temporal identification of the cortical network underlying the suppression of the M50 auditory response after a repeated stimulation, a process conceptualized as the gating out mechanism, may advance understanding of the neural ability to inhibit redundant information, since a disruption of this ability is often associated with pathological conditions. This study challenges the accepted model of the M50 gating as a preattentive, automatic inhibitory process by investigating whether a voluntary attention directed at the second tone of a pair could affect the gating out phenomenon at the cortical level. MEG recordings (Elekta 306-channel and magnetically shielded room at the Biomagnetic Center in Jena, Germany) and the multi-dipole Calibrated Start Spatio-Temporal method were used to identify the M50 cortical network evoked by the paired-click paradigm in 19 healthy young subjects (21-38 years). Two consecutive (ISI=500 ms) identical short tones (S1 and S2, duration=20ms, f=1200Hz, ITI=8 ± 1s) were used to evoke standard gating cortical responses. In the second condition, the task was to direct attention toward the second tone and to respond to a rarely presented non-identical second tone of the pair (R=1300Hz, p(S1R) = 0.3) . Preliminary results indicated the activation of 3-4 brain regions in the 30-100 ms time interval, including bilateral superior temporal gyrus (STG), prefrontal (PF) and parietal (PA) regions. Targeting attention toward the second tone enhanced the M50 amplitude of the bilateral STG responses to the repeated stimulus S2. These results demonstrate that voluntary attention can modulate the gating out phenomenon opening a possibility of using attention control as a potentially efficient mechanism for reducing the gating disorders in some pathological conditions.

M50 auditory network; gating; attentional modulation; MEG

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