High-density Event-related Potentials Study Research Articles

Impaired early information processing in adult ADHD: a high-density ERP study

BackgroundChildren with attention-deficit/hyperactivity disorder (ADHD) often demonstrate sensory processing difficulties in the form of altered sensory modulation, which may contribute to their symptomatology. Our objective was to investigate the neurophysiological correlates of sensory processing deficits and the electrophysiological characteristics of early information processing in adult ADHD, measured by the P1 event-related potential (ERP).MethodsWe obtained ERPs during a Go/NoGo task from 26 adult patients with ADHD and 25 matched controls using a high-density 128-channel BioSemi ActiveTwo recording system.ResultsADHD patients had a significantly reduced P1 component at occipital and inferotemporal scalp areas compared to controls. The reduction was associated with inattention and hyperactivity symptom severity, as measured by the Conners’ Adult ADHD Rating Scale. ADHD patients with higher inattention scores had significantly smaller P1 amplitudes at posterior scalp sites, while higher hyperactivity scores were associated with higher P1 amplitudes.ConclusionsDeficits in early sensory processing, as measured by the P1 ERP component, are present in adult ADHD patients and are associated with symptom severity. These findings are suggestive of bottom-up cognitive deficits in ADHD driven by impairments in early visual processing, and provide evidence that sensory processing problems are present at the neurophysiological level in this population.

Facial identity influences facial expression recognition: A high-density ERP study

The relationship between facial identity and facial expression processing has long been debated. Although previous facial recognition models indicate that facial identity and facial expression processing are independent, psychological studies using the selective attention task (the Garner paradigm) have revealed an asymmetrical relationship between the perception of identity and emotional expressions in faces: while facial expression does not influence facial identity recognition, facial identity influences facial expression recognition. We used the Garner paradigm and recorded high-density event-related potentials (ERPs) to investigate the influence of facial identity on facial expression recognition. Twenty participants judged the expression of faces, while the irrelevant dimension of identity was either held constant (control condition) or varied (orthogonal condition). We recorded 128-channel EEGs while participants completed the facial expression task. We analyzed the two major components of early visual stages: P1 and N170. ERP results revealed a significant main effect of condition on the N170 latency. These results suggest that facial identity influences facial expression recognition in the N170 that reflects the structural encoding of faces. Thus, information on facial expression might be computed based on the unique structure of individual faces.

Stereo viewing modulates three-dimensional shape processing during object recognition: A high-density ERP study.

The role of stereo disparity in the recognition of 3-dimensional (3D) object shape remains an unresolved issue for theoretical models of the human visual system. We examined this issue using high-density (128 channel) recordings of event-related potentials (ERPs). A recognition memory task was used in which observers were trained to recognize a subset of complex, multipart, 3D novel objects under conditions of either (bi-) monocular or stereo viewing. In a subsequent test phase they discriminated previously trained targets from untrained distractor objects that shared either local parts, 3D spatial configuration, or neither dimension, across both previously seen and novel viewpoints. The behavioral data showed a stereo advantage for target recognition at untrained viewpoints. ERPs showed early differential amplitude modulations to shape similarity defined by local part structure and global 3D spatial configuration. This occurred initially during an N1 component around 145–190 ms poststimulus onset, and then subsequently during an N2/P3 component around 260–385 ms poststimulus onset. For mono viewing, amplitude modulation during the N1 was greatest between targets and distracters with different local parts for trained views only. For stereo viewing, amplitude modulation during the N2/P3 was greatest between targets and distracters with different global 3D spatial configurations and generalized across trained and untrained views. The results show that image classification is modulated by stereo information about the local part, and global 3D spatial configuration of object shape. The findings challenge current theoretical models that do not attribute functional significance to stereo input during the computation of 3D object shape.

'Time-shrinking perception' in the visual system: a psychophysical and high-density ERP study.

'Time-shrinking perception (TSP)' is a unique perceptual phenomenon in which the duration of two successive intervals (T1 and T2) marked by three auditory stimuli is perceived as equal even when they are physically different. This phenomenon provides a link between time and working memory; however, previous studies have mainly been performed on the auditory modality but not the visual modality. To clarify the neural mechanism of visual TSP, we performed a psychophysical experiment and recorded event-related potentials (ERPs) under different T1/T2 combinations. Three successive black/white sinusoidal gratings (30ms duration) were presented to the participants. In the psychophysical experiment, either T1 or T2 was varied from 240 to 560ms in 40-ms steps, while T2 or T1 was fixed at 400ms. Participants judged whether T1 and T2 were equal or not by pressing a button. ERPs were recorded from 128 scalp electrodes, while T1 was varied from 240, 320, and 400ms with the 400ms T2 duration, and vice versa. Behavioral data showed asymmetrical assimilation: When -80ms≤(T1-T2)≤+120ms, TSP was observed in the T1-varied condition. When -120ms≤(T1-T2)≤+80ms, it was also observed in the T2-varied condition. These asymmetric time ranges in vision were different from those in the auditory modality. ERP data showed that contingent negative variation (CNV) appeared in the fronto-central region at around 300-500ms during T2 presentation in the T1<T2 condition. In the /240/400/ pattern, the CNV amplitude was decreased at around 350ms. In contrast, P3 appeared at the parietal region about 450-650ms after T2 in the T1>T2 condition. In the /400/240/ pattern, P3 amplitude was greater than those of other temporal patterns. These neural responses corresponded to participants' perception that T1 and T2 were not equal. The neural responses in the fronto-central region were involved with endogenous temporal attention for discrimination. Moreover, neural responses in the parietal region were engaged in exogenous temporal attention. Therefore, fronto-parietal neural responses underlie temporal perception in vision.

Disturbances in Response Inhibition and Emotional Processing as Potential Pathways to Violence in Schizophrenia: A High-Density Event-Related Potential Study.

Increased susceptibility to emotional triggers and poor response inhibition are important in the etiology of violence in schizophrenia. Our goal was to evaluate abnormalities in neurophysiological mechanisms underlying response inhibition and emotional processing in violent patients with schizophrenia (VS) and 3 different comparison groups: nonviolent patients (NV), healthy controls (HC) and nonpsychotic violent subjects (NPV). We recorded high-density Event-Related Potentials (ERPs) and behavioral responses during an Emotional Go/NoGo Task in 35 VS, 24 NV, 28 HC and 31 NPV subjects. We also evaluated psychiatric symptoms and impulsivity. The neural and behavioral deficits in violent patients were most pronounced when they were presented with negative emotional stimuli: They responded more quickly than NV when they made commission errors (ie, failure of inhibition), and evidenced N2 increases and P3 decreases. In contrast, NVs showed little change in reaction time or ERP amplitude with emotional stimuli. These N2 and P3 amplitude changes in VSs showed a strong association with greater impulsivity. Besides these group specific changes, VSs shared deficits with NV, mostly N2 reduction, and with violent nonpsychotic subjects, particularly P3 reduction. Negative affective triggers have a strong impact on violent patients with schizophrenia which may have both behavioral and neural manifestations. The resulting activation could interfere with response inhibition. The affective disruption of response inhibition, identified in this study, may index an important pathway to violence in schizophrenia and suggest new modes of treatment.

Blunted Neural Responses to Reward in Remitted Major Depression: A High-Density Event-Related Potential Study

BackgroundMajor depressive disorder (MDD) is a highly recurrent condition, and improving our understanding of the abnormalities that persist in remitted MDD (rMDD) may provide insight into mechanisms that contribute to relapse. Reward learning deficits linked to dysfunction in frontostriatal regions are characteristic of MDD. Although initial behavioral evidence of reward learning deficits in rMDD has emerged, it is unclear whether these deficits reflect impairments in neural reward processing that persist into remission. MethodsWe examined behavioral reward learning and 128-channel event-related potentials (ERPs) during a well-validated probabilistic reward task in 26 individuals with rMDD and 34 control subjects with no history of depression. Temporospatial principal components analysis was used to separate overlapping ERP components, and group differences in neural activity in a priori regions were examined using low-resolution electromagnetic tomography. ResultsIndividuals with rMDD displayed reduced behavioral reward learning and blunted ERP amplitude to reward feedback. The reduction in ERP amplitude occurred at a principal components analysis factor that peaked during the time at which phasic reward feedback-related signaling—hypothesized to originate in the striatum and project to the anterior cingulate cortex—is thought to modulate scalp-recorded activity. Consistent with this finding, low-resolution electromagnetic tomography analyses revealed reduced activity in the anterior cingulate cortex in the rMDD group, and this blunting correlated with poorer reward learning. ConclusionsThese findings suggest that the reward learning impairment observed in acute MDD persists into full remission and that these impairments may be attributable to abnormalities in the neural processes that support reward feedback monitoring, particularly within the anterior cingulate cortex.

Self-referential processing in depressed adolescents: A high-density event-related potential study.

Despite the alarming increase in the prevalence of depression during adolescence, particularly among female adolescents, the pathophysiology of depression in adolescents remains largely unknown. Event-related potentials (ERPs) provide an ideal approach to investigate cognitive-affective processes associated with depression in adolescents, especially in the context of negative self-referential processing biases. In this study, healthy (n = 30) and depressed (n = 22) female adolescents completed a self-referential encoding task while ERP data were recorded. To examine cognitive-affective processes associated with self-referential processing, P1, P2, and late positive potential (LPP) responses to negative and positive words were investigated, and intracortical sources of scalp effects were probed using low-resolution electromagnetic tomography (LORETA). Additionally, we tested whether key cognitive processes (e.g., maladaptive self-view, self-criticism) previously implicated in depression related to ERP components. Relative to healthy female subjects, depressed females endorsed more negative and fewer positive words, and free recalled and recognized fewer positive words. With respect to ERPs, compared with healthy female adolescents, depressed adolescents exhibited greater P1 amplitudes following negative words, which was associated with a more maladaptive self-view and self-criticism. In both early and late LPP responses, depressed females showed greater activity following negative versus positive words, whereas healthy females demonstrated the opposite pattern. For both P1 and LPP, LORETA revealed reduced inferior frontal gyrus activity in response to negative words in depressed versus healthy female adolescents. Collectively, these findings suggest that the P1 and LPP reflect biased self-referential processing in female adolescents with depression. Potential treatment implications are discussed. (PsycINFO Database Record

Inhibitory control and visuo-spatial reversibility in Piaget's seminal number conservation task: a high-density ERP study

The present high-density event-related potential (ERP) study on 13 adults aimed to determine whether number conservation relies on the ability to inhibit the overlearned length-equals-number strategy and then imagine the shortening of the row that was lengthened. Participants performed the number-conservation task and, after the EEG session, the mental imagery task. In the number-conservation task, first two rows with the same number of tokens and the same length were presented on a computer screen (COV condition) and then, the tokens in one of the two rows were spread apart (INT condition). Participants were instructed to determine whether the two rows had an identical number of tokens. In the mental imagery task, two rows with different lengths but the same number of tokens were presented and participants were instructed to imagine the tokens in the longer row aligning with the tokens in the shorter row. In the number-conservation task, we found that the amplitudes of the centro-parietal N2 and fronto-central P3 were higher in the INT than in the COV conditions. In addition, the differences in response times between the two conditions were correlated with the differences in the amplitudes of the fronto-central P3. In light of previous results reported on the number-conservation task in adults, the present results suggest that inhibition might be necessary to succeed the number-conservation task in adults even when the transformation of the length of one of the row is displayed. Finally, we also reported correlations between the speed at which participants could imagine the shortening of one of the row in the mental imagery task, the speed at which participants could determine that the two rows had the same number of tokens after the tokens in one of the row were spread apart and the latency of the late positive parietal component in the number-conservation task. Therefore, performing the number-conservation task might involve mental transformation processes in adults.

Differential roles of spatial frequency on reading processes for ideograms and phonograms: A high-density ERP study

The neural substrate of the dissociation between reading Japanese ideograms (Kanji) and phonograms (Kana) is currently unclear. To test whether spatial frequency (SF) information is responsible for this phenomenon, we recorded high-density event-related potentials (ERPs) with unfiltered or spatially filtered word stimuli in Japanese-speaking subjects. Kanji (early-learned, late-learned), Kana (word, non-word), and scrambled characters served as stimuli. Fourier analysis revealed that Kanji and Kana were characterized by high-SF (HSF) and low-SF (LSF) information, respectively. In ERPs with unfiltered stimuli, bilateral occipital P100, left occipitotemporal N170 and fronto-central N400 were elicited. Scrambled characters did not evoke left-lateralized N170 or clear N400. Under the LSF condition, P100 and N170 latencies for Kanji were significantly longer than those for Kana. In the HSF condition, P100 and N170 latencies for late-learned Kanji were significantly longer than those for early-learned Kanji. There was no significant difference in the N400 between Kanji and Kana in both SF conditions. These results suggest that early visual responses, but not the semantic component, are influenced by SF. This indicates a close link between Kana and LSF information, and between Kanji and HSF information. The differential effects of SF could underlie the neural basis of the differences between Kanji and Kana reading.

A high-density ERP study reveals latency, amplitude, and topographical differences in multiple sclerosis patients versus controls

To quantify latency, amplitude and topographical differences in event-related potential (ERP) components between multiple sclerosis (MS) patients and controls and to compare ERP findings with results from the paced auditory serial addition test (PASAT). Fifty-four subjects (17 relapsing remitting (RRMS) patients, 16 secondary progressive (SPMS) patients, and 21 controls) completed visual and auditory oddball tasks while data were recorded from 134 EEG channels. Latency and amplitude differences, calculated using composite mean amplitude measures, were tested using an ANOVA. Topographical differences were tested using statistical parametric mapping (SPM). In the visual modality, P2, P3 amplitudes and N2 latency were significantly different across groups. In the auditory modality, P2, N2, and P3 latencies and N1 amplitude were significantly different across groups. There were no significant differences between RRMS and SPMS patients on any ERP component. There were topographical differences between MS patients and controls for both early and late components for the visual modality, but only in the early components for the auditory modality. PASAT score correlated significantly with auditory P3 latency for MS patients. There were significant ERP differences between MS patients and controls. The present study indicated that both early sensory and later cognitive ERP components are impaired in MS patients relative to controls.

Propranolol selectively blocks the enhanced parietal old/new effect during long-term recollection of unpleasant pictures: A high density ERP study

Evidence from both animal and human research suggests that the formation of emotional memories is triggered by the beta-adrenergic system. To confirm whether modulation of central beta-adrenergic transmission is specifically involved in the neural signature of memory performance, the pre-encoding effect of propranolol (80 mg) on event-related potentials (ERPs) was measured in a placebo-controlled, double-blind, parallel-group study in 46 male healthy subjects using high density EEG and source imaging analysis during encoding and retrieval (after 1 week) of IAPS pictures of unpleasant, neutral and pleasant contents; for recognition 90 old pictures were randomly mixed with 90 new pictures. During retrieval correctly remembered old pictures elicited a significantly larger positive voltage change over the centro-parietal cortex than new pictures. Propranolol significantly reduced this old/new difference of the mean ERP amplitudes (500–800 ms) for unpleasant but not for neutral and pleasant memories. This effect correlated with salivary alpha-amylase activity, a surrogate for central adrenergic stimulation. In conclusion, propranolol selectively blocked the neural signature of unpleasant memories by mechanisms in which the parietal cortex seems to be specifically involved.

Sensory and motor attentional modulation during the manual gap effect in humans: a high-density ERP study.

The present study investigated reaction time (RT) and event-related potential (ERP) differences between gap and step conditions using visual stimulation and manual responses. RTs during the gap condition were facilitated with respect to those of the step condition. The ERPs, which were obtained from electrodes placed at 58 scalp sites, showed differences when the gap and step conditions were compared for the following components: an early positive component centred at the vertex, an enhanced P1 component, a frontal negativity, a negative lateralized motor potential, and an increased P3. All these results suggest that the facilitation induced by the gap is mediated by a modulation of the neural circuits involved in sensory, motor, and cognitive functions.