Decreased spatial frequency sensitivities for processing faces in male patients with chronic schizophrenia

ObjectiveSchizophrenia impairs early visual cognitive processing. Low and high spatial frequency (LSF, HSF) visual information are differentially processed in humans. We investigated whether electrophysiological abnormalities exist in visual processing for spatial frequency (SF)-filtered neutral/emotional faces in schizophrenics.MethodsSubjects consisted of 16 male chronic schizophrenics and 23 controls. Event-related potentials (ERPs) to SF-filtered (LSF or HSF) and unfiltered (broad SF; BSF) pictures of neutral, happy, and fearful faces were recorded at 20 scalp sites. The relationships between the P100 (P1)/N170 amplitudes and the Global Assessment of Functioning (GAF) scores in patients were also evaluated.ResultsFor the P1 amplitudes at O1/O2, controls exhibited a significant LSF > BSF difference, while schizophrenics showed no LSF > BSF difference. For the N170 amplitudes at T5/T6, controls revealed a significant HSF > BSF difference, while schizophrenics showed no such difference. For the P1 latencies, controls but not schizophrenics showed a significant difference (LSF > BSF = HSF). For the N170 latencies, no significant SF differentiation was found between the two groups. For both P1 and N170 amplitudes, no significant effects of facial expressions were observed in controls and patients regardless of SFs. There were significant negative correlations between the GAF scores and the N170 amplitudes to BSF faces in schizophrenics, but not for P1 amplitudes.ConclusionsSchizophrenics showed abnormal P1 and N170 responses to SF changes in faces, thus indicating decreased SF sensitivities for processing of faces.SignificanceAbnormal early visual processing may underlie some of the deficits associated with face recognition in schizophrenia.     

Positive and negative affective processing exhibit dissociable functional hubs during the viewing of affective pictures

Recent resting‐state functional magnetic resonance imaging (fMRI) studies using graph theory metrics have revealed that the functional network of the human brain possesses small‐world characteristics and comprises several functional hub regions. However, it is unclear how the affective functional network is organized in the brain during the processing of affective information. In this study, the fMRI data were collected from 25 healthy college students as they viewed a total of 81 positive, neutral, and negative pictures. The results indicated that affective functional networks exhibit weaker small‐worldness properties with higher local efficiency, implying that local connections increase during viewing affective pictures. Moreover, positive and negative emotional processing exhibit dissociable functional hubs, emerging mainly in task‐positive regions. These functional hubs, which are the centers of information processing, have nodal betweenness centrality values that are at least 1.5 times larger than the average betweenness centrality of the network. Positive affect scores correlated with the betweenness values of the right orbital frontal cortex (OFC) and the right putamen in the positive emotional network; negative affect scores correlated with the betweenness values of the left OFC and the left amygdala in the negative emotional network. The local efficiencies in the left superior and inferior parietal lobe correlated with subsequent arousal ratings of positive and negative pictures, respectively. These observations provide important evidence for the organizational principles of the human brain functional connectome during the processing of affective information. Hum Brain Mapp, 36:415–426, 2015. © 2014 Wiley Periodicals, Inc.     

How time modulates spatial responses

Behavioural evidence suggests a left-to-right directionality in the representation of elapsing time. We tested whether this representation produces a spatial attentional shift that activates a corresponding left-to-right spatial response code. Fourteen participants judged whether a cross lasted for a short (1 sec) or a long (2 sec) duration with left and right responses, respectively, or vice versa, while event-related potentials (ERPs) were measured. Responses were faster when participants judged short and long durations with their left and right hand, respectively, than vice versa. In these compatible conditions only (short-left; long-right), ERP negativity developed over the right motor scalp region around the short duration, a finding that is compatible with an early pre-activation of left-hand responses, and over the left motor region around the long duration, suggesting a later pre-activation of right hand responses. These findings confirm that in this task elapsing time is represented from left to right, and that this representation generates corresponding response codes that influence performance.     

Electrocortical correlates of control of selective attention to spatial frequency

In the present study, we investigated control of selective attention to spatial frequency patterns, using a cueing paradigm. Subjects either used the instruction embedded in a word cue to prepare for the upcoming test stimulus (transient attention condition) or used the instruction they received before a block of trials (sustained reference condition), under completely similar stimulus conditions. The pattern of differential cue responses between these two conditions, reflecting top-down attentional control processes, was different between two groups of subjects, effectively canceling each other out. Despite comparable behavioral performance on both cues and targets, one group (n = 4) elicited a fronto-central-parietal positivity, starting 500 ms postcue over frontal and prefrontal areas, later including more central and posterior scalp sites, whereas another group (n = 8) started 400 ms postcue over central sites with a negativity, growing in strength over time and stabilizing over fronto-central sites. Only the group of eight subjects showed some evidence of occipital pretarget biasing activity. Independent of group, source modeling of the attentional control activity showed that attentional control was initiated in anterior, not posterior, parts of the brain. Furthermore, different underlying sources were found for both groups, in addition to signs of differential processing of target stimuli. Possible individual differences in attentional control ability and its relation to usage of different brain areas to deal with the task demands are discussed in more detail.     

Arousal modulates valence effects on both early and late stages of affective picture processing in a passive viewing task

Valence and arousal are primary dimensions of affective stimuli. An interaction of these two factors on affective processing is largely unknown. In this study, the processing of affective pictures was investigated in an orthogonal valence (positive vs. negative) by arousal (high vs. low) task design. Participants were instructed to passively view each presented picture and did not need to make any responses. The valence by arousal interaction was observed on three event-related potential (ERP) components, including the P2 (160–190 ms), N2 (220–320 ms) and late positive potential (LPP) (400–700 ms). This interaction revealed that negative pictures evoked larger neural responses compared with positive pictures (i.e., negative bias) at the high-arousal level, whereas negative pictures evoked smaller neural responses than positive pictures (i.e., positive offset) at the low-arousal level. The current results suggest that the effect of emotional valence on affective picture perception is modulated by levels of arousal at both early and late stages of processing. Finally, the main effect of valence was evident in the P1 component (90–110 ms) and arousal effect in the N1 component (120–150 ms).     

Perceptual load affects spatial and nonspatial visual selection processes: an event-related brain potential study

One major question toward understanding selective attention regards the efficiency of selection. One theory contends that this efficiency in vision is determined primarily by the perceptual load (PL) imposed by the relevant stimuli; if this load is high enough to fill attentional capacity, irrelevant stimuli will be excluded before they interfere with task performance, but if this load is lower the spare capacity will be directed automatically to the irrelevant information, which will then interfere with task performance. The current study attempts to test and extend this theory in order to understand better the role of PL by examining its effects on event-related brain potentials (ERPs), voltage fluctuations recorded at the scalp that reflect underlying cognitive operations. Stimuli were presented one at a time, and subjects were instructed to respond to rare deviant stimuli that appeared within a relevant stimulus channel and to ignore stimuli in an irrelevant channel, where channel was defined by either spatial (left, right) or nonspatial (red, blue) attributes in separate tasks. PL was manipulated by varying the similarity between the target/deviant and standard stimulus, and increases in PL were found to increase the magnitude of the relevant-irrelevant difference waveforms in both tasks at predicted temporal windows. These findings suggest that PL affects attentional selection that is tonically maintained across many experimental trials, and does so not only when selection is spatially based but also when it is based upon nonspatial cues.     

Neural dynamics of inflectional and derivational morphology processing in the human brain

We investigated neural distinctions between inflectional and derivational morphology and their interaction with lexical frequency using the mismatch negativity (MMN), an established neurophysiological index of experience-dependent linguistic memory traces and automatic syntactic processing. We presented our electroencephalography (EEG) study participants with derived and inflected words of variable lexical frequencies against their monomorphemic base forms in a passive oddball paradigm, along with acoustically matched pseudowords. Sensor space and distributed source modelling results showed that at 100–150 msec after the suffix onset, derived words elicited larger responses than inflected words. Furthermore, real derived words showed advantage over pseudo-derivations and frequent derivations elicited larger activation than less frequent ones. This pattern of results is fully in line with previous research that explained lexical MMN enhancement by an activation of strongly connected word-specific long-term memory circuits, and thus suggests stronger lexicalisation for frequently used complex words. At the same time, a strikingly different pattern was found for inflectional forms: higher response amplitude for pseudo-inflections than for real inflected words, with no clear frequency effects. This is fully in line with previous MMN results on combinatorial processing of (morpho)syntactic stimuli: higher response to ungrammatical morpheme strings than grammatical ones, which does not depend on the string's surface frequency. This pattern suggests that, for inflectional forms, combinatorial processing route dominates over whole-form storage and access. In sum, our results suggest that derivations are more likely to form unitary representations than inflections which are likely to be processed combinatorially, and imply at least partially distinct brain mechanisms for the processing and representation of these two types of morphology. These dynamic mechanisms, underpinned by perisylvian networks, are activated rapidly, at 100–150 msec after the information arrives at the input, and in a largely automatic fashion, possibly providing neural basis for the first-pass morphological processing of spoken words.     

Initial evidence for sex-specific effects of early emotional abuse on affective processing in bipolar disorder

PurposeThis study investigates the effect of sex and childhood trauma on affective processing in bipolar disorder (BPD) patients.MethodsIn a sample of fifty-six BPD patients, we administered the Childhood Trauma Questionnaire (CTQ), and the Iowa Gambling Task (IGT) and the Affective Go/No-Go (AGNG) to measure affective processing. Analysis of Variance (ANOVA) was used to evaluate the effect of sex and childhood trauma on IGT; Repeated-Measures ANOVAs to measure accuracy and bias measures across conditions on the AGNG.ResultsIn the context of childhood abuse, females evidenced a more conservative cognitive style than males by selecting fewer cards from the disadvantageous decks [F(1, 49) = 14.218; P < 0.001] and showed an improvement throughout the task, as noted in a normal learning curve [F(1.49) = 4.385; P = 0.041)]. For the AGNG, an interaction specific to the negative valence stimuli on response bias measures was found. Abused females scored higher (mean = 8.38; SD = 6.39) than abused males (mean = 0.69; SD = 1.19) [F(1.46) = 6.348; P = 0.015].ConclusionSeverity of childhood trauma was significantly different between sexes. In the context of a history of emotional abuse, male bipolar patients tended toward a more risk-taking behavior compared to female. Further investigations are needed to elucidate potential pathophysiological mechanisms underlying this interaction.     

The effect of spatial frequency on chromatic and achromatic steady-state visual evoked potentials.

OBJECTIVE: Little is known about the physiological properties of the major components of steady-state visual evoked potentials (VEPs). Based on the hypothesis that isoluminant color and high contrast pattern differentially activate the parvo- and magnocellular pathways, we studied difference in spatial frequency function between chromatic and achromatic VEPs to sinusoidal gratings. METHODS: Steady-state VEPs to isoluminant chromatic (red-green) and high contrast (90%) achromatic (black-white) sinusoidal gratings with nine spatial frequencies (0.5 to 8.0 cycles/degrees (cpd)) at 4 Hz (8 reversals/s) were recorded in 13 normal subjects. VEPs were Fourier analyzed to obtain phase and amplitude of the second (2F) and fourth (4F) harmonic responses. RESULTS: The 2F amplitude of chromatic VEPs decreased above 4.0 cpd in a low-pass function while that of achromatic VEPs showed a band-pass function with a peak at 4.0 cpd. The 4F amplitude of chromatic VEPs was not affected significantly by spatial frequency whereas that of achromatic VEPs exhibited a high-pass function. The phases of 2F and 4F showed a non-monotonic function of spatial frequency in both chromatic and achromatic stimuli with peaks at middle spatial frequencies. CONCLUSION: Chromatic and achromatic visual stimuli differently affected 2F and 4F components, which thus suggests that 2F and 4F components are generated from different neuronal subgroups largely in the parvocellular pathway.     

Electrophysiological correlates of spatial orienting towards angry faces: a source localization study

The goal of this study was to examine behavioral and electrophysiological correlates of involuntary orienting toward rapidly presented angry faces in non-anxious, healthy adults using a dot-probe task in conjunction with high-density event-related potentials and a distributed source localization technique. Consistent with previous studies, participants showed hypervigilance toward angry faces, as indexed by facilitated response time for validly cued probes following angry faces and an enhanced P1 component. An opposite pattern was found for happy faces suggesting that attention was directed toward the relatively more threatening stimuli within the visual field (neutral faces). Source localization of the P1 effect for angry faces indicated increased activity within the anterior cingulate cortex, possibly reflecting conflict experienced during invalidly cued trials. No modulation of the early C1 component was found for affect or spatial attention. Furthermore, the face-sensitive N170 was not modulated by emotional expression. Results suggest that the earliest modulation of spatial attention by face stimuli is manifested in the P1 component, and provide insights about mechanisms underlying attentional orienting toward cues of threat and social disapproval.     

Newborn brain event-related potentials revealing atypical processing of sound frequency and the subsequent association with later literacy skills in children with familial dyslexia

The role played by an auditory-processing deficit in dyslexia has been debated for several decades. In a longitudinal study using brain event-related potentials (ERPs) we investigated 1) whether dyslexic children with familial risk background would show atypical pitch processing from birth and 2) how these newborn ERPs later relate to these same children’s pre-reading cognitive skills and literacy outcomes. Auditory ERPs were measured at birth for tones varying in pitch and presented in an oddball paradigm (1100 Hz, 12%, and 1000 Hz, 88%). The brain responses of the typically reading control group children (TRC group, N = 25) showed clear differentiation between the frequencies, while those of the group of reading disability with familial risk (RDFR, 8 children) and the group of typical readers with familial risk (TRFR, 14 children) did not differentiate between the tones. The ERPs of the latter two groups differed from those of the TRC group. However, the two risk groups also showed a differential hemispheric ERP pattern. Furthermore, newborn ERPs reflecting passive change detection were associated with phonological skills and letter knowledge prior to school age and with phoneme duration perception, reading speed (RS) and spelling accuracy in the 2nd grade of school. The early obligatory response was associated with more general pre-school language skills, as well as with RS and reading accuracy (RA). Results suggest that a proportion of dyslexic readers with familial risk background are affected by atypical auditory processing. This is already present at birth and also relates to pre-reading phonological processing and speech perception. These early differences in auditory processing could later affect phonological representations and reading development. However, atypical auditory processing is unlikely to suffice as a sole explanation for dyslexia but rather as one risk factor, dependent on the genetic profile of the child.     

Native-like brain processing of syntax can be attained by university foreign language learners

Using event-related potentials (ERPs), we examined the neurocognition of late-learned second language (L2) Spanish in two groups of typical university foreign-language learners (as compared to native (L1) speakers): one group with only one year of college classroom experience, and low-intermediate proficiency (L2 Low), and another group with over three years of college classroom experience as well as 1–2 semesters of immersion experience abroad, and advanced proficiency (L2 Advanced). Semantic violations elicited N400s in all three groups, whereas syntactic word-order violations elicited LAN/P600 responses in the L1 and L2 Advanced groups, but not the L2 Low group. Indeed, the LAN and P600 responses were statistically indistinguishable between the L1 and L2 Advanced groups. The results support and extend previous findings. Consistent with previous research, the results suggest that L2 semantic processing always depends on L1-like neurocognitive mechanisms, whereas L2 syntactic processing initially differs from L1, but can shift to native-like processes with sufficient proficiency or exposure, and perhaps with immersion experience in particular. The findings further demonstrate that substantial native-like brain processing of syntax can be achieved even by typical university foreign-language learners.     

Behavioral and brain oscillatory correlates of affective processing in subclinical depression

Named among the most dangerous diseases of the modern era, depression is characterized primarily by distortions in the affective sphere. Despite extensive investigations of underlying the neural background, mechanisms of the distortion still remain unknown. The current study analyzed brain oscillatory dynamics in different frequencies during resting state and presentation of affective stimuli in nonclinical individuals with high Beck Depression Inventory–II (BDI–II) scores (HB) versus controls. Both behavioral and electrocortical “markers” of clinical depression were apparent at subclinical level. A resting-state electroencephalogram (EEG) of HB revealed increased power in low frequencies, predominantly in the frontal cortical areas, that is in accordance with a “spatio-temporal dysfunction” model of depression. Related to that, transition from an eyes-closed to eyes-open condition was associated with diminished alpha blockade in HB, suggesting difficulties with the relocation of attention focus from inner processes toward environmental stimuli. Subsequently, independently of a sign of emotion, five out of six discrete emotions were evaluated as less valenced and four out of six as less intense by HB than by controls, corroborating the view of emotion context insensitivity (ECI) associated with depression. Underlying brain oscillatory dynamics revealed that depression was associated with deficits in the early, implicit, processing stages of emotional stimuli. Later processing stages were characterized by prominent power surges in low and alpha frequencies, presumably indicating emotion upregulation processes and increased engagement of cognitive mechanisms in affective tasks. The study provides brain oscillatory-based mechanisms of emotion processing distortions associated with depression.     

Face processing in Pervasive Developmental Disorder (PDD): the roles of expertise and spatial frequency

Summary Both a reduced face expertise and a basic abnormality in visual information, e.g. spatial frequency, processing have been proposed as possible causes of the abnormal face processing in Pervasive Developmental Disorder (PDD). This study investigated both the roles of expertise and spatial frequency for face processing in PDD. Event-related potentials (ERPs) and dipole sources were measured in response to (upright/inverted) high- and low-pass filtered faces, houses, and stimuli for which children with PDD were experts. ERP analyses for specific posterior electrodes showed no differences between children with PDD and matched controls, but source analyses did. These showed that controls activated specialized brain sources for the processing of faces, which was dependent on low spatial frequency content. However, children with PDD did not. Importantly, present results argue against the idea that this is due to a reduced face expertise on the part of the children with PDD, but instead support an abnormality in spatial frequency processing.     

Spatiotemporal dynamics of affective picture processing revealed by intracranial high‐gamma modulations

Our comprehension of the neural mechanisms underlying emotional information processing has largely benefited from noninvasive electrophysiological and functional neuroimaging techniques in recent years. However, the spatiotemporal dynamics of the neural events occurring during emotional processing remain imprecise due to the limited combination of spatial and temporal resolution provided by these techniques. This study examines the modulations of high‐frequency activity of intracranial electroencephalography recordings associated with affective picture valence, in epileptic patients awaiting neurosurgery. Recordings were obtained from subdural grids and depth electrodes in eight patients while they viewed a series of unpleasant, pleasant and neutral pictures from the International Affective Picture System. Broadband high‐gamma (70–150 Hz) power was computed for separate 100‐ms time windows and compared according to ratings of emotional valence. Compared to emotionally neutral or pleasant pictures, unpleasant stimuli were associated with an early and long‐lasting (≈200–1,000 ms) bilateral increase in high‐gamma activity in visual areas of the occipital and temporal lobes, together with a late and transient (≈500–800 ms) decrease found bilaterally in the lateral prefrontal cortex (PFC). Pleasant pictures were associated with increased gamma activity in the occipital cortex, compared to the emotionally neutral stimuli. Consistent with previous studies, our results provide direct evidence of emotion‐related modulations in the visual ventral pathway during picture processing. Results in the lateral PFC also shed light on the neural mechanisms underlying its role in negative emotions processing. This study demonstrates the utility of intracranial high‐gamma modulations to study emotional process with a high spatiotemporal precision. Hum Brain Mapp, 36:16–28, 2015.. © 2014 Wiley Periodicals, Inc.     

Event-related brain potential correlates of emotional face processing

Results from recent event-related brain potential (ERP) studies investigating brain processes involved in the detection and analysis of emotional facial expression are reviewed. In all experiments, emotional faces were found to trigger an increased ERP positivity relative to neutral faces. The onset of this emotional expression effect was remarkably early, ranging from 120 to 180ms post-stimulus in different experiments where faces were either presented at fixation or laterally, and with or without non-face distractor stimuli. While broadly distributed positive deflections beyond 250ms post-stimulus have been found in previous studies for non-face stimuli, the early frontocentrally distributed phase of this emotional positivity is most likely face-specific. Similar emotional expression effects were found for six basic emotions, suggesting that these effects are not primarily generated within neural structures specialised for the automatic detection of specific emotions. Expression effects were eliminated when attention was directed away from the location of peripherally presented emotional faces, indicating that they are not linked to pre-attentive emotional processing. When foveal faces were unattended, expression effects were attenuated, but not completely eliminated. It is suggested that these ERP correlates of emotional face processing reflect activity within a neocortical system where representations of emotional content are generated in a task-dependent fashion for the adaptive intentional control of behaviour. Given the early onset of the emotion-specific effects reviewed here, it is likely that this system is activated in parallel with the ongoing evaluation of emotional content in the amygdala and related subcortical brain circuits.     

Auditory and visual event-related potentials in alcoholics: abnormalities of components and brain electrical field

Alterations of ERPs recorded over midline scalp sites have frequently been reported in alcoholics. To assess the P3 and other ERP components topographically, auditory and visual ERPs were recorded from 33 scalp electrodes in abstinent alcoholics and healthy controls using an oddball paradigm. At tze Cz electrode the alcoholics showed decreased visual N1 and increased auditory N2 amplitudes. Topographically, the negative centroids of the visual N1 and P3 and the auditory N2 differed between groups, and the positive centroid of the visual P3 was displaced toward the right hemisphere. While no valid diagnostic classification could be obtained by using the traditional ERP component P3 recorded from Pz, the combination of visual N1 and auditory N2 amplitudes at Cz with centroid parameters amounted to 51% explained variance and 92% correct discrimination of alcoholics from controls. Abnormalities of N1 amplitude and P3 topography similar to the current findings in alcoholics have previously been described for schizophrenics. Received: 2 July 1999 / Accepted: 14 April 2000     

Deficient processing of alcohol cues in the addicted brain: Evidence from event-related potential microstates

ObjectivePatients with alcohol use disorder (AUD) show altered brain responses to alcohol cues as compared to healthy controls. Event-related potential (ERP) studies mostly focus on the P3, which is usually diminished in AUD patients. The few studies that have investigated earlier components have yielded inconsistent results. The present study aimed at identifying the onset of impaired alcohol cue processing in AUD patients, as well as the association between neurophysiological processing and subjective craving.MethodsA sample of 15 inpatients with AUD and 15 healthy controls completed a cue reactivity task with alcohol-related, neutral, and scrambled pictures. Multichannel-EEG was recorded from 70 scalp electrodes, and ERP microstates were analyzed.ResultsPatients displayed impaired neurophysiological processing, as indexed by a weaker P3 and a weaker, insensitive P1. The blunted P1 was associated with higher subjective craving.ConclusionsImpaired alcohol cue processing in AUD emerges early, at the stage of sensory processing. Such deficient initial processing seems crucial to understanding cue reactivity processes in the brain and in the subjective experience of craving.SignificanceThe results highlight the importance of investigating early ERP components preceding the P3, and contribute to the debate on the onset of information-processing dysfunction in the addicted brain.