The acute effect of low-dose alcohol on working memory during mental arithmetic

Ego depletion and implicit and explicit determinants of condom use intentions: an experimental study among young men

BACKGROUND

The Reflective Impulsive Model of Strack and Deutsch (2004) is a dual-process model and could be a dynamic theoretical framework of sexual risk behavior that is able to predict condom use under different circumstances. If we apply the Reflective Impulsive Model to sexual risk behavior, implicit attitudes regarding sexual risk behavior should have a stronger impact on behavior when working memory capacity is low. Explicit attitudes have a strong impact on intentions, which diminishes as participants have less working memory capacity.

METHODS

In this study, we induced a state of ego depletion to examine the impact of low working memory capacity on implicit and explicit attitudes and condom use intentions. Young, male participants ( N = 66) were randomly assigned to either an ego depletion condition (difficult calculus task) or a placebo condition (easy calculus task). At baseline, a questionnaire measuring explicit attitudes and intentions to use a condom, and an Implicit Association Test measuring implicit attitudes towards condoms were administered. After the ego calculus task, participants once more completed the questionnaire and Implicit Association Test.

RESULTS

We found no evidence that ego depletion had an effect on intentions to use a condom in young men. Explicit attitudes predicted intentions to use a condom, regardless of participants' state. We found no relationship between implicit condom attitudes and intentions to use a condom, neither in the ego depletion nor in the placebo condition.

CONCLUSIONS

The implications of this null finding are discussed.

Effects of acute alcohol administration on working memory: a systematic review and meta-analysis

RATIONALE

Alcohol-induced executive function deficits may underlie associations between alcohol, self-regulation, and hazardous behaviors. Studies examining the effects of alcohol administration on working memory, an important executive functioning component, have produced mixed findings. Acute alcohol effects on working memory remain unclear.

OBJECTIVES

We aimed to conduct a systematic review and meta-analysis on the effects of acute alcohol administration on working memory outcomes in studies of healthy adults.

METHODS

We performed a systematic search of PubMed, MEDLINE, and PsycINFO from inception to June 2021. Studies were included if they met criteria, including healthy participants and administration of quantified alcohol doses against comparative controls. Data extracted included primary working memory outcomes, alcohol doses, and study characteristics. Study quality was assessed using an established validity measure. Working memory task type, alcohol dose, control condition type, and sex/gender composition were explored as moderators using mixed-effects models and meta-regressions.

RESULTS

Thirty-two studies (1629 participants) provided sufficient data for 54 comparisons between alcohol and control conditions. Random-effects meta-analysis indicated that alcohol administration produced significant, small- to medium-sized working memory decrements (g [95% CI] =  - 0.300 [- 0.390 to - 0.211], p < 0.001). Moderation analyses suggested that these effects differed as a function of task type, dose, control condition type, and sex/gender composition. The average quality rating across studies was good.

CONCLUSIONS

Alcohol administration significantly impaired working memory performance, particularly when executive-related manipulation processes were involved. Future research is needed to investigate how alcohol-induced working memory impairments relate to compromised self-regulation, hazardous behavior, and negative drinking consequences.

Understanding ethanol's acute effects on medial prefrontal cortex neural activity using state-space approaches

Acute ethanol (EtOH) intoxication results in several maladaptive behaviors that may be attributable, in part, to the effects of EtOH on neural activity in medial prefrontal cortex (mPFC). The acute effects of EtOH on mPFC function have been largely described as inhibitory. However, translating these observations on function into a mechanism capable of delineating acute EtOH's effects on behavior has proven difficult. This review highlights the role of acute EtOH on electrophysiological measurements of mPFC function and proposes that interpreting these changes through the lens of dynamical systems theory is critical to understand the mechanisms that mediate the effects of EtOH intoxication on behavior. Specifically, the present review posits that the effects of EtOH on mPFC N-methyl-d-aspartate (NMDA) receptors are critical for the expression of impaired behavior following EtOH consumption. This hypothesis is based on the observation that recurrent activity in cortical networks is supported by NMDA receptors, and, when disrupted, may lead to impairments in cognitive function. To evaluate this hypothesis, we discuss the representation of mPFC neural activity in low-dimensional, dynamic state spaces. This approach has proven useful for identifying the underlying computations necessary for the production of behavior. Ultimately, we hypothesize that EtOH-related alterations to NMDA receptor function produces alterations that can be effectively conceptualized as impairments in attractor dynamics and provides insight into how acute EtOH disrupts forms of cognition that rely on mPFC function. This article is part of the special Issue on 'Neurocircuitry Modulating Drug and Alcohol Abuse'.

Changes in the Electroencephalographic Activity in Response to Odors Produced by Organic Compounds

Abstract. Volatile organic compounds are widely used to manufacture various products in addition to research purposes. They play an important role in the air quality of outdoor and indoor with a pleasant or unpleasant odor. It is well known that the odor of chemicals with different structures can affect brain functions differently. In general, organic compounds are mainly characterized by their functional groups. Acetic acid, acetaldehyde, acetone, and acetonitrile are widely used laboratory chemicals with the same methyl group, but different functional groups. Hence, the present study was aimed to investigate whether the exposure of these four chemicals (10%) exhibits the same electroencephalographic (EEG) activity or different. For this purpose, the EEG was recorded in 20 male healthy volunteers. The EEG was recorded from 32 electrodes located on the scalp, based on the International 10–20 system with modified combinatorial nomenclature. The results indicated that tested subjects are less sensitive to acetic acid odor than other three chemicals. The absolute theta activity significantly increased at Cp5 and F8 regions, and the relative mid-beta (RMB) significantly decreased at Fc1 region during the exposure of acetic acid. On the other hand, acetaldehyde, acetone, and acetonitrile produced EEG changes in many indices such as relative theta, relative gamma, relative high beta, relative beta, relative slow beta, the ratio of alpha to high beta, and spectral edge frequencies. However, there was no significant change in the absolute wave activity. Although acetaldehyde, acetone, and acetonitrile odors affected almost similar EEG indices, they exhibited changes in different brain regions. The variations in the EEG activity of these chemicals may be due to the activation of different olfactory receptors, odor characteristics, and structural arrangements.

Clarifying the neurobehavioral sequelae of moderate drinking lifestyles and acute alcohol effects with aging

Epidemiological estimates indicate not only an increase in the proportion of older adults, but also an increase in those who continue moderate alcohol consumption. Substantial literatures have attempted to characterize health benefits/risks of moderate drinking lifestyles. Not uncommonly, reports address outcomes in a single outcome, such as cardiovascular function or cognitive decline, rather than providing a broader overview of systems. In this narrative review, retaining focus on neurobiological considerations, we summarize key findings regarding moderate drinking and three health domains, cardiovascular health, Type 2 diabetes (T2D), and cognition. Interestingly, few investigators have studied bouts of low/moderate doses of alcohol consumption, a pattern consistent with moderate drinking lifestyles. Here, we address both moderate drinking as a lifestyle and as an acute event. Review of health-related correlates illustrates continuing inconsistencies. Although substantive reductions in risk for cardiovascular and T2D events are reported, robust conclusions remain elusive. Similarly, whereas moderate drinking is often associated with enhanced cognition and lower dementia risk, few benefits are noted in rates of decline or alterations in brain structure. The effect of sex/gender varies across health domains and by consumption levels. For example, women appear to differentially benefit from alcohol use in terms of T2D, but experience greater risk when considering aspects of cardiovascular function. Finally, we observe that socially relevant alcohol doses do not consistently impair performance in older adults. Rather, older drinkers demonstrate divergent, but not necessarily detrimental, patterns in neural activation and some behavioral measures relative to younger drinkers. Taken together, the epidemiological and laboratory studies reinforce the need for greater attention to key individual differences and for the conduct of systematic studies sensitive to age-related shifts in neurobiological systems.

Altered oscillatory brain dynamics of emotional processing in young binge drinkers

Heavy episodic drinking, also termed binge drinking, is commonly practiced by young adults. It is accompanied by a range of cognitive, affective, and social problems, but the neural dynamics underlying changes in emotional functions is poorly understood. To investigate the behavioral and brain indices of affective processing as a function of binge drinking, young, healthy participants (23.3 ± 3.3 years) were assigned to two groups (n = 32 each) based on their drinking habits. Binge drinking (BD) participants reported drinking heavily with at least five binge episodes in the last 6 months, whereas light drinkers (LD) reported no more than one binge episode in the last 6 months. Participants provided subjective ratings of emotionally evocative images with negative, positive, erotic, and neutral themes mostly selected from the International Affective Picture System (IAPS). Electroencephalography (EEG) signal was recorded with a 64-channel system and analyzed in theta frequency band (4-7 Hz) with Morlet wavelets. Subjective ratings of the IAPS pictures were equivalent across both groups. However, affective modulation of event-related theta power both during early appraisal and later integrative processing stages was attenuated in BD, particularly those engaging in high-intensity drinking. These findings suggest that binge drinking is associated with altered neurophysiological indices of affective functions that are reflected in lower theta responsivity to emotions. The blunted long-range cortico-cortical and corticolimbic integration is consistent with compromised affective functions in alcohol use disorder. These findings may have implications for diagnostic and intervention strategies in heavy alcohol users.

Direct Assessment of Alcohol Consumption in Mental State Using Brain Computer Interfaces and Grammatical Evolution

Alcohol consumption affects the function of the brain and long-term excessive alcohol intake can lead to severe brain disorders. Wearable electroencephalogram (EEG) recording devices combined with Brain Computer Interface (BCI) software may serve as a tool for alcohol-related brain wave assessment. In this paper, a method for mental state assessment from alcohol-related EEG recordings is proposed. EEG recordings are acquired with the Emotiv EPOC+, after consumption of three separate doses of alcohol. Data from the four stages (alcohol-free and three levels of doses) are processed using the OpenViBE platform. Spectral and statistical features are calculated, and Grammatical Evolution is employed for discrimination across four classes. Obtained results in terms of accuracy reached high levels (89.95%), which renders the proposed approach suitable for direct assessment of the driver’s mental state for road safety and accident avoidance in a potential in-vehicle smart system.

Neuroelectric responses of sportsmen and sedentaries under cognitive stress

Stress and anxiety are states which sportsmen are continuously exposed to. Our study aimed to evaluate neuroelectrical peripheral and central nervous system responses of sportsmen (SPR) and sedentary individuals (SED) during concentration grid test (CGT) employed under time pressure. Forty three SPR and 33 SED participated in the study. Neuroelectrical responses were simultaneously obtained during baseline and CGT. All responses were observed to increase under stress in both SED and SPR. The SPR's stress related peripheral responses were lower than SED's. When central values were evaluated a stress related increase according to baseline was observed in all frequency powers in all of the participants. Statistical comparison of increase rates revealed a significantly greater increase in beta in SED compared to SPR. Beta has been associated to alertness and cortical arousal. As SED exhibit greater beta increase under stress compared to SPR their state of cortical arousal and alertness may be interpreted to be higher than SPR. However the SPR's weak increase in beta and their lower peripheral responses taken together may imply that they are better in stress management. In fact according to their performance scores the SPR's higher level of performance under stress compared to SED shows that they are better at maintaining and focusing their attention under stress than SED.

Blood Alcohol Concentration-Related Lower Performance in Immediate Visual Memory and Working Memory in Adolescent Binge Drinkers

The binge drinking (BD) pattern of alcohol consumption is prevalent during adolescence, a period characterized by critical changes to the structural and functional development of brain areas related with memory and cognition. There is considerable evidence of the cognitive dysfunctions caused by the neurotoxic effects of BD in the not-yet-adult brain. Thus, the aim of the present study was to evaluate the effects of different blood alcohol concentrations (BAC) on memory during late adolescence (18–19 years old) in males and females with a history of BD. The sample consisted of 154 adolescents (67 males and 87 females) that were classified as refrainers if they had never previously drunk alcoholic drinks and as binge drinkers if they had drunk six or more standard drink units in a row for men or five or more for women at a minimum frequency of three occasions in a month, throughout the previous 12 months. After intake of a high acute dose of alcohol by binge drinkers or a control refreshment by refrainers and binge drinkers, subjects were distributed into four groups for each gender according to their BAC: BAC0-R (0 g/L, in refrainers), BAC0-BD (0 g/L, in binge drinkers), BAC1 (0.3 – 0.5 g/L, in binge drinkers) or BAC2 (0.54 – 1.1 g/L, in binge drinkers). The subjects’ immediate visual memory and working memory were then measured according to the Wechsler Memory Scale (WMS-III). The BAC1 group showed lower scores of immediate visual memory but not of working memory, while lower performance in both memories were found in the BAC2 group. Therefore, the brain of binge drinkers with moderate BAC could be employing compensatory mechanisms from additional brain areas to perform a working memory task adequately, but these resources would be undermined when BAC is higher (>0.5 g/L). No gender differences were found in BAC-related lower performance in immediate visual memory and working memory. In conclusion, immediate visual memory is more sensitive than working memory to the neurotoxic effects of alcohol in adolescent binge drinkers of both genders, being a BAC-related lower performance, and without obvious differences between males and females.

Prenatal alcohol exposure potentiates chronic neuropathic pain, spinal glial and immune cell activation and alters sciatic nerve and DRG cytokine levels

A growing body of evidence indicates that prenatal alcohol exposure (PAE) may predispose individuals to secondary medical disabilities later in life. Animal models of PAE reveal neuroimmune sequelae such as elevated brain astrocyte and microglial activation with corresponding region-specific changes in immune signaling molecules such as cytokines and chemokines. The aim of this study was to evaluate the effects of moderate PAE on the development and maintenance of allodynia induced by chronic constriction injury (CCI) of the sciatic nerve in adult male rat offspring. Because CCI allodynia requires the actions of glial cytokines, we analyzed lumbar spinal cord glial and immune cell surface markers indicative of their activation levels, as well as sciatic nerve and dorsal root ganglia (DRG) cytokines in PAE offspring in adulthood. While PAE did not alter basal sensory thresholds before or after sham manipulations, PAE significantly potentiated adult onset and maintenance of allodynia. Microscopic analysis revealed exaggerated astrocyte and microglial activation, while flow cytometry data demonstrated increased proportions of immune cells with cell surface major histocompatibility complex II (MHCII) and β-integrin adhesion molecules, which are indicative of PAE-induced immune cell activation. Sciatic nerves from CCI rats revealed that PAE potentiated the proinflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor-alpha (TNFα) protein levels with a simultaneous robust suppression of the anti-inflammatory cytokine, IL-10. A profound reduction in IL-10 expression in the DRG of PAE neuropathic rats was also observed. Taken together, our results provide novel insights into the vulnerability that PAE produces for adult-onset central nervous system (CNS) pathological conditions from peripheral nerve injury.

Influence of Fragrances on Human Psychophysiological Activity: With Special Reference to Human Electroencephalographic Response

The influence of fragrances such as perfumes and room fresheners on the psychophysiological activities of humans has been known for a long time, and its significance is gradually increasing in the medicinal and cosmetic industries. A fragrance consists of volatile chemicals with a molecular weight of less than 300 Da that humans perceive through the olfactory system. In humans, about 300 active olfactory receptor genes are devoted to detecting thousands of different fragrance molecules through a large family of olfactory receptors of a diverse protein sequence. The sense of smell plays an important role in the physiological effects of mood, stress, and working capacity. Electrophysiological studies have revealed that various fragrances affected spontaneous brain activities and cognitive functions, which are measured by an electroencephalograph (EEG). The EEG is a good temporal measure of responses in the central nervous system and it provides information about the physiological state of the brain both in health and disease. The EEG power spectrum is classified into different frequency bands such as delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz) and gamma (30-50 Hz), and each band is correlated with different features of brain states. A quantitative EEG uses computer software to provide the topographic mapping of the brain activity in frontal, temporal, parietal and occipital brain regions. It is well known that decreases of alpha and beta activities and increases of delta and theta activities are associated with brain pathology and general cognitive decline. In the last few decades, many scientific studies were conducted to investigate the effect of inhalation of aroma on human brain functions. The studies have suggested a significant role for olfactory stimulation in the alteration of cognition, mood, and social behavior. This review aims to evaluate the available literature regarding the influence of fragrances on the psychophysiological activities of humans with special reference to EEG changes.

Effects of Age and Acute Moderate Alcohol Administration on Neurophysiology During Simulated Driving

BACKGROUND

Driver age and blood alcohol concentration are both important factors in predicting driving risk; however, little is known regarding the joint import of these factors on neural activity following socially relevant alcohol doses. We examined age and alcohol effects on brain oscillations during simulated driving, focusing on 2 region-specific frequency bands implicated in task performance and attention: parietal alpha power (PAP; 8 to 12 Hz) and frontal theta power (FTP; 4 to 7 Hz).

METHODS

Participants included 80 younger (aged 25 to 35 years) and 40 older (aged 55 to 70 years) community-dwelling, moderate drinkers. Participants consumed placebo, low, or moderate doses of alcohol designed to achieve target peak breath alcohol concentrations of 0, 0.04, or 0.065 g/dl, respectively. Electrophysiological measures were recorded during engagement in a simulated driving task involving 4 scenarios of varied environmental complexity.

RESULTS

A main effect of age was detected in FTP, but neither an alcohol effect nor interactions were observed. For PAP, an age-by-alcohol interaction was detected. Relative to placebo controls, older and younger participants receiving low-dose (0.04 g/dl) alcohol evinced divergent PAP alterations, with a pattern of higher power among older participants and lower power among younger participants. This interaction was noted across the varied environmental contexts.

CONCLUSIONS

These findings are consistent with the hypothesis that compared with younger individuals, older drivers may be differentially susceptible to alcohol effects. While these age-by-alcohol interactions in neural activity are provocative, further investigation exploring the mechanisms and behavioral correlates of these effects will be crucial in determining their behavioral impact.

Effects of Age and Acute Moderate Alcohol Administration on Electrophysiological Correlates of Working Memory Maintenance

BACKGROUND

Previous studies suggest older adults may be differentially susceptible to the acute neurobehavioral effects of moderate alcohol intake. To our knowledge, no studies have addressed acute moderate alcohol effects on the electrophysiological correlates of working memory in younger and older social drinkers. This study characterized alcohol-related effects on frontal theta (FTP) and posterior alpha power (PAP) associated with maintenance of visual information during a working memory task.

METHODS

Older (55 to 70 years of age; n = 51, 29 women) and younger (25 to 35 years of age; n = 70, 39 women) community-dwelling moderate drinkers were recruited for this study. Participants were given either placebo or an active dose targeting breath alcohol concentrations (BrACs) of 0.04 or 0.065 g/dl. Following absorption, participants completed a visual working memory task assessing cue recognition following a 9-s delay. FTP and PAP were determined via Fourier transformation and subjected to 2 (age group) × 3 (dose) × 2 (repeated: working memory task condition) mixed models analysis.

RESULTS

In addition to expected age-related reductions in PAP, a significant age group × dose interaction was detected for PAP such that 0.04 g/dl dose level was associated with greater PAP in younger adults but lower PAP in their older counterparts. PAP was lower in older versus younger adults at both active doses. Further mixed models revealed a significant negative association between PAP and working memory efficiency for older adults. No effects of age, dose, or their interaction were noted for FTP.

CONCLUSIONS

Results bolster the small but growing body of evidence that older adults exhibit differential sensitivity to the neurobehavioral effects of moderate alcohol use. Given the theoretical role of PAP in attentional and working memory function, these findings shed light on the attentional mechanisms underlying effects of acute moderate alcohol on working memory efficiency in older adults.

Executive Functioning in Alcohol Use Studies: A Brief Review of Findings and Challenges in Assessment

There is a wealth of research about the links between executive functioning (EF) and alcohol use. However, difficulty may arise in interpreting findings because of the variability between studies regarding the specific components of EF measured, as well as the variability of tasks used to examine each EF construct. The current article considers each of these problems within the context of a literature review that focuses on two topics: (1) the efficacy of EF in predicting alcohol use and alcohol-related consequences, and (2) the effect of acute alcohol intoxication on EF task performance. An additional goal was to identify and describe commonly used EF measures with the intention of providing alcohol researchers information on the assessment of different EF domains. Our findings indicate that there is strong evidence supporting a relation between EF difficulties (particularly response inhibition and information updating) and alcohol use, with additional evidence of a significant interaction between EF and implicit associations on alcohol use. In contrast, research supporting a link between set shifting abilities and later alcohol use is scarce. Additionally, this review found evidence of alcohol acutely affecting many EF processes (particularly response inhibition). Overall, there is a need to replicate these findings with commonly used EF tasks (versus developing numerous tasks within individual laboratories) to better advance our understanding of the relation between EF and alcohol use.

Computer-aided diagnosis of alcoholism-related EEG signals

Alcoholism is a severe disorder that affects the functionality of neurons in the central nervous system (CNS) and alters the behavior of the affected person. Electroencephalogram (EEG) signals can be used as a diagnostic tool in the evaluation of subjects with alcoholism. The neurophysiological interpretation of EEG signals in persons with alcoholism (PWA) is based on observation and interpretation of the frequency and power in their EEGs compared to EEG signals from persons without alcoholism. This paper presents a review of the known features of EEGs obtained from PWA and proposes that the impact of alcoholism on the brain can be determined by computer-aided analysis of EEGs through extracting the minute variations in the EEG signals that can differentiate the EEGs of PWA from those of nonaffected persons. The authors advance the idea of automated computer-aided diagnosis (CAD) of alcoholism by employing the EEG signals. This is achieved through judicious combination of signal processing techniques such as wavelet, nonlinear dynamics, and chaos theory and pattern recognition and classification techniques. A CAD system is cost-effective and efficient and can be used as a decision support system by physicians in the diagnosis and treatment of alcoholism especially those who do not specialize in alcoholism or neurophysiology. It can also be of great value to rehabilitation centers to assess PWA over time and to monitor the impact of treatment aimed at minimizing or reversing the effects of the disease on the brain. A CAD system can be used to determine the extent of alcoholism-related changes in EEG signals (low, medium, high) and the effectiveness of therapeutic plans.

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.

Dose-related effects of alcohol on cognitive functioning

We assessed the suitability of six applied tests of cognitive functioning to provide a single marker for dose-related alcohol intoxication. Numerous studies have demonstrated that alcohol has a deleterious effect on specific areas of cognitive processing but few have compared the effects of alcohol across a wide range of different cognitive processes. Adult participants (N = 56, 32 males, 24 females aged 18–45 years) were randomized to control or alcohol treatments within a mixed design experiment involving multiple-dosages at approximately one hour intervals (attained mean blood alcohol concentrations (BACs) of 0.00, 0.048, 0.082 and 0.10%), employing a battery of six psychometric tests; the Useful Field of View test (UFOV; processing speed together with directed attention); the Self-Ordered Pointing Task (SOPT; working memory); Inspection Time (IT; speed of processing independent from motor responding); the Traveling Salesperson Problem (TSP; strategic optimization); the Sustained Attention to Response Task (SART; vigilance, response inhibition and psychomotor function); and the Trail-Making Test (TMT; cognitive flexibility and psychomotor function). Results demonstrated that impairment is not uniform across different domains of cognitive processing and that both the size of the alcohol effect and the magnitude of effect change across different dose levels are quantitatively different for different cognitive processes. Only IT met the criteria for a marker for wide-spread application: reliable dose-related decline in a basic process as a function of rising BAC level and easy to use non-invasive task properties.

Event-Related Oscillations in Alcoholism Research: A Review

Alcohol dependence is characterized as a multi-factorial disorder caused by a complex interaction between genetic and environmental liabilities across development. A variety of neurocognitive deficits/dysfunctions involving impairments in different brain regions and/or neural circuitries have been associated with chronic alcoholism, as well as with a predisposition to develop alcoholism. Several neurobiological and neurobehavioral approaches and methods of analyses have been used to understand the nature of these neurocognitive impairments/deficits in alcoholism. In the present review, we have examined relatively novel methods of analyses of the brain signals that are collectively referred to as event-related oscillations (EROs) and show promise to further our understanding of human brain dynamics while performing various tasks. These new measures of dynamic brain processes have exquisite temporal resolution and allow the study of neural networks underlying responses to sensory and cognitive events, thus providing a closer link to the physiology underlying them. Here, we have reviewed EROs in the study of alcoholism, their usefulness in understanding dynamical brain functions/dysfunctions associated with alcoholism as well as their utility as effective endophenotypes to identify and understand genes associated with both brain oscillations and alcoholism.

Acute effects of MDMA (3,4-methylenedioxymethamphetamine) on EEG oscillations: alone and in combination with ethanol or THC (delta-9-tetrahydrocannabinol)

RATIONALE

Typical users of 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") are polydrug users, combining MDMA with alcohol or cannabis [most active compound: delta-9-tetrahydrocannabinol (THC)].

OBJECTIVES

The aim of the present study was to investigate whether co-administration of alcohol or THC with MDMA differentially affects ongoing electroencephalogram (EEG) oscillations compared to the administration of each drug alone.

METHODS

In two separate experiments, 16 volunteers received four different drug conditions: (1) MDMA (100 mg); (2) alcohol clamp (blood alcohol concentration = 0.6‰) or THC (inhalation of 4, 6 and 6 mg, interval of 1.5 h); (3) MDMA in combination with alcohol or THC; and (4) placebo. Before and after drug administration, electroencephalography was recorded during an eyes closed resting state.

RESULTS

Theta and alpha power increased after alcohol intake compared to placebo and reduced after MDMA intake. No interaction between alcohol and MDMA was found. Significant MDMA x THC effects for theta and lower-1-alpha power indicated that the power attenuation after the combined intake of MDMA and THC was less than the sum of each drug alone. For the lower-2-alpha band, the intake of MDMA or THC alone did not significantly affect power, but the intake of combined MDMA and THC significantly decreased lower-2-alpha power.

CONCLUSIONS

The present findings indicate that the combined intake of MDMA and THC, but not of MDMA and alcohol, affects ongoing EEG oscillations differently than the sum of either one drug alone. Changes in ongoing EEG oscillations may be related to the impaired task performance that has often been reported after drug intake.

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.

The acute effect of low-dose alcohol on working memory during mental arithmetic: II. Changes of nonlinear and linear EEG-complexity in the theta band, heart rate and electrodermal activity

OBJECTIVE AND HYPOTHESIS

Nonlinear and linear methods of EEG-complexity analysis and autonomic measures were used to characterize processes accompanying performance in a mental arithmetic task challenged by low ("social") alcohol doses. It was expected that alcohol in such doses will dampen changes of task-related EEG-synchronization in the theta band, and those of heart rate and electrodermal activity (EDA).

METHODS

In the mental arithmetic task addition and working memory, effort was required. The EEG, ECG and EDA were recorded in 5 conditions: task, placebo-task, low dose-task (0.2 g/kg alcohol), high dose-task (0.4 g/kg alcohol). Omega-complexity and synchronization likelihood (SL) were computed of the theta band of the EEG.

RESULTS

Task-related decrease of the Omega-complexity and increase of the SL was found in the theta frequency band. Following alcohol consumption, these changes did not develop as seen especially for SL in the anterior area, although the significant effects were elicited by task performance. Conspicuous task-evoked increases were observed for ECG and EDA which were even more enhanced by alcohol.

CONCLUSIONS

Task-induced significant changes of the Omega-complexity and that of SL indicate increased synchrony in the theta band, probably corresponding to working memory effort. Both of these measures proved to be sensitive for the effect of low alcohol dose although these alcohol-elicited changes were not statistically significant. Task-induced heart rate and EDA increases were further intensified by alcohol probably indicating its activating effect on these autonomic measures in the dose range studied.