Visual Oddball Stimuli Research Articles

Auditory and Visual Oddball Stimulus Processing Deficits in Schizophrenia and the Psychosis Risk Syndrome: Forecasting Psychosis Risk With P300.

Identification of neurophysiological abnormalities associated with schizophrenia that predate and predict psychosis onset may improve clinical prediction in the psychosis risk syndrome (PRS) and help elucidate the pathogenesis of schizophrenia. Amplitude reduction of the P300 event-related potential component reflects attention-mediated processing deficits and is among the most replicated biological findings in schizophrenia, making it a candidate biomarker of psychosis risk. The relative extent to which deficits in P300 amplitudes elicited by auditory and visual oddball stimuli precede psychosis onset during the PRS and predict transition to psychosis, however, remains unclear. Forty-three individuals meeting PRS criteria, 19 schizophrenia patients, and 43 healthy control (HC) participants completed baseline electroencephalography recording during separate auditory and visual oddball tasks. Two subcomponents of P300 were measured: P3b, elicited by infrequent target stimuli, and P3a, elicited by infrequent nontarget novel stimuli. Auditory and visual target P3b and novel P3a amplitudes were reduced in PRS and schizophrenia participants relative to HC participants. In addition, baseline auditory and visual target P3b, but not novel P3a, amplitudes were reduced in 15 PRS participants who later converted to psychosis, relative to 18 PRS non-converters who were followed for at least 22 months. Furthermore, target P3b amplitudes predicted time to psychosis onset among PRS participants. These results suggest that P300 amplitude deficits across auditory and visual modalities emerge early in the schizophrenia illness course and precede onset of full psychosis. Moreover, target P3b may represent an important neurophysiological vulnerability marker of the imminence of risk for psychosis.

Role of the anterior insular cortex in integrative causal signaling during multisensory auditory-visual attention.

Coordinated attention to information from multiple senses is fundamental to our ability to respond to salient environmental events, yet little is known about brain network mechanisms that guide integration of information from multiple senses. Here we investigate dynamic causal mechanisms underlying multisensory auditory-visual attention, focusing on a network of right-hemisphere frontal-cingulate-parietal regions implicated in a wide range of tasks involving attention and cognitive control. Participants performed three 'oddball' attention tasks involving auditory, visual and multisensory auditory-visual stimuli during fMRI scanning. We found that the right anterior insula (rAI) demonstrated the most significant causal influences on all other frontal-cingulate-parietal regions, serving as a major causal control hub during multisensory attention. Crucially, we then tested two competing models of the role of the rAI in multisensory attention: an 'integrated' signaling model in which the rAI generates a common multisensory control signal associated with simultaneous attention to auditory and visual oddball stimuli versus a 'segregated' signaling model in which the rAI generates two segregated and independent signals in each sensory modality. We found strong support for the integrated, rather than the segregated, signaling model. Furthermore, the strength of the integrated control signal from the rAI was most pronounced on the dorsal anterior cingulate and posterior parietal cortices, two key nodes of saliency and central executive networks respectively. These results were preserved with the addition of a superior temporal sulcus region involved in multisensory processing. Our study provides new insights into the dynamic causal mechanisms by which the AI facilitates multisensory attention.

Novelty detection is enhanced when attention is otherwise engaged: an event-related potential study

Novel stimuli are detected and evaluated quickly, suggesting that processing them is a priority for the brain. In the present study, the effects of attention on this early visual novelty processing were investigated in two experiments using the event-related potential (ERP) technique. In the first experiment, participants performed two tasks that varied in the amount of attention available for novel stimuli. In the Visual Oddball task, participants responded to an infrequent target presented among standard and novel stimuli. In the Working Memory task, participants saw the same stimuli, but they could ignore them. Instead, participants had to keep six letters in working memory and report one of these letters at the end of the trial; attention was thus maximally allocated away from the visual oddball stimuli. In line with attention being fully occupied in the Working Memory task, the P3a to the visual oddball stimuli was smaller in the Working Memory than in the Visual Oddball task. In contrast, the anterior N2 component to task-irrelevant stimuli was enhanced in the Working Memory task. These findings suggest that the initial detection of novel stimuli is enhanced (large anterior N2) when few attentional resources are available, which is inconsistent with earlier findings that if anything, the N2 is enhanced by attention. In a second experiment, a condition was added in which working memory load was low, but visual oddball stimuli were task-irrelevant. Results from this experiment showed that while the reduction in P3a amplitude was due to task irrelevance, the enhanced anterior N2 was linked to a high working memory load. This suggests that novelty detection is enhanced when attention is otherwise engaged.

On the time course of synchronization patterns of neuronal discharges in the human brain during cognitive tasks.

Using intracerebral EEG recordings in a large cohort of human subjects, we investigate the time course of neural cross-talk during a simple cognitive task. Our results show that human brain dynamics undergo a characteristic sequence of synchronization patterns across different frequency bands following a visual oddball stimulus. In particular, an initial global reorganization in the delta and theta bands (2–8 Hz) is followed by gamma (20–95 Hz) and then beta band (12–20 Hz) synchrony.

Hyperbaric oxygen treatment improved neurophysiologic performance in brain tumor patients after neurosurgery and radiotherapy

Cognitive performance often is impaired permanently in long-term brain tumor survivors after neurosurgery and radiotherapy. Hyperbaric oxygen treatment (HBOT) stimulates neovascularization of hypoperfused tissue and may result in improved functionality of damaged tissue. In this pilot study, clinical neurophysiologic tests were used to assess the effect of HBOT on brain performance. Ten long-term brain tumor survivors received HBOT for severe cognitive deficits after neurosurgery and radiosurgery. Patients were tested before HBOT and at 6 weeks and 4 months after HBOT. The tests comprised a quantitative electroencephalographic (EEG) examination, the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for memory performance, and 2 cognitive tests, the number connection test (NCT) and the continuous reaction time test (CRTT). Late event-related components (LERCs) of averaged evoked EEG responses to a visual odd-ball stimulus were analyzed from whole-head activity maps. For comparison, a control group of healthy individuals (no HBOT) also were investigated. After HBOT, the amplitude of the LERC with the longest latency, P3b (involved in object interpretation) was improved significantly (P = .02). The amplitudes of the N200 (occipital, negative) and the intermediate P3a (centroparietal, positive), LERCs with shorter latencies, and of a small, positive, occipital visual component did not change. Neither latencies nor reaction times changed after HBOT. However, P3a and P3b (parietal, positive) latencies were longer in survivors than in healthy individuals. The NCT produced inconclusive results, but the IQCODE revealed an improvement. When outcomes of the NCT, CRTT, IQCODE, and P3b amplitudes were evaluated in common tests, HBOT appeared to provide substantial improvement (P<.006). On the basis of the current results, the authors concluded tentatively that HBOT improves neurophysiologic performance in long-term brain tumor survivors.

Auditory and visual P300 reflecting cognitive improvement in patients with schizophrenia with quetiapine: A pilot study

We recorded event-related potentials (ERPs) in patients with schizophrenia before and after treatment with quetiapine, to investigate this drug's effects on cognitive function. Auditory and visual oddball stimulus discrimination paradigms were presented to patients with schizophrenia ( N = 20) before and after 3 months' treatment with quetiapine. The 2-stimulus auditory oddball paradigm used a standard tone (1000 Hz, 75 dB, 80%) and a target tone (2000 Hz, 75 dB, 20%). The 2-stimulus visual oddball paradigm used a standard stimulus (small circle, 80%) and a target stimulus (large circle, 20%). Patients' severity of psychopathology was initially evaluated with the Positive and Negative Syndrome Scale (PANSS) and was likewise re-evaluated after treatment. After treatment with quetiapine, patients' P300 amplitudes increased over baseline for both tasks (auditory stimuli, P < 0.01; visual stimuli, P < 0.01) and their P300 latencies for both target stimuli decreased significantly (auditory stimuli, P < 0.001; visual stimuli, P < 0.01). Visual P300 amplitude was negatively correlated with the severity of positive symptoms at the Fz electrode before the treatment ( r = − 0.45, P < 0.05). After treatment with quetiapine, there were no significant correlations between severity of positive or negative symptoms and visual P300 amplitudes for midline electrodes. These findings suggest that the reduced and delayed P300 may be a state marker for schizophrenia, which may in turn be modulated by positive symptoms, and also suggest that the amplitude and latency for both auditory and visual tasks may be decreased by quetiapine treatment. Based on these results, we suggest that the atypical antipsychotic quetiapine may improve some aspects of cognitive domains in patients with schizophrenia.

Effects of Alcohol on Performance on a Distraction Task During Simulated Driving

Prior studies report that accidents involving intoxicated drivers are more likely to occur during performance of secondary tasks. We studied this phenomenon, using a dual-task paradigm, involving performance of a visual oddball (VO) task while driving in an alcohol challenge paradigm. Previous functional MRI (fMRI) studies of the VO task have shown activation in the anterior cingulate, hippocampus, and prefrontal cortex. Thus, we predicted dose-dependent decreases in activation of these areas during VO performance. Forty healthy social drinkers were administered 3 different doses of alcohol, individually tailored to their gender and weight. Participants performed a VO task while operating a virtual reality driving simulator in a 3T fMRI scanner. Analysis showed a dose-dependent linear decrease in Blood Oxygen Level Dependent activation during task performance, primarily in hippocampus, anterior cingulate, and dorsolateral prefrontal areas, with the least activation occurring during the high dose. Behavioral analysis showed a dose-dependent linear increase in reaction time, with no effects associated with either correct hits or false alarms. In all dose conditions, driving speed decreased significantly after a VO stimulus. However, at the high dose this decrease was significantly less. Passenger-side line crossings significantly increased at the high dose. These results suggest that driving impairment during secondary task performance may be associated with alcohol-related effects on the above brain regions, which are involved with attentional processing/decision-making. Drivers with high blood alcohol concentrations may be less able to orient or detect novel or sudden stimuli during driving.

Event-related potential P2 derived from visual attention to the hemi-space. Source localization with LORETA

This study aimed to measure event-related potential P2 using electroencephalography (EEG), and to locate equivalent current sources related to visual attention in the hemi-space. The amplitude of P2 increases when subjects perceive the stimuli or pay attention to the stimuli. Six volunteer subjects were directed to look at a train of visual oddball stimuli. The oddball stimuli consisted of a square on one side and a circle on the other side of the visual field. Subjects were requested to push a button at the visual cue 800 ms after the target stimuli were displayed. EEG activities were recorded at 64 points over the head. Low-resolution brain electromagnetic tomography (LORETA) was used for the source estimation. Event-related potential P2 was observed at around 200 ms after the onset of the target stimuli. The activity of the parietal and frontal region at P2 changed according to the attention to the hemi-visual field. The activity of the P2 may be located on the parietal lobe, and the frontal lobe (the frontal eye field) may be also activated according to the attention.