Information processing components of the auditory event related potential are reduced by cocaine

Gender-Specific Interactions in a Visual Object Recognition Task in Persons with Opioid Use Disorder

Opioid use disorder (OUD)-associated overdose deaths have reached epidemic proportions worldwide over the past two decades, with death rates for men reported at twice the rate for women. Using a controlled, cross-sectional, age-matched (18-56 y) design to better understand the cognitive neuroscience of OUD, we evaluated the electroencephalographic (EEG) responses of male and female participants with OUD vs. age- and gender-matched non-OUD controls during a simple visual object recognition Go/No-Go task. Overall, women had significantly slower reaction times (RTs) than men. In addition, EEG N200 and P300 event-related potential (ERP) amplitudes for non-OUD controls were significantly larger for men, while their latencies were significantly shorter than for women. However, while N200 and P300 amplitudes were not significantly affected by OUD for either men or women in this task, latencies were also affected differentially in men vs. women with OUD. Accordingly, for both N200 and P300, male OUD participants exhibited longer latencies while female OUD participants exhibited shorter ones than in non-OUD controls. Additionally, robust oscillations were found in all participants during a feedback message associated with performance in the task. Although alpha and beta power during the feedback message were significantly greater for men than women overall, both alpha and beta oscillations exhibited significantly lower power in all participants with OUD. Taken together, these findings suggest important gender by OUD differences in cognitive processing and reflection of performance in this simple visual task.

Dopaminergic and norepinephrinergic modulation of endogenous event-related potentials: A systematic review and meta-analysis

Event-related potentials (ERPs) represent the cortical processing of sensory, motor or cognitive functions invoked by particular events or stimuli. A current theory posits that the catecholaminergic neurotransmitters dopamine (DA) and norepinephrine (NE) modulate a number of endogenous ERPs during various cognitive processes. This manuscript aims to evaluate a leading neurotransmitter hypothesis with a systematic overview and meta-analysis of pharmacologic DA and NE manipulation of specific ERPs in healthy subjects during executive function. Specifically, the frontally-distributed P3a, N2, and Ne/ERN (or error-related negativity) are supposedly modulated primarily by DA, whereas the parietally-distributed P3b is thought to be modulated by NE. Based on preceding research, we refer to this distinction between frontally-distributed DA-sensitive and parietally-distributed NE-sensitive ERP components as the Extended Neurobiological Polich (ENP) hypothesis. Our systematic review and meta-analysis indicate that this distinction is too simplistic and many factors interact with DA and NE to influence these specific ERPs. These may include genetic factors, the specific cognitive processes engaged, or elements of study design, i.e. session or sequence effects or data-analysis strategies.

Acute effects of cocaine and cannabis on response inhibition in humans: an ERP investigation

Substance abuse has often been associated with alterations in response inhibition in humans. Not much research has examined how the acute effects of drugs modify the neurophysiological correlates of response inhibition, or how these effects interact with individual variation in trait levels of impulsivity and novelty seeking. This study investigated the effects of cocaine and cannabis on behavioural and event-related potential (ERP) correlates of response inhibition in 38 healthy drug using volunteers. A double-blind placebo-controlled randomized three-way crossover design was used. All subjects completed a standard Go/NoGo task after administration of the drugs. Compared with a placebo, cocaine yielded improved accuracy, quicker reaction times and an increased prefrontal NoGo-P3 ERP. Cannabis produced opposing results; slower reaction times, impaired accuracy and a reduction in the amplitude of the prefrontal NoGo-P3. Cannabis in addition decreased the amplitude of the parietally recorded P3, while cocaine did not affect this. Neither drugs specifically affected the N2 component, suggesting that pre-motor response inhibitory processes remain unaffected. Neither trait impulsivity nor novelty seeking interacted with drug-induced effects on measures of response inhibition. We conclude that acute drug effects on response inhibition seem to be specific to the later, evaluative stages of response inhibition. The acute effects of cannabis appeared less specific to response inhibition than those of cocaine. Together, the results show that the behavioural effects on response inhibition are reflected in electrophysiological correlates. This study did not support a substantial role of vulnerability personality traits in the acute intoxication stage.

Opposite effects of cannabis and cocaine on performance monitoring

Drug use is often associated with risky and unsafe behavior. However, the acute effects of cocaine and cannabis on performance monitoring processes have not been systematically investigated. The aim of the current study was to investigate how administration of these drugs alters performance monitoring processes, as reflected in the error-related negativity (ERN), the error positivity (Pe) and post-error slowing. A double-blind placebo-controlled randomized three-way crossover design was used. Sixty-one subjects completed a Flanker task while EEG measures were obtained. Subjects showed diminished ERN and Pe amplitudes after cannabis administration and increased ERN and Pe amplitudes after administration of cocaine. Neither drug affected post-error slowing. These results demonstrate diametrically opposing effects on the early and late phases of performance monitoring of the two most commonly used illicit drugs of abuse. Conversely, the behavioral adaptation phase of performance monitoring remained unaltered by the drugs.

The utility of P300 as a schizophrenia endophenotype and predictive biomarker: clinical and socio-demographic modulators in COGS-2

Reduced auditory P300 amplitude is a robust schizophrenia deficit exhibiting the qualities of a viable genetic endophenotype. These include heritability, test-retest reliability, and trait-like stability. Recent evidence suggests that P300 may also serve as a predictive biomarker for transition to psychosis during the schizophrenia prodrome. Historically, the utility of the P300 has been limited by its clinical nonspecificity, cross-site measurement variability, and required EEG expertise. The Consortium on the Genetics of Schizophrenia (COGS-2) study provided an opportunity to examine the consistency of the measure across multiple sites with varying degrees of EEG experience, and to identify important modulating factors that contribute to measurement variability. Auditory P300 was acquired from 649 controls and 587 patients at 5 sites. An overall patient deficit was observed with effect size 0.62. Each site independently observed a significant patient deficit, but site differences also existed. In patients, site differences reflected clinical differences in positive symptomatology and functional capacity. In controls, site differences reflected differences in racial stratification, smoking and substance use history. These factors differentially suppressed the P300 response, but only in control subjects. This led to an attenuated patient-control difference among smokers and among African Americans with history of substance use. These findings indicate that the P300 can be adequately assessed quantitatively, across sites, without substantial EEG expertise. Measurements are suitable for both genetic endophenotype analyses and studies of psychosis risk and conversion. However, careful attention must be given to selection of appropriate comparison samples to avoid misleading false negative results.

Characterizing the cognitive effects of cocaine: a comprehensive review

Understanding the cognitive sequela of repeated cocaine use is a growing area of research and is crucial to the development of cognitive models of addiction. We systematically reviewed all available placebo-controlled and case-controlled studies on the acute and long-term effects of cocaine on cognitive functioning. In order to compare the magnitude of cognitive effects across cognitive domains we conducted several meta-analyses on a subset of data from long-term effect studies. Studies on acute cocaine administration suggest enhancement of response inhibition and psychomotor speed, while all other domains appear to be unaffected or not investigated adequately. Long-term effects of cocaine show a wide array of deteriorated cognitive functions, indicating that long term cocaine use is characterized by a general cognitive impairment across functions, rather than by specific cognitive deficits. Literature on long-term cocaine effects is more substantial than literature on acute effects. This comprehensive review outlines possible dissociations and similarities of acute vs. long-term cocaine effects in the human brain. Atherosclerosis after cocaine exposure may underlie cognitive dysfunction, suggesting involvement of multiple brain areas. Acute drug studies are important to the future development of addiction models.

[The p300 cognitive event-related potential. I. Theoretical and psychobiologic perspectives]

The P300 is a positive wave which arises when an attended stimulus is detected. Its parameters depend on a number of variables, in particular the subject's mental state, the task that has to be accomplished, the significance of the stimulus, and the degree of attention. It can be recorded with accuracy, and the different stages of information processing can therefore be analyzed. The P300 wave shows the modifications in neuronal activity which take place during the cognitive process: P300 latency provides an indirect indication of the duration of the processes involved in stimulus discrimination while its amplitude, which is influenced by a number of variables, provides an index of the intensity of the energetic activation or arousal involved. The P300 wave consists of several components which reflect distinct information-processing events (P3a, P3b, P3e, P-SR, P-CR). According to the theoretical models, it is hypothesized that P300 could either represent the adaptation of the working memory to further environmental input ('context updating'), or indicate a closing process ('context closure') in information processing. As regards the physiological aspect of P300 and its association with cortical networks, various studies have suggested that several cortical generators of P300 may co-exist: the medial temporal lobe, the temporo-parietal junction, and the medial and lateral frontal lobe. Psychopharmacological studies have shown that different neurotransmitter systems are involved in the generation and modulation of P300, namely the cholinergic, noradrenergic, dopaminergic, serotoninergic and gabaergic systems. It appears that the noradrenergic agonists increase the amplitude of P300, dopaminergic agonists may have a biphasic effect (increase/reduction), while cholinergic antagonists and gabaergic agonists reduce P300 amplitude and prolong its latency.

Event-related potential evidence for frontal cortex effects of chronic cocaine dependence

We examined the effects of cocaine dependence and cocaine and alcohol codependence on the P3A event-related potential component. Ten chronic cocaine-dependent subjects, 10 chronic cocaine and alcohol codependent subjects, and 20 controls were studied in an auditory paradigm that included target, nontarget, and novel rare nontarget conditions. Substance-dependent subjects were abstinent from cocaine and/or alcohol for 2-6 weeks. Eighteen of these subjects (4 chronic cocaine-dependent subjects, 4 chronic cocaine/alcohol codependent subjects, and 10 normal controls) were also studied in an analogous visual paradigm. In the auditory modality, the latency of the P3A response in the novel rare nontarget condition was delayed and its amplitude was reduced in both substance-dependent samples compared to controls. Comparable results were found for the smaller samples studied in the visual modality. These results suggest that chronic cocaine dependence produces deficits in frontal cortex functions.

P300 assessment of opiate and cocaine users: effects of detoxification and buprenorphine treatment

We assessed cognitive function following heroin and cocaine detoxification and investigated whether buprenorphine treatment improves the disruptive effects of detoxification. Three groups of male volunteers meeting DSM-III-R criteria for concurrent opiate and cocaine dependence were tested using an auditory oddball paradigm before and after detoxification, and again on the 15th day of either buprenorphine or placebo treatment. There were no significant differences in P300 amplitude, latency, or topographic distribution between drug-dependent subjects and controls on admission day. Following detoxification there was a significant decrease in P300 amplitude in the drug-dependent group at a time when self-reported signs of withdrawal were minimal. Buprenorphine treatment significantly reversed the P300 amplitude decrement following detoxification, whereas placebo-treated subjects continued to show depressed P300 amplitudes. These data demonstrate that buprenorphine treatment is effective in eliminating detoxification-induced impairments in one measure of cognitive ability.

Cocaine's effects on speech sound identification and reaction times in baboons

The effects of cocaine on speech sound discriminations was examined to determine whether cocaine's previously demonstrated effect in reducing speech sound discriminability was dependent upon either the type of stimuli employed (simple tones versus complex speech) or the procedure (stimulus detection versus stimulus discrimination). Because of demonstrated similarities in the way that baboons and humans discriminate speech, and in the way the CNS is thought to encode and process speech sounds in these two species, baboons were trained to perform a choice procedure to identify the occurrence of different synthetic vowel sounds (see text). Animals held down a lever and released the lever only when one of four target vowels sounded, and not when a fifth, standard vowel sounded. Acute IM administration of cocaine (0.0032-1.0 mg/kg) produced dose-dependent decreases in vowel discriminability that were mostly due to elevations in false alarms (i.e., releases to the standard vowel) following cocaine. Cocaine also shortened reaction times to the stimuli in two of three baboons, but to a much lesser extent than observed previously. These results suggest that cocaine may interfere with the ability of the CNS to process the acoustic cues in speech sounds, and that the effects of cocaine on reaction times may depend upon the complexity of the reaction time procedure employed.

Learning versus performance effects of cocaine on discriminative heart rate conditioning in rats

The study examined the effects of cocaine on learning and performance of a classically conditioned heart rate (HR) discrimination in rats involving two auditory conditioned stimuli (CSs). In the discrimination protocol, one CS (CS+) was paired with the shock unconditioned stimulus (US) on a consistent basis and the other CS (CS-) was always presented alone. Four groups received an IP injection of 1, 3, 10, or 30 mg/kg cocaine and a fifth group received saline. Shortly after the injections, all groups were given six CS-alone trials, followed by 24 randomly sequenced discrimination conditioning trials (12 CS+ and 12 CS-). Approximately 72 h later, all groups were given six test trials with each CS in the absence of cocaine to evaluate the presence or absence of discrimination learning. All cocaine groups showed impaired discrimination performance on the discrimination conditioning trials, reductions in early pretest CS-alone responses, and reductions in resting HR. However, on the non-drug test trials discrimination performance was normal in all cocaine groups. The results established that in spite of major changes in HR dynamics, learning of the HR discrimination was not affected by cocaine but that cocaine did interfere with the performance of the discrimination. Except for the highest 30 mg group, the performance decrement appeared to be related to a cocaine-produced reduction in the capacity to inhibit bradycardia responding to the safe CS-. It was suggested that this loss of inhibitory control may have been due to cocaine changes in a corticothalamic pathway that controls inhibition of bradycardia to a safe CS-.

Effects of cocaine on simple reaction times and sensory thresholds in baboons

The effects of chronic, daily administration of cocaine on auditory and visual reaction times and thresholds were studied in baboons. Single intramuscular injections of cocaine hydrochloride (0.1 to 5.6 mg/kg) were given once daily for periods of 10 to 25 days, and were followed immediately by psychophysical tests designed to assess cocaine's effects on simple reaction times as on auditory and visual threshold functions. Consistent reductions in reaction times were frequently observed over the cocaine dose range of 0.32 to 1.0 mg/kg; at higher doses, either decreases or increases in reaction times were observed, depending upon the animal. Lowered reaction times generally occurred immediately following the 1st day's cocaine injection, and continued through all subsequent days during the dose administration period, suggesting little development of tolerance or sensitivity to these reaction-time effects. Reaction-time decreases showed a U-shaped dose-effect function. The greatest decreases in reaction times occurred from 0.32 to 1.0 mg/kg, and produced an average reaction-time decrease of 10 to 12%. Concurrently measured auditory and visual thresholds showed no systematic changes as a function of cocaine dose. Pausing was observed during performance of the psychophysical tasks, with the length of total session pause times being directly related to cocaine dose.

The effects of acute cocaine administration on auditory event-related potentials in rats

Cocaine administration has been shown to affect several sites in the limbic forebrain. The nucleus accumbens has been implicated as an important site for the reinforcing aspects of this drug whereas, the amygdala and hippocampus may be more involved in drug conditioning and/or drug induced changes in the perception of stimuli. In the present study, auditory event-related potentials (ERPs) were utilized to explore the effects of cocaine on sensory processing in several limbic sites. Eleven adult male Wistar rats were stereotaxically implanted with electrodes aimed at the dentate gyrus, dorsal hippocampus (CA1-CA2), amygdala, and nucleus accumbens. The rats received intraperitoneal injections of either saline, 2.5, 5.0, 10.0 or 20 mg/kg of cocaine. The ERPs were recorded in response to an auditory 'oddball' paradigm consisting of frequently and infrequently presented tones. Cocaine was found to produce a dose dependent decrease in the variance of the amplitude of several ERP components in the amygdala and the hippocampal formation but not in the nucleus accumbens. Cocaine also produced a decrease in the latency of the N1 component in the amygdala. No significant changes were observed in the amplitude of the ERP components following any of the cocaine doses studied, suggesting that cocaine may not increase the salience of auditory stimuli in these structures. The observed reduction in the variance of the ERPs may suggest an increased focussing of the animals' attention to the auditory stimuli. These studies also suggest that the sensory/cognitive aspects involved in cocaine's actions, as quantified by ERPs, may primarily involve the hippocampal formation and the amygdala, but not the nucleus accumbens.

The P50 component of the auditory evoked potential and subtypes of schizophrenia

Decreased amplitude of the P50 component of the averaged evoked potential has been reported in schizophrenic patients. In an attempt to determine the relationship of this decrease to subtype diagnosis, we compared P50 amplitudes in 24 neuroleptic-free schizophrenic patients with paranoid (n = 13) versus nonparanoid (n = 11) subtype diagnoses. Eleven normal subjects and 11 cocaine users served as control groups. The schizophrenic patients were studied again after they had been treated with neuroleptics for 2 weeks. The control groups were studied again at least 2 weeks later. At baseline, the nonparanoid patients had significantly lower P50 amplitudes than did the normal subjects. The paranoid patients did not differ from the normal control subjects. The cocaine users had significantly decreased P50 amplitudes as compared with the normal control subjects. Neuroleptic treatment had no effect on P50 amplitudes in the paranoid patients but normalized amplitudes in the nonparanoid patients. The data suggest that P50 measurements may be useful in identifying subtypes of schizophrenia.

Electrophysiological and neuropsychological effects of a central alpha 2-antagonist atipamezole in healthy volunteers

We studied the electrophysiological and neuropsychological effects of acute modulation of central noradrenergic (NA) transmission using a specific alpha 2-antagonist atipamezole (ATI) in sic healthy volunteers. ATI had effects on resting EEG, auditory event-related potentials and neuropsychological tests. Quantitative EEG revealed increased total power in frontal, parietal and temporo-occipital areas without significant changes in the mean or peak frequencies. Event-related potentials showed no effects on the active attention-related processing negativity or the passive mismatch negativity, but frontally recorded mean amplitude of target-P300 was decreased. Neuropsychological tests after ATI revealed improvement in Digit Span, more errors in Word Recognition task, and no effects on Moss spatial recognition task. In healthy subjects with intact NA systems and without any attention deficit, ATI produced evident NA overactivity. ATI decreased the spontaneous thalamocortical oscillation of EEG and improved focused attention (Digit Span). It impaired, however, more divided attention (decreased mean P300 amplitude, increased errors in Word Recognition).

The P300 event-related potentials in dementia of the Alzheimer type. Correlations between P300 and monoamine metabolites

We studied auditory event-related potentials (ERPs) in 40 patients with dementia of the Alzheimer type (DAT). Peak latencies and amplitudes of N100, P200 and P300 components were measured. To study the possible relationships between the ERPs and monoaminergic neurotransmitter functions, CSF neurotransmitter metabolites were also analyzed. In patients with DAT, the P300 amplitude was significantly reduced and the P300 latency was prolonged. CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were decreased. The P300 amplitude was significantly correlated with the 5-HIAA concentration. There were no correlations between the P300 components and the HVA concentration. These findings suggest that the serotonergic system modulates the P300 component of ERPs in patients with DAT.

Effects of self-reported drug use and antisocial behavior on evoked potentials in adolescents

From a sample of 35 adolescents, 17 were chosen who represented extremes of self-reported drug use and delinquent behavior. Three comparison groups were derived: Group 1, n = 7, high drug use/high delinquency; Group 2, n = 4 no drug use/high delinquency; Group 3, n = 6, no drug use/no delinquency. The three groups were similar for age, IQ, race and neighborhood characteristics. Group 1 showed significantly more drug use than Groups 2 and 3; Groups 1 and 2 had comparable levels of delinquency which were significantly greater than Group 3. The subjects performed the auditory oddball task under conditions of low and high background noise. In the high background noise condition, Group 1 had longer latency P300 responses than Groups 2 and 3, while Group 2 had smaller N100 amplitude than Groups 1 and 3. Performance was similar for each group and no group differences occurred in the low background noise condition. The results support and extend previous research on the relationship between attentional and cognitive processes, and delinquent and drug using behaviors.

Auditory event-related potentials in adolescents at risk for drug abuse

We evaluated sensory and cognitive information processing in noninstitutionalized delinquent male adolescents and in age-matched low delinquency controls. Detailed psychometric testing documented the nature of the aggressive behavior of these young men. Deficits in information processing, as assessed by event-related potential (ERP) techniques, were observed at several levels of the auditory system in the delinquent group. The delinquent group showed delays in wave V of the brainstem auditory evoked potential, shorter N100 latency, and decreased slow wave amplitude of cognitive event-related potentials when subjects were asked to perform a mental task in a noisy environment. It remains to be determined whether or not such information-processing deficiencies are common among delinquent populations and how they might influence the development of delinquent behavior and drug abuse.

Detection of benzodiazepine receptor occupancy in the human brain by positron emission tomography

Benzodiazepine receptor occupancy in the brain following oral administration of clonazepam (CZP) with a dose of 30 micrograms/kg in six healthy young men and a further dose of 50 micrograms/kg in one of the subjects was estimated by carbon-11 labeled Ro15-1788 and positron emission tomography (PET). The effects of CZP on the latency of auditory event-related potentials (P300) were also studied. Overall brain 11C uptake was depressed and the % inhibition of 11C uptake in the gray matter of the brain at 30 min after [11C]Ro15-1788 injection was 15.3-23.5% (mean, n = 6) following 30 micrograms/kg CZP when compared with that in the control experiment without any previous treatment. The 11C uptake in the cerebral cortex in the subject who received both doses decreased in a dose-related manner after 30 micrograms/kg and 50 micrograms/kg CZP. The P300 latency was prolonged significantly by 30 micrograms/kg CZP [31.6 +/- 16.3 ms (mean +/- SD, n = 6), P less than 0.05]. The P300 latency in the same subject was prolonged in a dose-related manner by 30 micrograms/kg and 50 micrograms/kg CZP. The technique using [11C]Ro15-1788 and PET permits comparison of the pharmacological effects with the percentage of receptor sites which benzodiazepines occupy in the human brain. P300 also seems to be useful to investigate the pharmacological effects of benzodiazepines.

Effects of cocaine on the brain-stem auditory evoked potential in the Long-Evans rat

The present study examined the effects of an acute psychoactive dose of cocaine hydrochloride (HCl) in the rat, using the brain-stem auditory evoked potential (BAEP) as an objective, quantitative measure of this substance's effects on brain and auditory electrophysiology. The animals were 8 adult Long-Evans rats (4 female, 4 male). BAEPs were recorded from skull screw electrodes during a baseline period as well as 30-90 min after cocaine HCl treatment (10 mg/kg, i.p.). Normothermia was maintained to control for possible temperature-related effects. Cocaine's effects on the BAEP were examined over a broad range of stimulus intensities (intensity profiles) and repetition rates (rate profiles). Cocaine prolonged latencies of several BAEP components at low stimulus intensities and shortened these latencies at high stimulus intensities. The average BAEP threshold was also increased by cocaine treatment. These results were not strong, but were suggestive of a recruitment type change in auditory function. Cocaine treatment had no convincing effects on the BAEP as a function of stimulus repetition rate.

Event-related EEG field changes in aroused subjects and schizophrenic patients

The average auditory event-related potential (AAEP) to nonmeaningful stimuli has maximum vertex negative and positive amplitudes at about 100 and 200 msec, respectively. This "vertex potential" was studied under different arousal conditions in 15 normal men and 30 chronic schizophrenic subjects using the average event-related vector electro-encephalogram (AEVE) and the AAEP. The AEVE shows the path, in time, of the event-related electric field vector. To produce intramodal arousal, normal subjects also had EEG recordings made during the random sounding of a loud bell. AAEPs and AEVEs were calculated for spontaneous changes in arousal, as indicated by EEG delta band power. Bell arousal of the normal subjects increased the AAEP and AEVE measures of vertex potential maxima, thus increasing the existing differences between normals and schizophrenics. Analysis of the AEVE path indicates that arousal increased the electric field intensity, but probably did not alter, within the first 250 msec, the spatial distribution of the cortical EEG generators. After 250 msec, a reorganization of generators was indicated for the three groups. Schizophrenics differed from normals in the decreased maximum intensity of the vertex negative electric field, which was indicated by both the AEVE and AAEP.

Cocaine effects on electroencephalographic cognitive event-related potentials and performance

The effects of cocaine on electroencephalographic indices, information processing and motor performance were measured in 12 normal volunteers. They were tested with an auditory continuous performance task before, 60 and 180 min after a 3 mg/kg oral dose of cocaine hydrochloride or placebo in a double-blind counterbalanced crossover design. EEG from Fz, Cz and Pz were averaged for the eye movement-free correct trials. N100, P200, P300 components and CNV were measured. Cocaine increased N100 amplitude for the warning stimulus and CNV amplitude. P300 amplitude and latency, reaction time and sensory sensitivity (d') were not altered by cocaine. The increase in N100 and CNV amplitude may reflect mobilization of additional attentional resources to produce optimal performance on the task when subjects were distracted by the cardiovascular, subjective and other cocaine effects.