P3b Component Research Articles

Electrophysiological correlates of category induction: PSW amplitude as an index of identifying shared attributes

Event-related potentials (ERPs) were recorded from 15 healthy adults while they performed a category induction task. Two geometric figures characterized by three dimensions (color, shape, and stripe orientation) were presented simultaneously to subjects who were asked to identify their shared attributes. Pairs of figures sharing common attributes composed the category induction condition and pairs of identical figures composed the non-induction condition. It was hypothesized that non-induction only involves abstracting shared attributes from one stimulus, but category induction involves identifying shared attributes by comparing the two stimuli. The ERP waves elicited by induction and non-induction did not differ on N1, P2 and P3b components, but larger frontal N2 and smaller central-parietal PSW components were elicited by category induction. These results suggest that the processing of category induction is reflected in the PSW 400–650ms post-stimulus.

Familial Risk for Depression and P3b Component as a Possible Neurocognitive Vulnerability Marker

Objective: Complex genetic mechanisms are involved in the vulnerability to depressive disorders and cognitive dysfunctions found in depression. This study was performed to explore the effect of the familial risk for depression on electrophysiological correlates of attentional functions as demonstrated by an event-related potential (ERP) go/no-go experiment. Methods: The component P3b as an indicator of target detection processing was investigated in two groups of healthy subjects with or without a family history of depression (n = 14 each). An electrophysiological source localization method (LORETA) was employed to allow a neuro-anatomical interpretation for the ERP data. Results: The group with a familial risk for depression showed a reduced P3b amplitude over left temporal areas in contrast to the control group. This two-dimensional effect was associated with a significantly reduced activation of the left middle temporal gyrus. Conclusions: The P3b amplitude decrement might represent a neurocognitive vulnerability marker for the development of depression.

Behavioural and neurophysiological correlates of bivalent and univalent responses during task switching

A hallmark of human behaviour is its flexibility. In any given circumstance there is typically a range of possible responses that could be selected. In the current study participants were presented with stimulus displays that afforded two simple cognitive tasks and were required to switch predictably between them. The judgements for each task were either uniquely mapped onto separate effectors (univalent conditions) or else mapped onto shared effectors (bivalent condition). The results demonstrated that whilst behavioural switch costs were similar across the mapping conditions, these conditions differed in the patterns of brain activity observed during task preparation and early visual processing of the target. Specifically, a cue-locked switch-related late frontal negativity was present over frontal sensors for the bivalent condition only, and a target-locked N1 over occipital sensors was larger in the bivalent condition than the univalent conditions. In contrast, a switch-related target-locked P3b component was common to all mapping conditions. These findings are discussed with respect to differences in processing demands for switching between tasks with bivalent versus univalent responses.

Changes in a late positive component of evoked potentials in the GO/NOGO test after cryocingulotomy

The influence of cingulotomy on the components of brain evoked potentials detected by a modified GO/NOGO paradigm was investigated. Patients with a diagnosis of heroin dependence (13 subjects) participated in the study. For medical indications, patients were treated with stereotaxic anterior cryocingulotomy in order to reduce the compulsive need that makes the drug dependence intractable. A two-stimulus modification of the GO/NOGO paradigm developed in our laboratory was used in this study. Cingulotomy did not change significantly the early (in the 100-to 200-ms range) components evoked by visual or auditory stimuli. The positive component evoked by the GO stimuli also did not change. This component corresponds to the P3b component observed in the ODD BALL paradigm. The only component that changed after the anterior cingulotomy was a late component generated by the NOGO stimuli in the 400-ms range, which was distributed in the medial frontocentral area. Thus, we have obtained a direct confirmation of the relationship between this component and the activity of the anterior cingulate gyrus. Analysis of the individual evoked potentials allows us to conclude that the suggested modification of the GO/NOGO test and methods for correcting artifacts in the statistical analysis of differences may be regarded as a reliable approach to the assessment of the functional activity of the anterior cingulate gyrus in humans.

Intelligence and P3 components of the event-related potential elicited during an auditory discrimination task with masking

The relationship between fluid intelligence (indexed by scores on Raven Progressive Matrices) and auditory discrimination ability was examined by recording event-related potentials from 48 women during the performance of an auditory oddball task with backward masking. High ability (HA) subjects exhibited shorter response times, greater response accuracy, larger P3b amplitude and shorter P3b latency to target stimuli than the lower ability (LA) subjects. There were no differences between high and low ability groups for the P3a component of the ERP. Correlation and multiple regression analyses indicated that frontal P3b latency and, to a smaller extent, P3b amplitude are the best predictors of mental ability. These results are consistent with previous studies reporting a relation between intelligence and ERPs and provide further evidence that individual differences in mental ability are reflected in the P3b component, an electrocortical index of the efficiency of stimulus evaluation processes.

Normative Variation of P3a and P3b from a Large Sample

Abstract. The P3a and P3b components were elicited in 120 (60 females, 60 males) young adults using a visual three-stimulus event-related brain potential (ERP) oddball paradigm in which subjects responded to an infrequent target. The major purpose of the paper was to provide a statistically strong characterization of these related P300 subcomponents. P3a components were obtained from the infrequently presented distracter stimulus, which was a large blue square. P3b components were obtained from the target stimulus, which was a blue circle that differed slightly in diameter from the standard stimulus blue circle. Amplitude measures demonstrated that P3a was maximum at Cz, and P3b was maximum at Pz; latency measures increased for both potentials from frontal to parietal recording sites. P3a and P3b from females were larger and later than those from male subjects, with topographic and appreciable individual difference variability observed. P3a was generally unrelated to response time. P3b amplitude was negatively correlated over right frontal areas with P3b latency and positively correlated over right parietal areas to response time. Theoretical implications are discussed.

Heterogeneity in the Patterns of Neural Abnormality in Autistic Spectrum Disorders: Evidence from ERP and MRI

Autistic spectrum disorder (ASD) refers to a heterogeneous group of social communication problems. Research into the neural basis of ASD has revealed abnormalities in a number of different regions of the brain. However, the literature is highly inconsistent. One possible explanation for these discrepancies is differences in intelligence. Children with ASD and below average intelligence may be hypothesised to show additional or different neural abnormalities. This possibility was explored using structural magnetic resonance imaging (MRI) and event-related potentials (ERP). Two groups of children with ASD were studied, those with average or above average intelligence (high ASD group) and those with below average intelligence (low ASD group). The structural MRI data were analysed using voxel-based morphometry (VBM). Using the family-wise error threshold, results showed bilateral abnormality common to the two ASD groups in the cerebellum, fusiform gyrus and frontal cortex. In addition, a number of regions were found to be significantly different in the two ASD groups: regions of the cerebellum showed increased grey matter density bilaterally in the high ASD group, but decreased grey matter density bilaterally in the low ASD group. Further, compared to the high ASD group, additional bilateral abnormalities were found in the postcentral gyrus and regions of the dorsolateral prefrontal cortex in the low ASD group. Using the less stringent false discovery rate (FDR) threshold, differences were also seen in the medial temporal lobes. ERPs also showed differences between the two ASD groups. Whereas the ERPs of the high ASD group were not significantly different from those of the controls, the low ASD group had delayed novelty P3a responses and reduced amplitude target P3b components. These data provide convergent ERP and MRI evidence for the heterogeneity of neural abnormality in ASD in relation to variations in intelligence.

Generators of the gamma-band activities in response to rare and novel stimuli during the auditory oddball paradigm

In this study, we report the cortical sources of the gamma-band activity emitted during the auditory oddball paradigm using the adaptive beamformer algorithm and non-parametric permutation test and then compare them with those of the P3a and P3b components. The results of the gamma-band current sources revealed that the same gamma-band activities are in process during the rare target and novelty task. In the low (30–55 Hz) gamma-band activity, the common sources were localized in the (inferior) anterior cingulate and adjacent inferior frontal cortex. In the high (65–85 Hz) gamma-band activity, the generator was represented in the superior frontal cortex. On the other hand, the P3a and P3b generators showed widespread distributions including the well-known fronto-parietal network [J. Polich, Theoretical overview of P3a and P3b, in: J. Polish (Ed.), Detection of Change: Event-Related Potential and fMRI Findings, Kluwer Academic Press, Boston, 2003, pp. 83–98]. In conclusion, the same frontal generators of gamma-band activities in the present study may be associated with the functions of attentional control for the binding of consecutive cognitive stages corresponding to earlier P3a and later P3b components, which have distinct source distributions except for some overlaps.

Visual P300s in long-term abstinent chronic alcoholics.

Evidence of reduced P3b amplitudes in chronic alcoholics and individuals at risk for developing alcoholism suggest that the P3b may be an endophenotypic marker for alcoholism. If this is the case, then long-term abstinent alcoholics (LTAAs) should exhibit reduced P3b amplitudes. Thus far, P3b studies on chronic alcoholics have focused primarily on samples with relatively short-term abstinence (less than 15 months). This study examines the amplitude and latency of the P3b and P3a event-related brain electrical components in LTAAs compared with normal controls (NCs) and whether these measures are related to alcohol use and other subject variables. Electroencephalographs (EEGs) were recorded on 48 LTAAs (mean abstinence=6.7 years) compared with 48 age-matched and gender-matched NCs during a visual P300 experiment consisting of standard, target, and rare nontarget conditions. This paradigm elicited the P3b (target condition) and the P3a (rare nontarget condition) components. Long-term abstinent alcoholics had reduced P3b amplitudes and increased P3b latencies in comparison with NCs. Long-term abstinent alcoholics also exhibited delayed P3a components, but no P3a amplitude reductions. Alcohol use variables, a family history of alcohol problems, and the duration of alcohol abstinence were not associated with any amplitude or latency variables. Even after very prolonged abstinence, reduced P3b amplitudes are present in chronic alcoholics and are not associated with any family history or alcohol use variables. These results provide equivocal support for reduced P3b amplitude being an endophenotypic marker for alcoholism, but are also consistent with P3b being affected by a threshold of alcohol abuse, with the effect not resolving over long periods of abstinence.

Voluntary stimulus production enhances deviance processing in the brain

Humans often get information by voluntary action. However, little is known about how stimulus processing is modulated by self-production of stimuli. In the present study, event-related brain potentials were recorded from 16 student volunteers performing an auditory three-stimulus oddball task in two conditions. In the self condition, the stimuli were triggered by participants' voluntary button presses. In the auto condition, the same stimuli were presented automatically by a computer with the same interstimulus intervals as those in the self condition. Perceptually deviant nontarget stimuli elicited a larger P3 and a larger subsequent positivity in the self condition than in the auto condition, whereas low-deviant target stimuli elicited a P3 with equally high amplitude in both conditions. The findings suggest that voluntary stimulus production enhances orienting of attention (reflected in the P3a component) and subsequent memory updating (reflected in the P3b component) for deviant stimuli, but does not affect the response to task-relevant stimuli. Voluntary action may activate the perceptual representation of its most frequent outcomes and this anticipatory activation may make deviant stimuli more salient in the context.

Arousal and valence effects on event-related P3a and P3b during emotional categorization

Due to the adaptive value of emotional situations, categorizing along the valence dimension may be supported by critical brain functions. The present study examined emotion–cognition relationships by focusing on the influence of an emotional categorization task on the cognitive processing induced by an oddball-like paradigm. Event-related potentials (ERPs) were recorded from subjects explicitly asked to categorize along the valence dimension (unpleasant, neutral or pleasant) deviant target pictures embedded in a train of standard stimuli. Late positivities evoked in response to the target pictures were decomposed into a P3a and a P3b and topographical differences were observed according to the valence content of the stimuli. P3a showed enhanced amplitudes at posterior sites in response to unpleasant pictures as compared to both neutral and pleasant pictures. This effect is interpreted as a negativity bias related to attentional processing. The P3b component was sensitive to the arousal value of the stimulation, with higher amplitudes at several posterior sites for both types of emotional pictures. Moreover, unpleasant pictures evoked smaller amplitudes than pleasant ones at fronto-central sites. Thus, the context updating process may be differentially modulated by the affective arousal and valence of the stimulus. The present study supports the assumption that, during an emotional categorization, the emotional content of the stimulus may modulate the reorientation of attention and the subsequent updating process in a specific way.

P300 after head injury: Pseudodelay caused by reduced P3A amplitude

Objective We compared conventional P300 analysis with source analysis in normal subjects and head-injury patients. Based on earlier findings of improved P300 component identification and reduced P3B latency variability with source analysis in normal subjects, our aim was to investigate whether source analysis could improve the distinction between these groups. Methods In total, 21 healthy control subjects and 21 patients with mild to moderate head injury were included in this study. A standard auditory 2-tone oddball paradigm was used. Latencies and amplitudes obtained with conventional P300 analysis were compared with source analysis results. Results With conventional analysis, head-injury patients had delayed P300 latencies and reduced P300 amplitudes in comparison to controls, while source analysis showed no latency differences for both P3A and P3B components. Instead, source analysis indicated absence of P3A components in 43% of patients. Conclusions The P300 delay in head-injury patients, observed with conventional analysis, is a pseudodelay caused by decreased P3A amplitudes. Consequently, the unaffected P3B component with its later latency determines conventional P300 latency in these patients. Significance Conventional P300 latency cannot be used to conclude that there was delayed early stimulus processing in head-injury patients.

Hemispheric lateralization patterns and psychotic experiences in healthy subjects

The hypothesis that psychotic experiences in healthy subjects are associated with a dysfunction of the right hemisphere is supported by some, but not all, available studies. Differences in gender composition of study samples may explain in part the divergent findings. The present study was carried out in 42 healthy, right-handed university students. Scores on the Schizophrenia and Paranoia scales of the Minnesota Multidimensional Personality Inventory-2 were used in correlation analyses and to define a High- and a Low-Psychotic group. Brain Electrical Microstates and Low Resolution Electromagnetic Tomography (LORETA) source analyses of the auditory P300 (P3a and P3b) components of the event-related potential, as well as a battery of neuropsychological tests, were used to assess hemispheric functioning. Scores on the Paranoia scale were positively associated with a leftward shift of the P3a topographic descriptors in females but not in males. When comparing High-Psychotic and Low-Psychotic females, a leftward shift of P3a descriptors and an increased cortical activation in left fronto-temporal areas were observed in the High-Psychotic group. Our results demonstrated gender-related differences in the pattern of hemispheric imbalance associated with psychotic experiences in healthy subjects.

Evoked brain potentials in adolescents in normal conditions and in attention deficit during solution of tasks requiring recognition of short-duration acoustic stimuli

This study compares the effectiveness of the frequency-based recognition of short acoustic stimuli in groups of adolescents with attention deficit and normal measures of attention in conditions of the standard "oddball" paradigm. Stimuli of duration 50 msec yielded insignificant intergroup differences, though adolescents with attention deficit discriminated signal of duration 11 msec significantly worse. These showed significant differences in evoked brain potentials even with standard stimuli, with a significantly greater amplitude for N2b waves and a decreased P3b component. Evoked potentials obtained in response to the deviant stimulus were characterized by a P3b wave of reduced amplitude in the group with attention deficit. These data provide evidence that adolescents with attention deficit show defined abnormalities in the processing of acoustic sensory information at the cortical level.

EEG-correlated fMRI of P3b component in P300 waves

Electroencephalography-correlated functional magnetic resonance imaging (EEG/fMRI) can be used to identify blood oxygen level-dependent (BOLD) signal changes associated with both physiological and pathological EEG events. Here, we implemented continuous and simultaneous EEG/fMRI to identify BOLD signal changes related to P3b component of P300, and 64 channels of EEG were recorded in 11 subjects during Landot Ring task inside a 1.5 T functional magnet resonance (MR) scanner using an MR-compatible EEG recording system. Functional scanning by echoplanar imaging covered almost the entire cerebrum every 2 s, leaving gaps of 2 s without scanning. Off-line MRI artifact subtraction software was applied to obtain continuous EEG data. Additionally, a P300 wave matched filter was constructed to inspect P300 wave occurrence following every target stimulus, target stimuli inspected to induce P300 were detected and their MRI scan number were then used as input for an event-related fMRI analysis. Finally MRI statistical parametric maps were constructed and corrected for multiple comparisons. By random effect group analysis, activations were detected in the right superior parietal lobule and bilaterally in inferior parietal lobule(p<0.001, uncorrected). The results demonstrated the upper regions were sources of P3b component and involved in target detection in memory comparison task.

Using automated morphometry to detect associations between ERP latency and structural brain MRI in normal adults

Despite the clinical significance of event-related potential (ERP) latency abnormalities, little attention has focused on the anatomic substrate of latency variability. Volume conduction models do not identify the anatomy responsible for delayed neural transmission between neural sources. To explore the anatomic substrate of ERP latency variability in normal adults using automated measures derived from magnetic resonance imaging (MRI), ERPs were recorded in the visual three-stimulus oddball task in 59 healthy participants. Latencies of the P3a and P3b components were measured at the vertex. Measures of local anatomic size in the brain were estimated from structural MRI, using tissue segmentation and deformation morphometry. A general linear model was fitted relating latency to measures of local anatomic size, covarying for intracranial vault volume. Longer P3b latencies were related to contractions in thalamus extending superiorly into the corpus callosum, white matter (WM) anterior to the central sulcus on the left and right, left temporal WM, the right anterior limb of the internal capsule extending into the lenticular nucleus, and larger cerebrospinal fluid volumes. There was no evidence for a relationship between gray matter (GM) volumes and P3b latency. Longer P3a latencies were related to contractions in left temporal WM, and left parietal GM and WM near the interhemispheric fissure. P3b latency variability is related chiefly to WM, thalamus, and lenticular nucleus, whereas P3a latency variability is not related as strongly to anatomy. These results imply that the WM connectivity between generators influences P3b latency more than the generators themselves do.

P.7.028 Effect of caffeine on the reversed continuous performance test (R-CPT) in high impulsive individuals

Objective: The continuous performance test (CPT) is successfully applied to evaluate attentional performance in attention-deficit hyperactivity disorder (ADHD)-children. The aim of the present study was to investigate the changes of the topographic P300-features in relation to methylphenidate-medication and to different attentional processes in primer- and distractor-conditions.Methods: Twenty-one-channel-ERPs of 17 ADHD-boys were analyzed with reference-independent methods. Four quasi stable microstates within the time frames of conventional P100, P200, P3a and P3b components were identified by means of a data-driven segmentation procedure.Results: In segment 3 topographical assessment yielded a significant occipital and right-shift of the positive centroid, longer centroid distance and higher amplitudes in primer- than in distractor conditions. MPH increased the amplitude and distance in primer and distractor-condition, without changing the topography. In segment 4 the electric fieldstrength of distractor-conditions collapsed, whereas the primer condition showed a strong fronto-parietallly oriented potential-field. There was a tendency to higher amplitudes due to MPH-medication.Conclusions: These results indicate a robust neurophysiologic differentiation of cognitive processes. MPH activates an early (P3a) covert attention process indicated by increased amplitudes and centroid. No effects were seen in later processes. Based on these effects, we propose to use the amplitude- and distance-increase in microstate 3 as an indicator of MPH efficacy in ADHD-boys.

The perception of fearful and happy facial expression is modulated by anxiety: an event-related potential study

Anxiety is supposed to interfere with cognitive and emotional processing and high level of trait-anxiety has been associated with an attentional bias for fearful faces, even in sub-clinical anxiety. On the basis of the Spielberger State and Trait Anxiety Inventory (STAI), twenty students were grouped as low vs. high anxious. Pictures from the Ekman and Friesen series were used in an event-related potentials study to investigate the neurophysiological correlates of the emotional processing of fear and happiness in sub-clinical anxiety. Subjects were confronted with a visual oddball design, in which they had to detect, as quickly as possible, deviant happy or fearful faces amongst a train of standard stimuli (neutral faces). Anxiety does not modify early perceptual (N100, P100, N170, VPP) or attentional (N2b) component, but later components are affected. Indeed, high anxious subjects are faster to detect deviant faces as suggested by earlier reaction times and P3b component. However, they show a reduced ability to process the emotional content of faces, this deficit being indexed by a decreased N300 component. Indeed, N300 is supposed to be particularly sensitive to affective features of stimuli rather than to physical characteristics. We propose that the earlier P3b observed in high anxious subjects could be interpreted as a way to overcome the deficient emotional appraisal by a more salient conscious processing.

Electrophysiological study of contextual variations in a short-term face recognition task

Event-related potentials (ERPs) were recorded during two short-term recognition tasks using unfamiliar faces. These experiments are based on the process dissociation procedure (PDP), whereby the exclusion criterion was an intrinsic context or extrinsic context, the facial expression (Experiment 1) or background (Experiment 2), respectively. The results indicate that retrieval orientation, in addition to extensive strategic control, affects both the frontal (N250) and temporoparietal (P3b) components. Furthermore, these data indicate that an early frontal modulation interacts between processing that bears on the face (interactive intrinsic context) and processing that bears on two objects at the same time (interactive extrinsic context), in which, in the latter case, that the background change led to an early modulation at the frontal sites in the left hemisphere. These results are consistent with the idea that frontal effects reflect differences in the nature of the information during retrieval and postretrieval processes involved. Furthermore, that the left posterior repetition effect appears to be a manifestation of the retrieval of relevant contextual information that perturbs the recognition decision, whereas the right posterior repetition effect reflects to be the outcome of the retrieval of the face as a whole. Finally, results are in concordance with the hypothesis that the difference during recognition with or without source memory may be in the strength of the relationship between the target and the contextual information to be retrieved. In essence, that automatic and controlled processes in a given context depends on both task-related and target-related constraints.

N400 and category exemplar associative strength

The main purpose of this study was to examine if the N400 amplitude can be considered an index of category exemplar strength of association in a semantic categorization task. Series of six words from a particular semantic category were used as context, and the strength of association between the seventh word and the category was manipulated. Moreover, subjects were asked to perform two different tasks: one consisting of reading the words for comprehension and the other of making a decision regarding the congruence of the ending word. Results showed that the N400 component was elicited by whichever word that was not the best exemplar for the category (atypical members and nonmember of the category). No interaction between type of ending word and type of task was found around 400 ms poststimuli although the P3b component was present for infrequent stimuli in the decision task. It is concluded that the N400 amplitude is sensitive to category membership although no specific attention to the semantic relationship between words was required.