Event-related Potentials Parameters Research Articles

Event related potentials in patients with transient global amnesia—A prospective controlled study

ObjectiveThe aim of this study is to evaluate changes in the latencies and amplitudes of event-related potential (ERP) components as well as cognitive habituation in patients with transient global amnesia (TGA) in order to further characterize the pathology of this syndrome. MethodsClinical data of 43 consecutive patients with TGA was collected at a university neurology department. Follow-up examination was performed at an average of 17months after TGA. Results were compared to 43 age- and sex-matched healthy control subjects. ResultsAll ERP latencies of patients examined within 10days after the TGA period were significantly increased, and the P3 amplitude was significantly decreased as compared to healthy control subjects. The rate of pathological P3 latencies was significantly higher in TGA patients. A normal P3 latency habituation was detected in 84% of all healthy controls (mean habituation 10ms) and in 33% of all TGA patients (mean habituation −6ms). There was no significant improvement of all latencies and the other ERP parameters, including the loss of habituation, after a mean observation period of 17months. The data of three patients who were measured during the TGA period suggest a severe impairment of ERP during this period. ConclusionsOur findings give new insight into the pathology of TGA and put into question if TGA is an event of a simple transient character. In this first investigation of cognitive habituation in patients with TGA, we found a characteristic loss of cognitive habituation similar to observations in migraine.

Correlations of the Characteristics of Event-Related Potentials with the Contents of Some Chemical Elements in the Organism of Urban Teenager Residents (According to a Longitudinal Observation)

We examined correlations of the characteristics of event-related potentials (ERPs) recorded according to a two-stimulus go/no-go paradigm (with measurements of the reaction time) with the contents of seven essential and potentially harmful elements in a group of teenagers (15 boys and 15 girls). Electrophysiological examinations and measurements of the contents of chemical elements in samples of a biologically stable tissue (hairs) using X-ray fluorescence analysis were carried out during three years (age of the subjects increased from 12 to 14 years). Nonparametric correlation analysis by Spearman was used. In 12- and 13-year-old teenagers, the element balance was characterized by deficiencies of Ca, Fe, and Mn; in 14-year-old subjects, an excess of Ni and a noticeably excessive content of Pb in hairs were found. Statistically significant correlations (0.37 < r < 0.64) of the amplitudes and latencies of ERPs with the contents of the above elements were observed (20 and 7 cases, respectively). Correlations of the ERP parameters with the contents of chemical elements were more clearly expressed in the case of deficiencies of essential elements in 12- and 13-year-old teenagers; in older subjects (14 years), manifestations of such correlations demonstrated a trend toward limitation.

Electrophysiological differences in sensorineural hearing loss patients with and without problem-tinnitus

EnAbstract Objects Problem-tinnitus refers to tinnitus that is sufficiently severe to produce a major disruption in the patient’s life; tinnitus of such severity involves a number of regions of the auditory system and other brain systems may also play an essential role. Auditory brainstem responses (ABR) and event-related potentials (ERP) were recorded from sensorineural hearing loss (SNHL) patients with problem-tinnitus and were then compared with responses from normal hearing and hearing loss tinnitus-free patients. Aim To study whether differences exist in ABR and/or ERP parameters in SNHL patients with and without problem-tinnitus when matched as closely as possible for hearing loss, age, and sex to investigate the mechanism responsible for tinnitus. Materials and Methods Ninety participants were included in this study. They were divided into two groups: the study group included 66 participants with bilateral symmetrical SNHL that did not exceed a moderate degree. The study group was divided into two subgroups: 36 patients had problem-tinnitus and 30 patients were tinnitus-free (SNHL, age, and sex matched). Participants in each of these subgroups were compared with each other and were also compared with 24 healthy individuals in the control group (age and sex matched with the study group). All participants were subjected to a basic audiological evaluation and electrophysiological tests (ABR and ERP). Results This work had shown a higher prevalence of ABR abnormalities in tinnitus patients in comparison with either the control group or the SNHL tinnitus-free group. Statistically significant differences were found in III–V and I–V interpeak latencies and in the VI amplitude ratio in problem-tinnitus female patients compared with tinnitus-free female patients. Meanwhile, in problem tinnitus male patients when compared with tinnitus-free male patients at III–V interpeak latencies and at VI amplitude ratio. As regards the results of ERP in this work, an increase in latency and amplitude reduction were found. Statistically significant differences were observed regarding both the mean latency values of waves N1, P2, and P300 and the amplitude mean values of P2 and P300 when we compared the problem-tinnitus subgroup with either the tinnitus-free subgroup or the control group (both female and male patients. Conclusion A variety of ABR and ERP components are altered in tinnitus patients; this would indicate impairment in both the central auditory pathway and central auditory processing. Thus, it is suggested that this form of ABR, ERP testing could be considered as an objective measure to complement behavioral, audiologic, and other physiologic methods of assessing tinnitus, rather than a single definitive tinnitus measure in an attempt to supplement and thereby extend knowledge of the nature and origins of tinnitus. Furthermore, these results provide the basis for future neurofeedback-based tinnitus therapies aiming at maximizing the ability to shift attention away from the tinnitus.

Psychological Adaptation Potential of the Personality: Peculiarities of Event-Related EEG Potentials

In a group of 68 adults of both sexes, we examined correlations between the level of psychological adaptability of the personality (diagnosed using the Maklakov questionnaire) and parameters of event-related potentials (ERPs) recorded in the course of performance of two behavioral test acts including a motor component. In task A, it was necessary to maximally rapidly press the button after an imperative signal preceded by a warning signal, while a definite time interval (limited by two pressings of the button) should be measured in task B. Parameters of the contingent negative variation, CNV, potential P300 and, in task B, readiness potential, RP, were measured in C3 and C4 leads. High amplitudes of ERPs (RP, P300, and CNV in task A) and smaller variability of the indices of working efficiency corresponded, in the whole, to higher estimates of psychological adaptability in general and of separate aspects of the latter estimated according to the scales of the used questionnaire. Probable mechanisms of the peculiarities of neurodynamic constitution determining the level of the psychological adaptability of the individual, on the one hand, and of the ERP parameters, on the other hand, are discussed.

Cognition and event-related potentials in adult-onset non-demented myotonic dystrophy type 1

Objective To clarify the cognitive and event-related potentials (ERPs) profiles of adult-onset genetically-proven non-demented myotonic dystrophy type 1 (DM1). Methods Fourteen DM1 patients and matched 14 normal controls were enrolled. DM1 patients were compared with normal controls, using a variety of neuropsychological tests; an auditory “oddball” counting paradigm for the ERPs, and low-resolution brain electromagnetic tomography (LORETA). For patients, ERPs and neuropsychological parameters were correlated with CTG repeat size, duration of illness, grip strength, and arterial blood gas analysis. Results Frontal lobe dysfunction, prolonged N1 latency, and attenuated N2/P3 amplitudes were observed in DM1. Longer CTG repeat size was associated with fewer categories achieved on Wisconsin Card Sorting Test. Greater grip strength was associated with better scores on color-word “interference” of Stroop test. P3 latency was negatively correlated with PaO 2. LORETA revealed significant hypoactivities at the orbitofrontal and medial temporal lobe, cingulate, and insula. There was no correlation between ERPs and CTG expansion. Conclusions Adult-onset non-demented DM1 presented frontal lobe dysfunction. Absence of correlations between CTG repeat size and objective ERP parameters suggested CTG expansion in lymphocytes does not directly contribute to cognitive dysfunction. Significance CTG expansion in lymphocytes does not directly contribute to cognitive dysfunction of adult-onset non-demented DM1.

Effects of Correct and Wrong Answers on ERPs Recorded under Conditions of the Continuous Performance Test in ADHD/Normal Participants

Parameters of event-related potentials (ERPs) regarding correct and wrong answers under conditions of the continuous performance test (CPT) were measured in 50 adult subjects characterized by different levels of sustained attention with the absence/presence of attention deficit/hyperactivity disorders (ADHD). For ERP extraction, the average for each group of signals, which were time-locked to the onset of stimuli, was calculated; two ERP groups were considered separately for correct and wrong answers. In both groups, the P300 wave was clearly observed. The time dynamics of ERP components were investigated in six defined time blocks. At the peak of P300, a prominent component of brain activity could be observed. Some ERP morphological features (704 items) were extracted from these potentials. The results indicated that 11 of the obtained features showed a significant (P < 0.01) relation to the level of sustained attention. When comparing correct and wrong answers, 10 features in the normal group and 3 features in the ADHD group demonstrated significant differences (P < 0.05), which means that the participant’s response is reflected in the features of EEG signal. The results reveal a promising relation between CPT results and some parameters of brain signals, which can be used for further evaluations of the sustained attention level.

Effect of vitamin E supplementation with exercise on cognitive functions and total antioxidant capacity in older people.

We investigated the effects of six months vitamin E administration on cognition evaluated by event-related potentials in exercising older subjects. Randomised controlled trial. Retirement home in Antalya, Turkey. Fifty-seven adults aged 60-85 years were randomly assigned to one of four groups: sedentary control (C), vitamin E (V), exercise training (E) and vitamin E under training (EV). V and EV groups were received vitamin E at a dose of 900 IU/day P.O. for 6 months. Trained groups were subjected to walking exercise involved 3 sessions per week for 6 months. Walking duration was gradually increased during 8 weeks, and stayed constant until the end of training period. Participants were begun walking at % 70 heart rate reserve for 20 min/day at the first two weeks, and walking duration was increased by 5 minutes/day of each week until subjects were reached a level of 50 min/day by week 8. Plasma vitamin E concentration, total antioxidant capacity and two parameters of event-related potentials namely P3 latency and amplitude were performed on all study groups both before and after training. Significant improvement in P3 latency was found in exercising groups. However, no significant differences were found between vitamin and other groups for P3 latency. Amplitude measurements were found unaltered among all groups. We concluded that although six months training results improvement in P3 latency, vitamin E supplementation does not affect cognitive function evaluated by event-related potentials in older subjects.

ERP differences of pre-lexical processing between dyslexic and non-dyslexic children

The present Event-Related Potential (ERP) study aimed to investigate group differences in the early processing stages of 36 dyslexic and 24 non-dyslexic 8–12 year old children performing a lexical decision (word/pseudoword judgment) task. Our data showed larger amplitudes of negative-going waveforms in non-dyslexic children than dyslexic children over occipital/occipitotemporal electrodes at about 220 ms after stimulus onset. This electrophysiological response has previously been identified in adult readers and labeled as the N170 component. Notably, as reflected by the topographic maps children irrespective of group processed the linguistic stimuli bilaterally and we did not observe any differences in ERP parameters in words and pseudowords within groups. Contrarily, behavioral responses indicate that words were more quickly recognized than pseudowords irrespective of group. By applying post-hoc ROI analyses based on a source estimation approach (sLORETA) we observed that non-dyslexic participants, when compared to dyslexic children, demonstrated significantly stronger current density over the left hemispheric inferior temporal lobe when processing pseudowords. We concluded that impaired reading is reflected by the decreased amplitude of the early lexical component N170. The lack of a left hemispheric processing preference in both groups and similar activation for words and pseudowords can be considered a lack of reading experience and less established reading system in children. Our results indicate that dyslexic children commit fewer specialized neuronal circuits for processing print and confirm the reasoning that acquiring reading skills requires cortical reorganization over occipitotemporal regions.

Prenatal exposure to methylmercury and PCBs affects distinct stages of information processing: An event-related potential study with Inuit children

Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are seafood contaminants known for their adverse effects on neurodevelopment. This study examines the relation of developmental exposure to these contaminants to information processing assessed with event-related potentials (ERPs) in school-aged Inuit children from Nunavik (Arctic Québec). In a prospective longitudinal study on child development, exposure to contaminants was measured at birth and 11 years of age. An auditory oddball protocol was administered at 11 years to measure ERP components N1 and P3b. Multiple regression analyses were performed to examine the associations of levels of the contaminants to auditory oddball performance (mean reaction time, omission errors and false alarms) and ERP parameters (latency and amplitude) after control for potential confounding variables. A total of 118 children provided useable ERP data. Prenatal MeHg exposure was associated with slower reaction times and fewer false alarms during the oddball task. Analyses of the ERP parameters revealed that prenatal MeHg exposure was related to greater amplitude and delayed latency of the N1 wave in the target condition but not to the P3b component. MeHg effects on the N1 were stronger after control for seafood nutrients. Prenatal PCB exposure was not related to any endpoint for sample as a whole but was associated with a decrease in P3b amplitude in the subgroup of children who had been breast-fed for less than 3 months. Body burdens of MeHg and PCBs at 11 years were not related to any of the behavioural or ERP measures. These data suggest that prenatal MeHg exposure alters attentional mechanisms modulating early processing of sensory information. By contrast, prenatal PCB exposure appears to affect information processing at later stages, when the information is being consciously evaluated. These effects seem to be mitigated in children who are breast-fed for a more extended period.

PTSD, but not childhood maltreatment, modifies responses to unpleasant odors

Childhood maltreatment (CM) as well as posttraumatic stress disorder (PTSD) is said to result in functional changes to amygdalae and orbitofrontal cortex. Thus, it might be expected to change olfactory function in adults with a CM-history and current PTSD symptomatology as amygdalae and orbitofrontal cortex are of major importance for olfactory information processing. To explore this we investigated olfactory function in 31 women with current psychopathology and a history of CM, 28 without CM, and 27 healthy women. We used the “Sniffin' Sticks” threshold and identification test and analyzed chemosensory event-related potentials. Participants were also asked to complete a questionnaire to access current symptoms of posttraumatic stress disorder (PTSD). We found no significant difference between the CM-Group and the two control groups, but PTSD severity correlated significantly with odor identification scores and with parameters of event-related potentials in response to unpleasant stimuli. The results indicate preferential processing of unpleasant stimuli in PTSD patients irrespective of the childhood history.

Specificity of recognition of fragmented images in seven- to eight-year-old children: Analysis of event-related potentials

The topography and parameters of event-related potentials (ERPs) recorded during the presentation of incomplete images with different fragmentation were analyzed in seven- to eight-year-old children. The degree and mode of the involvement of different cortical zones at different stages of analysis and processing of fragmented images were determined. It was found in children that the prefrontal cortical areas were involved in the recognition of incomplete images in the same way as in adults. Age-related differences manifested themselves in a lower intensity of the slow positive complex in children, reflecting the decision-making and information retention processes required for the preparation of an answer.

Mild cognitive impairment and event-related potentials in patients with cerebral atrophy and leukoaraiosis

The influence of cerebral atrophy and leukoaraiosis (LA) on the degree and profile of cognitive impairment remains unclear. The aim of the study was to assess neuropsychological features of cognitive performance and parameters of event-related potentials (ERP) in subjects with generalised cerebral atrophy and LA. Department of Neurology, University of Medicine. Forty-two patients with LA and/or cerebral atrophy and twenty controls. Neuropsychological testing (NT) included Mini Mental State Examination (MMSE), Auditory Verbal Learning Test (AVLT) and Trail Making Test (TMT). Auditory ERPs were performed and parameters of the N2 and P3 components were compared in the patients and controls. Relationships were analysed between radiological indices of atrophy and LA, and NT and ERP results. Results of NT suggested generalised mild cognitive impairment in all the patients. P3 and N2 latencies were longer in the patients than in controls, especially in the LA subgroup. Correlations were found for indices of atrophy, AVLT and ERP parameters. There was a predominant influence of age upon ERP parameters and radiological indices. Cerebral atrophy and LA result in deficits in memory and attention. NT and ERP may be used as complementary methods in the assessment of cognitive impairment in patients with cerebral atrophy and LA.

Dichotic listening revisited: Trial-by-trial ERP analyses reveal intra- and interhemispheric differences

The dichotic listening (DL) paradigm is often used to assess brain asymmetries at the behavioral level. The aim of this study was to evaluate the dynamic temporal and topographical characteristics of event related potentials (ERPs) obtained with diotic and dichotic consonant–vowel (CV) stimuli from the same subjects. We used a novel approach in which we concurrently analyzed on a trial-by-trial basis ERP parameters during trials that resulted in a right ear advantage (REA) or left ear advantage (LEA) or that were presented under diotic (homonymous) conditions. CV syllables were used as auditory stimuli (/ba/, /da/, /ga/, /ka/, /pa/, /ta/). The EEG measurements were performed with 64 channels by mainly focusing on the N1P2, N2P3 and late negativity (LN) components. Overall, behavioral data revealed a clear REA. The central area showed higher amplitudes than the other locations for N1P2 responses. Additionally, responses were faster for the diotic, compared to the dichotic conditions. The LN had shorter latencies in trials resulting in a REA, compared with those producing a LEA. This result makes it likely that the overall REA is a time-bound effect, which can be explained by the structural theory of Kimura. Furthermore, the results demonstrated a specific spatiotemporal shift from central to frontal areas between N1P2 and LN that was pronounced in dichotic trials. This shift points towards the involvement of frontal areas in resolving conflicting input.

Event-related potentials associated with a shift in the strategy of visual perception during recognition of a hierarchical stimulus

Recording of event-related potentials (ERPs) was used to study the brain mechanisms of shifting the strategy of recognition of the global and local levels of a hierarchical image by adult subjects. A shift in the strategy of visual recognition results in substantial changes in ERP parameters in the caudal and frontocentral cortical areas. The activation effect of the switchover from one recognition strategy to another is associated with an increase in the amplitude of early ERP components (C1, P100, and N150) of the caudal cortical areas. Changes in the late ERP components associated with processing of significant information features during the shift in the recognition strategy are observed in the frontal areas within the interval 388–579 ms, with the amplitude of components N300 and N400 increasing.

Neurotoxic effect of antiretroviral agents on CNS

Methods In a retrospective cross-sectional study, parameters of event-related potentials (ERPs) were analysed from patients receiving HAART with ddI, ddC, d4T for at least 3 month (n = 60) with a mean intake of 24 ± 6 months (mv ± 1 SD). Results were compared to a control group receiving HAART without these substances. The latency of P2, N2, P3 and the amplitude of P3 of ERPs and the mean reaction time were analysed. Cognitive impairment (CI) and distal-symmetric polyneuropathy (DSP) were investigated using routine clinical and neurophysiological methods.

Recognition of fragmented images and mechanisms of memory

Analysis of the topography and parameters of event-related potentials (ERPs) recorded during the presentation of incomplete images with different fragmentation aided in study of the role of different cortical zones and the order of their involvement in the recognition process. The role of the frontal cortical areas at different stages of perception of fragmented images was established. The differences in the ERPs induced by recognized and unrecognized stimuli in the frontal and frontal-temporal derivations in the interval 30–83 ms were associated with the appearance of early positivity in response to recognized images and development of early negativity in response to unrecognized stimuli. The N300 component associated with recognition was stronger in these cortical zones during identification of images. A late positive complex appeared in the frontal areas earlier than in other areas. Involvement of the caudal visual areas in the recognition process was reflected by enhancement of the components P100, P250, and N400. Our results suggest that the frontal areas play the main role in the recognition of fragmented images because they are the structures that organize extraction of traces from long-term modality-specific memory using a system of afferent and efferent links and determine the strategy of information analysis necessary for the solution of a given task.

Intérêt des potentiels évoqués cognitifs dans la détection des troubles cognitifs précoces dans la sclérose en plaques

In Multiple Sclerosis (MS), one of the most frequent neurological diseases in young adults, cognitive dysfunctions have been under considered whereas their evolution may produce a fronto-sous-cortical deterioration and more than half of the MS patients present such dysfunctions. Nevertheless sensory evoked-potentials are classically used in this disease, event-related potentials (ERP) are not included in the clinical exploration of MS. Two studies are presented aimed at further tracking the usefulness of ERP for detecting early cognitive dysfunctions in MS. All of the patients presented a relapsing remitting MS for less than 5 years with a moderate physical handicap and complained from their memory. They performed a neuropsychological set and ERP were elicited using the oddball paradigm in both modalities, visual and auditory. In the first study, 10 patients without cognitive dysfunction at the neuropsychological evaluation and 10 patients with an attention deficit participated with 10 age-matched controls. In the second study, 10 patients with memory impairment at the neuropsychological evaluation and 10 age-matched controls were included. Our data argue for an earlier modification of ERP parameters in the visual modality than in the auditory one, even before the modification of cognitive scores. In both studies, P300 parameters were correlated to neuropsychological performances (and especially to the attention examination in the first study and to memory tests in the second study) in both modalities. Taking into account the clinical usefulness of ERPs, it is nowadays important to include this electrophysiological method in evaluation and follow-up of MS, and not only using the auditory modality but also the visual presentation in order to detect earlier cognitive dysfunctions even before modification of neuropsychological performances.

Neural mechanisms of auditory sensory processing in children with high intelligence

To investigate the differences in event-related potential parameters related to children's intelligence, 18 intellectually gifted children and 18 average children participated in this study. The electroencephalograms were recorded the auditory sensory memory that elicited the mismatch negativity (MMN) and late discriminative negativity (LDN), as well as involuntary attention switch that elicited the P3a and early MMN were analyzed. The results indicated that children with high intelligence had comparatively larger MMN, LDN, early MMN, P3a amplitudes, and earlier peak latency in LDN than average children. The enhanced neural function of the intellectually gifted children might be due to more spatially and temporally coordinated neural network, faster neural processing speed and more efficient neural activation functions.

Electrophysiological Effects of Stimulant Treatment on Inhibitory Control in Children with Attention-Deficit/Hyperactivity Disorder

To examine the electrophysiological effects of methylphenidate (MPH) on inhibitory control in children with attention deficit/hyperactivity disorder (ADHD). Twelve children with ADHD performed the Stop Signal Task (SST) while event related potentials (ERP) were obtained. Each child completed two testing sessions, once on placebo and again on an individualized dose of MPH, with the order of medication administration counterbalanced. The following ERP parameters were studied: the N200, often seen as a measure of the activation of the inhibitory process, and the NoGo-P3, which may represent the degree of performance monitoring and/or error detection. MPH significantly improved behavioral performance on the SST. During successful inhibitions, MPH also significantly increased the amplitude of the right frontal N200, while during unsuccessful inhibitions MPH increased the amplitude of the NoGo-P3. MPH may improve inhibitory control by enhancing brain mechanisms that trigger the inhibitory process and make stopping a motor act more probable (reflected by increased N200) and by increasing attentional resources to the task when unsuccessful inhibitions occur (as reflected by increased NoGo-P3). These results are consistent with functional imaging studies suggesting a role for the right frontal inferior cortex and the cingulate cortex in the pathophysiology of ADHD.

Delayed post-ictal event-related potentials do not differentiate between generalized tonic-clonic seizures and syncope

The differentiation between generalized tonic-clonic seizure (GTCS) and syncope is an important clinical problem. Corroborative investigations, which are requested when history is unclear or insufficient, have limited diagnostic value. The aim of our study was to determine whether auditory event-related potentials (ERPs) can be utilized in post-event differentiation between GTCS and syncope. ERPs were recorded in 18 patients with a single seizure and in 21 patients following syncope, either on one or two occasions. ERP latencies and amplitudes were compared between groups and sessions. No significant differences of P3, N2, P2 and N1 latencies and P3, N2 and P2 amplitudes were found between patients following a single GTCS as compared to patients following syncope on either session. Post-event ERPs are insufficient to differentiate between GTCS and syncope. Further investigations are needed to evaluate the influence of different post-event intervals and ERP paradigms on ERP parameters in patients with GTCS.