4 research outputs found
Paired Associative Stimulation of the Auditory System: A Proof-Of-Principle Study
Background
Paired associative stimulation (PAS) consisting of repeated application of transcranial magnetic stimulation (TMS) pulses and contingent exteroceptive stimuli has been shown to induce neuroplastic effects in the motor and somatosensory system. The objective was to investigate whether the auditory system can be modulated by PAS.
Methods
Acoustic stimuli (4 kHz) were paired with TMS of the auditory cortex with intervals of either 45 ms (PAS(45 ms)) or 10 ms (PAS(10 ms)). Two-hundred paired stimuli were applied at 0.1 Hz and effects were compared with low frequency repetitive TMS (rTMS) at 0.1 Hz (200 stimuli) and 1 Hz (1000 stimuli) in eleven healthy students. Auditory cortex excitability was measured before and after the interventions by long latency auditory evoked potentials (AEPs) for the tone (4 kHz) used in the pairing, and a control tone (1 kHz) in a within subjects design.
Results
Amplitudes of the N1-P2 complex were reduced for the 4 kHz tone after both PAS(45 ms) and PAS(10 ms), but not after the 0.1 Hz and 1 Hz rTMS protocols with more pronounced effects for PAS(45 ms). Similar, but less pronounced effects were observed for the 1 kHz control tone.
Conclusion
These findings indicate that paired associative stimulation may induce tonotopically specific and also tone unspecific human auditory cortex plasticity
Figure 1
<p>A) Single pulses of paired associative stimulation conditions (PAS(45 ms), PAS(10 ms)). P1 reflects the onset of cortical processing of the auditory stimulus in secondary auditory cortex. Thus, for both PAS conditions cortical processing starts after the TMS stimulus with the PAS(45 ms) being more close to the P1 than the PAS(10 ms). Therefore both conditions are considered inhibitory with a more pronounced inhibition for the PAS(45 ms). B) Study design (AEPs = acoustic evoked potentials; TMS =  transcranial magnetic stimulation; PAS = paired associative stimulation). C) Protocol of the measurement of auditory evoked potentials.</p
Amplitudes of the N1-P2 complex (difference of the amplitudes of both components) (mean±se).
<p>N1 amplitudes were averaged for the time interval from 75 to 125 ms and P2 amplitudes from 150 to 250 ms at fronto-central electrodes (F3, F1, Fz, F2, F4, FC3, FC1, FCz, FC2, FC4, C3, C1, Cz, C2, C4, CP1, CPz, CP2).</p
Topographies from 0 to 0.38s averaged in steps of 0.02s for the grand average of all pre stimulation conditions.
<p>Topographies from 0 to 0.38s averaged in steps of 0.02s for the grand average of all pre stimulation conditions.</p