Auditory sensory memory as indicated by mismatch negativity in chronic alcoholism

Targeting electroencephalography for alcohol dependence: A narrative review

BACKGROUND

Electroencephalography (EEG)-based electrophysiological techniques have made progress in diagnosing and treating alcohol dependence in recent years.

AIMS

The article reviews the latest literature in this field.

MATERIALS AND METHODS

Alcohol dependence, which is common and prone to relapsing, poses a serious threat to individuals, families, and society. At present, the objective detection methods for alcohol dependence in clinic are not enough. As electrophysiological techniques developed in psychiatry, some researches on EEG-based monitoring methods are of great significance in the diagnosis and treatment of alcohol dependence.

DISCUSSION

As electrophysiological techniques developed in psychiatry, some researches on EEG-based monitoring methods such as resting electroencephalography (REEG), event-related potentials (ERP), event-related oscillations (ERO), and polysomnography (PSG), was reported.

CONCLUSION

In this paper, the status of electrophysiological researches on EEG in alcoholics are reviewed in detail.

Auditory mismatch detection, distraction, and attentional reorientation (MMN-P3a-RON) in neurological and psychiatric disorders: A review

Involuntary attention allows for the detection and processing of novel and potentially relevant stimuli that lie outside of cognitive focus. These processes comprise change detection in sensory contexts, automatic orientation toward this change, and the selection of adaptive responses, including reorientation to the original goal in cases when the detected change is not relevant for task demands. These processes have been studied using the Event-Related Potential (ERP) technique and have been associated to the Mismatch Negativity (MMN), the P3a, and the Reorienting Negativity (RON) electrophysiological components, respectively. This has allowed for the objective evaluation of the impact of different neuropsychiatric pathologies on involuntary attention. Additionally, these ERP have been proposed as alternative measures for the early detection of disease and the tracking of its progression. The objective of this review was to integrate the results reported to date about MMN, P3a, and RON in different neurological and psychiatric disorders. We included experimental studies with clinical populations that reported at least two of these three components in the same experimental paradigm. Overall, involuntary attention seems to reflect the state of cognitive integrity in different pathologies in adults. However, if the main goal for these ERP is to consider them as biomarkers, more research about their pathophysiological specificity in each disorder is needed, as well as improvement in the general experimental conditions under which these components are elicited. Nevertheless, these ERP represent a valuable neurophysiological tool for early detection and follow-up of diverse clinical populations.

Formation and decay of auditory short-term memory in the macaque monkey

Echoic memory (EM) is a short-lived, precategorical, and passive form of auditory short-term memory (STM). A key hallmark of EM is its rapid exponential decay with a time constant between 1 and 2 s. It is not clear whether auditory STM in the rhesus, an important model system, shares this rapid exponential decay. To resolve this shortcoming, two rhesus macaques were trained to perform a delayed frequency discrimination task. Discriminability of delayed tones was measured as a function of retention duration and the number of times the standard had been repeated before the target. Like in the human, our results show a rapid decline of discriminability with retention duration. In addition, the results suggest a gradual strengthening of discriminability with repetition number. Model-based analyses suggest the presence of two components of auditory STM: a short-lived component with a time constant on the order of 550 ms that most likely corresponds to EM and a more stable memory trace with time constants on the order of 10 s that strengthens with repetition and most likely corresponds to auditory recognition memory. NEW & NOTEWORTHY This is the first detailed quantification of the rapid temporal dynamics of auditory short-term memory in the rhesus. Much of the auditory information in short-term memory is lost within the first couple of seconds. Repeated presentations of a tone strengthen its encoding into short-term memory. Model-based analyses suggest two distinct components: an echoic memory homolog that mediates the rapid decay and a more stable but less detail-rich component that mediates strengthening of the trace with repetition.

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.

Why cognitive event-related potentials (ERPs) should have a role in the management of alcohol disorders

Alcohol dependence is currently one of the most serious public health problems. Indeed, 3-8% of all deaths worldwide are attributable to effects of alcohol consumption. Although the first step in alcohol dependence treatment is straightforward, the main problem for clinicians lies with the prevention of relapse, as 40-70% of patients who only undergo psychosocial therapy resume alcohol use within a year following treatment. This review of the literature regarding event-related potentials (ERPs) is focused on two major neurocognitive factors that partially account for the inability of many alcoholics to remain abstinent: attentional biases towards alcohol-related stimuli that increase the urge to drink, and impaired response inhibition towards these cues that makes it more difficult for alcoholics to resist the temptation to drink. On this basis, we propose new research avenues to better implement ERPs in the management of alcohol disorders, according to four main directions that relate to (1) the development of ERP serial recordings; (2) the promotion of a multi-component ERP approach; (3) the definition of multi-site guidelines; and (4) the use of more representative laboratory situations through the use of more compelling environments.

Changes of auditory event-related potentials in ovariectomized rats injected with d-galactose: Protective role of rosmarinic acid

Rosmarinic acid (RA), which has multiple bioactive properties, might be a useful agent for protecting central nervous system against age related alterations. In this context, the purpose of the present study was to investigate possible protective effects of RA on mismatch negativity (MMN) component of auditory event-related potentials (AERPs) as an indicator of auditory discrimination and echoic memory in the ovariectomized (OVX) rats injected with d-galactose combined with neurochemical and histological analyses. Ninety female Wistar rats were randomly divided into six groups: sham control (S); RA-treated (R); OVX (O); OVX+RA-treated (OR); OVX+d-galactose-treated (OD); OVX+d-galactose+RA-treated (ODR). Eight weeks later, MMN responses were recorded using the oddball condition. An amplitude reduction of some components of AERPs was observed due to ovariectomy with or without d-galactose administiration and these reduction patterns were diverse for different electrode locations. MMN amplitudes were significantly lower over temporal and right frontal locations in the O and OD groups versus the S and R groups, which was accompanied by increased thiobarbituric acid reactive substances (TBARS) and hydroxy-2-nonenal (4-HNE) levels. RA treatment significantly increased AERP/MMN amplitudes and lowered the TBARS/4-HNE levels in the OR and ODR groups versus the O and OD groups, respectively. Our findings support the potential benefit of RA in the prevention of auditory distortion related to the estrogen deficiency and d-galactose administration at least partly by antioxidant actions.

Effects of pre- and postnatal exposure to extremely low-frequency electric fields on mismatch negativity component of the auditory event-related potentials: Relation to oxidative stress

In our previous study, the developmental effects of extremely low-frequency electric fields (ELF-EF) on visual and somatosensory evoked potentials in adult rats were studied. There is no study so far examining the effects of 50 Hz electric field (EF) on mismatch negativity (MMN) recordings after exposure of rats during development. Therefore, our present study aimed to investigate MMN and oxidative brain damage in rats exposed to EF (12 kV/m, 1 h/day). Rats were divided into four groups, namely control (C), prenatal (Pr), postnatal (Po), and prenatal+postnatal (PP). Pregnant rats of Pr and PP groups were exposed to EF during pregnancy. Following birth, rats of PP and Po groups were exposed to EF for three months. After exposure to EF, MMN was recorded by electrodes positioned stereotaxically to the surface of the dura, and then brain tissues were removed for histological and biochemical analyses. The MMN amplitude was higher to deviant tones than to standard tones. It was decreased in all experimental groups compared with the C group. 4-Hydroxy-2-nonenal (4-HNE) levels were significantly increased in the Po group with respect to the C group, whereas they were significantly decreased in the PP group compared with Pr and Po groups. Protein carbonyl levels were significantly decreased in the PP group compared with C, Pr, and Po groups. EF decreased MMN amplitudes were possibly induced by lipid peroxidation.

Event-related potentials in substance use disorders: a narrative review based on articles from 1984 to 2012

Mechanisms that mediate the transition from occasional, controlled, drug use to the impaired control that characterizes severe dependence are still a matter of investigation. The etiology of substance use disorders (SUDs) is complex, and in this context of complexity, the concept of "endophenotype," has gained extensive popularity in recent years. The main aim of endophenotypes is to provide a simpler, more proximal target to discover the biological underpinnings of a psychiatric syndrome. In this view, neurocognitive and neurophysiological impairments that suggest functional impairments associated with SUDs have been proposed as possible endophenotypes. Because of its large amplitude and relatively easy elicitation, the most studied of the cognitive brain event-related potentials (ERPs), the P300 component, has been proposed as one possible candidate. However, if a P300 amplitude alteration is a common finding in SUDs, it is also observable in other psychiatric afflictions, suggesting that the associations found may just reflect a common measure of brain dysfunction. On this basis, it has been proposed that a multivariate endophenotype, based on a weighted combination of electrophysiological features, may provide greater diagnostic classification power than any single endophenotype. The rationale for investigating multiple features is to show that combining them provides extra useful information that is not available in the individual features, leading ultimately to a multivariate phenotype.The aim of the present article is to outline the potential usefulness of this kind of "combined electrophysiological procedure" applied to SUDs. We present a review of ERP studies, combining data from people with SUD, family members, and normal control subjects, to verify whether the combination of 4ERPs (P50, MMN, P300, and N400) may produce profiles of cortical anomalies induced by different types of SUD (alcohol vs cocaine vs cannabis vs heroin).

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.

The mismatch negativity (MMN)--a unique window to disturbed central auditory processing in ageing and different clinical conditions

In this article, we review clinical research using the mismatch negativity (MMN), a change-detection response of the brain elicited even in the absence of attention or behavioural task. In these studies, the MMN was usually elicited by employing occasional frequency, duration or speech-sound changes in repetitive background stimulation while the patient was reading or watching videos. It was found that in a large number of different neuropsychiatric, neurological and neurodevelopmental disorders, as well as in normal ageing, the MMN amplitude was attenuated and peak latency prolonged. Besides indexing decreased discrimination accuracy, these effects may also reflect, depending on the specific stimulus paradigm used, decreased sensory-memory duration, abnormal perception or attention control or, most importantly, cognitive decline. In fact, MMN deficiency appears to index cognitive decline irrespective of the specific symptomatologies and aetiologies of the different disorders involved.

Auditory sensory memory and language abilities in former late talkers: a mismatch negativity study

The present study investigated whether (a) a reduced duration of auditory sensory memory is found in late talking children and (b) whether deficits of sensory memory are linked to persistent difficulties in language acquisition. Former late talkers and children without delayed language development were examined at the age of 4 years and 7 months using mismatch negativity (MMN) with interstimulus intervals (ISIs) of 500 ms and 2000 ms. Additionally, short-term memory, language skills, and nonverbal intelligence were assessed. MMN mean amplitude was reduced for the ISI of 2000 ms in former late talking children both with and without persistent language deficits. In summary, our findings suggest that late talkers are characterized by a reduced duration of auditory sensory memory. However, deficits in auditory sensory memory are not sufficient for persistent language difficulties and may be compensated for by some children.

Chronic alcoholism: insights from neurophysiology

INTRODUCTION

Increasing knowledge of the anatomical structures and cellular processes underlying psychiatric disorders may help bridge the gap between clinical signs and basic physiological processes. Accordingly, considerable insight has been gained in recent years into a common psychiatric condition, i.e., chronic alcoholism.

MATERIAL AND METHODS

We reviewed various physiological parameters that are altered in chronic alcoholic patients compared to healthy individuals--continuous electroencephalogram, oculomotor measures, cognitive event-related potentials and event-related oscillations--to identify links between these physiological parameters, altered cognitive processes and specific clinical symptoms.

RESULTS

Alcoholic patients display: (1) high beta and theta power in the resting electroencephalogram, suggesting hyperarousal of their central nervous system; (2) abnormalities in smooth pursuit eye movements, in saccadic inhibition during antisaccade tasks, and in prepulse inhibition, suggesting disturbed attention modulation and abnormal patterns of prefrontal activation that may stem from the same prefrontal "inhibitory" cortical dysfunction; (3) decreased amplitude for cognitive event-related potentials situated along the continuum of information-processing, suggesting that alcoholism is associated with neurophysiological deficits at the level of the sensory cortex and not only disturbances involving associative cortices and limbic structures; and (4) decreased theta, gamma and delta oscillations, suggesting cognitive disinhibition at a functional level.

DISCUSSION

The heterogeneity of alcoholic disorders in terms of symptomatology, course and outcome is the result of various pathophysiological processes that physiological parameters may help to define. These alterations may be related to precise cognitive processes that could be easily monitored neurophysiologically in order to create more homogeneous subgroups of alcoholic individuals.

The mismatch negativity (MMN) in basic research of central auditory processing: a review

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream.

Mismatch negativity impairment associated with alcohol consumption in chronic alcoholics: A scalp current density study

Previous studies, based on amplitude and latency measurements of auditory event-related brain potentials, yielded inconclusive results about the status of mismatch negativity (MMN) in chronic alcoholics. The present study explores scalp current density (SCD) dynamics during MMN latency range in alcoholics, and correlates electrical SCD results with clinical data of the patients. SCD was computed from 30 electrodes in 16 abstinent chronic alcoholics and 16 healthy control volunteers in a paradigm on MMN elicited by duration changes. Reduced activity was observed in left frontal and right anterior and posterior temporal areas during MMN in alcoholics. Alcohol consumption correlated negatively with SCD intensity in these regions. Delayed activation was observed in the left posterior temporal area in the patients. Alcohol abstinence duration correlated positively with SCD intensity in this region. These results point to an impairment of automatic brain processing mechanisms associated with auditory change detection in chronic alcoholism. The present results suggest a reorganization of the computational neurodynamics of automatic auditory change detection linked to the amount of alcohol consumed in abstinent chronic alcoholics.

The mismatch negativity in cognitive and clinical neuroscience: Theoretical and methodological considerations

Mismatch negativity (MMN) component of the event-related brain potentials has become popular in cognitive and clinical brain research during the recent years. It is an early response to a violation of an auditory rule such as an infrequent change in the physical feature of a repetitive sound. There is a lot of evidence on the association of the MMN parameters and behavioral discrimination ability, although this relationship is not always straight-forward. Since the MMN reflects sound discrimination accuracy, it can be used for probing how well different groups of individuals perceive sound differences, and how training or remediation affects this ability. In the present review, we first introduce some of the essential MMN findings in probing sound discrimination, memory, and their deficits. Thereafter, issues which need to be taken into account in MMN investigations as well as new improved recording paradigms are discussed.

A comparison of the mismatch negativity and a differential waveform response

A mismatch negativity response (MMN) and a new differential waveform were derived in an effort to evaluate a neural refractory or recovery effect in adult listeners. The MMN was elicited using oddball test runs in which the standard and deviant stimuli differed in frequency To derive the differential waveform, the same standard and deviant stimuli were presented alone. MMN responses were obtained by subtracting the averaged responses to standards from the deviants. The differential waveforms were obtained by subtracting the averaged responses to standards presented alone from deviants presented alone. Scalp topography for the MMN and differential waveforms were similar. A significant (p <.05) positive and negative correlation was found between the earlier and later components of the bimodal MMN and the NI and P2 component of the differential waveform, respectively. Further, N1 and P2 of the differential waveform were significant (p <.05) predictor variables of early and late peak amplitudes of the MMN. These results suggest that refractory effects may overlay/modify the morphology of the MMN waveform.

The utility of neurophysiological markers in the study of alcoholism

OBJECTIVE

This review attempts to differentiate neuroelectric measures (electroencephalogram (EEG), event-related potentials (ERPs) and event-related oscillations (EROs)) related to acute and chronic effects of alcohol on the brain from those that reflect underlying deficits related to the predisposition to develop alcoholism and related disorders. The utility of these neuroelectric measures as endophenotypes for psychiatric genetics is evaluated.

METHODS

This article reviews the main findings of EEG and ERP abnormalities in alcoholics, offspring of alcoholics at high risk to develop alcoholism and the electrophysiological effects of alcohol on high risk compared to low-risk offspring. It highlights findings using EROs, a fast developing tool in examining brain function and cognition. It also reviews evidence of genetic findings related to these electrophysiological measures and their relationship to clinical diagnosis.

RESULTS

Many of these abnormal neuroelectric measures are under genetic control, may precede the development of alcoholism, and may be markers of a predisposition toward the development of a spectrum of disinhibitory conditions including alcoholism. Genetic loci underlying some neuroelectic measures that involve neurotransmitter systems of the brain have been identified.

CONCLUSIONS

Quantitative neuroelectric measures (EEG, ERPs, EROs) provide valuable endophenotypes in the study of genetic risk to develop alcoholism and related disorders.

SIGNIFICANCE

Genetic studies of neuroelectric endophenotypes offer a powerful strategy for identifying susceptibility genes for developing psychiatric disorders, and provide novel insights into etiological factors.

Auditory sensory gating deficit in abstinent chronic alcoholics

P50 event-related potential was studied in abstinent chronic alcoholics to determine whether they had normal sensory gating. Repeated tones were presented to 17 recently detoxified chronic alcoholic patients and 17 healthy subjects while EEG was recorded. Low-resolution tomography (LORETA) was performed to obtain cerebral sources of P50. Abstinent chronic alcoholics showed reduced P50 sensory gating. Present results suggest an inhibitory deficit in early pre-attentive auditory sensory processing in chronic alcoholism.

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.

Abnormal CNV in chronic heavy drinkers

OBJECTIVE

We used the contingent negative variation (CNV), a slow negative shift in the human electroencephalogram, to investigate the effects of heavy chronic alcohol use on frontal lobe function.

METHODS

Event-related potentials (ERPs) were recorded from 30 heavy drinkers (HD) and 30 age-, sex-, and education-matched light or non-drinkers (LD), using a classical two-stimulus reaction time (RT) paradigm. Structural magnetic resonance images and neuropsychological tests were also administered.

RESULTS

The amplitude of the late CNV was significantly reduced in HD relative to light drinkers. Moreover, diminished CNV amplitudes in HD appear to be closely related to the amount of recent alcohol consumption. There were no significant differences in neuropsychological measures of frontal lobe function and frontal lobe volume between light and HD. However, in HD, reduced late CNV amplitudes were associated with decreased frontal lobe gray matter volume and poor performance on the Trail Making Test B. In LD but not in HD, late CNV amplitude correlated positively with RT, suggesting that the late CNV reflects some aspect of motor and cognitive preparation.

CONCLUSIONS

The inverse relationships between frontal lobe gray matter volume, performance on the Trail Making Test B, and late CNV amplitude in HD suggest that the ERP abnormalities observed in the current study may be indices of alcohol-related damage to the frontal lobe. The lack of a significant relationship between CNV amplitude and RT in HD suggests that chronic heavy alcohol use may disrupt response preparation.

Electrophysiological evidence of abnormal activation of the cerebral network of involuntary attention in alcoholism

OBJECTIVE

Increased distractibility is a common impairment in alcoholism, but objective evidence has remained elusive. Here, a task designed to investigate with event-related brain potentials (ERPs) the neural mechanism underlying distraction was used to show abnormal involuntary orienting of attention in chronic alcoholism.

METHODS

Fifteen alcoholics and 17 matched healthy controls were instructed to ignore auditory stimuli while concentrating in the discrimination of immediately following visual stimuli. The auditory sequences contained repetitive standard tones occasionally replaced by deviant tones of slightly higher frequency, or by complex novel sounds.

RESULTS

Deviant tones and novel sounds distracted visual performance, i.e. increased reaction time to visual stimuli, similarly in patients and controls. Compared to controls, however, alcoholics showed ERP abnormalities, i.e. enhanced P3a amplitudes over the left frontal region, and a positive posterior deflection instead of the frontally distributed reorienting negativity (RON).

CONCLUSIONS

The enhanced P3a to novelty and subsequent positive wave instead of RON in alcoholics suggests encoding into working memory of task-irrelevant auditory events and provides neurophysiological markers of impaired involuntary attention mechanisms in chronic alcoholism.