Reduced Resource Optimization in Male Alcoholics: N400 in a Lexical Decision Paradigm

Abstract

Background Event Related Potential (ERP) studies have highlighted some measures, notably P3 amplitude, that are associated with both state and trait deficits in alcoholism, while studies examining N400 amplitude in alcoholism are few. The present study aims to examine changes in the N400 component, an electrophysiological correlate of semantic priming, in event-related potentials from a lexical decision task in 87 alcohol dependent subjects and 57 community controls. Method Each subject was presented with 300 stimuli sequentially in a quasi-randomized design, where 150 stimuli were words and 150 were non-words. The subjects made a lexical decision indicating the word/nonword status with a button press. Among the words, 50 words (primed) were always preceded by their antonyms (prime, n=50), whereas the remaining 50 words were unrelated. N400 amplitude and latency measures were compiled from ERPs to the primed and unprimed words. Corresponding reaction time and response characteristics were also analyzed. Results Control subjects revealed a significant attenuation of the N400 response to the primed word when compared to the unprimed word. Significantly less attenuation was observed in alcohol dependent subjects. No significant group differences were seen for latency and behavioral measures. All subjects had slower RT for unprimed words compared to primed words; however significantly less reaction time savings between the unprimed and primed condition was noted for alcoholics. Conclusion These results suggest a reduced flexibility in the cognitive networks and a lack of resource optimization in alcoholics. The reduced attenuation of N400 during the primed condition in the alcohol dependent subjects may reflect an inability to engage similar neuronal substrates associated with semantic relatedness as seen in the controls. As diminished N400 attenuation during priming is observed in both alcoholics and high risk subjects, it may be a marker of risk and a good endophenotype for alcoholism.

N4 component responses to pre-pulse startle stimuli in young adults: Relationship to alcohol dependence

“…In one study a lexical decision task was employed to study 87 alcohol dependent subjects and 57 community controls. In that study alcohol dependent participants were found to display less attenuation of the N400 response to primed words when compared to unprimed words (Roopesh et al, 2010). Additionally, similar findings were observed for a group of high risk offspring of alcoholics as compared to low risk children where the same finding of a lack of attenuation for primed words was observed (Roopesh et al, 2009).…”

“…Electrophysiological studies of individuals with alcohol dependence and subjects with a family history of alcoholism have demonstrated that deficits in a number of event-related potential (ERPs) components, with robust findings observed for late positivities (300-450 msec) (this literature is very large and there are a number of excellent reviews, see Begleiter and Porjesz, 1999, Porjesz and Begleiter, 2003, Porjesz et al, 2005, Campanella et al, 2009]) and more recently late negativities (300-650 msec) as well (see Roopesh et al, 2009, 2010). …”

Understanding alcohol use disorders with neuroelectrophysiology

“…Reduced N4 amplitude of the difference waveform between primed and unprimed words has been reported (Nixon et al, 2002). Similarly, in a recent semantic decision task there was less attenuation of N400 amplitudes to primed words when compared to unprimed words in alcoholics, a phenomenon that was intact in the controls (Porjesz et al, 2002b; Roopesh et al, 2010) (Fig. 23.4).…”

Spatio-temporal processing of words and nonwords: Hemispheric laterality and acute alcohol intoxication

“…Even though some evidence suggests that verbal skills are relatively well preserved in individuals with alcohol dependence (Oscar-Berman and Schendan, 2000; Parsons, 1987), ERP studies indicate deficits in semantic processing. Studies of abstinent long-term alcoholics indicate reduced N400 amplitudes, suggesting that such individuals do not benefit from priming induced by sentential or single-word paradigms (Ceballos et al, 2005; Nixon et al, 2002; Roopesh et al, 2010). Furthermore, similar priming deficiencies found in individuals with a family history of alcoholism (Roopesh et al, 2009) suggest a genetic component (Almasy et al, 2001).…”