Dose-related effect of alcohol on mismatch negativity and reaction time performance

Effects of benzodiazepine and orexin receptor antagonist on cognitive function revealed by auditory event-related potentials

BACKGROUND

Cognitive decline after oral administration of sedatives, such as benzodiazepines, is a serious side effect. Suvorexant, an orexin receptor antagonist, has a favorable tolerability and a limited side-effect profile.

AIM

The purpose of this study was to estimate the cognitive decline 1 day after oral medication with lormetazepam, a benzodiazepine, and suvorexant by comparing mismatch negativity (MMN) and P300 reflecting auditory discrimination function.

METHODS

Sixty healthy subjects (42 males) were randomly assigned to three groups receiving suvorexant 20 mg, lormetazepam 2 mg, or placebo in this double-blind, randomized control study. Event-related potential recordings during an auditory oddball task and a digit symbol substitution test (DSST) were performed 1 day after oral administration.

RESULTS

MMN, on the day after oral administration, was significantly attenuated in the lormetazepam group compared with the other two groups, but there was no difference between the suvorexant and placebo groups. No significant difference was found in P300 amplitudes and DSST scores among the three groups.

CONCLUSION

These findings suggest that suvorexant, unlike benzodiazepine, is not associated with cognitive deficits, as revealed by MMN but not P300. This study shows a neurophysiological difference in the effects of suvorexant and benzodiazepine on cognitive function.

Alcohol and Neural Dynamics: A Meta-analysis of Acute Alcohol Effects on Event-Related Brain Potentials

BACKGROUND

An understanding of alcohol's acute neural effects could augment our knowledge of mechanisms underlying alcohol-related cognitive/motor impairment and inform interventions for addiction. Focusing on studies employing event-related brain potential methods, which offer a direct measurement of neural activity in functionally well-characterized brain networks, we present the first meta-analysis to explore acute effects of alcohol on the human brain.

METHODS

Databases were searched for randomized laboratory alcohol-administration trials assessing brain activity using event-related potentials. Hedges' g coefficients were pooled using 3-level random-effects meta-regression.

RESULTS

Sixty independent randomized controlled trials met inclusion (total N = 2149). Alcohol's effects varied significantly across neural systems, with alcohol leading to reductions in event-related potential components linked with attention (P3b), g = -0.40, 95% CI (-0.50, -0.29), automatic auditory processing (mismatch negativity), g = -0.44, 95% CI (-0.66, -0.22), and performance monitoring (error-related negativity), g = -0.56, 95% CI (-0.79, -0.33). These effects were moderated by alcohol dose, emerging as significant at doses as low as 0.026% blood alcohol concentration and increasing to moderate/large at 0.12%. In contrast, irrespective of dose, relatively small or nonsignificant alcohol effects emerged in other processing domains, including those linked to executive control (N2b responses) and stimulus classification (N2c responses).

CONCLUSIONS

Contrary to traditional conceptualizations of alcohol as a "dirty drug" with broad central nervous system depressant effects, results instead support accounts positing targeted alcohol effects in specific processing domains. By identifying alcohol effects on brain systems involved in performance monitoring and attention, results move toward the identification of mechanisms underlying alcohol-related impairment as well as factors reinforcing addiction.

Using Mismatch Negativity to Investigate the Pathophysiology of Substance Use Disorders and Comorbid Psychosis

Substance use disorders (SUDs) have a devastating impact on society and place a heavy burden on health care systems. Given that alcohol, tobacco, and cannabis use have the highest prevalence, further understanding of the underlying pathophysiology of these SUDs is crucial. Electroencephalography is an inexpensive, temporally superior, and translatable technique which enables investigation of the pathobiology of SUDs through the evaluation of various event-related potential components, including mismatch negativity (MMN). The goals of this review were to investigate the effects of acute and chronic alcohol, tobacco, and cannabis use on MMN among nonpsychiatric populations and patients with comorbid psychosis. A literature search was performed using the database PubMed, and 36 articles met our inclusion and exclusion criteria. We found a pattern of attenuation of MMN amplitude among patients with alcoholism across acute and chronic alcohol use, and this dysregulation was not heritable. Reports were limited, and results were mixed on the effects of acute and chronic tobacco and cannabis use on MMN. Reports on comorbid SUDs and psychosis were even fewer, and also presented mixed findings. These preliminary results suggest that MMN deficits may be associated with SUDs, specifically alcohol use disorder, and serve as a possible biomarker for treating these common disorders.

Alcohol use in bipolar disorder: A neurobiological model to help predict susceptibility, select treatments and attenuate cortical insult

In a series of neurophysiological and neuroimaging studies we investigated the neurobiology related to alcohol use in young people with bipolar disorder. Impairments were identified across frontal and temporal representations of event-related potential and proton magnetic resonance spectroscopy markers; mismatch negativity and in vivo glutathione, respectively. We propose these findings reflect impairments in the N-methyl-D-aspartate receptor and antioxidant capacity. This review seeks to place these findings within the broader literature in the context of two propositions: 1. Pathophysiological impairments in N-methyl-D-aspartate receptor functioning in bipolar disorder contribute to susceptibility toward developing alcohol problems. 2. Alcohol aggravates bipolar disorder neuroprogression via oxidative stress. A neurobiological model that incorporates these propositions is presented, with a focus on the potential for N-methyl-D-aspartate receptor antagonism and glutathione augmentation as potential adjunctive pharmacotherapies to treat the comorbidity. While this review highlights the importance of alcohol monitoring and reduction strategies in the treatment of bipolar disorder, the clinical impact of the proposed model remains limited by the lack of controlled trials of novel pharmacological interventions.

The N-methyl-D-aspartate receptor as a neurobiological intersection between bipolar disorder and alcohol use: a longitudinal mismatch negativity study

BACKGROUND

Comorbid risky alcohol use in bipolar disorder (BD) is recognized for its high prevalence and clinical relevance, though understanding of its neurobiological underpinning is limited. The N-methyl-D-aspartate (NMDA) receptor has recognized alterations in BD and is a major site of ethanol's effects in the brain. The present study aimed to examine the NMDA receptor system in adolescents and young adults with BD by evaluating the longitudinal changes in a robust marker of NMDA function, mismatch negativity (MMN), in relation to changes in alcohol use patterns.

METHODS

Forty-six BD patients (aged 16-30) were recruited at baseline and 59% (n = 27) returned for follow-up 17.9 +/- 7.3 months later. At both time-points a two-tone, passive, duration-deviant MMN paradigm was conducted and alcohol measures were collected. Pearson's correlations were performed between changes in MMN amplitudes and changes in alcohol use. Multiple regression was used to assess whether MMN amplitudes at baseline could predict alcohol use at follow-up.

RESULTS

Reduction in risky drinking patterns was associated with increased temporal MMN and decreased fronto-central MMN. Larger temporal MMN at baseline was a significant predictor of greater alcohol use at follow-up.

CONCLUSIONS

Results suggest risky alcohol use in BD may further compound pre-existing NMDA receptor abnormalities and, importantly, reducing alcohol use early in stages of illness is associated with changes in MMN. This highlights the importance of monitoring alcohol use from first presentation. In addition, preliminary results present an exciting potential for utility of MMN as a neurobiological marker used to determine risk for alcohol misuse in BD.

Different effects of alcohol on automatic detection of colour, location and time change: a mismatch negativity study

The effects of alcohol on pre-attentive processing have been well studied in the past decades. However, the majority of studies focus on pre-attentive auditory processing and only a few studies have examined the effects of alcohol on visual processing. This study investigates the effects of alcohol on automatic pre-attentive processing of visual changes in colour, location and duration. We compared the mean amplitudes and the amplitude decline ratios of visual mismatch negativity (vMMN) responses elicited for small and large changes in image colour, location and duration in 12 individuals under the influence of alcohol and in a placebo condition. The vMMN amplitudes for changes in location and duration significantly decreased in the alcohol condition as compared with the placebo condition, and the magnitude of decrease was not related to the magnitude of change in the deviant stimuli. However, the amplitude of colour vMMN, in the alcohol condition, did not change significantly compared to the placebo condition. These results show that pre-attentive visual processing is impaired by alcohol, and that this impairment may be feature-specific. In addition, this impairment was not related to the magnitude of stimuli change.

Risky alcohol use predicts temporal mismatch negativity impairments in young people with bipolar disorder

Alcohol misuse in bipolar disorder (BD) has a negative impact on illness progression. The NMDA/glutamatergic system is implicated in BD pathophysiology and is critically involved in the effects of alcohol on the brain. Mismatch negativity (MMN) is purported to reflect NMDA receptor output, providing a measure for investigating this association. Forty-two patients and 34 controls (16-30 years) were split into low and high-risk drinkers (based on the Alcohol Use Disorders Identification Test) and underwent a two-tone passive auditory oddball, duration deviant MMN paradigm. Multiple regression models revealed risky drinking and BD diagnosis were predictors of impaired temporal MMN. Potentially reflecting an additive effect of alcohol on a perturbed NMDA/glutamatergic system in BD, these findings highlight alcohol as both a modifiable risk factor of neurobiological impairments and as a potential confounder in MMN studies. Given the increasing use of glutamatergic agents for BD treatment, this finding is important clinically.

Understanding alcohol use disorders with neuroelectrophysiology

Neurocognitive deficits associated with impairments in various brain regions and neural circuitries, particularly involving frontal lobes, have been associated with chronic alcoholism, as well as with a predisposition to develop alcohol use and related disorders (AUDs). AUD is a multifactorial disorder caused by complex interactions between behavioral, genetic, and environmental liabilities. Neuroelectrophysiologic techniques are instrumental in understanding brain and behavior relationships and have also proved very useful in evaluating the genetic diathesis of alcoholism. This chapter describes findings from neuroelectrophysiologic measures (electroencephalogram, event-related potentials, and event-related oscillations) related to acute and chronic effects of alcohol on the brain and those that reflect underlying deficits related to a predisposition to develop AUDs and related disorders. The utility of these measures as effective endophenotypes to identify and understand genes associated with brain electrophysiology, cognitive networks, and AUDs has also been discussed.

Speed isn't everything: complex processing speed measures mask individual differences and developmental changes in executive control

The rate at which people process information appears to influence many aspects of cognition across the lifespan. However, many commonly accepted measures of 'processing speed' may require goal maintenance, manipulation of information in working memory, and decision-making, blurring the distinction between processing speed and executive control and resulting in overestimation of processing speed contributions to cognition. This concern may apply particularly to studies of developmental change, as even seemingly simple processing speed measures may require executive processes to keep children and older adults on task. We report two new studies and a re-analysis of a published study, testing predictions about how different processing speed measures influence conclusions about executive control across the lifespan. We find that the choice of processing speed measure affects the relationship observed between processing speed and executive control, in a manner that changes with age, and that choice of processing speed measure affects conclusions about development and the relationship among executive control measures. Implications for understanding processing speed, executive control, and their development are discussed.

Effects of alcohol on auditory pre-attentive processing of four sound features: evidence from mismatch negativity

RATIONALE

Studies have shown that alcohol could impair automatic pre-attentive change detection. However, several earlier studies which investigated alcohol-induced effects on single auditory feature independently were different from each other on the results. Meanwhile, only few auditory features have been investigated yet. Therefore, it is meaningful to investigate effects of alcohol on multiple auditory features in one experiment.

OBJECTIVES

This study investigates the effects of alcohol on automatic pre-attentive change detection of four kinds of auditory features (frequency, intensity, location, and duration) in one experiment.

METHODS

This study, using multi-feature oddball paradigm, compares and analyzes mismatch negativity (MMN) elicited by four kinds of auditory features (frequency, intensity, location, and duration), of 12 participants, under alcohol (0.65 g/kg) and non-alcohol condition.

RESULTS

Compared to non-alcohol condition, amplitudes of all the four MMN types significantly declined under alcohol condition, and their amplitude decline ratios decreased as deviant magnitude became larger. Latencies of frequency and intensity MMN were delayed while latencies of location and duration MMN were not delayed significantly.

CONCLUSION

Alcohol impaired automatic pre-attentive change detection of all the four auditory features (frequency, intensity, location, and duration). However, the alcohol-induced impairment magnitude on automatic pre-attentive detection of the four auditory features was different from each other. According to analysis of amplitude, frequency seems to be affected most among the four auditory features. According to analysis of latency, only frequency and intensity were affected.

The effects of energy drink in combination with alcohol on performance and subjective awareness

RATIONALE

This study investigated the coadministration of an energy drink with alcohol to study the effects on subjective intoxication and objective performance.

OBJECTIVES

This study aims to evaluate the objective and subjective effects of alcohol versus placebo at two alcohol doses, alone and in combination with an energy drink, in a balanced order, placebo-controlled, double-blind design.

METHODS

Two groups of ten healthy volunteers, mean (SD) age of 24 (6.5), participated in the study. One group consumed energy drink containing 80 mg of caffeine and the other consumed a placebo drink, with both receiving two alcohol doses (0.046 and 0.087% breathalyser alcohol concentration). Tests included breath alcohol assessment, objective measures of performance (reaction time, word memory and Stroop task) and subjective visual analogue mood scales.

RESULTS

Participants showed significantly impaired reaction time and memory after alcohol compared to the no alcohol condition and had poorer memory after the higher alcohol dose. Stroop performance was improved with the energy drink plus alcohol combination compared to the placebo drink plus alcohol combination. Participants felt significant subjective dose-related impairment after alcohol compared to no alcohol. Neither breath alcohol concentration nor the subjective measures showed a significant difference between the energy drink and the placebo energy drink when combined with alcohol.

CONCLUSIONS

Subjective effects reflected awareness of alcohol intoxication and sensitivity to increasing alcohol dose. There were no overall significant group differences for subjective measures between energy drink and placebo groups in the presence of alcohol and no evidence that the energy drink masked the subjective effects of alcohol at either dose.

Effects of alcohol on attention orienting and dual-task performance during simulated driving: an event-related potential study

Driving is a complex task and is susceptible to inattention and distraction. Moreover, alcohol has a detrimental effect on driving performance, possibly due to alcohol-induced attention deficits. The aim of the present study was to assess the effects of alcohol on simulated driving performance and attention orienting and allocation, as assessed by event-related potentials (ERPs). Thirty-two participants completed two test runs in the Divided Attention Steering Simulator (DASS) with blood alcohol concentrations (BACs) of 0.00%, 0.02%, 0.05%, 0.08% and 0.10%. Sixteen participants performed the second DASS test run with a passive auditory oddball to assess alcohol effects on involuntary attention shifting. Sixteen other participants performed the second DASS test run with an active auditory oddball to assess alcohol effects on dual-task performance and active attention allocation. Dose-dependent impairments were found for reaction times, the number of misses and steering error, even more so in dual-task conditions, especially in the active oddball group. ERP amplitudes to novel irrelevant events were also attenuated in a dose-dependent manner. The P3b amplitude to deviant target stimuli decreased with blood alcohol concentration only in the dual-task condition. It is concluded that alcohol increases distractibility and interference from secondary task stimuli, as well as reduces attentional capacity and dual-task integrality.

Cognitive Event-Related Potentials and Alcoholism

The discipline of neuropsychiatry tries to bridge the gap between neurology and psychiatry in order to gain insight into the biological bases of psychiatric disorders. A principal tool is electrophysiological assessments, as, for instance, event-related potentials (ERPs). In this paper, we will review the current main findings concerning the status of cognitive ERPs in a specific psychiatric disease, i.e., chronic alcoholism. First, delayed P300 latency and reduced P300 amplitude are a common and robust finding in chronic alcoholics. Our aim will be to insert this empirical finding into the growing knowledge of molecular actions of alcohol and genetic patterns of alcohol dependence together with a more precise identification of alcohol-influenced neuronal and psychopathological processes. We will show how this may help us to reach a better understanding of this pathology. Second, an important set of data also pointed out that earlier ERP components, such as the N100, the mismatch negativity (MMN), the P100, and the N170, were also affected by chronic consumption of alcohol. Therefore, as the entire information-processing system seemed to be altered, these results deserved to be discussed, at least concerning their main clinical implications. Finally, although long term consequences of alcohol abuse have been extensively described, little is known about the detrimental effect on neural and cognitive processes of massive alcohol intake over a short period of time (e.g., binge drinking). Recent data on this new and challenging issue will be outlined.

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.

Mismatch negativity: no difference between controls and abstinent alcoholics

BACKGROUND

A number of studies have examined the amplitude of the mismatch negativity (MMN) evoked potential as a measure of a brain inhibitory deficit in alcoholics or those at risk for alcoholism. The current study examined MMN in alcoholics abstinent an average of 6.7 years (with a minimum of six months abstinence) compared to controls. This study examined the association of MMN with alcoholism family history density, with indices of the presence and severity of externalizing disorders (a risk-factor for alcoholism), and with alcohol use variables.

METHODS

Electroencephalograms were gathered on 76 subjects (38 controls, 38 abstinent alcoholics) during a nonattending mismatch negativity experiment. Measures of alcoholism family history density, disinhibited personality traits, and antisocial symptoms served as measures of risk-factors known to be associated with a genetic liability to alcoholism. Alcohol use variables were used as measures of alcoholism severity.

RESULTS

There were no differences in MMN amplitude or latency between controls and abstinent alcoholics. There also were no significant associations between MMN measures and the measures of risk for alcoholism or with the severity of alcohol use or duration of abstinence.

CONCLUSIONS

The results suggest that MMN is neither affected in chronic alcoholics nor associated with alcoholism vulnerability, and thus does not reflect a trait marker of alcoholism or alcoholism risk. The current results do not address effects on MMN of acute alcohol ingestion or withdrawal from alcohol.

Effects of the 5-HT2A agonist psilocybin on mismatch negativity generation and AX-continuous performance task: implications for the neuropharmacology of cognitive deficits in schizophrenia

Previously the NMDA (N-methyl-D-aspartate) receptor (NMDAR) antagonist ketamine was shown to disrupt generation of the auditory event-related potential (ERP) mismatch negativity (MMN) and the performance of an 'AX'-type continuous performance test (AX-CPT)--measures of auditory and visual context-dependent information processing--in a similar manner as observed in schizophrenia. This placebo-controlled study investigated effects of the 5-HT(2A) receptor agonist psilocybin on the same measures in 18 healthy volunteers. Psilocybin administration induced significant performance deficits in the AX-CPT, but failed to reduce MMN generation significantly. These results indirectly support evidence that deficient MMN generation in schizophrenia may be a relatively distinct manifestation of deficient NMDAR functioning. In contrast, secondary pharmacological effects shared by NMDAR antagonists and the 5-HT(2A) agonist (ie disruption of glutamatergic neurotransmission) may be the mechanism underlying impairments in AX-CPT performance observed during both psilocybin and ketamine administration. Comparable deficits in schizophrenia may result from independent dysfunctions of 5-HT(2A) and NMDAR-related neurotransmission.

Acute nicotine effects on auditory sensory memory in tacrine-treated and nontreated patients with Alzheimer's disease: an event-related potential study

The auditory mismatch negativity (MMN) event-related brain potential (ERP) reflects the storage of information in acoustic sensory memory. Thirteen patients with Alzheimer's disease (AD), 6 receiving treatment with the cholinesterase inhibitor, tacrine [tetrahydroaminoacridine (THA)], and 7 receiving no treatment, were administered 2 mg of nicotine polacrilex and placebo. MMNs were recorded with 1- and 3-s interstimulus intervals (ISIs) during pre- and post-placebo/nicotine administration. Amplitudes decreased from pre- to post-placebo recordings in nontreated patients but remained stable in THA-treated patients. Comparison of pre- and post-nicotine MMNs found amplitude increases with nicotine in nontreated but not in THA-treated patients. MMN latencies were shortened by nicotine in both treatment groups. These exploratory findings suggest that nicotine-improved strength of acoustic sensory memory traces and speed of acoustic sensory discrimination in AD are differentially affected by chronic tacrine treatment.

Mismatch negativity in young children of alcoholics from high-density families

The mismatch negativity (MMN) component of event-related potentials was recorded from a group of young children of alcoholics (n = 19, 8 females) with a high-density family history of alcoholism and from a control group (n = 23, 12 females), between 8 and 15 years of age. A dichotic listening task was used, and subjects had to pay attention to an oddball paradigm in one ear and ignore the stimuli in the other ear. The event-related potentials elicited by the standard unattended tones were subtracted from those elicited by the infrequent deviant unattended tones, and the MMN was measured at 10 frontal and central electrodes. No group differences were observed in peak latency, peak amplitude, and mean amplitude of the MMN. These results indicated that preattentive mechanisms of mismatch detection were not impaired in young subjects at high risk for alcoholism. Results are discussed in relation to differences in electrophysiological indexes of automatic versus controlled information processing and in relation to the characteristics of the sample.

Impaired mismatch negativity (MMN) generation in schizophrenia as a function of stimulus deviance, probability, and interstimulus/interdeviant interval

Schizophrenia is a severe mental disorder associated with disturbances in perception and cognition. Event-related potentials (ERP) provide a mechanism for evaluating potential mechanisms underlying neurophysiological dysfunction in schizophrenia. Mismatch negativity (MMN) is a short-duration auditory cognitive ERP component that indexes operation of the auditory sensory ('echoic') memory system. Prior studies have demonstrated impaired MMN generation in schizophrenia along with deficits in auditory sensory memory performance. MMN is elicited in an auditory oddball paradigm in which a sequence of repetitive standard tones is interrupted infrequently by a physically deviant ('oddball') stimulus. The present study evaluates MMN generation as a function of deviant stimulus probability, interstimulus interval, interdeviant interval and the degree of pitch separation between the standard and deviant stimuli. The major findings of the present study are first, that MMN amplitude is decreased in schizophrenia across a broad range of stimulus conditions, and second, that the degree of deficit in schizophrenia is largest under conditions when MMN is normally largest. The pattern of deficit observed in schizophrenia differs from the pattern observed in other conditions associated with MMN dysfunction, including Alzheimer's disease, stroke, and alcohol intoxication.

Effects of naltrexone and ethanol on auditory event-related brain potentials

Acute effects of ethanol (0.55 g/kg) and the opioid antagonist naltrexone (50 mg) on auditory event-related brain potentials (ERP) (i.e., electrical brain activity time-locked to sensory stimuli) were investigated in 13 healthy social drinkers, using a double-blind, placebo-controlled, design. The subjects' task was to attend to tones presented to a designated ear while ignoring tones to the other, and to detect deviant tones among the attended tones. When administered alone, naltrexone significantly reduced the amplitude of the later part of negative difference (Nd[l]), suggesting impaired selective attention. However, this effect might have been caused by naltrexone-induced nausea. Ethanol, when ingested alone, attenuated the amplitude of the N1, and increased the peak latencies of the mismatch negativity (MMN) and N2b that have been suggested to reflect automatic change detection in audition and allocation of attentional resources to processing of stimulus deviance, respectively. In contrast, the P1 amplitude was augmented by alcohol, but only when the tones were attended. When ethanol and naltrexone were simultaneously ingested, however, the alcohol-induced P1 amplitude augmentation was canceled, thus tentatively suggesting opioidergic mediation of this alcohol effect. In contrast, the MMN peak latency was increased significantly more in the interaction condition than in the ethanol condition, thus suggesting that the detrimental effects of alcohol on involuntary attention switching were augmented by naltrexone. Furthermore, the N2b amplitude was significantly suppressed in the interaction condition, suggesting attentional impairment.

Mismatch negativity subcomponents and ethyl alcohol

Effects of ethanol (0.55 and 0.85 g/kg) on event-related potentials were investigated by presenting 50-ms standard and 25-ms deviant pure tones to 9 social drinkers during a reading task, in a single-blind, placebo-controlled paradigm. Whereas the lower ethanol dose had no impact on ERPs with an 0.8-s inter-stimulus interval (ISI), it attenuated the N1, P2, and mismatch negativity (MMN) amplitudes with a longer ISI of 2.4 s. The higher alcohol dose increased the N1 peak latency with both ISIs. It also suppressed the N1 and MMN amplitudes with the longer ISI. The MMN suppression did not, however, occur at scalp sites below the Sylvian fissure, thus suggesting that ethanol affected only the frontal MMN subgenerator. Moreover, the different dose responses of the N1, P2, and MMN (subcomponents) to ethanol may indicate that the neurotransmitter systems underlying their generation are, to some extent, different.

Effects of ethanol and auditory distraction on forced choice reaction time

Effects of ethanol (0.55 g/kg) and auditory distraction on visual forced choice reaction time (RT) were investigated in 10 healthy social drinkers, using a single-blind, placebo-controlled, crossover design. Subjects were to respond by pressing a button either with their right-hand index or middle finger, depending on whether an odd or an even digit was presented on a PC screen. In control blocks, the digits were presented alone, whereas in distraction blocks they were shortly preceded by either a frequent "standard" tone of 600 Hz, or an infrequent tone that was either a 660 Hz "deviant" tone or a "novel" sound (e.g., telephone ringing). Alcohol reduced the hit rate by increasing the amount of errors, but had no effect on the RT, thus supporting the previous observations. In the placebo condition, the RT was prolonged by the deviant and novel sounds, and the hit rate was reduced by the deviant tones. During ethanol intoxication, however, the reduction in hit rate caused by the deviant tones was significantly smaller. This suggests that the attention-capturing effects of the deviant sounds were suppressed by ethanol, thus demonstrating a detrimental effect of ethanol on involuntary attention.