Relationship between event-related potentials and cognitive dysfunction in multiple sclerosis: A systematic review

OBJECTIVE

This systematic review aimed to evaluate if event-related potentials (ERPs) can be a relevant tool for cognitive dysfunction diagnosis in Multiple Sclerosis (MS).

METHODS

Four databases were consulted (PubMed, Embase, Scielo, and Web of Science). The included studies should include adults with clear MS diagnoses, independently of having cognitive complaints, and all should have been submitted to ERPs (P300, N400 or mismatch negativity (MMN)). The main outcomes evaluated were ERPs' amplitude and/or latency.

RESULTS

425 studies were obtained initially from all databases, with 26 studies fulfilling the eligibility criteria. P300 was the most used ERP (25 studies), showing a reduced amplitude or an increased latency in 84% of those. N400 was evaluated in one study, showing also abnormal results. MMN was addressed in two studies with inconsistent findings. Some studies further suggest that ERPs may show earlier abnormal results compared with neuropsychological tests.

CONCLUSIONS

Most MS patient groups revealed ERP abnormalities, suggesting that these neurophysiological tests may be a relevant and appropriate diagnostic aid method for cognitive impairment in MS.

SIGNIFICANCE

The use of ERPs in MS patients seems able to demonstrate cognitive impairment and its use should be considered as part of the regular patient evaluation.

Evaluation of Event-Related Potentials in Somatic Diseases - Systematic Review

Many somatic illnesses (e.g. hypertension, diabetes, pulmonary and cardiac diseases, hepatitis C, kidney and heart failure, HIV infection, Sjogren's disease) may impact central nervous system functions resulting in emotional, sensory, cognitive or even personality impairments. Event-related potential (ERP) methodology allows for monitoring neurocognitive processes and thus can provide a valuable window into these cognitive processes that are influenced, or brought about, by somatic disorders. The current review aims to present published studies on the relationships between somatic illness and brain function as assessed with ERP methodology, with the goal to discuss where this field of study is right now and suggest future directions.

Bilingual problem size effect: an ERP study of multiplication verification and production in two languages

The problem size effect (PSE) is defined by better performance solving small problems (e.g., 2x4) than large problems (e.g., 8x9). For monolinguals, the PSE is larger when problems are presented in unfamiliar formats (e.g., written words), reflecting increased processing difficulty. Bilinguals are typically faster and more accurate at retrieving multiplication facts in the language of learning (LA+) than in their other language (LA-). We hypothesized that the less familiar arithmetic language (i.e., LA-) would elicit larger PSEs than LA+. Here, fluent Spanish-English bilingual adults verified spoken multiplication problems presented in LA+ and LA- while event-related potentials (ERPs) were recorded (Experiment 1A). To further promote language differences, we increased task difficulty by presenting problems at a faster pace (Experiment 1B) and requiring bilinguals to verbally produce solutions (Experiment 2). Language differences in performance were only observed for Experiment 2, where solutions were produced more slowly in LA- than LA+. In the ERPs, a PSE was driven by larger P300s for small than large solutions. A language effect was only observed under time pressure where LA- elicited a PSE at the 2nd operand. Additionally, the PSE was smaller for LA- at the solution. This suggests that categorizing multiplication facts is more effortful in LA-. In sum, very subtle language differences arise in fluent bilinguals when problems are more difficult, such as larger problems presented under time pressure in a weaker language. Critically, the effect of LA+ is at the level of response production and not access to the facts from memory.

The Impact of Irritability and Callous Unemotional Traits on Reward Positivity in Youth with ADHD and Conduct Problems

Children with attention-deficit/hyperactivity disorder (ADHD) and conduct problems exhibit significant variability in functioning and treatment response that cannot be fully accounted for by differences in symptom severity. Reward responsivity (RR) is a potential transdiagnostic means to account for this variability. Irritability and callous-unemotional (CU) traits moderate associations between both ADHD and conduct problems with multiple realms of functioning. Both are theorized to be associated with RR, but associations in clinical samples are unknown. In 48 youth ages 5-12 with ADHD referred for treatment of conduct problems, we examined RR using a guessing task where participants select a door icon to win and lose money. Analyses focused on the reward positivity (RewP) event-related potential in response to gain and loss feedback, which reliably peaks approximately 300 ms after feedback. Frequentist and Bayesian approaches assessed main effects of ADHD, Conduct Disorder (CD) and non-irritable Oppositional Defiant Disorder (ODD) symptoms with RR, plus interactions between symptoms and affective dimensions (irritability, CU). CD and ODD were hypothesized to be associated with altered RR, with irritability and CU moderating these associations. Across models, a reliable CD x irritability interaction emerged, indicating enhanced RewP when irritability was elevated and CD symptoms were low. CU did not moderate any associations with RR, and little support was found for associations between RR and other symptom domains. As neural response to reward varied with levels of irritability and CD symptoms, RR may hold potential as a clinically-relevant biomarker in youth with ADHD and conduct problems.

On the syllable structure effect in European Portuguese: Evidence from ERPs

Syllable effects during visual word recognition have been observed for CV but not for CVC syllables, a puzzling effect that is not explained either by the distributional frequencies of CV and CVC syllables, syllable complexity, or syllabic neighbourhood density. Furthermore, in European Portuguese (EP), syllable effects have not been found for pseudowords, suggesting that syllable activation might not precede lexical activation. Here, we combined a colour-congruency lexical decision task with the collection of electroencephalographic (EEG) data to investigate syllable effects in EP for CV and CVC words and pseudowords, with the latter presenting a match (CVC_O+P+) or a mismatch (CVC_O+P-) between their orthographic (O) and phonological (P) syllable structure to further ascertain the locus (i.e., orthographic and/or phonological) of syllable effects. Results showed syllable congruency effects in the N100, P200, and N400 ERP components for CV and CVC words suggesting the influence of different factors underlying the syllable structure effect.

Association of lifetime major depressive disorder with enhanced attentional sensitivity measured with P3 response in young adult twins

Major depression is associated with alterations in the auditory P3 event-related potential (ERP). However, the persistence of these abnormalities after recovery from depressive episodes, especially in young adults, is not well known. Furthermore, the potential influence of substance use on this association is poorly understood. Young adult twin pairs (N=177) from the longitudinal FinnTwin16 study were studied with a psychiatric interview, and P3a and P3b ERPs elicited by task-irrelevant novel sounds and targets, respectively. Dyadic linear mixed-effect models were used to distinguish the effects of lifetime major depressive disorder from familial factors and effects of alcohol problem drinking and tobacco smoking. P3a amplitude was significantly increased and P3b latency decreased, in individuals with a history of lifetime major depression, when controlling the fixed effects of alcohol abuse, tobacco, gender, twins' birth order, and zygosity. These results suggest that past lifetime major depressive disorder may be associated with enhanced attentional sensitivity.

Musical and linguistic syntactic processing in agrammatic aphasia: An ERP study

Language and music rely on complex sequences organized according to syntactic principles that are implicitly understood by enculturated listeners. Across both domains, syntactic processing involves predicting and integrating incoming elements into higher-order structures. According to the Shared Syntactic Integration Resource Hypothesis (SSIRH; Patel, 2003), musical and linguistic syntactic processing rely on shared resources for integrating incoming elements (e.g., chords, words) into unfolding sequences. One prediction of the SSIRH is that people with agrammatic aphasia (whose deficits are due to syntactic integration problems) should present with deficits in processing musical syntax. We report the first neural study to test this prediction: event-related potentials (ERPs) were measured in response to musical and linguistic syntactic violations in a group of people with agrammatic aphasia (n=7) compared to a group of healthy controls (n=14) using an acceptability judgement task. The groups were matched with respect to age, education, and extent of musical training. Violations were based on morpho-syntactic relations in sentences and harmonic relations in chord sequences. Both groups presented with a significant P600 response to syntactic violations across both domains. The aphasic participants presented with a reduced-amplitude posterior P600 compared to the healthy adults in response to linguistic, but not musical, violations. Participants with aphasia did however present with larger frontal positivities in response to violations in both domains. Intriguingly, extent of musical training was associated with larger posterior P600 responses to syntactic violations of language and music in both groups. Overall, these findings are not consistent with the predictions of the SSIRH, and instead suggest that linguistic, but not musical, syntactic processing may be selectively impaired in stroke-induced agrammatic aphasia. However, the findings also suggest a relationship between musical training and linguistic syntactic processing, which may have clinical implications for people with aphasia, and motivates more research on the relationship between these two domains.

Event-related potentials in insomnia reflect altered perception of sleep

STUDY OBJECTIVES

Insomnia is defined by the subjective complaint of poor sleep as well as daytime impairments. Since polysomnography (PSG) typically shows only modest sleep impairment, some still unidentified property of sleep, not mirrored in PSG, may be modified in insomnia.One possible mechanistic hypothesis is that insomnia patients may be more sensitive to inevitably occurring internal or external stimuli during the night, causing brief sleep disruptions then perceived as wake time.

METHODS

Auditory event-related potentials (ERP) to low intensity (50 dB SPL) synthesized guitar tones played continuously throughout two nights of polysomnographically registered sleep were obtained in fifty patients with insomnia disorder (ID, without comorbidities) and 50 age- and sex- matched good sleeper controls (GSC) for each sleep stage and NREM/REM cycle. Phasic and tonic REM were treated as separate stages. Latencies and amplitudes of components P1, N1 and P2 were measured and analyzed by multivariate repeated-measures ANCOVA including effects of group, night, cycle and age.

RESULTS

ID showed reduced P2 amplitudes relative to GSC specifically in phasic REM sleep. The same reduction also correlated with the amount of sleep misperception across groups. Independent component analysis showed a frontal negativity to contribute most to this group difference.

CONCLUSIONS

The present finding can be interpreted as increased mismatch negativity (MMN) in ID, reflecting automated detection of change in the auditory system and a concomitant orienting response. Specifically phasic REM sleep appears to be vulnerable to sensory afferences in ID patients, possibly contributing to the perception of being awake.

Neurophysiological correlates of alcohol-specific inhibition in alcohol use disorder and its association with craving and relapse

OBJECTIVE

This study investigates neurophysiological correlates of general and alcohol-specific inhibitory control in patients with Alcohol Use Disorder (AUD), focusing on its association with individual craving levels and with relapse at three-month follow-up.

METHODS

59 abstinent AUD patients and 20 healthy controls performed a Go/NoGo task incorporating alcohol-related and neutral stimuli during 64-channel electroencephalography (EEG) recording, yielding four event-related potentials (ERP) per participant (NoGo-Alcohol, Go-Alcohol, NoGo-Neutral, Go-Neutral). Whole-scalp randomization-based statistics assessed effects of the factors group (patients/controls or relapsers/abstainers), craving level, response type (NoGo/Go) and picture type (alcohol/neutral) on topography and signal strength of the ERP components N2 and P3.

RESULTS

No differences on group level were observed between patients and controls. However, analyses incorporating individual craving indicated that the topographic difference between alcohol-related and neutral NoGo-N2 components increased with craving. Moreover, topographic differences in the alcohol-related and neutral NoGo-P3 component allowed for differentiation between relapsers and abstainers.

CONCLUSIONS

In alcohol-related contexts, the response inhibition conflict reflected in the NoGo-N2 seems enhanced in patients with high craving. The inhibition-sensitive NoGo-P3 varies in relapsers but not in abstainers between neutral and alcohol-related contexts.

SIGNIFICANCE

In AUD patients, neurophysiological correlates of inhibition vary with alcohol-related contexts and craving, and might be indicative of relapse risk.

The Role of Glutamate in Language and Language Disorders - Evidence from ERP and Pharmacologic Studies

Current models of language processing do not address mechanisms at the neurotransmitter level, nor how pharmacologic agents may improve language function(s) in seemingly disparate disorders. L-Glutamate, the primary excitatory neurotransmitter in the human brain, is extensively involved in various higher cortical functions. We postulate that the physiologic role of L-Glutamate neurotransmission extends to the regulation of language access, comprehension, and production, and that disorders in glutamatergic transmission and circuitry contribute to the pathogenesis of neurodegenerative diseases and sporadic-onset language disorders such as the aphasic stroke syndromes. We start with a review of basic science data pertaining to various glutamate receptors in the CNS and ways that they may influence the physiological processes of language access and comprehension. We then focus on the dysregulation of glutamate neurotransmission in three conditions in which language dysfunction is prominent: Alzheimer's Disease, Fragile X-associated Tremor/Ataxia Syndrome, and Aphasic Stroke Syndromes. Finally, we review the pharmacologic and electrophysiologic (event related brain potential or ERP) data pertaining to the role glutamate neurotransmission plays in language processing and disorders.

The Neurophysiology of Implicit Alcohol Associations in Recently Abstinent Patients With Alcohol Use Disorder: An Event-Related Potential Study Considering Gender Effects

BACKGROUND

Neuroscientific models of alcohol use disorders (AUDs) postulate an imbalance between automatic, implicit, and controlled (conscious) processes. Implicit associations towards alcohol indicate the automatically attributed appeal of alcohol-related stimuli. First, behavioral studies indicate that negative alcohol associations are less pronounced in patients compared to controls, but potential neurophysiological differences remain unexplored. This study investigates neurophysiological correlates of implicit alcohol associations in recently abstinent patients with AUD for the first time, including possible gender effects.

METHODS

A total of 62 patients (40 males and 22 females) and 21 controls performed an alcohol valence Implicit Association Test, combining alcohol-related pictures with positive (incongruent condition) or negative (congruent condition) words, while brain activity was recorded using 64-channel electroencephalography. Event-related potentials (ERPs) for alcohol-negative and alcohol-positive trials were computed. Microstate analyses investigated the effects of group (patients, controls) and condition (incongruent, congruent); furthermore, possible gender effects in patients were analyzed. Significant effects were localized with standardized low-resolution brain electromagnetic topography analysis.

RESULTS

Although no behavioral group differences were found, ERPs of patients and controls were characterized by distinct microstates from 320 ms onwards. ERPs between conditions differed only in patients with higher signal strength during incongruent trials. Around 600 ms, controls displayed higher signal strength than patients. A gender effect mirrored this pattern with enhanced signal strength in females as opposed to male patients. Around 690 ms, a group-by-valence interaction indicated enhanced signal strength in congruent compared to incongruent trials, which was more pronounced in controls.

CONCLUSIONS

For patients with AUD, the pattern, timing, and source localization of effects suggest greater effort regarding semantic and self-relevant integration around 400 ms during incongruent trials and attenuated emotional processing during the late positive potential timeframe. Interestingly, this emotional attenuation seemed reduced in female patients, thus corroborating the importance of gender-sensitive research and potential treatment of AUD.

Cognitive, neural and endocrine functioning during late pregnancy: An Event-Related Potentials study

This study investigated cognitive, neural and endocrine function during late pregnancy. One of the first to examine brain ERPs in pregnant women, the study is unique in its focus on response inhibition function. In the study, cognitive function was evaluated by a digit-symbol coding test, an arithmetic ability test, and a visual stop-signal task which places enhanced demands on impulse control and response inhibition, considered a hallmark of executive function. Brain activity was measured by scalp-recorded Event-Related Potentials (ERPs) during the stop-signal task. HPA axis reactivity was assessed by measuring salivary cortisol levels before and after experimental sessions. Test performance, ERPs and cortisol reactivity were compared across groups of 23 women in their third trimester of pregnancy and 22 non-pregnant controls. Pregnant women scored lower than the control group on the digit-symbol coding test. On the stop-signal task, both groups had similar error rates, but pregnant women had longer response times to Go trials. On the Stop condition of the task in which a response must be inhibited, pregnant women demonstrated significantly better performance. At the electrophysiological level, in response to Go stimuli pregnant women exhibited greater amplitude of P2 than controls. In response to Stop-signals, pregnant women had lesser amplitudes of P1 and N2 and greater amplitude of P3. Cortisol reactivity to the test session was significantly more pronounced in non-pregnant women with significant correlations found between cortisol reactivity and behavioral responses. The results suggest that response patterns of women in late pregnancy are less impulsive and more cautious and controlled.

Retooling Computational Techniques for EEG-Based Neurocognitive Modeling of Children's Data, Validity and Prospects for Learning and Education

This paper describes continuing research on the building of neurocognitive models of the internal mental and brain processes of children using a novel adapted combination of existing computational approaches and tools, and using electro-encephalographic (EEG) data to validate the models. The guiding working model which was pragmatically selected for investigation was the established and widely used Adaptive Control of Thought-Rational (ACT-R) modeling architecture from cognitive science. The anatomo-functional circuitry covered by ACT-R is validated by MRI-based neuroscience research. The present experimental data was obtained from a cognitive neuropsychology study involving preschool children (aged 4-6), which measured their visual selective attention and word comprehension behaviors. The collection and analysis of Event-Related Potentials (ERPs) from the EEG data allowed for the identification of sources of electrical activity known as dipoles within the cortex, using a combination of computational tools (Independent Component Analysis, FASTICA; EEG-Lab DIPFIT). The results were then used to build neurocognitive models based on Python ACT-R such that the patterns and the timings of the measured EEG could be reproduced as simplified symbolic representations of spikes, built through simplified electric-field simulations. The models simulated ultimately accounted for more than three-quarters of variations spatially and temporally in all electrical potential measurements (fit of model to dipole data expressed as R 2 ranged between 0.75 and 0.98; P < 0.0001). Implications for practical uses of the present work are discussed for learning and educational applications in non-clinical and special needs children's populations, and for the possible use of non-experts (teachers and parents).

Combined Effects of Electroacupuncture and Behavioral Training on Learning-Memory Ability and Event-Related Potential P300 in Rats with Mid/Advanced Cerebral Infarction

Background:

The effectiveness of the combination of electroacupuncture (EA) and behavioral training (BT) for mid/advanced cerebral infarction (M/ACI) and related mechanisms remains unclear. This study aimed to investigate the combined effects on the learning-memory ability and event-related potential P300 in rats with M/ACI.

Methods:

Eighty rats with M/ACI were divided into Group Model (M), Group EA, Group BT, and Group EA-BT (n = 20) according to the random number with five healthy rats in Group Control (CON). On the 6^th week after modeling, EA, BT, and EA-BT were given to Group EA, Group BT, and Group EA-BT, respectively, whereas Group M and Group CON were not given any intervention. Y-maze test and P300 were recorded before and after the intervention.

Results:

After intervention, the P300 latency was lower and the amplitude was higher in the Group EA-BT, Group EA, and Group BT than before (for latency, t = −7.638, −4.334, and −5.916; for amplitude, t = 8.125, 3.846, and 5.238; P < 0.01), with Group EA-BT superior to Group EA (for latency, t = −3.708; for amplitude, t = 3.653; P < 0.01) and Group BT (for latency, t = −2.067; for amplitude, t = 2.816; P < 0.05), with no significant difference between Group BT and EA (for latency, t = −1.439; for amplitude, t = 1.075; P > 0.05). While the performances of Y-maze tests in the Group EA-BT, Group EA, and Group BT were all better than before (t = 10.359, 4.520, and 7.791, P < 0.01), with Group EA-BT better than Group EA (t = 5.627, P < 0.01) and Group BT (t = 2.913, P < 0.01) respectively, and Group BT better than Group EA (t = 2.912, P < 0.01).

Conclusion:

EA or BT can affect P300 in rats with M/ACI, and the combination of these two methods can significantly improve the learning-memory ability.

Effects of Risperidone and Paliperidone on Brain-Derived Neurotrophic Factor and N400 in First-Episode Schizophrenia

Background:

Risperidone and paliperidone have been the mainstay treatment for schizophrenia and their potential role in neuroprotection could be associated with brain-derived neurotrophic factor (BDNF) and N400 (an event-related brain potential component). So far, different effects on both BDNF and N400 were reported in relation to various antipsychotic treatments. However, few studies have been conducted on the mechanism of risperidone and paliperidone on BDNF and N400. This study aimed to compare the effects of risperidone and paliperidone on BDNF and the N400 component of the event-related brain potential in patients with first-episode schizophrenia.

Methods:

Ninety-eight patients with first-episode schizophrenia were randomly divided into the risperidone and paliperidone groups and treated with risperidone and paliperidone, respectively, for 12 weeks. Serum BDNF level, the latency, and amplitude of the N400 event-related potential before and after the treatment and Positive and Negative Syndrome Scale (PANSS) scores were compared between the two groups.

Results:

A total of 94 patients were included in the final analysis (47 patients in each group). After the treatment, the serum BDNF levels in both groups increased (all P < 0.01), while no significant difference in serum BDNF level was found between the groups before and after the treatment (all P > 0.05). After the treatment, N400 amplitudes were increased (from 4.73 ± 2.86 μv and 4.51 ± 4.63 μv to 5.35 ± 4.18 μv and 5.52 ± 3.08 μv, respectively) under congruent condition in both risperidone and paliperidone groups (all P < 0.01). Under incongruent conditions, the N400 latencies were shortened in the paliperidone group (from 424.13 ± 110.42 ms to 4.7.41 ± 154.59 ms, P < 0.05), and the N400 amplitudes were increased in the risperidone group (from 5.80 ± 3.50 μv to 7.17 ± 5.51 μv, P < 0.01). After treatment, the total PANSS score in both groups decreased significantly (all P < 0.01), but the difference between the groups was not significant (P > 0.05). A negative correlation between the reduction rate of the PANSS score and the increase in serum BDNF level after the treatment was found in the paliperidone group but not in the risperidone group.

Conclusions:

Both risperidone and paliperidone could increase the serum BDNF levels in patients with first-episode schizophrenia and improve their cognitive function (N400 latency and amplitude), but their antipsychotic mechanisms might differ.

Sensory and semantic activations evoked by action attributes of manipulable objects: Evidence from ERPs

"Two route" theories of object-related action processing posit different temporal activation profiles of grasp-to-move actions (rapidly evoked based on object structure) versus skilled use actions (more slowly activated based on semantic knowledge). We capitalized on the exquisite temporal resolution and multidimensionality of Event-Related Potentials (ERPs) to directly test this hypothesis. Participants viewed manipulable objects (e.g., calculator) preceded by objects sharing either "grasp", "use", or no action attributes (e.g., bar of soap, keyboard, earring, respectively), as well as by action-unrelated but taxonomically-related objects (e.g., abacus); participants judged whether the two objects were related. The results showed more positive responses to "grasp-to-move" primed objects than "skilled use" primed objects or unprimed objects starting in the P1 (0-150 ms) time window and continuing onto the subsequent N1 and P2 components (150-300 ms), suggesting that only "grasp-to-move", but not "skilled use", actions may facilitate visual attention to object attributes. Furthermore, reliably reduced N400s (300-500 ms), an index of semantic processing, were observed to taxonomically primed and "skilled use" primed objects relative to unprimed objects, suggesting that "skilled use" action attributes are a component of distributed, multimodal semantic representations of objects. Together, our findings provide evidence supporting two-route theories by demonstrating that "grasp-to-move" and "skilled use" actions impact different aspects of object processing and highlight the relationship of "skilled use" information to other aspects of semantic memory.

An ERP Study of Response Inhibition in the Auditory Domain in Children with Fetal Alcohol Spectrum Disorders

BACKGROUND

Previous event-related potential (ERP) studies of response inhibition in children with fetal alcohol spectrum disorder (FASD) have used a visual Go/NoGo task to study the impact of prenatal alcohol exposure on response inhibition. No studies exist using auditory versions of the task; thus, it is unclear how the deficits observed in visual tasks translate into the auditory domain.

METHODS

This study examined ERPs using an auditory Go/NoGo paradigm in a sample of 35 school-age children-18 with heavy prenatal alcohol exposure and 17 normally developing controls.

RESULTS

Alcohol-exposed children performed as well as controls in terms of inhibiting their responses; however, their reaction times were significantly slower under the Go condition. As in the ERP visual Go/NoGo task previously administered to these children, group differences were seen in early perceptual processing, specifically related to stimulus discrimination, with a decrease in P2 amplitude in the alcohol-exposed group. The control group exhibited greater N2 amplitude in the NoGo compared to the Go condition while the alcohol-exposed group did not, suggesting a group difference in the neural substrates underlying conflict monitoring. The alcohol-exposed group demonstrated longer latency P3 with reduced amplitude, suggesting poorer allocation of attention. The alcohol-exposed group also exhibited a late positive component (LPC) similar to the one observed in the previous visual ERP study. This LPC may indicate compensatory neurophysiological function related to resetting of attentional control networks in preparation for the next trial. None of the ERP outcomes in this study were related to potential confounders which included cognitive and socioeconomic measures as well as ADHD diagnosis.

CONCLUSIONS

The observed ERP group differences point to elements of perceptual and attentional processing likely to be involved in the performance deficits often observed in children with FASD. We also observed changes in ERPs related to conflict monitoring/response inhibition, highlighting fetal alcohol-related effects on how the brain responds when there is need to identify and respond to environmental cues by switching away from a prepotent motor response to an inhibited state.

Spontaneous emotion regulation: differential effects on evoked brain potentials and facial muscle activity

Late positive potentials (LPPs) were found to be decreased during down-regulation and increased during up-regulation of positive and negative emotions. However, previous studies lack ecological validity, since they explicitly instructed their participants to use certain regulation strategies. The goal of our study was to test an ecologically more valid paradigm of emotion regulation. We therefore investigated the effects of freely chosen emotion regulation strategies on LPPs and additionally assessed facial EMG responses and valence and arousal ratings as control variables. Responses to positive IAPS pictures were marked by pleasant valence ratings and high activations of M. zygomaticus major, negative pictures elicited unpleasant valence ratings and high activations of M. corrugator supercilii, and both, positive and negative pictures, went along with increased arousal ratings and LPPs. Importantly, ratings and EMG activity were intensified through up-regulation and attenuated through down-regulation of emotions, while LPPs were increased through both up-and down-regulation. We conclude that LPPs in paradigms with free choice of emotion regulation strategies might be a marker of attentional resources required for the selection of adequate emotion up- and down-regulation strategies, while LPP effects following emotion regulation with specific, instructed strategies reflect modulated arousal processes.

Partial sleep deprivation does not alter processes involved in semantic word priming: event-related potential evidence

Sleep deprivation has generally been observed to have a detrimental effect on tasks that require sustained attention for successful performance. It might however be possible to counter these effects by altering cognitive strategies. A recent semantic word priming study indicated that subjects used an effortful predictive-expectancy search of semantic memory following normal sleep, but changed to an automatic, effortless strategy following total sleep deprivation. Partial sleep deprivation occurs much more frequently than total sleep deprivation. The present study therefore employed a similar priming task following either 4h of sleep or following normal sleep. The purpose of the study was to determine whether partial sleep deprivation would also lead to a shift in cognitive strategy to compensate for an inability to sustain attention and effortful processing necessary for using the predicative expectancy strategy. Sixteen subjects were presented with word pairs, a prime and a target that were either strongly semantically associated (cat...dog), weakly associated (cow...barn) or not associated (apple...road). The subject's task was to determine if the target word was semantically associated to the prime. A strong priming effect was observed in both conditions. RTs were slower, accuracy lower, and N400 larger to unassociated targets, independent of the amount of sleep. The overall N400 did not differ as a function of sleep. The scalp distribution of the N400 was also similar following both normal sleep and sleep loss. There was thus little evidence of a difference in the processing of the target stimulus as a function of the amount sleep. Similarly, ERPs in the period between the onset of the prime and the subsequent target also did not differ between the normal sleep and sleep loss conditions. In contrast to total sleep deprivation, subjects therefore appeared to use a common predictive expectancy strategy in both conditions. This strategy does however require an effortful sustaining of attention, and may not have been entirely successful when sleep was restricted. A slight but significant decrease in accuracy was noted.

Event-related potential responses to the acute and chronic effects of alcohol in adolescent and adult Wistar rats

BACKGROUND

This study explored the hypothesis that adolescent ethanol (EtOH) exposure may cause long-lasting changes in EtOH sensitivity by exploring the age-related effects of acute alcohol on intoxication and on event-related potential (ERP) responses to acoustic stimuli in EtOH-naïve adolescent and adult male Wistar rats and in adult rats that were exposed to chronic EtOH/control conditions during adolescence.

METHODS

EtOH-naïve adolescent (postnatal day 32 [PD32]) and adult male rats (PD99) were included in the first study. In a second study, rats were exposed to 5 weeks of EtOH vapor (blood EtOH concentrations at 175 mg%) or air from PD24 to 59 and allowed to mature until PD90. In both studies, rats were implanted with cortical recording electrodes, and the effects of acute EtOH (0.0, 1.5, and 3.0 g/kg) on behavioral and ERP responses were assessed.

RESULTS

Adolescents were found to have higher amplitude and longer latency P3a and P3b components at baseline as compared to adult rats, and EtOH was found to produce a robust dose-dependent increase in the latency of the P3a and P3b components of the auditory ERP recorded in cortical sites in both adolescents and adults. However, EtOH produced significantly larger delays in P3a and P3b latencies in adults as compared to adolescents. Acute EtOH administration was also found to produce a robust dose-dependent increase in the latency of the P3a and P3b components in adult animals exposed to EtOH vapor as adolescents and air exposed controls; however, larger acute EtOH-induced increases in P3a and P3b latencies were seen in controls as compared to adolescent vapor exposed rats.

CONCLUSIONS

Adolescent rats have a less intense P3 latency response to acute EtOH administration when compared to adult rats. Exposure to chronic EtOH during adolescence can cause "retention" of the adolescent phenotype of reduced P3 latency sensitivity to EtOH.

Natural stimuli from three coherent modalities enhance behavioral responses and electrophysiological cortical activity in humans

Cues that involve a number of sensory modalities are processed in the brain in an interactive multimodal manner rather than independently for each modality. We studied multimodal integration in a natural, yet fully controlled scene, implemented as an interactive game in an auditory-haptic-visual virtual environment. In this imitation of a natural scene, the targets of perception were ecologically valid uni-, bi- and tri-modal manifestations of a simple event-a ball hitting a wall. Subjects were engaged in the game while their behavioral and early cortical electrophysiological responses were measured. Behavioral results confirmed that tri-modal cues were detected faster and more accurately than bi-modal cues, which, likewise, showed advantages over unimodal responses. Event-Related Potentials (ERPs) were recorded, and the first 200 ms following stimulus onset was analyzed to reveal the latencies of cortical multimodal interactions as estimated by sLORETA. These electrophysiological findings indicated bi-modal as well as tri-modal interactions beginning very early (~30 ms), uniquely for each multimodal combination. The results suggest that early cortical multimodal integration accelerates cortical activity and, in turn, enhances performance measures. This acceleration registers on the scalp as sub-additive cortical activation.

Intentional retrieval suppression can conceal guilty knowledge in ERP memory detection tests

Brain-activity markers of guilty knowledge have been promoted as accurate and reliable measures for establishing criminal culpability. Tests based on these markers interpret the presence or absence of memory-related neural activity as diagnostic of whether or not incriminating information is stored in a suspect's brain. This conclusion critically relies on the untested assumption that reminders of a crime uncontrollably elicit memory-related brain activity. However, recent research indicates that, in some circumstances, humans can control whether they remember a previous experience by intentionally suppressing retrieval. We examined whether people could use retrieval suppression to conceal neural evidence of incriminating memories as indexed by Event-Related Potentials (ERPs). When people were motivated to suppress crime retrieval, their memory-related ERP effects were significantly decreased, allowing guilty individuals to evade detection. Our findings indicate that brain measures of guilty knowledge may be under criminals' intentional control and place limits on their use in legal settings.

Species-specific effects of pigmentation negation on the neural response to faces

Face processing is limited in scope as a function of experience - discrimination ability and face-specific behavioral effects are reduced in out-group faces. Nonetheless, other-species faces phylogenetically close to our own may be processed by similar mechanisms as human faces. Presently, we asked whether or not the well-known effect of contrast-negation on face recognition (Galper, 1970) was exclusive to human faces or generalized to monkey faces. Negation disrupts face pigmentation substantially, allowing us to examine species-specific use of surface cues as a function of expertise. We tested adult observers behaviorally and electrophysiologically: participants completed a 4AFC discrimination task subject to manipulations of face species and independent negation of image luminance and image chroma, and the same stimuli were used to collect event-related potentials in a go/no-go task. We predicted that expertise for human faces would lead to larger deleterious effects of negation for human faces in both tasks, reflected in longer RTs for correct responses in the discrimination task and species-specific modulation of the N170 and P200 by contrast-negation. Our results however, indicate that behaviorally, luminance and chroma negation affect discrimination performance in a species-independent manner, while similar effects of contrast-negation effects are evident in each species at different components of the ERP response.

Correlation analysis of the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in children

INTRODUCTION

 The effects of lead on children's health have been widely studied.

AIM

 To analyze the correlation between the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in Brazilian children.

METHODS

 This retrospective study evaluated 20 children ranging in age from 7 to 14 years at the time of audiological and electrophysiological evaluations. We performed periodic surveys of the lead concentration in the blood and basic audiological evaluations. Furthermore, we studied the auditory evoked potential long latency N2 and cognitive P3 by analyzing the absolute latency of the N2 and P3 potentials and the P3 amplitude recorded at Cz. At the time of audiological and electrophysiological evaluations, the average concentration of lead in the blood was less than 10 ug/dL.

RESULTS

 In conventional audiologic evaluations, all children had hearing thresholds below 20 dBHL for the frequencies tested and normal tympanometry findings; the auditory evoked potential long latency N2 and cognitive P3 were present in 95% of children. No significant correlations were found between the blood lead concentration and latency (p = 0.821) or amplitude (p = 0.411) of the P3 potential. However, the latency of the N2 potential increased with the concentration of lead in the blood, with a significant correlation (p = 0.030).

CONCLUSION

 Among Brazilian children with low lead exposure, a significant correlation was found between blood lead levels and the average latency of the auditory evoked potential long latency N2; however, a significant correlation was not observed for the amplitude and latency of the cognitive potential P3.

Effect of emotional valence on episodic memory stages as indexed by event-related potentials

Several investigations have shown that emotional events show superior recall than non-emotional ones. However, the cortical mechanisms underlying the episodic recall of emotional scenes are still poorly understood. Our main aim was to compare the magnitude of the Event-Related brain Potentials (ERP) old-new effect related to emotionally unpleasant, pleasant and neutral photographic images. As expected, correct recognition of all types of images elicited three topographically distinct ERP components sensitive to the classical old-new recognition effect. The results revealed that the behavioral performances were mainly sensitive to arousal, while the ERP old/new effect over posterior regions (300 – 1000 ms) was exclusively affected by unpleasantness. A later component (1000 – 1400 ms) showed an inverted old/ new effect at parietal sites, which was also sensitive to unpleasantness. These results imply that ERP reflecting episodic conscious recollection and post-retrieval monitoring are clearly affected both by valence and arousal.