Alcohol impairs auditory processing of frequency changes and novel sounds: a combined MEG and EEG study.

RATIONALE

Alcohol has been shown to impair involuntary attention studied by event-related potentials using mismatch negativity (MMN) and P3a.

OBJECTIVES

However, no studies have investigated whether alcohol affects the magnetic counterparts of N1 (N1m), MMN (MMNm) and P3a (P3am).

METHODS

Auditory evoked potentials and magnetic fields elicited by infrequent deviant tones differing in frequency (5% and 20% change) and novel sounds were recorded with whole-head magnetoencephalography (MEG) and electroencephalography (EEG). Stimuli were presented separately to the left and right ear. Eleven right-handed subjects were studied in a double-blind, placebo-controlled (0.8 g/kg ethanol or juice), cross-over design. N1m, MMNm, and P3am were calculated from the channel pair at the temporal cortex showing the strongest responses in the hemisphere contralateral to the stimulation. N1, MMN and P3a were analyzed from 12 electrodes at the midline frontocentral area.

RESULTS

Alcohol reduced bilaterally N1, N1m, MMN and MMNm amplitudes. P3a amplitudes, but not P3am amplitudes were also significantly decreased. No effects of alcohol on the latencies of N1, MMN and P3a or their magnetic counterparts were observed.

CONCLUSIONS

Alcohol impairs the processing of tones, frequency change and novel sounds at different phases of auditory processing similarly in both hemispheres. MEG provides us with additional information unobtainable with EEG about the effects of alcohol on the neural correlates of cognition.