P300 Parameters Over the Lifespan: Validating Target Ranges from an In-Clinic Platform

Background: Evoked potential (ERP) markers extracted from an EEG exam can provide novel sources of information regarding brain function allowing changes in cognition, from conditions such as concussion or unhealthy aging, to be measured and tracked over time. Age-related targets can provide useful guides for practitioners, trainers, and patients seeking to optimize and track brain function over time. Objective 1: To compare age-related changes in auditory P300 metrics of latencies and amplitudes collected in the course of routine clinical evaluations with published trends from research. Objective 2: To establish within-person test-retest variances for these P300 metrics. Objective 3: To validate a method for presenting age-stratified target ranges of P300 metrics. Participants: One thousand seven-hundred and seventy-eight reference subjects aged 13-90. Methods: Audio P300 was measured as part of a health screening exam for studies through Colorado University, Children's Hospital Colorado, Boone Heart Institute, WAVi Co., and various clinics alongside other clinical evaluations. Results: The age-related trends in both the P300 latency and amplitude measured in clinic match the age-related trends from previous research. In particular, the 2 control group endpoints at 20 and 90 years match the linear slopes predicted for age-related decline from early studies, and the inclusion of all ages produces a maturation prediction of a recent meta analysis where metrics peak near 20 years of age. Large between-person variances are observed across all studies but within-person variances remain consistent with previous studies. Conclusion: In-clinic measures of P300 latency and amplitude corroborate the age-related trends of published research taken over the last several decades. Large between-person variance remains, leaving P300 best suited for within-person comparison.

Effect of inhibition indexed by auditory P300 on transmission of visual sensory information

Early electroencephalographic studies that focused on finding brain correlates of psychic events led to the discovery of the P300. Since then, the P300 has become the focus of many basic and clinical neuroscience studies. However, despite its wide applications, the underlying function of the P300 is not yet clearly understood. One line of research among the many studies that have attempted to elucidate the underlying subroutine of the P300 in the brain has suggested that the physiological function of the P300 is related to inhibition. While some intracranial, behavioral, and event-related potential studies have provided support for this theory, little is known about the inhibitory mechanism. In this study, using alpha event-related desynchronization (ERD) and effective connectivity, based on the causal (one-way directed) relationship between alpha ERD and P300 sources, we demonstrated that P300’s associated inhibition is implemented at a higher information processing stage in a localized brain region. We discuss how inhibition as the primary function of the P300 is not inconsistent with ’resource allocation’ and ’working memory updating’ theories about its cognitive function. In light of our findings regarding the scope and information processing stage of inhibition of the P300, we reconcile the inhibitory account of the P300 with working memory updating theory. Finally, based on the compensatory behavior of alpha ERD at the time of suppression of the P300, we propose two distinct yet complementary working memory mechanisms (inhibition and desynchronizing excitation) that render target perception possible.

NORMATIVE DATA OF COGNITIVE ASSESSMENT BY AUDITORY P300 EVENT RELATED POTENTIAL, MONTREAL COGNITION ASSESSMENT AND CHOICE REACTION TIME AND ITS VARIATION WITH AGE AND GENDER IN UTTARAKHAND REGION OF INDIA.

Background: Tests like auditory P300 event related potential, neuro-psychometric pen pencil Montreal Cognition Assessment Test (MOCA) and Choice reaction time have been used as indexes of cognitive function. Thus this study has been planned with the aim to evaluate cognitive ability of a normal adult to nd out normative data and its, variation with age and gender in Uttarakhand region of India. Materials and Method: This cross-sectional study was carried out in the department of Physiology of AIIMS, Rishikesh on 52 healthy with ages ranging from 20 to 40 years, equal number of male & female volunteers with the ability to understand test procedures. Following tests were performed in the given order for uniformity during 11-1 pm timing of a day: 1. Event Related Potential-P300 2. Neuro-psychometric assessment (Hindi Montreal Cognitive Assessment -HMOCA test) and 3. Choice Reaction Time. Results and Conclusion: Mean of P300 Latency is 310 ± 37.14 msec, mean of P300 Amplitude is 14 ± 7.5 uv (from Cz electrode site), mean of Montreal Score is 24.81±3.25, and mean of CRT is 584.5 ±84.06 ms in all the subjects. All the parameters are better in younger age group. All the parameters are better in male except MOCA score

Auditory evoked potential P300 characteristics in adults with and without idiopathic bilateral tinnitus

Background and Aim: Based on neurophysio­logical measurements, auditory and non-audi­tory pathways are involved in tinnitus. People who experience tinnitus may suffer from several problems such as attention disorder. The audi­tory evoked potential P300 is an endogenous response and depends on cognitive processes like attention. The purpose of this study was to compare the auditory P300 characteristics (amp­litude and latency) in adults with and without tinnitus. Methods: Participants were 20 adults with idio­pathic bilateral tinnitus with mean duration of 8.4 ± 4.73 months, and 20 healthy adults. The P300 was recorded using oddball paradigm con­sisted of two standard (1000 Hz) and target sti­muli (2000 Hz). To reduce eye blink during recording, all participants was instructed to look at and fixate on a dot sign located in front of them. The tinnitus handicap inventory (THI) was completed and pitch matching (PM) and loudness matching (LM) were measured in tinn­itus group. Results: P300 amplitude was lower at both Fz and Cz electrode placements in tinnitus patients compared to the normal group, but it was not statistically significant (p = 0.57). Tinnitus pati­ents had delayed latency at Fz and Cz, but this difference was not significant either psychomet­ric and psychoacoustic assessment had no statis­tically significant correlation with P300 ampli­tude and latency. Conclusion: It seems that P300 characteristics are not different between adults with and with­out idiopathic bilateral tinnitus, may be due to using low sample size. Keywords: Tinnitus; auditory evoked potential P300; attention

Special Issue on Brain Machine/Computer Interface and its Application

Brain machine/computer interface (BMI/BCI) technologies are based on analyzing brain activity to control machines and support the communication of commands and messages. To sense brain activities, a functional NIRS and electroencephalogram (EEG) that has been developed for that purpose is often employed. Analysis techniques and algorithms for the NIRS and EEG signals have also been created, and human support systems in the form of BMI/BCI applications have been developed. In the field of rehabilitation, BMI/BCI is used to control environment control systems and electric wheelchairs. In medicine, BMI/BCI is used to assist in communications for patient support. In industry, BMI/BCI is used to analyze sensibility and develop novel games. This special issue on Brain Machine/Computer Interface and its Application includes six interesting papers that cover the following topics: an EEG analysis method for human-wants detection, cognitive function using EEG analysis, auditory P300 detection, a wheelchair control BCI using SSVEP, a drone control BMI based on SSVEP that uses deep learning, and an improved CMAC model. We thank all authors and reviewers of the papers and the Editorial Board of Journal of Robotics and Mechatronics for its help with this special issue.

Convolutional Neural Network Transfer Learning Applied to the Affective Auditory P300-Based BCI

Brain-computer interface (BCI) enables us to interact with the external world via electroencephalography (EEG) signals. Recently, deep learning methods have been applied to the BCI to reduce the time required for recording training data. However, more evidence is required due to lack of comparison. To reveal more evidence, this study proposed a deep learning method named time-wise convolutional neural network (TWCNN), which was applied to a BCI dataset. In the evaluation, EEG data from a subject was classified utilizing previously recorded EEG data from other subjects. As a result, TWCNN showed the highest accuracy, which was significantly higher than the typically used classifier. The results suggest that the deep learning method may be useful to reduce the recording time of training data.

O10.2. DEFICIENT VISUAL ODDBALL STIMULUS PROCESSING PREDICTS PSYCHOSIS ONSET: RESULTS FROM THE NORTH AMERICAN PRODROME LONGITUDINAL STUDY

Background Clinical outcomes vary among young people with the psychosis risk syndrome (PRS), with approximately 20% of individuals progressing to a psychotic disorder over 2–3 years and 30% achieving clinical remission. The identification of neurophysiological abnormalities associated with schizophrenia that predate and predict psychosis onset may enhance the accuracy of clinical outcome prediction in the PRS and help elucidate the pathogenic mechanisms of psychosis onset. Auditory P300 event-related potential (ERP) component amplitude reductions are well established in schizophrenia and reflect early attention-mediated information processing deficits. Recent studies employing auditory oddball tasks have shown that P300 amplitude deficits in PRS individuals are associated with later clinical outcomes, including both conversion to full-blown psychosis and remission from the at-risk state. The present study examined whether these effects extend to P300 in the visual modality using visual oddball task data collected as part of the North American Prodrome Longitudinal Study. Specifically, we evaluated whether visual P300 amplitudes are reduced in the PRS and predict future clinical outcomes. Methods 540 individuals meeting PRS criteria and 229 healthy individuals completed baseline EEG recording during a visual oddball task. Visual P300 subcomponents were measured in response to two stimulus types: (1) infrequent target stimuli, reflecting top-down allocation of attention (target P3b), and (2) infrequent non-target novel distractor stimuli, reflecting bottom-up orienting of attention (novelty P3a). P300 amplitudes of PRS participants who converted to psychosis (n=70) were compared with those of PRS non-converters who were followed clinically for 24 months and continued to be symptomatic (n=131) or fully remitted from the PRS (n=87). Results Group comparison effects did not differ by stimulus type. Visual P300 amplitudes were not significantly reduced in the PRS group relative to healthy individuals (p=.25). However, baseline target P3b and novelty P3a amplitudes were reduced in PRS individuals who later converted to psychosis relative to all PRS non-converters, including those who remitted (p=.006, d=.44) and those who remained symptomatic (p=.015, d=.37), as well as healthy individuals (p=.001, d=.44). Baseline P300 amplitudes were similar among healthy controls, PRS remitters, and PRS individuals who remained symptomatic (ps>.45). Moreover, visual P300 amplitudes differentiated future psychosis converters after accounting for PRS symptom severity. Finally, both target P3b and novelty P3a amplitudes predicted the time to psychosis onset in PRS participants (p=.03 and p=.02, respectively), such that more deficient P300 amplitudes were associated with shorter time to conversion. Discussion Baseline visual P300 amplitudes were reduced in future PRS converters relative to non-converters, with effect sizes comparable to those reported in previous auditory P300 studies of the PRS. Results implicate visual P300 as a neurophysiological vulnerability marker that predicts clinical outcomes among PRS individuals, including future transition to psychosis. Accordingly, together with prior auditory P300 studies, results suggest that P300 may have the potential to contribute to personalized early intervention in the PRS by distinguishing individuals with the greatest risk for psychotic illness, who require the most aggressive treatment, from those who may need minimal intervention.