ABSTRACT
It has been suggested that chronic alcoholism may lead to altered neural mechanisms related to inhibitory processes. Here, we studied auditory N1 suppression phenomena (i.e. amplitude reduction with repetitive stimuli) in chronic alcoholic patients as an early-stage information-processing brain function involving inhibition by the analysis of the N1 event-related potential and time-frequency computation (spectral power and phase-resetting). Our results showed enhanced neural theta oscillatory phase-resetting underlying N1 generation in suppressed N1 event-related potential. The present findings suggest that chronic alcoholism alters neural oscillatory synchrony dynamics at very early stages of information processing.
Subject(s)
Alcohol-Induced Disorders, Nervous System/physiopathology , Alcoholism/physiopathology , Auditory Perception/drug effects , Cognition Disorders/physiopathology , Sensory Gating/physiology , Theta Rhythm/drug effects , Acoustic Stimulation , Adult , Alcoholism/complications , Auditory Perception/physiology , Brain/drug effects , Brain/physiopathology , Central Nervous System Depressants/adverse effects , Chronic Disease , Cognition Disorders/chemically induced , Electroencephalography , Ethanol/adverse effects , Evoked Potentials/drug effects , Evoked Potentials/physiology , Humans , Male , Middle Aged , Neural Inhibition/drug effects , Neural Inhibition/physiology , Reaction Time/drug effects , Reaction Time/physiology , Sensory Gating/drug effectsABSTRACT
OBJECTIVE: Increased distractibility is a common impairment in alcoholism, but objective evidence has remained elusive. Here, a task designed to investigate with event-related brain potentials (ERPs) the neural mechanism underlying distraction was used to show abnormal involuntary orienting of attention in chronic alcoholism. METHODS: Fifteen alcoholics and 17 matched healthy controls were instructed to ignore auditory stimuli while concentrating in the discrimination of immediately following visual stimuli. The auditory sequences contained repetitive standard tones occasionally replaced by deviant tones of slightly higher frequency, or by complex novel sounds. RESULTS: Deviant tones and novel sounds distracted visual performance, i.e. increased reaction time to visual stimuli, similarly in patients and controls. Compared to controls, however, alcoholics showed ERP abnormalities, i.e. enhanced P3a amplitudes over the left frontal region, and a positive posterior deflection instead of the frontally distributed reorienting negativity (RON). CONCLUSIONS: The enhanced P3a to novelty and subsequent positive wave instead of RON in alcoholics suggests encoding into working memory of task-irrelevant auditory events and provides neurophysiological markers of impaired involuntary attention mechanisms in chronic alcoholism.
