Comparison of midlatency auditory sensory gating at short and long interstimulus intervals.
BACKGROUND
Suppression of P50, N100 and P200 auditory evoked responses in a dual-click procedure is considered an index for the multistage sensory gating process. Whereas most studies use a protocol with long interstimulus intervals of 8-12 s between the stimuli pairs, there is also evidence that sensory gating occurs at much lower intervals. The aim of the study was to investigate whether a simple modified dual-click protocol with short interstimulus intervals elicts similar sensory gating ratios compared to the classic protocol.


METHODS
P50, N100 and P200 amplitudes and sensory gating ratios were measured in 23 healthy subjects with 2 different dual-click protocols in 1 session: (1) a simple oddball modified with short interstimulus intervals of about 2.8 s (ISI2), and (2), the classic used with long intervals of about 8 s (ISI8).


RESULTS
The amplitudes of the P50, N100 and P200 responses were mostly comparable and correlated between both protocols. Mean sensory gating ratios (ISI8/ISI2) were as follows: P50, 35.4/36.4%; N40P50, 36.1/39.9%; N100, 44.4/48.4%; P200, 46.8/43.3%; N100P200, 45.3/41.8%; all differences between protocols, p > 0.1. P50 ratio scores did not show a sufficient correlation between protocols [intraclass correlation coefficient (ICC) P50, 0.13; N40P50, 0.0] compared to N100 (ICC, 0.79), P200 (ICC, 0.6) and N100P200 (ICC, 0.61).


CONCLUSIONS
Our results contradict the assumption that long interstimulus intervals of about 8 s are absolutely necessary to elicit a marked sensory gating phenomenon for P50, N100 and P200 auditory responses (at least when using a protocol with a simple attention task). However, because only healthy subjects were investigated, no prediction can be made for psychiatric patients, in whom neuronal processing may be different.
Rentzsch
Johannes
J
Campus Mitte, Department of Psychiatry, Charité - Universitatsmedizin Berlin, Berlin, Germany. johannes.rentzsch@charite.de
de Castro
Ana Gomez-Carrillo
AG
Neuhaus
Andres
A
Jockers-Scherübl
Maria C
MC
Gallinat
Jürgen
J
D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001306:Auditory Pathways / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D055139:Sensory Gating / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult