Acute effects of alcohol on neural correlates of episodic memory encoding

Integrating and fragmenting memories under stress and alcohol

Stress can powerfully influence the way we form memories, particularly the extent to which they are integrated or situated within an underlying spatiotemporal and broader knowledge architecture. These different representations in turn have significant consequences for the way we use these memories to guide later behavior. Puzzlingly, although stress has historically been argued to promote fragmentation, leading to disjoint memory representations, more recent work suggests that stress can also facilitate memory binding and integration. Understanding the circumstances under which stress fosters integration will be key to resolving this discrepancy and unpacking the mechanisms by which stress can shape later behavior. Here, we examine memory integration at multiple levels: linking together the content of an individual experience, threading associations between related but distinct events, and binding an experience into a pre-existing schema or sense of causal structure. We discuss neural and cognitive mechanisms underlying each form of integration as well as findings regarding how stress, aversive learning, and negative affect can modulate each. In this analysis, we uncover that stress can indeed promote each level of integration. We also show how memory integration may apply to understanding effects of alcohol, highlighting extant clinical and preclinical findings and opportunities for further investigation. Finally, we consider the implications of integration and fragmentation for later memory-guided behavior, and the importance of understanding which type of memory representation is potentiated in order to design appropriate interventions.

The impact of sensation seeking personality trait on acute alcohol-induced disinhibition

BACKGROUND

Acute alcohol-related behavioral disinhibition has been well studied. But whether individual differences in the personality trait sensation seeking affect alcohol-induced behavioral disinhibition remains uncertain.

METHODS

The present study used functional near-infrared spectroscopy (fNIRS) technique and a response inhibition task (i.e., Go/No-Go) to determine the impact of the sensation seeking trait on the relationship between acute alcohol administration and inhibitory control capacity, and further investigate the neural mechanisms underlying this behavioral effect. Twenty-five high-sensation seekers and twenty-six low-sensation seekers were enrolled in this study. These participants attended two sessions: once for alcohol intake (0.5g/kg) and once for placebo intake (0g/kg).

RESULTS

Our results showed that high-sensation seekers relative to low-sensation seekers showed a significant decrease in inhibition accuracy under alcohol versus the placebo condition. Moreover, reduced prefrontal activity following acute alcohol consumption was more pronounced in high-sensation seekers compared with low-sensation seekers.

CONCLUSIONS

These findings showed that alcohol-induced behavioral disinhibition was affected by the personality trait sensation seeking and that recruitment of the prefrontal cortex contributed to the observed behavioral effect.

The Role of Coping Behaviors and Intoxication in Trauma Symptomology Subsequent to Sexual Victimization

College women are at an elevated risk for sexual victimization (SV) and secondary physical and psychological consequences. While some women experience negative outcomes such as posttraumatic stress disorder (PTSD), others experience reduced or complete absence of distress following SV. The variation in outcomes may be associated with the victim's level of intoxication, which may in turn affect their processing of and coping with the event. We examined the effects of SV severity on PTSD via coping and intoxication using a moderated mediation analysis among female college students (N = 375). Results demonstrate that coping mediates the association between SV severity and PTSD symptomology; however, intoxication did not moderate these associations. Results suggest that regardless of intoxication, SV severity influences various coping styles and plays an important role in a victim's adjustment post-victimization.

The impact of post-encoding alcohol consumption on episodic memory recall and remember-know responses in heavy drinkers

Introduction

People often consume alcohol following trauma, particularly in response to distressing memories. To date, little is known about how post-encoding alcohol consumption influences episodic memory recall for negative events. Understanding these effects may help to improve support for trauma victims - for example, witnesses and victims of crimes.

Methods

We tested 60 participants who self-described as heavy drinkers. After watching an analog trauma film, half were allocated to consuming a moderate dose of alcohol (Alcohol-Exposed group), while half received a placebo drink (Placebo-Control group). Immediately and after a one-week delay, participants recalled the event via free and cued recall tasks. Participants also gave remember-know responses and confidence ratings, elucidating alcohol's effect on experiential memory.

Results

Free recall performance was similar for the Alcohol-Exposed group and the Placebo-Control group during Sessions 1 and 2. The Alcohol-Exposed group benefitted more from the delayed repeated retrieval attempt. For the cued recall task, the Alcohol-Exposed group provided more "Do not Know" responses compared to the Placebo-Control group in both sessions. For the Alcohol-Exposed group only "Correct Know" responses increased from Session 1 to 2. Although memory performance improved across sessions, confidence levels decreased from Session 1 to 2 in the Alcohol-Exposed group.

Discussion

Post-encoding alcohol consumption appears to impact immediate episodic memory retrieval; however, this effect is only temporary in nature. No evidence was found that alcohol primarily reduces remembering responses. Much like previous findings focusing on pre-encoding alcohol consumption (Hagsand et al., 2017), current findings suggest that providing individuals who drank alcohol after witnessing an incident with a delayed repeated retrieval attempt can lead to more complete and accurate testimonies.

Comorbidity of Post-Traumatic Stress Disorder and Alcohol Use Disorder: Animal Models and Associated Neurocircuitry

Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are prevalent neuropsychiatric disorders and frequently co-occur concomitantly. Individuals suffering from this dual diagnosis often exhibit increased symptom severity and poorer treatment outcomes than those with only one of these diseases. Lacking standard preclinical models limited the exploration of neurobiological mechanisms underlying PTSD and AUD comorbidity. In this review, we summarize well-accepted preclinical model paradigms and criteria for developing successful models of comorbidity. We also outline how PTSD and AUD affect each other bidirectionally in the nervous nuclei have been heatedly discussed recently. We hope to provide potential recommendations for future research.

A Longitudinal Examination of Alcohol-Related Blackouts as a Predictor of Changes in Learning, Memory, and Executive Function in Adolescents

INTRODUCTION

In adolescents, the relationship between alcohol-related blackouts (ARBs) and distinct cognitive changes lasting beyond intoxication is unclear. We examined ARBs as a predictor of persistent changes in the development of learning, memory, and executive function in participants from the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study.

METHODS

Descriptive analyses of the NCANDA sample (N = 831, 50.9% female, 12-21 years at baseline) identified ARB patterns within participants with an ARB history (n = 106). Latent growth curve modeling evaluated ARB-related performance changes on four neuropsychological measures across five years, excluding baseline data to reduce the magnitude of practice effects over time (n = 790). Measures included the Penn Conditional Exclusion Test (PCET), Penn Letter N-back Test (PLBT), Penn Facial Memory Test immediate (PFMT_i), and delayed (PFMT_d) recognition trials, and the Rey Complex Figure Test copy (RCFT_c), immediate recall (RCFT_i), and delayed recall (RCFT_d) trials. Multivariate models were fit for raw accuracy scores from each measure, with ARB history (i.e., presence of past-year ARBs) as the main independent variable. Age, sex, race, socioeconomic status, assessment site, and alcohol use (i.e., past-year frequency) were included as covariates. Interaction effects between ARB history and alcohol use frequency were tested.

RESULTS

By year five, 16% of participants had experienced at least one ARB (59% of whom reported > 1 ARB and 57% of whom had an ARB lasting > 1 h). After controlling for demographics and alcohol use, ARB history predicted attenuated PFMT_d performance growth at year one. Interaction effects between ARB history and alcohol use frequency predicted attenuated PFMT_d performance growth at years one and two. ARB history predicted attenuated RCFT_i and RCFT_d performance growth by year four, but not PCET or PLBT performance over time. By contrast, greater past-year alcohol use predicted attenuated PFMT_i and PFMT_d performance growth between years two and four in adolescents without an ARB history.

CONCLUSION

We found that ARBs predict distinct, lasting changes in learning and memory for visual information, with results suggesting that the developing brain is vulnerable to ARBs during adolescence and emerging adulthood.

The morning after the night before: Alcohol-induced blackouts impair next day recall in sober young adults

Binge-drinking in adolescents and young adults is a widespread problem, however, an often unreported consequence of binge-drinking behaviour is an alcohol-induced memory blackout (MBO). An MBO is a transient amnesic event resulting from rapid, excessive alcohol consumption. Here, we examine the short-term impact of an alcohol-induced MBO event (testing < 20 hours after blackout) on memory performance in people who have experienced a high volume of MBOs. In addition, we aimed to test the hypothesis that people who experience a high volume of MBOs may have poorer recall than non-blackout controls in either sober or intoxicated states. Three episodic memory paradigms consisting of free recall, serial recall, and depth of encoding tasks, were conducted by a group of alcohol drinkers who had never experienced a memory blackout, and those who reported at least 9 in the preceding 12-months. Studies were completed sober and after alcohol by all participants, and sober but after blackout by the experimental group. Accuracy of recall was assessed with linear mixed effects modelling for all experiments and conditions. Recall rate both before and after alcohol consumption was similar between groups, with poorer recall after drinking alcohol by all participants in all three studies. After blackout, MBO participants showed no significant improvement from their intoxicated state in serial recall and depth of encoding tasks, but an improvement in free recall. Further analysis of these findings revealed that 10 out of 23 participants showed significantly impaired performance after blackout during free recall, extending up to 17 participants in serial recall. In general, alcohol reduced recall rate in both blackout and control participants similarly, but recall following MBO remained poor. Our evidence suggests that alcohol-induced blackouts impair memory functioning the next day, and future research should establish the duration of deficits after an acute alcohol-induced blackout episode.

Acute Alcohol Intake Produces Widespread Decreases in Cortical Resting Signal Variability in Healthy Social Drinkers

BACKGROUND

Acute alcohol intoxication has wide-ranging neurobehavioral effects on psychomotor, attentional, inhibitory, and memory-related cognitive processes. These effects are mirrored in disruption of neural metabolism, functional activation, and functional network coherence. Metrics of intraregional neural dynamics such as regional signal variability (RSV) and brain entropy (BEN) may capture unique aspects of neural functional capacity in healthy and clinical populations; however, alcohol's influence on these metrics is unclear. The present study aimed to elucidate the influence of acute alcohol intoxication on RSV and to clarify these effects with subsequent BEN analyses.

METHODS

26 healthy adults between 25 and 45 years of age (65.4% women) participated in 2 counterbalanced sessions. In one, participants consumed a beverage containing alcohol sufficient to produce a breath alcohol concentration of 0.08 g/dl. In the other, they consumed a placebo beverage. Approximately 35 minutes after beverage consumption, participants completed a 9-minute resting-state fMRI scan. Whole-brain, voxel-wise standard deviation was used to assess RSV, which was compared between sessions. Within clusters displaying alterations in RSV, sample entropy was calculated to assess BEN.

RESULTS

Compared to the placebo, alcohol intake resulted in widespread reductions in RSV in the bilateral middle frontal, right inferior frontal, right superior frontal, bilateral posterior cingulate, bilateral middle temporal, right supramarginal gyri, and bilateral inferior parietal lobule. Within these clusters, significant reductions in BEN were found in the bilateral middle frontal and right superior frontal gyri. No effects were noted in subcortical or cerebellar areas.

CONCLUSIONS

Findings indicate that alcohol intake produces diffuse reductions in RSV among structures associated with attentional processes. Within these structures, signal complexity was also reduced in a subset of frontal regions. Neurobehavioral effects of acute alcohol consumption may be partially driven by disruption of intraregional neural dynamics among regions involved in higher-order cognitive and attentional processes.

Alcohol Intoxication and Cognition: Implications on Mechanisms and Therapeutic Strategies

Binge alcohol drinking is highly prevalent in young adults and results in 30% deaths per year in young males. Binge alcohol drinking or acute alcohol intoxication is a risk factor for developing alcohol use disorder (AUD). Three FDA approved drugs are currently in use as therapy for AUD; however, all of them have contra-indications and limitations. Structural brain imaging studies in alcoholics have shown defects in the brain regions involved in memory, cognition and emotional processing. Positron emission tomography (PET) using radiotracers (e.g., 18FDG) and measuring brain glucose metabolism have demonstrated diagnostic and prognostic utility in evaluating patients with cognitive impairment. Using PET imaging, only a few exclusive human studies have addressed the relationship between alcohol intoxication and cognition. Those studies indicate that alcohol intoxication causes reduction in brain activity. Consistent with prior findings, a recent study by us showed that acute alcohol intoxication reduced brain activity in the cortical and subcortical regions including the temporal lobe consisting the hippocampus. Additionally, we have observed a strong correlation between reduction in metabolic activity and spatial cognition impairment in the hippocampus after binge alcohol exposure. We have also demonstrated the involvement of a stress response protein, cold inducible RNA binding protein (CIRP), as a potential mechanistic mediator in acute alcohol intoxication. In this review, we will first discuss in detail prior human PET imaging studies on alcohol intoxication as well as our recent study on acute alcohol intoxication, and review the existing literature on potential mechanisms of acute alcohol intoxication-induced cognitive impairment and therapeutic strategies to mitigate these impairments. Finally, we will highlight the importance of studying brain regions as part of a brain network in delineating the mechanism of acute alcohol intoxication-induced cognitive impairment to aid in the development of therapeutics for such indication.

Acute alcohol and cognition: Remembering what it causes us to forget

Addiction has been conceptualized as a specific form of memory that appropriates typically adaptive neural mechanisms of learning to produce the progressive spiral of drug-seeking and drug-taking behavior, perpetuating the path to addiction through aberrant processes of drug-related learning and memory. From that perspective, to understand the development of alcohol use disorders, it is critical to identify how a single exposure to alcohol enters into or alters the processes of learning and memory, so that involvement of and changes in neuroplasticity processes responsible for learning and memory can be identified early. This review characterizes the effects produced by acute alcohol intoxication as a function of brain region and memory neurocircuitry. In general, exposure to ethanol doses that produce intoxicating effects causes consistent impairments in learning and memory processes mediated by specific brain circuitry, whereas lower doses either have no effect or produce a facilitation of memory under certain task conditions. Therefore, acute ethanol does not produce a global impairment of learning and memory, and can actually facilitate particular types of memory, perhaps particular types of memory that facilitate the development of excessive alcohol use. In addition, the effects on cognition are dependent on brain region, task demands, dose received, pharmacokinetics, and tolerance. Additionally, we explore the underlying alterations in neurophysiology produced by acute alcohol exposure that help to explain these changes in cognition and highlight future directions for research. Through understanding the impact that acute alcohol intoxication has on cognition, the preliminary changes potentially causing a problematic addiction memory can better be identified.

An experimental examination of the effects of alcohol consumption and exposure to misleading postevent information on remembering a hypothetical rape scenario

We experimentally examined the effects of alcohol consumption and exposure to misleading postevent information on memory for a hypothetical interactive rape scenario. We used a 2 beverage (alcohol vs. tonic water) × 2 expectancy (told alcohol vs. told tonic) factorial design. Participants (N = 80) were randomly assigned to conditions. They consumed alcohol (mean blood alcohol content = 0.06%) or tonic water before engaging in the scenario. Alcohol expectancy was controlled by telling participants they were consuming alcohol or tonic water alone, irrespective of the actual beverage they were consuming. Approximately a week later, participants were exposed to a misleading postevent narrative and then recalled the scenario and took a recognition test. Participants who were told that they had consumed alcohol rather than tonic reported fewer correct details, but they were no more likely to report incorrect or misleading information. The confidence-accuracy relationship for control and misled items was similar across groups, and there was some evidence that metacognitive discrimination was better for participants who were told that they had consumed alcohol compared with those told they had tonic water. Implications for interviewing rape victims are discussed.

Nitric oxide blockade in mediodorsal thalamus impaired nicotine/ethanol-induced memory retrieval in rats via inhibition of prefrontal cortical pCREB/CREB signaling pathway

Reciprocal connections between the mediodorsal thalamic nucleus (MD) and the prefrontal cortex (PFC) are important for memory processes. Since the co-abuse of nicotine and ethanol affects memory formation, this study investigated the effect of nitric oxide inhibition in the MD on memory retrieval induced by co-administration of nicotine and ethanol. Subsequently, western blot analysis was used to evaluate how this change would alter the PFC pCREB/CREB signaling pathway. Male Wistar rats were bilaterally cannulated into the MD and the memory retrieval was measured by passive avoidance task. Intraperitoneal (i.p.) administration of ethanol (1 g/kg, i.p) 30 min before the test impaired memory retrieval and caused ethanol-induced amnesia. Subcutaneous (s.c.) administration of nicotine (0.05-0.2 mg/kg, s.c.) prevented ethanol-induced amnesia and improved memory retrieval. Intra-MD microinjection of a nitric oxide synthase (NOS) inhibitor, L-NAME (0.5-1 μg/rat) inhibited the improving effect of nicotine (0.2 mg/kg, s.c.) on ethanol-induced amnesia, while intra-MD microinjection of a precursor of nitric oxide, l-arginine (0.25-1 μg/rat), potentiated such effect. Noteworthy, intra-MD microinjection of the same doses of L-NAME or l-arginine by itself had no effect on memory retrieval. Furthermore, intra-MD microinjection of L-NAME (0.05, 0.1 and 0.3 μg/rat) reversed the l-arginine improving effect on nicotine response. Successful memory retrieval significantly increased the p-CREB/CREB ratio in the PFC tissue. Ethanol-induced amnesia, however, decreased this ratio in the PFC while the co-administration of nicotine and ethanol increased the PFC CREB signaling. Interestingly, the inhibitory effect of L-NAME and the potentiating effect of l-arginine on nicotine response were associated with the decrease and increase of the PFC p-CREB/CREB ratio respectively. It can be concluded that MD-PFC connections are involved in the combined effects of nicotine and ethanol on memory retrieval. The mediodorsal thalamic NO system possibly mediated this interaction via the pCREB/CREB signaling pathways in the PFC.

The Artery of Aphasia, A Uniquely Sensitive Posterior Temporal Middle Cerebral Artery Branch that Supplies Language Areas in the Brain: Anatomy and Report of Four Cases

BACKGROUND

Arterial disruption during brain surgery can cause devastating injuries to wide expanses of white and gray matter beyond the tumor resection cavity. Such damage may occur as a result of disrupting blood flow through en passage arteries. Identification of these arteries is critical to prevent unforeseen neurologic sequelae during brain tumor resection. In this study, we discuss one such artery, termed the artery of aphasia (AoA), which when disrupted can lead to receptive and expressive language deficits.

METHODS

We performed a retrospective review of all patients undergoing an awake craniotomy for resection of a glioma by the senior author from 2012 to 2018. Patients were included if they experienced language deficits secondary to postoperative infarction in the left posterior temporal lobe in the distribution of the AoA. The gross anatomy of the AoA was then compared with activation likelihood estimations of the auditory and semantic language networks using coordinate-based meta-analytic techniques.

RESULTS

We identified 4 patients with left-sided posterior temporal artery infarctions in the distribution of the AoA on diffusion-weighted magnetic resonance imaging. All 4 patients developed substantial expressive and receptive language deficits after surgery. Functional language improvement occurred in only 2/4 patients. Activation likelihood estimations localized parts of the auditory and semantic language networks in the distribution of the AoA.

CONCLUSIONS

The AoA is prone to blood flow disruption despite benign manipulation. Patients seem to have limited capacity for speech recovery after intraoperative ischemia in the distribution of this artery, which supplies parts of the auditory and semantic language networks.

Autobiographical memory compromise in individuals with alcohol use disorders: Towards implications for psychotherapy research

It has been found that Autobiographical memory (i.e., memory for personal experiences and facts about the self) are not properly maintained in people with alcohol-use disorders (AUD). The present paper offers a comprehensive overview of findings regarding the consequences of AUD on autobiographical memory. More specifically, we offer a theoretical model (the AMAUD Autobiographical Memory and Alcohol Use Disorders model) according to which chronic alcohol consumption compromises emotion regulation as well as executive control, which maintains the construction of autobiographical memory. Compromises in emotional regulation and executive functioning can be linked to a weak aspiration to construct detailed memories (i.e., autobiographical overgenerality), compromises of subjective reliving, anterograde amnesia, negative self-defining memories, and a difficulty to mentally project oneself forward in time to generate complex autobiographical representations and self-images. By gathering cognitive and clinical aspects of autobiographical decline in AUD, this model constitutes a theoretical foundation that may lead to a better understanding of this decline. Different clinical perspectives are proposed for developing personalized autobiographical memory rehabilitation programs for individuals with AUD.

Witnesses stumbling down memory lane: The effects of alcohol intoxication, retention interval, and repeated interviewing

Intoxicated eyewitnesses are often discredited by investigators and in court, but few studies have examined how alcohol affects witnesses' memory. The primary aim of the present study was to examine how intoxication (alcohol vs. control), retention interval (immediate vs. one week delay), and number of interviews (one vs. two interviews) affect witnesses' memory. The participants (N = 99) were randomly assigned to consume either orange juice or alcohol mixed with orange juice, and they all witnessed a filmed mock crime afterwards. The recall took place either (a) immediately and after a one week delay or (b) after a one week delay only. No main effect of alcohol was found on the quantity or quality of the witnesses' statements. Both intoxicated and sober witnesses recalled more details, and were more accurate, during immediate compared to delayed recall. For witnesses interviewed twice, an average of 30% new details were provided in the second compared to the first interview, and these were highly accurate. In sum, contrary to what one can expect, intoxicated witnesses with a low to moderate blood alcohol concentration (below 0.10%) were reliable witnesses.

Thinking after Drinking: Impaired Hippocampal-Dependent Cognition in Human Alcoholics and Animal Models of Alcohol Dependence

Alcohol use disorder currently affects approximately 18 million Americans, with at least half of these individuals having significant cognitive impairments subsequent to their chronic alcohol use. This is most widely apparent as frontal cortex-dependent cognitive dysfunction, where executive function and decision-making are severely compromised, as well as hippocampus-dependent cognitive dysfunction, where contextual and temporal reasoning are negatively impacted. This review discusses the relevant clinical literature to support the theory that cognitive recovery in tasks dependent on the prefrontal cortex and hippocampus is temporally different across extended periods of abstinence from alcohol. Additional studies from preclinical models are discussed to support clinical findings. Finally, the unique cellular composition of the hippocampus and cognitive impairment dependent on the hippocampus is highlighted in the context of alcohol dependence.

Extinction learning is slower, weaker and less context specific after alcohol

Alcohol is frequently involved in psychological trauma and often used by individuals to reduce fear and anxiety. We examined the effects of alcohol on fear acquisition and extinction within a virtual environment. Healthy volunteers were administered alcohol (0.4 g/kg) or placebo and underwent acquisition and extinction from different viewpoints of a virtual courtyard, in which the conditioned stimulus, paired with a mild electric shock, was centrally located. Participants returned the following day to test fear recall from both viewpoints of the courtyard. Skin conductance responses were recorded as an index of conditioned fear. Successful fear acquisition under alcohol contrasted with impaired extinction learning evidenced by persistent conditioned responses (Experiment 1). Participants’ impairments in extinction under alcohol correlated with impairments in remembering object-locations in the courtyard seen from one viewpoint when tested from the other viewpoint. Alcohol-induced extinction impairments were overcome by increasing the number of extinction trials (Experiment 2). However, a test of fear recall the next day showed persistent fear in the alcohol group across both viewpoints. Thus, alcohol impaired extinction rather than acquisition of fear, suggesting that extinction is more dependent than acquisition on alcohol-sensitive representations of spatial context. Overall, extinction learning under alcohol was slower, weaker and less context-specific, resulting in persistent fear at test that generalized to the extinction viewpoint. The selective effect on extinction suggests an effect of alcohol on prefrontal involvement, while the reduced context-specificity implicates the hippocampus. These findings have important implications for the use of alcohol by individuals with clinical anxiety disorders.

Alcohol use across the lifespan: An analysis of adolescent and aged rodents and humans

Adolescence and old age are unique periods of the lifespan characterized by differential sensitivity to the effects of alcohol. Adolescents and the elderly appear to be more vulnerable to many of alcohol's physiological and behavioral effects compared to adults. The current review explores the differential effects of acute alcohol, predominantly in terms of motor function and cognition, in adolescent and aged humans and rodents. Adolescents are less sensitive to the sedative-hypnotic, anxiolytic, and motor-impairing effects of acute alcohol, but research results are less consistent as it relates to alcohol's effects on cognition. Specifically, previous research has shown adolescents to be more, less, and similarly sensitive to alcohol-induced cognitive deficits compared to adults. These equivocal findings suggest that learning acquisition may be differentially affected by ethanol compared to memory, or that ethanol-induced cognitive deficits are task-dependent. Older rodents appear to be particularly vulnerable to the motor- and cognitive-impairing effects of acute alcohol relative to younger adults. Given that alcohol consumption and abuse is prevalent throughout the lifespan, it is important to recognize age-related differences in response to acute and long-term alcohol. Unfortunately, diagnostic measures and treatment options for alcohol dependence are rarely dedicated to adolescent and aging populations. As discussed, although much scientific advancement has been made regarding the differential effects of alcohol between adolescents and adults, research with the aged is underrepresented. Future researchers should be aware that adolescents and the aged are uniquely affected by alcohol and should continue to investigate alcohol's effects at different stages of maturation.

Attention to advertising and memory for brands under alcohol intoxication

In an attempt to discover new possibilities for advertising in uncluttered environments marketers have recently begun using ambient advertising in, for instance, bars and pubs. However, advertising in such licensed premises have to deal with the fact that many consumers are under the influence of alcohol while viewing the ad. This paper examines the effect of alcohol intoxication on attention to and memory for advertisements in two experiments. Study 1 used a forced exposure manipulation and revealed increased attention to logos under alcohol intoxication consistent with the psychopharmacological prediction that alcohol intoxication narrows attention to the more salient features in the visual environment. Study 2 used a voluntary exposure manipulation in which ads were embedded in a magazine. The experiment revealed that alcohol intoxication reduces voluntary attention to ads and leads to a significant reduction in memory for the viewed ads. In popular terms consuming one or two beers reduces brand recall from 40 to 36% while being heavily intoxicated further reduces brand recall to 17%.

The neuroscience of face processing and identification in eyewitnesses and offenders

Humans are experts in face perception. We are better able to distinguish between the differences of faces and their components than between any other kind of objects. Several studies investigating the underlying neural networks provided evidence for deviated face processing in criminal individuals, although results are often confounded by accompanying mental or addiction disorders. On the other hand, face processing in non-criminal healthy persons can be of high juridical interest in cases of witnessing a felony and afterward identifying a culprit. Memory and therefore recognition of a person can be affected by many parameters and thus become distorted. But also face processing itself is modulated by different factors like facial characteristics, degree of familiarity, and emotional relation. These factors make the comparison of different cases, as well as the transfer of laboratory results to real live settings very challenging. Several neuroimaging studies have been published in recent years and some progress was made connecting certain brain activation patterns with the correct recognition of an individual. However, there is still a long way to go before brain imaging can make a reliable contribution to court procedures.

Acute alcohol effects on contextual memory BOLD response: differences based on fragmentary blackout history

BACKGROUND

Contextual memory, or memory for source details, is an important aspect of episodic memory and has been implicated in alcohol-induced fragmentary blackouts (FBs). Little is known, however, about how neural functioning during contextual memory processes may differ between individuals with and without a history of FB. This study examined whether neural activation during a contextual memory task differed by history of FB and acute alcohol consumption.

METHODS

Twenty-four matched individuals with (FB+; n = 12) and without (FB-; n = 12) a history of FBs were recruited from a longitudinal study of alcohol use and behavioral risks and completed a laboratory beverage challenge followed by 2 functional magnetic resonance imaging (fMRI) sessions under no alcohol and alcohol (breath alcohol concentration = 0.08%) conditions. Task performance and brain hemodynamic activity during a block design contextual memory task were examined across 48 fMRI sessions.

RESULTS

Groups demonstrated no differences in performance on the contextual memory task, yet exhibited different brain response patterns after alcohol intoxication. A significant FB group by beverage interaction emerged in bilateral dorsolateral prefrontal cortex and posterior parietal cortex with FB- individuals showing greater blood oxygenation level-dependent response after alcohol exposure (p < 0.05).

CONCLUSIONS

Alcohol had differential effects on neural activity for FB+ and FB- individuals during recollection of contextual information, perhaps suggesting a neurobiological mechanism associated with alcohol-induced FB.

Characterization of the acute effects of alcohol on asymmetry of inferior frontal cortex activity during a Go/No-Go task using functional near-infrared spectroscopy

RATIONALE

Successful response inhibition is associated with right-lateralized inferior frontal cortex (IFC) activity, and alcohol impairs this inhibitory control, thereby enhancing false-alarm responses in the Go/No-Go task. However, the neural correlates of effect of alcohol on response inhibition remain unclear.

OBJECTIVE

This study characterized the acute effects of alcohol on IFC activity during Go/No-Go tasks using near-infrared spectroscopy (NIRS).

METHODS

Thirty-two subjects visited our laboratory twice: once for alcohol intake and once for placebo intake. On each visit, subjects performed Go/No-Go tasks immediately before and 10 min after intake of the alcohol or placebo. NIRS was used to evaluate IFC activity measured during Go/No-Go tasks.

RESULTS

Alcohol significantly enhanced false-alarm responses in No-Go trials. NIRS analysis showed that IFC activity was greater in the right hemisphere than in the left hemisphere prior to alcohol or placebo intake. This right hemispheric superiority was eliminated in response to alcohol but not in response to placebo. Correlation analysis showed that subjects with right-lateralized IFC activity made fewer false-alarm responses in No-Go trials and that alcohol-induced inhibition of hemispheric IFC asymmetry resulted in higher false-alarm rates.

CONCLUSION

These findings suggest that the right IFC may mediate the acute effects of alcohol on inhibitory control. When the alcohol impairs the right IFC activity, subjects cannot inhibit the pre-potent responses for No-Go trials, resulting in enhanced false-alarm responses. Thus, this study successfully demonstrated the neural correlates of the alcohol effect in the right IFC activity during inhibitory control processes.

The effects of a modest dose of alcohol on executive functioning and prospective memory

RATIONALE

Acute alcohol intoxication selectively impairs executive functioning and prospective memory (PM). Much previous researches in this area have used laboratory‐based tasks that may not mimic functions that individuals with dysexecutive syndrome have problems with in their everyday life. The present study aimed to assess the effects of a modest dose of alcohol on executive functioning and PM using a virtual reality task and investigate the role of executive planning in PM performance.

METHODS

Forty healthy participants were administered 0.4 g/kg alcohol or matched placebo in a double‐blind design. Executive function and PM were assessed using the Jansari-Agnew-Akesson-Murphy (JAAM) task, requiring participants to play the role of an office worker.

RESULTS

Alcohol intoxication selectively impaired executive function and PM. The participants in the alcohol condition performed worse on the planning, prioritisation, creativity and adaptability executive subscales and also on the time‐based and event‐based PM tasks. However, alcohol did not impair the selection executive function task or the action‐based PM task.

CONCLUSIONS

The results provide further support for the effects of alcohol on executive functioning and PM. In addition, the results suggest that such deficits may be present at relatively modest doses of alcohol and in the absence of a subjective feeling of intoxication.

Functional imaging of cognitive control during acute alcohol intoxication

BACKGROUND

The anterior cingulate and several other prefrontal and parietal brain regions are implicated in error processing and cognitive control. The effects of different doses of alcohol on activity within these brain regions during a functional magnetic resonance imaging (fMRI) task where errors are frequently committed have not been fully explored.

METHODS

This study examined the impact of a placebo [breath alcohol concentration (BrAC) = 0.00%], moderate (BrAC = 0.05%), and high (BrAC = 0.10%) doses of alcohol on brain hemodynamic activity during a functional MRI (fMRI) Go/No-Go task in 38 healthy volunteers.

RESULTS

Alcohol increased reaction time and false alarm errors in a dose-dependent manner. fMRI analyses showed alcohol decreased activity in anterior cingulate, lateral prefrontal cortex, insula, and parietal lobe regions during false alarm responses to No-Go stimuli.

CONCLUSIONS

These findings indicate that brain regions implicated in error processing are affected by alcohol and might provide a neural basis for alcohol's effects on behavioral performance.

Now everyone looks the same: alcohol intoxication reduces the own-race bias in face recognition

Several factors influence the reliability of eyewitness identification evidence. Typically, recognition for same-race faces is better than for different-race faces (the own-race bias), and alcohol intoxication decreases overall face recognition accuracy. This research investigated how alcohol intoxication influences the own-race bias. Asian and European participants completed tests of recognition memory for Asian and European faces when either mildly intoxicated (mean breath alcohol concentration of .05) or when sober. Compared to their sober counterparts, intoxicated participants showed a reduced own-race bias. Specifically, alcohol intoxication had a larger negative effect on the recognition of same-race faces compared to different-race faces. The legal and theoretical implications of these results are discussed.

Acute effects of alcohol on intrusive memory development and viewpoint dependence in spatial memory support a dual representation model

BACKGROUND

A dual representation model of intrusive memory proposes that personally experienced events give rise to two types of representation: an image-based, egocentric representation based on sensory-perceptual features; and a more abstract, allocentric representation that incorporates spatiotemporal context. The model proposes that intrusions reflect involuntary reactivation of egocentric representations in the absence of a corresponding allocentric representation. We tested the model by investigating the effect of alcohol on intrusive memories and, concurrently, on egocentric and allocentric spatial memory.

METHODS

With a double-blind independent group design participants were administered alcohol (.4 or .8 g/kg) or placebo. A virtual environment was used to present objects and test recognition memory from the same viewpoint as presentation (tapping egocentric memory) or a shifted viewpoint (tapping allocentric memory). Participants were also exposed to a trauma video and required to detail intrusive memories for 7 days, after which explicit memory was assessed.

RESULTS

There was a selective impairment of shifted-view recognition after the low dose of alcohol, whereas the high dose induced a global impairment in same-view and shifted-view conditions. Alcohol showed a dose-dependent inverted "U"-shaped effect on intrusions, with only the low dose increasing the number of intrusions, replicating previous work. When same-view recognition was intact, decrements in shifted-view recognition were associated with increases in intrusions.

CONCLUSIONS

The differential effect of alcohol on intrusive memories and on same/shifted-view recognition support a dual representation model in which intrusions might reflect an imbalance between two types of memory representation. These findings highlight important clinical implications, given alcohol's involvement in real-life trauma.

Effects of ethanol on hippocampal function during adolescence: a look at the past and thoughts on the future

It has been demonstrated by several laboratories that ethanol, both acute and chronic, produces effects that are age dependent. Specifically, adolescent rats are less sensitive to the hypnotic and motor-impairing effects of ethanol but are more sensitive to the hypothermic effects of the drug. However, the results on hippocampal function are not as clear. For example, there have been mixed findings regarding adolescent sensitivity of hippocampal-dependent (spatial) memory in response to ethanol. The current review explores the present state of the field as it relates to ethanol's effects in the hippocampus, particularly as it relates to spatial memory. In addition, we review potential neurobiological mechanisms that might underlie the age-dependent effects of ethanol in the hippocampus. Finally, future directions are proposed that will advance the state of the field as it relates to ethanol's effect during this developmental period.

Alcohol and the prefrontal cortex

The prefrontal cortex occupies the anterior portion of the frontal lobes and is thought to be one of the most complex anatomical and functional structures of the mammalian brain. Its major role is to integrate and interpret inputs from cortical and sub-cortical structures and use this information to develop purposeful responses that reflect both present and future circumstances. This includes both action-oriented sequences involved in obtaining rewards and inhibition of behaviors that pose undue risk or harm to the individual. Given the central role in initiating and regulating these often complex cognitive and behavioral responses, it is no surprise that alcohol has profound effects on the function of the prefrontal cortex. In this chapter, we review the basic anatomy and physiology of the prefrontal cortex and discuss what is known about the actions of alcohol on the function of this brain region. This includes a review of both the human and animal literature including information on the electrophysiological and behavioral effects that follow acute and chronic exposure to alcohol. The chapter concludes with a discussion of unanswered questions and areas needing further investigation.

Decreases in recollective experience following acute alcohol: a dose-response study

RATIONALE

Acute alcohol intoxication induces a selective impairment of recognition memory associated with conscious recollection whilst recognition based on familiarity is left intact.

OBJECTIVES

We aimed to further elucidate the acute effects of alcohol on recognition memory by assessing three different doses of alcohol and examining the way in which this affected the recollection and familiarity components of recognition memory in comparison to a placebo group.

METHODS

A double-blind independent design was used, and participants received either alcohol (0.4, 0.6 or 0.8 g/kg) or a placebo drink. Participants encoded word pairs with depth of processing manipulated under generate and read conditions. Recognition memory was assessed and recollective awareness was examined through use of the remember-know procedure.

RESULTS

Alcohol produced a dose-dependent reduction in recognition memory associated with recollection, evidenced by decreases in the number of correctly recognised items with 'remember' responses compared to placebo. Recognition based on a familiarity, evidenced by 'know' responses, showed no differences between groups or pattern of reduction compared to the placebo group. However, a negative correlation was found between recognition based on familiarity and levels of intoxication.

CONCLUSIONS

Alcohol-induced impairments in recognition memory occur in a dose-dependent manner, specifically driven by reductions in recognition associated with conscious awareness.

The Acute Effect of Alcohol on Various Memory Processes

This review surveys relevant and recent data of the pertinent literature regarding the acute effect of alcohol on various kinds of memory processes with special emphasis on working memory. The characteristics of different types of long-term memory (LTM) and short-term memory (STM) processes are summarized with an attempt to relate these to various structures in the brain. LTM is typically impaired by chronic alcohol intake but according to some data a single dose of ethanol may have long lasting effects if administered at a critically important age. The most commonly seen deleterious acute effect of alcohol to STM appears following large doses of ethanol in conditions of “binge drinking” causing the “blackout” phenomenon. However, with the application of various techniques and well-structured behavioral paradigms it is possible to detect, albeit occasionally, subtle changes of cognitive processes even as a result of a low dose of alcohol. These data may be important for the consideration of legal consequences of low-dose ethanol intake in conditions such as driving, etc.

Extinction learning of stimulus reward contingencies: The acute effects of alcohol

BACKGROUND

Recent theories suggest that extinction is, at least partly, new learning suppressing original associations between a conditioned stimulus and a conditioned response without severing those associations. During extinction alcohol via its effects on inhibitory control may reduce the ability to suppress the original associations between a conditioned stimulus and a conditioned response leading to an impairment of extinction learning. Thus, the present study is set out to examine the effects of alcohol on extinction learning to enhance current knowledge on mechanisms of extinction and conditions that might hamper extinction, which is an important aspect for the treatment of alcohol-dependent patients.

METHODS

Light to moderate social drinkers (N=32) acquired an instrumental reward seeking response. Extinction training of the reward seeking response was performed after administration of a dose of 0.8 g/kg alcohol resulting in a peak blood alcohol concentration ranging from 112 to 184 mg/dL. In addition, we assessed subjective alcohol effects and administered a Stop-Signal task which measures the ability to inhibit a pre-potent motor response.

RESULTS

Alcohol influenced subjective ratings of light-headedness and increased the Stop-Signal reaction time indicating disinhibiting effects. However, our results did not show any impairment of learning of extinction after the administration of alcohol. Behavioural as well as attentional responses indicated extinction of conditioned responses for both experimental groups.

CONCLUSIONS

These findings suggest that alcohol at a dose that impairs performance in a task of inhibitory control does not impair learning of extinction.