Signatures of emotional face processing measured by event-related potentials in 7-month-old infants

The ability to distinguish facial emotions emerges in infancy. Although this ability has been shown to emerge between 5 and 7 months of age, the literature is less clear regarding the extent to which neural correlates of perception and attention play a role in processing of specific emotions. This study's main goal was to examine this question among infants. To this end, we presented angry, fearful, and happy faces to 7-month-old infants (N = 107, 51% female) while recording event-related brain potentials. The perceptual N290 component showed a heightened response for fearful and happy relative to angry faces. Attentional processing, indexed by the P400, showed some evidence of a heightened response for fearful relative to happy and angry faces. We did not observe robust differences by emotion in the negative central (Nc) component, although trends were consistent with previous work suggesting a heightened response to negatively valenced expressions. Results suggest that perceptual (N290) and attentional (P400) processing is sensitive to emotions in faces, but these processes do not provide evidence for a fear-specific bias across components.     

Deficient auditory processing in children with Asperger Syndrome,as indexed by event-related potentials

Conflicting inputs from visual and vestibular afferents produce motion sickness and postural instability. However, the relationship of visual and vestibular inputs to each other remains obscure. In this study, we examined the development of subjective sickness- and balance-related symptoms and objective equilibrium ataxia induced by visual–vestibular conflict (VVC) stimulation using virtual reality. The subjective symptoms evaluated by Graybiel's and Hamilton's criteria got gradually worse during the VVC. The objective postural instability was not observed during the VVC, but it occurred immediately after the VVC. There was a time lag between the subjective symptoms and objective ataxia induced by VVC. Our study suggests that the VVC inputs are processed in different pathways causing subjective autonomic symptoms and postural instability in humans.     

Tonic pain grabs attention, but leaves the processing of facial expressions intact-evidence from event-related brain potentials

Emotion and attention are key players in the modulation of pain perception. However, much less is known about the reverse influence of pain on attentional and especially emotional processes. To this end, we employed painful vs. non-painful pressure stimulation to examine effects on the processing of simultaneously presented facial expressions (fearful, neutral, happy). Continuous EEG was recorded and participants had to rate each facial expression with regard to valence and arousal. Painful stimulation attenuated visual processing in general, as reduced P100 and late positive potential (LPP) amplitudes revealed, but did not interfere with structural encoding of faces (N170). In addition, early perceptual discrimination and sustained preferential processing of emotional facial expressions as well as affective ratings were not influenced by pain. Thus, tonic pain demonstrates strong attention-demanding properties, but this does not interfere with concurrently ongoing emotion discrimination processes. These effects point at partially independent effects of pain on emotion and attention, respectively.     

Memory development and event-related brain potentials in children

This review examines the evidence for the maturation of memory function during childhood using event-related brain potentials (ERP), and behavioral measures. It has been shown that brain structures implicated in different forms of memory mature during the first and into the second decade of life. Whereas the maturation rates of implicit and explicit memory have not been directly assessed in the literature, studies of the maturation of the corresponding brain regions imply that there should be a progression in the maturation of the different forms of memory. This review also motivates the use of brain imaging techniques for investigation of memory systems during the developing years. Although, only a handful of such studies with children are currently available, they demonstrate that such techniques can provide information that may be unavailable otherwise. For example, when children fail to generate the ERP old/new effect, an index of episodic retrieval, it has been suggested that they may lack the necessary pre-existing representations in their long-term lexical or semantic memories. Similarly, age-related differences in ERP scalp topography during source memory paradigms suggest that children, who do not appear to show frontal scalp activity, lack inputs from frontal regions that are necessary for successful retrieval of source information. Future research with children will reveal more details about the nature of mnemonic processing during the developmental years.     

Semantic processing of words in selective listening: an examination using recognition tests and event-related brain potentials

Two experiments were conducted to investigate the degree of semantic processing for unattended words. In a dichotic listening task, each participant was required to attend selectively to either a word sequence in one ear or a speech passage in the opposite ear. The selective listening was confirmed by attenuated P1-N1 and N400 waves of the event-related brain potential to unattended words. The N400 attenuation with semantic priming was observed only for attended words. In a following recognition test with a booklet and auditory presentation, the percentage of false alarms for "new" words (or lures) semantically related to "old" words was higher when the "old" words were attended in selective listening than when unattended. These findings suggest that selective attention can act before and/or at a level of semantic processing.     

Gender differences in the recognition of spatially transformed figures: Behavioral data and event-related potentials (ERPs)

With tasks involving action concept comprehension, many fMRI studies have reported brain activations in sensori-motor regions specific to effectors of the referent action. There is relatively less evidence whether such activations reflect early semantic access or late conceptual re-processing. Here we recorded event-related potentials when participants recognized noun-verb pairs. For Congruent pairs, the verb was the one most commonly associated with the noun (e.g., football-kick). Compared with a control condition, verbs in Congruent pairs showed priming effects in the time windows of 100-150 ms and 210-260 ms. Such activation seems to be specific to body part but not other aspects of the action as similar priming effect was also found when the noun and verb involved different actions though sharing the same body part (e.g., football-jump), documenting for the first time the early activation of body part representations in action concept comprehension.     

Gender differences in the recognition of spatially transformed figures: Behavioral data and event-related potentials (ERPs)

The gender differences in accuracy, reaction time (RT) and amplitude of the early P1 and N1 components of ERPs during recognition of previously memorized objects after their spatial transformation were examined. We used three levels of the spatial transformation: a displacement of object details in radial direction, and a displacement in combination with rotation of the details by ±0° to 45° and ±45° to 90°. The accuracy and the RT data showed a similarity of task performance in males and females. The effect of rotation was significantly greater than the effect of simple displacement, and the accuracy decreased, and the RT increased with the rotation angle in both genders. At the same time we found significant sex differences in the early stage of visual processing. In males the P1 peak amplitude at the P3/P4 sites increased significantly during the recognition of spatially transformed objects, and the wider the angle of rotation the greater the P1 peak amplitude. In contrast, in females the P1 peak amplitude did not depend on the rotation of figure details. The N1 amplitude revealed no gender differences, although the object transformation evoked somewhat greater changes in the N1 at the O1/O2 sites in females compared to males. This new fact that only males demonstrated the sensitivity of early perceptual stage to the transformation of objects adds information about the neurobiological basis of different strategies in the visual processing used by each gender.     

Perceptual interactions between visual processing of facial familiarity and emotional expression: An event-related potentials study during task-switching

Models of face processing suggest that facial familiarity and expression processes involve independent visual systems. But under some conditions, the two processes interact, as when selective attention is solicited, and/or when a link is established between consecutive stimuli. To assess these assumptions during perceptual face processing, event-related potentials (ERPs) were used while subjects discriminated either familiarity or expression in a task-switching paradigm. Switched trials were designed with competitor priming, the unattended dimension being previously attended. The results indicate interactions appearing in the right hemisphere during the perceptual encoding stage (N170) when subjects processed either familiarity or expression during switched trials. These interactions gain both hemispheres during memory retrieval (P2) and in terms of accuracy. Altogether, these results confirm the critical role of the right hemisphere in perceiving faces and their expressions. Moreover, they suggest that familiarity and expression can interact in both directions.     

Sex differences in brain maturation as measured using event-related potentials

Little is known about how sex influences functional brain maturation. The current study investigated sex differences in the maturation of event-related potential (ERP) amplitudes during an auditory oddball task (N = 170; age = 6-17 years). Performance improved with age. N200 amplitude declined with age: parietal sites showed earlier development than temporal and frontal locations. Girls showed greater bilateral frontal P300 amplitude development, approaching the higher values observed in boys during childhood. After controlling for age, right frontal P300 amplitude was associated with reaction time in girls. The findings demonstrate sex differences in ERP maturation in line with behavioral and neuroimaging studies.     

Configural processing in face recognition in schizophrenia

Introduction. There is currently substantial literature to suggest that patients with schizophrenia are impaired on many face-processing tasks. This study investigated the specific effects of configural changes on face recognition in groups of schizophrenia patients. Methods. In Experiment 1, participants identified facial expressions in upright faces and in faces inverted from their upright orientation. Experiments 2 and 3 examined recognition memory for faces and other non-face objects presented in upright and inverted orientations. Experiment 4 explored recognition of facial identity in composite images where the top half of one face was fused to the bottom half of another face to form a new face configuration. Results. In each experiment, the configural change had the same effect on face recognition for the schizophrenia patients as it did for control participants. Recognising inverted faces was more difficult than recognising upright faces, with a disproportionate effect of inversion on faces relative to other objects. Recognition of facial identity in face-halves was interfered with by the formation of a new face configuration. Conclusion. Collectively, these results suggest that people with schizophrenia rely on configural information to recognise photographs of faces.     

Motor and nonmotor event-related potentials during a complex processing task

Identification of the necessary stimulus properties to elicit the stimulus preceding negativity (SPN) has been the impetus for numerous research studies. The current study was conducted to explore the possibility that the SPN is an index of cognitive resource allocation. An auditory warning stimulus (S1) indicated whether an easy or difficult discrimination would occur at S2. The SPN was collected before a nonmotor discrimination task (S2) that consisted of identifying the higher of two bars. To eliminate the influence of motor processing prior to S2, a button press on the side of the higher bar was held until perception of a response cue (S3). Additionally, P3, contingent negative variation (CNV), and behavioral measures were collected to assist in assessing the SPN. Results indicated that although the SPN exhibited increased negativity, no differences were observed based on task difficulty. However, task difficulty did affect P3 data for both the warning tone and the discrimination task, an effect not observed for the CNV. Overall, the data did not support that hypothesis that the SPN provides an index of cognitive demand.     

Inhibition control and error processing in children with attention deficit/hyperactivity disorder: An event-related potentials study

We studied inhibitory control and error processing in a task requiring inhibition of a motor response. Behavioral and ERP indices were recorded in fourteen ADHD and fourteen healthy children aged between 6 and 10 years during the Stop signal task (SST). The ADHD group made more variable in RT and showed less accuracy, more omissions and choice errors. Also, the ADHD group had a tendency toward a lower probability of inhibition and a longer Stop signal reaction time. The ADHD group also displayed a flatter response inhibition slope compared to the control group. Smaller P1 in ADHD group reflected that the ADHD group has less efficient attention than the control group. Furthermore, the ADHD group showed normal ERN, reduced Pe (retrieved from response-locked epochs), and reduced LPW (retrieved from Stop signal-locked epochs), suggesting that they might be normal in early error monitoring process related to error detection, but show abnormal in later error monitoring process associated with a conscious evaluation of the error. Behavioral and ERP data of the present study show deficient selective attention, inhibitory control, and error processing in children of ADHD.     

Attentional processing in adults with ADHD as reflected by event-related potentials

Attention deficit/hyperactivity disorder (ADHD) is a well known childhood disease and well researched via event-related potentials (ERPs), but unfortunately there is little information on this illness in adults in ERPs. In the present study, 12 adults diagnosed with ADHD and 12 healthy control adults were examined with respect to ERPs in a visual Go/NoGo-experiment to gain information about target evaluation processing in these patients. Two attention-related ERP-components, the N1 and N2 were significantly increased for the ADHD adults compared to the healthy control adults. These findings were illustrated using source analysis results: In the time frame corresponding to the N1, significant increases of activity were found in the medial frontal gyrus and during the N2 time frame significant increases were detected in the lingual gyrus. The P300 showed a tendency towards decreased activity in the patient group, however, only a subsequent slow wave activity indicated significant differences. Neuronal activity related to early attentional mechanisms (N1 and N2) appears to be enhanced in ADHD patients. Together with the finding of a reduction in the P300, the data suggest that ADHD adults have learned to gather their attention more strongly than healthy adults in order to achieve the same results and compensate for their impairment. This is supported by the source analysis results which show activity in additional brain areas.     

Sequential processing of interaural timing differences for sound source segregation and spatial localization: evidence from event-related cortical potentials

Cortical processing of interaural timing differences (ITDs) was investigated with event-related potential (ERP) measurements in 16 human participants who were required in separate tasks to detect or to spatially localize dichotically embedded pitches. ITDs elicited three ERP components labeled ORN, N2, and P400. The ORN occurred at a latency of 150-250 ms and was elicited by ITDs regardless of location or task. In contrast, the N2 response (250-350 ms) was strongly modulated by location and showed larger amplitudes for the localization task than for the detection task. Finally, ITDs in the detection task elicited a P400 at a latency of 400-500 ms, but this response was entirely absent from ERPs elicited by identical stimuli in the localization task. These results are consistent with a sequential model of auditory perception in which segregation of concurrent sounds is followed by domain-specific processing of object location and identity.     

Typicality effect on holistic processing in face recognition

Many studies have claimed that faces are more holistically recognized than other objects. It is unclear, however, whether some faces are more holistically recognized than other faces. This study examined whether typical faces are more holistically recognized than distinctive faces. In order to measure the degree of holistic processing, I used an alignment effect, which is a kind of interference effect on the part processing by the holistic processing. The alignment effect was measured as performance difference between aligned and non-aligned presentation conditions. The size of the alignment effects reflects the degree of the holistic processing. The results showed that the typical and distinctive faces showed an equal size of the alignment effects. These results suggested that the typical faces were not more holistically recognized than the distinctive faces. The implication of this results for face recognition research was discussed.     

The effect of face inversion on intracranial and scalp recordings of event-related potentials

The face inversion effect (FIE) refers to a disproportionate disruption of the processing of face information by inverting faces. We investigated the FIE in epilepsy patients by simultaneous intracranial and scalp recordings of event-related potentials (ERPs). In scalp recordings, a typical FIE on ERPs was observed with increased latencies and amplitudes of the positive counterpart of the occipito-temporal N170, namely, the vertex positive potential (VPP), in response to inverted faces. Similar amplitude and latency increases were revealed for the intracranial N200 recorded over face-sensitive and non-face-sensitive areas in the lateral occipital cortex, but not in the ventral temporal cortex. Peak latencies did not differ between the scalp VPP and intracranial N200. Findings indicate that the lateral occipital cortex but not the ventral temporal cortex contributes primarily to the FIE observed in scalp recordings.     

An event-related potentials study of face identification and naming: the tip-of-the-tongue state

With the aim of identifying event-related potential (ERP) correlates of the tip-of-the-tongue (TOT) state, we employed a task involving identification and naming of the faces of famous people with three response categories: KNOW (correct naming), DON'T KNOW (name not known), and TOT. Before 450 ms, no differences are observed between TOT and KNOW conditions in ERPs related to face processing and recognition. The smaller mean amplitude in TOT than in KNOW responses over the 550-750-ms interval and the N-TOT difference wave are correlates of the onset of the TOT state, probably reflecting a division of processing resources and low activation of the lexical-phonological route. The smaller amplitude of a late negative wave (between 1350 and 1550 ms) in TOT than in DON'T KNOW responses, and the P-TOT difference wave, seem to indicate that an important amount of processing resources is engaged in resolving the TOT.