Event-related potentials during auditory oddball, and combined auditory oddball-visual paradigms

The purpose of the current study was to investigate the properties of a new modification of the classical auditory oddball paradigm (auditory oddball paradigm combined with passive visual stimulation, AERPs + VEPs) and compare the scalp topography obtained with the new paradigm and the classical auditory oddball paradigm (AERPs) in healthy humans. The responses to bimodal stimulation, and to the classical oddball paradigm were similar to those reported in other studies in terms of location, amplitudes, and latencies of P1, N1, P2, N2, and P300. The new modification of the oddball paradigm produced P300 at fronto-central locations in contrast to centro-parietal locations during the classical oddball paradigm. The amplitudes and latencies of P300 were also significantly larger during the new than the classical paradigm. Furthermore, the amplitudes of N1 and P2, but not N2 were significantly higher and differed in location during the new paradigm in response to both target and standard stimuli. The latencies of all three waves were significantly longer and the latency of P2 differed in location between the new and the classical paradigms in response to only the standard stimuli. The results of this study suggest that the new modification of the classical oddball paradigm produces different neural responses to the classical oddball paradigm. Therefore, this modification can be used to investigate dysfunctions in sensory and cognitive processing in clinical samples.     

Mapping of event-related potentials to auditory and visual odd-ball paradigms in controls

The paper reports the results of recordings and maps of event-related potentials (ERPs) obtained in normal subjects. ERPs were recorded from 19 scalp electrode derivations using both visual and acoustic paradigms. In normal subjects, topographical distribution of all ERP components is described in detail. Our findings in normals suggest that the early modulation of stimulus-related potentials could be located in primary associative areas, and that N2, P3a, P3b, and SW have different distributions.     

Effects of caffeine on event-related potentials: Comparison of oddball with single-tone paradigms

We investigated the acute effects of caffeine (500 mg) on event-related potentials (ERP) in 10 healthy subjects using standard oddball and single-tone paradigms. Event-related potentials were recorded before oral ingestion of caffeine or placebo and 30 min and 210 min after. The oddball paradigm, but not the single-tone paradigm, showed that the P300 amplitude and the area were significantly increased 30 min after ingestion of caffeine and significantly decreased 30 min after ingestion of placebo. The effects of caffeine disappeared at 210 min. Neither the P300 latency nor the reaction time changed significantly with the oddball paradigm. However, the reaction time was shortened 30 min after ingestion of caffeine with the single-tone paradigm. These findings suggest that the caffeine-induced increase in the P300 amplitude may have resulted from the increased allocation of attentional resources to the discriminating process which was not, however, accompanied by facilitation of the process and that caffeine may specifically stimulate the discriminating process involved in the oddball paradigm. In addition, the simple psychomotor performance of button-pressing in response to a tone signal was accelerated by caffeine.     

Cortical and subcortical visual event-related potentials to oddball stimuli in rabbits

Event-related potentials (ERPs) to changes in the visual environment were recorded in rabbits. In the oddball condition, infrequently presented (deviant) stimuli occurred in a series of frequently presented (standard) stimuli. In the deviant-alone condition, standards were omitted. ERPs to oddball-deviants differed from those to standards in all recording sites (cerebellar cortex, visual cortex, dentate gyrus). No corresponding differences were found between ERPs to deviants in the oddball condition and those in the deviant-alone condition. However, because ERPs to deviants in the deviant-alone condition and those to standards did not differ either, ERPs to stimulus changes in the oddball condition seemed to be dependent on the presence of standards, thus representing an analogue to mismatch negativity (MMN) in humans.     

Potentials evoked in human and monkey medial temporal lobe during auditory and visual oddball paradigms.

Event-related potentials (ERPs) were recorded from epileptic patients with electrodes chronically implanted in the medial temporal lobe (MTL) and other intracranial locations, and from monkeys with epidural, transcortical, and MTL electrodes. For both humans and monkeys, the eliciting events consisted of trains of auditory or visual stimuli in which a random 10-20% deviated in pitch or pattern from the remaining stimuli. The distribution of ERPs elicited by the rare (oddball) stimuli in both species was similar, consisting of a P3 recorded from the scalp or cortical surface and a slightly later, but temporally overlapping, focal negativity in the hippocampus and nearby MTL structures. The similarity between the patterns of ERPs in humans and monkeys establishes the feasibility of studying the electrogenesis of P3-like activity with detailed intracranial recordings in an animal model. The data also establish that the MTL ERPs in human patients represent a normal neurophysiological process unrelated to epilepsy.     

Mapping of event-related potentials to auditory and visual odd-ball paradigms in patients affected by different forms of dementia

The paper reports the results of recordings and maps of event-related potentials (ERPs) in patients with Alzheimer's disease (AD), progressive supranuclear palsy (PSP) and in subjects affected by dementia in multiple sclerosis (MS). ERPs were recorded from 19 scalp electrode derivations using both visual and acoustic paradigms. In 43% of AD patients, ERPs were normal; in 20%, although present, ERP components were delayed, while in the other 37% none of the N2 and P3 peaks could be recorded, because of abnormal topography of potentials on the scalp. In patients with PSP, the normal ERP sequence was not identified. In patients with MS delayed ERPs (50%), abnormal topography of ERPs (30%) and absence of ERPs (20%) were observed. The follow-up of AD patients showed a progressive alteration of ERPs. ERP topography alterations were observed in AD, PSP and MS patients with poorest cognitive performances.     

An event-related functional magnetic resonance imaging study of an auditory oddball task in schizophrenia

Schizophrenia is a diffuse brain disease that affects many facets of cognitive function. One of the most replicated findings in the neurobiology of schizophrenia is that the event-related potentials to auditory oddball stimuli are abnormal, effects believed to be related to abnormalities in attentional and memory processes. Although event-related potentials provide excellent resolution regarding the time course of information processing, such studies are poor at characterizing the spatial location of these abnormalities. To address this issue, we used event-related functional magnetic resonance imaging techniques to elucidate the neural areas underlying target detection in schizophrenia. Consistent with recent event-related functional magnetic resonance imaging results, target processing by control participants was associated with bilateral activation in the anterior superior temporal gyri, inferior and superior parietal lobules, and activation in anterior and posterior cingulate, thalamus, and right lateral frontal cortex. For the schizophrenic patients, selective deficits were observed in both the extent and strength of activation associated with target processing in the right lateral frontal cortex, thalamus, bilateral anterior superior temporal gyrus, anterior and posterior cingulate, and right inferior and superior parietal lobules. These findings are consistent with the evidence for abnormal processing of oddball stimuli suggested by event-related potential studies in schizophrenic patients, but provide much more detailed evidence regarding the anatomical sites implicated. These data are consistent with the hypothesis that schizophrenia is characterized by a widespread pathological process affecting many cerebral areas, including association cortex and thalamus.     

Event-related potentials elicited by distractors in an auditory oddball paradigm in schizophrenia

Patients with schizophrenia are affected more adversely than healthy controls by distracting conditions, due to their inability to adequately apportion attentional resources to targets or distractors. We attempted to re-evaluate the effects of distractors in 25 patients with chronic schizophrenia and in 12 controls. They performed an auditory target-detection task with 1500 Hz tone distractors and an additional control condition where a 1500-Hz tone was used as the target. The rate of target misses for patients with schizophrenia was 3.79% in non-distractor conditions and 14.79% in distractor conditions. Significantly reduced N100 responses to distractors and distractor condition targets were found. P300 responses to all target stimulus categories were reduced, but P300 responses to distractors were equal to those in the control group. There was a reduction of P300 amplitudes to distractors in both groups; however, only the control group showed significant enlargement of P300 amplitude when the distractors became the target stimuli. There is evidence that patients with schizophrenia tend to be less able to allocate their attentional resources adequately to target vs. distractor stimuli. When the distractors became the target stimuli, their responses remained unchanged, which suggests their inability to appropriately integrate stimulus information with contextual information.     

首发精神分裂症及其父母听觉ERP的研究

目的 印证首发精神分裂症及其父母是否存在认知功能障碍,并探讨事件相关电位是精神分裂症的遗传素质标志还是状态性标志.方法 从2010年1～12月期间在徐州市东方人民医院住院的患者中选取符合CCMD-3精神分裂症诊断标准的首发患者60例,作为患者组;选取精神分裂症患者生物学意义上的父母,共120例作为亲属组;选取无精神疾病家族史的健康志愿者作为对照组,共60例.分别对三组进行ERP检测.所得数据应用SPSS 13.0统计软件包处理分析,采用的主要统计学方法包括卡方检验、单因素方差分析和协方差分析.结果 (1)患者组、亲属组和对照组间N2、P3潜伏期和P3波幅差异均有统计学意义(均为P＜0.01);(2)患者组的N2潜伏期长于对照组(P＜0.05),亲属组和对照组的各潜伏期相比差异无统计学意义(均为P＞0.05);患者组和亲属组的P3波幅均明显低于对照组(均为P＜0.05),而患者组和亲属组P3波幅差异无统计学意义(P＞0.05).结论 (1)首发精神分裂症及其父母可能存在一定程度的认知功能障碍;(2)P3波幅倾向于精神分裂症的遗传素质性标志,N2潜伏期倾向于精神分裂症的状态性标志.     

Changes in event-related potentials in a three-stimulus auditory oddball task after mild head injury

Previous research has demonstrated changes in event-related potentials in a variety of cognitive tasks after severe closed head injury. We sought to establish if similar changes were present in patients who had sustained only apparently mild head injury (MHI) by recording event-related potentials in a group of 24 mild head injured and 24 control participants during a three-stimulus auditory target detection task. For this ‘oddball’ task participants were required to press a button every time they heard a rare target tone and to ignore rare novel sounds and frequent non-target tones. Neuropsychological test results indicated that the mild head injured group had mild memory and attention impairments. Analysis of behavioural performance on the three-stimulus ‘oddball’ task showed no difference in reaction times or error rates between the two groups. Target condition N2 deflections appeared to be larger in the mild head injured but peak amplitude measures revealed that this effect was not significant. There were no significant differences in the amplitude or latency of the P3b evoked by target stimuli or the P3a evoked by novel stimuli. However, a putative ‘O-wave’ or ‘reorienting negativity’ following the P3a was more negative in the mild head injured group suggesting increased activation of components of the attention network. These findings lend support to the hypothesis that MHI can cause subtle cognitive impairments that are associated with abnormal allocation of attention resources in the context of normal behavioural performance.     

Effect of vagal nerve stimulation on auditory and visual event-related potentials

Chronic unilateral vagal nerve stimulation (VNS) has been recently introduced into the therapy for intractable epileptic seizures. Its effect on cognitive functions in VNS-treated patients remains controversial. The aim of the present study was to evaluate the possible impact of therapeutic VNS on cognitive functions by means of event-related potentials analysis. Ten patients with medically intractable epilepsy, who had been implanted with VNS devices, participated in the study. Auditory and visual event-related potentials (ERPs) were repeatedly recorded, first just before the implantation of VNS devices, and then again 3-6 months after the device activation. The effect of lower intensity stimulation on the P3 component of ERPs was assessed. No significant differences were found in auditory ERPs; the latencies of P3 as well as N2/P3 peak-to-peak amplitudes were virtually identical. The same was true for mean P3 latencies of visual ERPs. However, higher visual N2/P3 peak-to-peak amplitudes were observed in the responses to targets that followed VNS, with a significant finding at the electrodes investigated. When comparing the effect of VNS on visual N2/P3 amplitude in each electrode separately, the most expressive differences were found in the frontal region. This observation supports the theory of a possible positive effect of low-intensity VNS on the cognitive functions.     

Abnormal hemodynamics in schizophrenia during an auditory oddball task.

BACKGROUND: Schizophrenia is a heterogeneous disorder characterized by diffuse brain abnormalities that affect many facets of cognitive function. One replicated finding in schizophrenia is abnormalities in the neural systems associated with processing salient stimuli in the context of oddball tasks. This deficit in the processing of salience stimuli might be related to abnormalities in orienting, attention, and memory processes. METHODS: Behavioral responses and functional magnetic resonance imaging data were collected while 18 patients with schizophrenia and 18 matched healthy control subjects performed a three-stimulus auditory oddball task. RESULTS: Target detection by healthy participants was associated with significant activation in all 38 regions of interest embracing distributed cortical and subcortical systems. Similar reproducibility was observed in healthy participants for processing novel stimuli. Schizophrenia patients, relative to control subjects, showed diffuse cortical and subcortical hypofunctioning during target detection and novelty processing, including bilateral frontal, temporal, and parietal cortices and amygdala, thalamus, and cerebellum. CONCLUSIONS: These data replicate and extend imaging studies of target detection in schizophrenia and present new insights regarding novelty processing in the disorder. The results are consistent with the hypothesis that schizophrenia is characterized by a widespread pathologic process affecting many cerebral areas, including cortical, subcortical, and cerebellar circuits.     

Single-trial analysis of oddball event-related potentials in simultaneous EEG-fMRI

There has recently been a growing interest in the use of simultaneous electroencephalography (EEG) and functional MRI (fMRI) for evoked activity in cognitive paradigms, thereby obtaining functional datasets with both high spatial and temporal resolution. The simultaneous recording permits obtaining event-related potentials (ERPs) and MR images in the same environment, conditions of stimulation, and subject state; it also enables tracing the joint fluctuations of EEG and fMRI signals. The goal of this study was to investigate the possibility of tracking the trial-to-trial changes in event-related EEG activity, and of using this information as a parameter in fMRI analysis. We used an auditory oddball paradigm and obtained single-trial amplitude and latency features from the EEG acquired during fMRI scanning. The single-trial P300 latency presented significant correlation with parameters external to the EEG (target-to-target interval and reaction time). Moreover, we obtained significant fMRI activations for the modulation by P300 amplitude and latency, both at the single-subject and at the group level. Our results indicate that, in line with other studies, the EEG can bring a new dimension to the field of fMRI analysis by providing fine temporal information on the fluctuations in brain activity.     

Interhemispheric asymmetry of event-related fields concerned with logical processing during auditory oddball stimulation.

This study investigated the cortex during logical processing of auditory information using a 122-channel dc-SQUID gradiometer. The experimental task was designed to require a simple logical decision prior to counting rare paired tones, which consisted of two different pitches and were presented to separate ears. Among six subjects, left and right predominant dipolar activity was observed in three subjects each. When the dipolar sources were superimposed on MR images, the inferior region of the supramarginal gyrus showed activation, suggesting that logical processing occurred in the association cortex but not in the auditory cortex. We propose a modified cognitive sequence model in which auditory information processed in Heschl's gyri is transmitted to the supramarginal gyrus to commence automatic detection processing.     

The intracranial topography of the P3 event-related potential elicited during auditory oddball.

In order to isolate the anatomical locus of neural activity primarily responsible for generating the scalp-recorded P3 (or P300), the topography of event-related potentials (ERPs) elicited during an auditory oddball task was compared between medial-to-lateral aspects of the frontal, parietal, and temporal lobes in 10 epileptic patients undergoing stereoelectroencephalography for seizure localization. Evidence of local ERP generation was obtained from each of these areas. Small amplitude P3-type potentials were sometimes observed to invert polarity across recording contacts in the frontal lobe. Large amplitude positive polarity P3-type components were observed in the lateral neocortex of the inferior parietal lobule (IPL), that rapidly attenuated in amplitude at more anterior, posterior, superior, inferior, and medial recording contacts. Large amplitude polarity inverting P3-type components were also observed to be highly localized to hippocampal contacts of temporal lobe electrodes. These data are discussed in the context of other recent studies of lesion effects, scalp topography, and intracranial recordings, and it is concluded that activity generated in the IPL is likely to make the major contribution to the scalp-recorded P3, with smaller contributions from these other sources. Finally, salient topographical differences between the intracranial distribution of the P3 and those of the N2 (or N200) and slow wave (SW) suggest that the generators of these components are not identical.     

Identical event-related potentials to target and frequent stimuli of visual oddball task recorded by intracerebral electrodes.

OBJECTIVE: The shape of visually elicited event-related potentials (ERP) of epileptic patients during their presurgical evaluation with intracerebral electrodes was investigated in the study. METHODS: Twenty intractable epileptic patients with depth electrodes at several intracranial locations in the frontal, temporal, parietal lobes, and in the amygdalo-hippocampal complex participated in the study. To evoke the ERP, a standard visual oddball task was used with target stimuli, and frequent non-habituated and habituated stimuli. The averaged responses of the 3 groups were superimposed and visually analyzed whether the shape appeared identical or non-identical. RESULTS: The EEG response to target and frequent stimuli was recorded in 660 intra-cerebral sites. In 88 sites (14 different patients) localized in the amygdala, parahippocampal gyrus, superior, middle, and inferior temporal gyri, fusiform and lingual gyri, sensorimotor cortex, prefrontal cortex, hippocampus, and cingulated gyrus, the identical ERPs to target and both groups of frequent stimuli were observed. In 442 sites located in the above listed structures, and in the basal ganglia and parietal cortex, the shape of the ERP differed from 0.3 to 0.47 s on after the stimulus. The remaining 130 sites did not yield the task-specific potential change. CONCLUSIONS: The existence of identical ERPs to target and frequent stimuli in the oddball task suggests that a part of mental operations underlying the brain engagement in this task is not dependent on the way of responding.     

Temporal instability of auditory and visual event-related potentials in posttraumatic stress disorder.

BACKGROUND: We examined P300 measures in patients with posttraumatic stress disorder (PTSD) and control subjects at two different time points to determine event-related potential (ERP) stability over time and the relationship of changes in ERPs to changes in symptom levels. METHODS: Auditory and visual P300 was recorded in a three-condition novelty oddball task in 25 male subjects with combat-related PTSD and 15 male combat-exposed normal control subjects at two time points separated by 6-12 months. Regression analyses were conducted to compare the temporal stability of ERP measures in PTSD and control subjects. Variability in ERP measures over time within PTSD subjects was examined for association with changes in symptom levels. RESULTS: There were no significant differences in P300 amplitude or latency in PTSD versus control subjects at either time point, regardless of stimulus type (target, novel) or modality (auditory, visual). Nine of 24 P300 measures were significantly less predictable over time in the PTSD group compared to control subjects. Variability of P300 measures over time was not associated with fluctuations in symptoms of depression or PTSD. CONCLUSIONS: P300 ERPs are more variable cross-sectionally and over time in PTSD subjects compared to trauma exposed control subjects. Measures of variability about the group mean appear to be more informative about the cognitive electrophysiology of PTSD than measures of central tendency.     

The recovery functions of auditory event-related potentials during split-second discriminations

We examined the recovery cycles of auditory event-related potentials (ERPs) in a high-speed auditory discrimination task and in passive conditions. Each trial contained 3 tones cued by a warning flash. In passive conditions, auditory ERPs consisted mainly of N1 (108 msec) and P2 (213 msec) components superimposed on a small CNV. The N1 and P2 were comparable in amplitude and both had prolonged refractory periods. In discriminative reaction time (DRT) conditions the same tones cued or inhibited press responses and elicited additional endogenous components (principally the Nd and P3). ERPs in DRT conditions were superimposed upon a prominent CNV that began after the warning cue and lasted throughout the signal delivery period. The N1 was larger in active than passive conditions and showed less marked refractory effects, while the P2 was smaller and showed more marked refractoriness. Differences between active and passive conditions could be explained by the presence of an endogenous negative potential (the Nd) with a short refractory period that was superimposed upon the N1 and P2. The P3 was recorded only in active conditions. At short ISIs (0.5 sec), P3 amplitudes were reduced and P3 latencies lengthened in parallel with prolongations in reaction time due to so-called psychological refractory period (PRP) effects. Both P3 recovery and the PRP reflected central mechanisms since they were observed at short ISIs when stimuli cueing different responses succeeded one another. N1 and P3 amplitudes diminished over the course of the experiment in both active and passive conditions. The decrease (amounting to about 30% of initial amplitudes) did not appear due to reductions in vigilance, since it was not accompanied by changes in reaction time or response accuracy, or by changes in other endogenous components (CNV or Nd). Short-term N1 habituation was unaffected by long-term amplitude reductions suggesting that independent mechanisms were responsible for the two phenomena.     

Assessment of visual working memory using event-related potentials.

OBJECTIVE: This study sought to determine if recognition/familiarity memory can be measured using event-related potentials (ERP) in response to a computer-adapted version of a commonly used non-verbal memory assessment instrument. If successful, resulting ERP would further our knowledge of the neurophysiology of recognition memory and could be used in a cognitive assessment battery for individuals whose capacity for verbal and/or non-verbal communication is impaired. METHODS: Behavioral and ERP responses were recorded during performance on a computer-adapted version of the Continuous Visual Memory Test (CVMT) [Trahan DE, Larrabee GJ. Continuous Visual Memory Test. Lutz, FL: Psychological Assessment Resources; 1988] and examined offline for recognition memory old/new effects. Behavioral performance was also compared with performance on an alternate form of the test under standard administration procedures. RESULTS: ERP to old (repeated) visual designs in the CVMT were more positive-going than those to new designs and reflected by both early frontal and late parietal old/new effects as commonly reported in the recognition memory literature. The behavioral results from the computer-adapted and standard administration versions of the CVMT showed a significant correlation. CONCLUSIONS: The computer-adapted ERP version of the CVMT provides a way to directly assess, using neurophysiological responses, the cognitive processes associated with recognition memory as measured by the CVMT. SIGNIFICANCE: The results from this study contribute to linking the functional and neurophysiological profile of memory produced by experimental neuroimaging research with traditional clinical neuropsychological assessment.     

Topography of visual event-related potentials during geometric and phonetic discriminations

Event-related potentials (ERPs) were obtained to letters during 3 tasks that involved a SIMPLE RESPONSE (SR) to each letter presentation, a FORM discrimination of the letters that formed a closed loop, and a RHYME discrimination of the letters that rhymed with the letter 'v'. The first task only required detection of the letters, the FORM task required a visual-spatial analysis, and the RHYME task, a grapheme-phoneme conversion of the letters followed by a determination of rhyming characteristics. The SR ERPs were morphologically different from the discriminative ERPs, notably by the absence of N2 and P3. The difference wave forms between the discrimination and SR conditions and between the targets and non-targets indicated differential topographies of components associated with the FORM and RHYME tasks in the 300 msec latency region. In both of these tasks, components exhibited distributions localized primarily in the occipital regions, whereas in the RHYME task they extended more anteriorly and encompassed temporo-parietal regions. Thus, although the stimulus presentation was visual, the requirement of a visual-auditory conversion in the RHYME task resulted in activity that was more proximal to auditory regions than when only a FORM analysis of the letters was required.