P300 Event-related Potential Research Articles

Mild cognitive impairment in mild brain injury (MBI) patients: An event related potential (ERP) and neuropsychology study.

Objectives: To evaluate auditory cognitive function in mild brain injury (MBI) patients, which is important to determine for rehabilitation and improve quality of their life.
 Methods: Participants (n=19/group) were divided into group 1 (G1-control), group 2 (G2/1st test-MBI/within 7 days of road traffic accident-RTA) and group 3 (G3/2nd test-MBI/2-6 months after RTA). Event related potentials (ERPs) were conducted using a 128-sensor net; participants counted silently rare target tone stimuli and ignored standard tones. Several neuropsychology tests like Verbal fluency test (PAS), Wisconsin Card Sorting Test (WCST), Rey Auditory Verbal and Learning Test (RAVLTIM, RAVLTDR and RAVLTTS) and Beck Depression Inventory (BDI) were subsequently administered.
 Results: Sensory (P50, N100) and cognitive (P300) ERP components were analysed from ERP waveforms. There were no significant group differences in amplitudes or latencies for all components across sites except P300 component amplitudes at T6 location. P50, N100 and P300 ERP components exhibited non-significantly increased amplitudes in G2 and G3 compared with G1 at all sites; non-significantly shorter latencies were identified at various sites. At several locations, G3 evoked non-significantly increased amplitudes and longer latencies with shorter latencies to other sites compared with G2 in all components. The MBI (G3) group exhibited significantly increased WCST, RAVLTIM and RAVLTDR scores compared with G1.
 Conclusion: These findings indicate MBI patients may have mild auditory, cognitive and executive dysfunctions with good auditory memory. MBI was associated with mild depression.
 Bangladesh Journal of Medical Science Vol.18(3) 2019 p.557-566

P36-F Neurophysiological assessment of cognitive functions in patients with multiple sclerosis

Background Cognitive dysfunction concerns about 40–75% of subjects with multiple sclerosis (MS). The aim of the study was to check the usefulness of neurophysiological examinations in assessment of cognitive functions in patients with MS. Material and methods 61 relapsing-remitting MS patients and 21 healthy volunteers participated in the study. The patients were divided into two groups: A - 30 patients with short disease duration (time from first symptoms was less than 5 years); and B - 31 patients with long disease duration (time from first symptoms was more than 10 years). Neurophysiological tests were performed in all patients: event related potential (P300), somatosensory evoked potentials (SSEP), visual evoked potentials (VEP). In addition, the Hospital Anxiety and Depression Scale (HADS), the Montreal Cognitive Assessment Scale (MoCA), and the Wechsler Intelligence Scale subscales (Lacks in Pictures and Symbols of Digits) were done. Results In patients with MS the mean latencies of P100, P23 and P300 were significantly longer than compared to controls. Prolongation of P300 was associated with worse education. Patients with longer disease duration had tendency to have longer latencies of P300. An association was found between results of psychometric tests and event-related potential P300. Conclusions Event related potential (P300) is useful in clinical practice to assess cognitive functions in MS patients.

Identification of subclinical cognitive impairment in chronic obstructive pulmonary disease using auditory P300 event related potential.

Adequate cognitive functioning in chronic obstructive pulmonary disease (COPD) patients is essential to understand the nature of the disease, adherence to treatment, and for leading a better quality of life. While cognitive impairment in severe forms of COPD have been well documented, identification of subclinical cognitive impairment in stable COPD patients remains crucial for planning prevention strategies. Hence the present study aimed to study and compare the cognitive function between the COPD patients, and normal individuals. The cognitive function was assessed in 42 stable COPD patients and 42 normal individuals with Mini Mental State Examination (MMSE), and auditory P300 event related potentials. Baseline characteristics and the cognitive parameters were compared between the COPD patients and the normal individuals; a p<0.05 was considered statistically significant. The latency of the P300 waves was significantly (p<0.05) prolonged (304.27±20.73 in COPD, 291.11± 24.53 in normal individuals), and the amplitude (4.36±1.56 in COPD, 5.46±3.12 in normal individuals) was significantly reduced in the COPD patients compared to the normal individuals. MMSE scores were also significantly (p<0.001) different between the COPD patients (26.97±0.89), and the normal individuals (27.80±0.83). Cognition may be affected even at the earlier stages of the disease among the COPD patients, as evident by changes in the P300 values. Auditory P300 event related potential may be used as an adjunct to the routine MMSE examination, as it serves as an effective tool in identifying the cognitive impairment in different stages of COPD. This may help the patients to adopt prevention strategies that help to avoid adverse effects on cognition in future.

A longitudinal study of event related potentials and correlations with psychosocial functioning and clinical features in first episode psychosis patients

BackgroundDeficits in auditory event-related potentials (ERPs), brain responses to stimuli indexing different cognitive processes, have been demonstrated widely in chronic schizophrenia (SZ) patients though much less is known about these responses across the early course of psychosis. The present study examined multiple ERP components in first episode psychosis (FEP) patients longitudinally and investigated the relationships between ERPs, psychosocial functioning, and clinical features over time. MethodsN1, P2, P3a, and P3b ERPs were elicited using a three-stimulus (novelty) auditory oddball paradigm. FEP patients included SZ-spectrum and psychotic bipolar disorder (BD) diagnoses. Data were collected from 41 patients at baseline, 20 patients at 12-month follow-up, 14 at 24-month follow-up, and 29 healthy control subjects. ResultsN1 and P2 ERPs were intact across the early stages of psychosis. Baseline P2 was significantly larger in BD than SZ patients. Reduced P3a and P3b ERPs were found in patients followed longitudinally and are stable over time. ERPs tracked distinct aspects of symptomology and medication, though specific associations were inconsistent across time. Baseline P3a amplitude predicted later psychosocial functioning. The pattern of correlations between ERP components in patients differed from controls. DiscussionBaseline P3a ERP, and PANSS general score were significant and independent predictors of later MCAS functioning at 12-month. Overall, individuals with worse functioning and greater symptomology produced smaller amplitudes. Our results highlight the heterogeneity within the FEP population. Correlation patterns among ERPs are similar between patients and controls. P3a and P3b amplitudes appear to link with higher-order cognitive and psychosocial functioning.

Processing differences between monolingual and bilingual young adults on an emotion n-back task

Bilingualism is associated with enhancement of executive control (EC) across the lifespan. Working memory and non-verbal emotion regulation both draw upon EC mechanisms so may also be affected by bilingualism, but these relationships are not fully understood. These relationships were explored using an n-back task with distracting emotional stimuli administered to young adults while continuous EEG was recorded. Monolinguals were faster but less accurate on the 2-back than bilinguals, and monolingual accuracy was more impeded by the presence of emotional stimuli than was that of bilinguals. The P300 event-related potential, a neural signature of working memory processing in the n-back, had smaller amplitudes in both groups on the 2-back than the 1-back, but attenuation in response to distracting emotional stimuli was greater for bilinguals than monolinguals. P300 latencies were also differentially affected by emotional stimuli in each group: Bilingual latencies were constant across emotions but monolingual latencies increased from neutral to angry conditions. In general, bilingual performance was less impacted by the emotional distraction than was that of the monolinguals. Additionally, bilinguals adjusted to the changing demands of the 1-back and 2-back conditions by recruiting neural networks to support different behavioral outcomes than monolinguals.

A Laboratory Word Memory Test Analogue Differentiates Intentional Feigning from True Responding Using the P300 Event-Related Potential.

Symptom exaggeration and feigned cognitive impairment occur commonly in forensic and medicolegal evaluations. As a result, methods to detect feigned cognitive impairment are an indispensable component of neuropsychological assessments. This study reports the results of two neurophysiological experiments using a forced-choice recognition task built from the stimuli of the Word Memory Test and Medical Symptom Validity Test as well as a new linguistically informed stimulus set. Participant volunteers were instructed either to do their best or to feign cognitive impairment consistent with a mild traumatic brain injury while their brain activity was monitored using event-related potentials (ERP). Experiment 1 varied instructions across individuals, whereas Experiment 2 varied instructions within individuals. The target brain component was a positive deflection indicating stimulus recognition that occurs approximately 300 ms after exposure to a stimulus (i.e., the P300). Multimodal comparison (P300 amplitude to behavioral accuracy) allowed the detection of feigned cognitive impairment. Results indicate that, for correct responses, P300s were equivalent for the simulated malingering and good effort conditions. However, for incorrect responses, feigned impairment produced reliable but significantly reduced P300 amplitudes. Although the P300 is an automatic index of recognition—even when knowledge is hidden—its amplitude appears capable of modulation by feigning strategies. Implications of this finding are discussed for research and clinical applications.

Mild cognitive impairment in Parkinson’s disease is associated with decreased P300 amplitude and reduced putamen volume

ObjectiveFunctional and structural brain alterations of cognitively normal Parkinson’s disease (PD-CN) and Parkinson’s disease mild cognitive impairment (PD-MCI) patients were investigated using event-related potentials (ERP) P300 and volumetric magnetic resonance imaging (MRI) parameters. MethodsTwenty three patients with PD-CN, 21 with PD-MCI, and 23 demographically-matched healthy controls were included. EEGs were recorded using a visual oddball task and mean amplitude and peak latency values of P300 were measured. Gray matter volumes (GMV) of thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala and nucleus accumbens were obtained using FMRIB Integrated Registration and Segmentation Tool. Correlations among P300, subcortical GMV and cognitive performances were assessed. ResultsPD-CN patients demonstrated reduced P300 amplitudes compared to healthy controls. PD-MCI patients had lower P300 amplitudes than both PD-CN patients and controls and reduced volumes of the putamen compared to controls. Both putamen volumes and P300 amplitudes showed moderate associations with executive functions. ConclusionsOur findings support that P300 amplitude may be a useful marker for the detection of preclinical changes before the appearance of cognitive and structural deterioration in PD, as shown by decreased frontal P300 amplitudes in PD-CN. The reduction further spread to centro-parietal areas in PD-MCI patients, which was accompanied by lower putamen volumes. SignificanceThis study is the first to report on changes in ERP P300 amplitude and subcortical volume in well-matched samples of PD-CN, PD-MCI and healthy controls.

The Influence of Acetaminophen on Task Related Attention.

Our study was designed to examine whether the pain reliever acetaminophen impacts the normal ebb-and-flow of off-task attentional states, such as captured by the phenomenon of mind wandering. In a placebo-controlled between-groups design, participants performed a sustained attention to response task while event-related potentials (ERPs) to target events were recorded. Participants were queried at random intervals for their attentional reports – either “on-task” or “off-task.” The frequency of these reports and the ERPs generated by the preceding target events were assessed. Behaviorally, the frequency of off-task attentional reports was comparable between groups. Electrophysiologically, two findings emerged: first, the amplitude of the P300 ERP component elicited by target events was significantly attenuated during off-task vs. on-task attentional states in both the acetaminophen and placebo groups. Second, the amplitude of the LPP ERP component elicited by target events showed a significant decrease during off-task attentional states that was specific to the acetaminophen group. Taken together, our findings support the conclusion that acetaminophen doesn’t impact our relative propensity to drift into off-task attentional states, but it does affect the depth of neurocognitive disengagement during off-task attentional states, and in particular, at the level of post-categorization stimulus evaluations indexed by the LPP.

T161. Effects of Ketamine Administration on the P300 Event-Related Potential: Implications for Schizophrenia

N-methyl-D-aspartate receptor (NMDAR) hypofunction has been implicated in the pathophysiology of schizophrenia and its associated cognitive impairments, including auditory processing deficits reflected by the P300 event-related potential (ERP) component. P300 amplitude reduction is one of the most widely replicated brain abnormalities observed in patients with schizophrenia. To test the hypothesized contribution of NMDAR hypofunction to P300 abnormalities, we examined the effects of the NMDAR antagonist ketamine on auditory P300 amplitudes in healthy individuals and compared these effects with those of schizophrenia.

S141. The P300 Event-Related Potential in Bipolar Disorder Compared to Healthy Control: A Systematic Review and Meta-Analysis

Neurophysiology enables us to measure functional dynamics of the human brain and can be useful towards elucidating the pathophysiology of bipolar disorder (BD). Specifically, P300 may be a biological marker for BD. However, previous findings from P300 studies have been inconsistent due to the heterogeneity of research methods, which make it difficult to understand the neurobiological significance of P300 in this disorder. The aim of this study is to conduct meta-analyses on P300 indices in patients with BD.

Cognitive Impairment and Treatment Compliance in Patients with Chronic Heart Failure

Objectives. To identify the risk factors for the development of cognitive impairments and the low treatment compliance seen in patients with chronic heart failure (CHF). Materials and methods. A total of 157 patients with CHF and 32 control subjects took part in the study. Neuropsychological investigations were carried out using a 30-min set of tests recommended by the NINDS-Canadian Stroke Standards – echocardioscopy, brain MRI scans, and cognitive event-related potentials (ERP) – along with assessment of treatment compliance. Results and conclusions. Treatment regime violations were seen in 62% of cases. Decreases in compliance were associated with increases in the severity of subcortical (frontal lobes) and periventricular leukoaraiosis, slowing of decision-taking processes (increases in the latency of the ERP P300 peak), and degradation of test performance for assessment of speech activity, optical-spatial, frontal-dysregulatory functions, and memory. Among patients with low treatment compliance, 58% showed frontal-dysregulatory cognitive disorders, 21% combined disorders, and 40% amnestic disorders. Risk factors for progression of cognitive disorders and low treatment compliance were a reduced fractional output and the restrictive type of diastolic cardiac dysfunction.

Distinctive Effects of Aerobic and Resistance Exercise Modes on Neurocognitive and Biochemical Changes in Individuals with Mild Cognitive Impairment.

Decreased levels of the neuroprotective growth factors, low-grade inflammation, and reduced neurocognitive functions during aging are associated with neurodegenerative diseases, such as Alzheimer's disease. Physical exercise modifies these disadvantageous phenomena while a sedentary lifestyle promotes them. The purposes of the present study included investigating whether both aerobic and resistance exercise produce divergent effects on the neuroprotective growth factors, inflammatory cytokines, and neurocognitive performance, and further exploring whether changes in the levels of these molecular biomarkers are associated with alterations in neurocognitive performance. Fifty-five older adults with amnestic MCI (aMCI) were recruited and randomly assigned to an aerobic exercise (AE) group, a resistance exercise (RE) group, or a control group. The assessment included neurocognitive measures [e.g., behavior and event-related potential (ERP)] during a task-switching paradigm, as well as circulating neuroprotective growth factors (e.g., BDNF, IGF-1, VEGF, and FGF-2) and inflammatory cytokine (e.g., TNF-α, IL-1β, IL-6, IL-8, and IL-15) levels at baseline and after either a 16-week aerobic or resistance exercise intervention program or a control period. Aerobic and resistance exercise could effectively partially facilitate neurocognitive performance [e.g., accuracy rates (ARs), reaction times during the heterogeneous condition, global switching cost, and ERP P3 amplitude] when the participants performed the task switching paradigm although the ERP P2 components and P3 latency could not be changed. In terms of the circulating molecular biomarkers, the 16-week exercise interventions did not change some parameters (e.g., leptin, VEGF, FGF-2, IL-1β, IL-6, and IL-8). However, the peripheral serum BDNF level was significantly increased, and the levels of insulin, TNF-α, and IL-15 levels were significantly decreased in the AE group, whereas the RE group showed significantly increased IGF-1 levels and decreased IL-15 levels. The relationships between the changes in neurocognitive performance (AR and P3 amplitudes) and the changes in the levels of neurotrophins (BDNF and IGF-1)/inflammatory cytokines (TNF-α) only approached significance. These findings suggested that in older adults with aMCI, not only aerobic but also resistance exercise is effective with regard to increasing neurotrophins, reducing some inflammatory cytokines, and facilitating neurocognitive performance. However, the aerobic and resistance exercise modes likely employed divergent molecular mechanisms on neurocognitive facilitation.

Effect of radiochemotherapy on the cognitive function and diffusion tensor and perfusion weighted imaging for high-grade gliomas: A prospective study

This study aimed to explore the effects of radiochemotherapy on the neurocognitive function of patients with high-grade gliomas (HGG). The mini-mental state examination (MMSE), Montreal Cognitive Assessment (MoCA), event-related potential P300 (ERP-P300), and specific MRI parameters were compared, and the associations between specific MRI parameters and different doses of radiation were determined for before and up to 12 months after radiotherapy. There were no significant differences in MMSE, MoCA, or ERP-P300 before and after radiotherapy. Compared with pre-radiochemotherapy, fractional anisotropy (FA) in the contralateral hippocampus decreased at 6 and 9 months after radiotherapy. FA in the ipsilateral hippocampus before radiochemotherapy decreased compared with 6 months after radiotherapy. Compared to the end of radiotherapy, as well as 3- and 6-months post-radiotherapy, the regional cerebral blood volume (rCBV) in the genu of the corpus was significantly lower at 12 months post-radiotherapy. Some MRI parameters in different regions of the brain were negatively correlated with the mean and maximum dose. There was no significant effect of radiochemotherapy on the neurocognitive functioning of patients with HGGs found before radiochemotherapy until 12 months after radiotherapy. The radiation-induced FA decrease in the bilateral hippocampus preceded cognitive dysfunction, and DTI of the hippocampus may provide a useful biomarker for predicting radiation-induced neurocognitive impairment in patients with HGGs.

Attentional bias and response inhibition in severe obesity with food disinhibition: a study of P300 and N200 event-related potential.

In obesity there is growing evidence for common mechanism between food intake regulation and substance use disorders, especially more attentional bias and less cognitive control. In the present study we investigated whether severely obese subjects with or without disordered eating exhibit electroencephalographic (EEG) event-related potential (ERP) modifications as observed in substance abusers. A total of 90 women were included; 30 in the normal-weight (NW) group (18.5 < BMI < 24.5 kg/m2; no food disinhibition or restriction on the Three-Factor Eating Questionnaire) and 60 participants with BMI ≥ 35 kg/m2 were separated into two groups (n = 30): without food disinhibition (disinhibition score ≤8; ObFD- group) and with food disinhibition (score >8; ObFD+). Clinical and metabolic parameters as well as compartmental aspects (Eating Disorders Inventory-2, EDI-2) were assessed. Participants underwent an ERP recording with an auditory oddball paradigm. The mean ± SD P300 amplitudes in Pz were significantly (p < 0.05) lower in ObFD- (12.4 ± 4.6) and ObFD+ (12.5 ± 4.4) groups than in the NW group (15.8 ± 5.9). The mean ± SD N200 amplitude in Cz was significantly lower in the ObFD- group (-2.0 ± 5.4) than in the NW group (-5.2 ± 4.2 vs; p = 0.035). N200 Cz amplitude was correlated with EDI-2 Binge eating risk score (ρ = 0.331; p = 0.01), EDI-2 Body Dissatisfaction score (ρ = 0.351; p = 0.007), and Drive for Thinness score (ρ = 0.26; p = 0.05). The present study provides evidence for reduction of P300 and N200 amplitude in obese women and that N200 amplitude may be related to more disordered eating and eating disorder risk. This leads to consider attentional bias and response inhibition as core mechanisms in obesity and as possible targets for new therapeutic strategy.

Combining CDP-choline and galantamine: Effects of a selective α7 nicotinic acetylcholine receptor agonist strategy on P50 sensory gating of speech sounds in healthy volunteers.

Schizophrenia (SCZ) patients and relatives have deficits in early cortical sensory gating (SG) typically measured by suppression of electroencephalography-derived P50 event-related potentials (ERPs) in a conditioning-testing (S1-S2) paradigm. Associated with alpha 7 nicotinic acetylcholine receptor (α7 nAChR) dysfunction and shown to be improved with nicotine and α7 nAChR agonists, SG has recently been shown to be improved in low P50 suppressing SCZ patients following acute CDP-choline treatment. This pilot study in healthy humans assessed the SG effects of an α7 nAChR strategy combining CDP-choline with galantamine, a positive allosteric modulator (PAM) of nAChRs, aimed at increasing and prolonging nicotinic receptor activity. The combined effect of CDP-choline (500 mg) and galantamine (16 mg) on speech P50 gating indices rP50 (S2/S1) and dP50 (S1-S2) was examined in 30 healthy participants stratified into low and high baseline P50 suppressors in a randomized, double-blind, placebo-controlled and counterbalanced design. In low suppressors, CDP-choline/galantamine (vs. placebo) improved rP50 and dP50 gating, and reduced S2P50 amplitudes. No P50 gating effects were observed in high suppressors; however, CDP-choline/galantamine (vs. placebo) increased their S2P50 amplitudes. Findings from this pilot study with CDP-choline/galantamine in a healthy, SCZ-like surrogate deficient gating sample are consistent with the association of α7 nAChR mechanisms in SG impairment in SCZ and support further research trials with CDP-choline and galantamine targeting sensory processes.

Sibling experience prevents neural tuning to adult faces in 10-month-old infants

Early facial experience provided by the infant's social environment is known to shape face processing abilities, which narrow during the first year of life towards adult human faces of the most frequently encountered ethnic groups. Here we explored the hypothesis that natural variability in facial input may delay neural commitment to face processing by testing the impact of early natural experience with siblings on infants' brain responses. Event-Related Potentials (ERPs) evoked by upright and inverted adult and child faces were compared in two groups of 10-month-old infants with (N = 21) and without (N = 22) a child sibling. In first-born infants, P1 ERP component showed specificity to upright adult faces that carried over to the subsequent N290 and P400 components. In infants with siblings no inversion effects were observed. Results are discussed in the context of evidence from the language domain, showing that neural commitment to phonetic contrasts emerges later in bilinguals than in monolinguals, and that this delay facilitates subsequent learning of previously unencountered sounds of new languages.

Repeated transcranial magnetic stimulation for treating the negative symptoms of schizophrenia

Objective To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) on the negative symptoms of chronic schizophrenia and on the P300 component of schizophrenics′ event-related potentials (ERPs). Methods Ninety convalescing schizophrenia patients were randomly divided into a 5 Hz group, a 10 Hz group and a 15 Hz group, each of 30. The three groups were treated with the corresponding 5 Hz, 10 Hz or 15 Hz rTMS once a day, five times a week for five consecutive weeks. The P300 ERPs of all three groups were tested before and after the treatment. Any curative effect was evaluated using the scale for the assessment of negative symptoms (SANS). Results After the treatment, the average SANS score of the 10 Hz group was significantly different from that before the treatment and also from those of the other two groups after the treatment. After the treatment, significant improvement was also observed in the amplitude of P300 in the 10 Hz group. The treatment′s effectiveness was negatively correlated with age and longer course of the disease. Conclusion rTMS at 10 Hz is the most effective of the protocols tested for improving the negative symptoms of schizophrenia and improving cognitive functioning. Key words: Schizophrenia; Transcranial magnetic stimulation; Event-related potentials

Alpha modulation during working memory encoding predicts neurocognitive impairment in ADHD.

Attention-deficit/hyperactivity disorder (ADHD) is associated with working memory (WM) deficits. However, WM is a multiprocess construct that can be impaired through several pathways, leaving the source of WM impairments in ADHD unresolved. In this study, we aim to replicate, in an independent sample, previously reported deficits in component processes of WM deficits in ADHD and expand to consider their implications for neurocognitive outcomes. In 119 children (7-14years old, 85 with ADHD), we used electroencephalography measures to quantify component processes during performance of a spatial working memory task. We quantified stimulus encoding using alpha range (8-12Hz) power; vigilance by the P2 event-related potential to cues; and WMmaintenance by occipital-alpha and frontal-theta (4-7Hz) power. These measures were evaluated against metrics of executive function, ADHD symptoms, and academic achievement. Encoding alpha-power decreases and cue P2 amplitude were attenuated in ADHD, whereas occipital-alpha power during maintenance was significantly greater in ADHD, consistent with a compensatory response to weak encoding. Weak alpha modulation during encoding was associated with poorer reading comprehension and executive function, as well as enhanced ADHD symptoms. Previously reported effects in frontal-theta power failed to replicate. Stimulus encoding, a component process of WM coupled to alpha modulation, is impaired in ADHD, and, unlike WM maintenance or vigilance processes, has implications outside of the laboratory via a relationship with executive function, and, to a weaker extent, reading comprehension.

Insights into cognitive decline in spinocerebellar Ataxia type 2: a P300 event-related brain potential study

BackgroundCognitive decline is a common non-motor feature characterizing Spinocerebellar Ataxia type 2 (SCA2) during the prodromal stage, nevertheless a reduced number of surrogate biomarkers of these alterations have been described.ObjectiveTo provide insights into cognitive dysfunction in SCA2 patients using P300 event-related potentials (ERP) and to evaluate these measures as biomarkers of the disease.MethodsA cross-sectional study was performed with 30 SCA2 patients, 20 preclinical carriers and 33 healthy controls, who underwent visual, auditory P300 ERPs, and neurological examinations and ataxia scoring.ResultsSCA2 patients showed significant increase in P300 latencies and decrease of P300 amplitudes for visual and auditory stimuli, whereas preclinical carriers exhibit a less severe, but significant prolongation of P300 latencies. Multiple regression analyses disclosed a significant effect of SARA score on visual P300 abnormalities in patients as well as of the time to ataxia onset on visual P300 latencies in preclinical carriers.ConclusionsThis paper demonstrated the role of P300 ERP for the study of attentional, discriminative and working memory abnormalities in SCA2 patients and for the search of surrogate biomarkers from prodromal to the symptomatic stages. Moreover, our findings provide psychophysiological evidences supporting the cerebellar involvement in cognitive processes and allows us to identify promising outcome measures for future trials focusing on cognitive dysfunction.

Classification of Motor Imagery Task by Using Novel Ensemble Pruning Approach

Brain-computer interface (BCI) assists communication for the disabled and handicapped. It is usually electroencephalogram (EEG) based and uses motor imagery (MI) in its operation. EEG signals are known for being nonstationary and are sensitive to artifacts from various sources such as the physical and mental state of the patient, their mood, their posture, and any external noise or distractions, etc. Processing of this data directly affects the classification accuracy, making it a critical step in any BCI system. Ensemble learning has been used for many kinds of BCI classification applications including MI and P300 event related potential, which has been proven to be robust. The purpose of this paper is to generate an algorithm that uses ensemble pruning method for EEG classification evoked by an MI task. In order to achieve this, we extracted the features of an EEG dataset and trained a range of support vector machines to make a diverse ensemble of classifiers. This ensemble is then pruned by using a novel optimization model by a difference of convex algorithm, which has not been used on EEG data before.