An ERP study on the time course of facial trustworthiness appraisal

The importance of facial trustworthiness for human interaction and communication is difficult to exaggerate. Reflections on daily experience indicate that the presence of a human face elicits rapid appraisals of its trustworthiness. Relatively little is known, however, about the exact brain processes related to this response. In the present study, event-related brain potentials were recorded during trustworthiness appraisals of various emotionally neutral faces. On the one hand, trustworthy faces elicited a more positive C1 than untrustworthy faces; a finding that might be related to initial stages of perceptual processing that categorizes faces on the basis of structural properties. On the other hand, untrustworthy faces elicited a more positive late positive component (LPC) than trustworthy faces, indicating that greater amounts of motivated attention are allocated to faces appearing to be untrustworthy. The LPC effect in this study was consistent with the prediction of the emotion overgeneralization hypothesis of trustworthy face evaluation.     

An ERP study on the time course of phonological and semantic activation in Chinese word recognition

With the event-related potential (ERP) technique, we examined the time course of phonological and semantic activation in Chinese word recognition. Participants did a semantic judgment task and a homophone judgment task over the same set of word pairs. Each pair was of either high or low word frequency and the two words were either unrelated or related semantically or phonologically, i.e., being homophones. For high-frequency words, both the semantically related pairs in the homophone task and the homophonic pairs in the semantic task elicited ERP responses different from the unrelated control pairs in the N400 component but not any component earlier, suggesting a similar time course for semantic and phonological activation. For low-frequency words, the semantically related pairs in the homophone task were associated with a similar modulation of N400. However, compared to the unrelated controls, the homophonic pairs in the semantic task elicited a larger P200, a component implicated in phonological processing in the literature, and thus demonstrated a phonological activation earlier than semantic activation. The results showed that word frequency affects the time course of semantic and phonological activation suggesting that phonology is not invariably activated before semantics in Chinese word recognition.     

Timing of stress and testing influence the long-lasting behavioral performance in rats

Three exposures (Days 1, 2 and 3) of rats to immobilization or immobilization combined with cold induced an alteration of exploratory behavior in an open space arena. When tested 1h after both stressors exposure, rats displayed a decrease in locomotor and rearing score. The deficit disappeared when rats were tested five days later and the performance remained unchanged in trials performed on days 9, 10, 15, 22 and 29 of the study. When testing was postponed five days after the third stressor exposure, a gradual reduction of the performance developed and the deficit persisted until the last trial on Day 29. Amphetamine, in a dose of 0.3 mg/kg revealed a sensitized response to the drug in the stressed animals. The results showed short- and long-lasting behavioral consequences of the used stressors, the long-term manifestation of the sequelae being dependent on the sequence and timing of stressor exposure and open space testing.     

Following the time course of face gender and expression processing: A task-dependent ERP study

The effects of task demands and the interaction between gender and expression in face perception were studied using event-related potentials (ERPs). Participants performed three different tasks with male and female faces that were emotionally inexpressive or that showed happy or angry expressions. In two of the tasks (gender and expression categorization) facial properties were task-relevant while in a third task (symbol discrimination) facial information was irrelevant. Effects of expression were observed on the visual P100 component under all task conditions, suggesting the operation of an automatic process that is not influenced by task demands. The earliest interaction between expression and gender was observed later in the face-sensitive N170 component. This component showed differential modulations by specific combinations of gender and expression (e.g., angry male vs. angry female faces). Main effects of expression and task were observed in a later occipito-temporal component peaking around 230 ms post-stimulus onset (EPN or early posterior negativity). Less positive amplitudes in the presence of angry faces and during performance of the gender and expression tasks were observed. Finally, task demands also modulated a positive component peaking around 400 ms (LPC, or late positive complex) that showed enhanced amplitude for the gender task. The pattern of results obtained here adds new evidence about the sequence of operations involved in face processing and the interaction of facial properties (gender and expression) in response to different task demands.     

Time course of affective processing bias in major depression: An ERP study

The current study investigated the time course of the affective processing bias in major depressive disorder (MDD) in a visual three-stimulus semantic oddball task using event-related potentials (ERPs). MDD patients showed decreased P1 latency over right posterior regions to negative relative to positive target stimuli, reflecting a very early onset of the negativity bias in emotional perception. Compared to controls, MDD patients showed enlarged anterior P2 amplitude to positive target stimuli, reflecting an affective bias in the early attentional stages of processing. In addition, MDD patients showed relatively high N2 and reduced P3 amplitudes to negative compared with positive target stimuli, as well as marginally reduced N2 amplitude to positive target stimuli compared with controls. This suggests that the negativity bias also occurs during later strategic evaluation stages. Therefore, the present study extended previous findings by demonstrating that the affective processing bias in MDD begins in the early stages of perceptual processing and continues at later cognitive stages.     

Variations in maternal care in the rat as a mediating influence for the effects of environment on development

Variations in maternal care have been widely considered as a critical influence in development. In the rat, variations in maternal behavior, particularly in licking/grooming, regulate the development of endocrine, emotional and cognitive responses to stress. These studies form the basis of a potentially useful model for the study of maternal effects in mammals. In this paper we provide a detailed methodological investigation into this model of maternal behavior, providing an analysis of the frequency, temporal dynamics, and transmission of maternal licking/grooming in several large cohorts. Frequency data indicate that licking/grooming is normally distributed across dams. The peak in licking/grooming occurs in the first few days postpartum and gradually declines. Dams designated as High or Low LG mothers differ in this behavior only during the first week postpartum. Observations over Days 2 to 5 postpartum are essential for the reliable assessments of individual differences in maternal behavior. Individual differences in licking/grooming behavior are stable across multiple litters, and are not associated with differences in litter size, weaning weight of pups, or gender ratio of the litter. We also observed no significant differences in the amount of licking/grooming received by individual pups within a litter, though variation does exist. Finally, maternal licking/grooming is transmitted to female offspring, though there is considerable within-litter variation in the expression of this behavior. Overall, these findings indicate considerable, normal variations in licking/grooming in the rat that are a stable, individual characteristic of rat dams.     

An ERP study on the processing of common fractions

The aim of this study was to examine how adults processed common fractions with common numerators under two distinct conditions. Whereas participants were presented with only common fractions in a “simple” condition, a “complex” condition involved the random presentation of common fractions as well as decimal fractions. In both conditions, participants were required to assess whether various “target” fractions were larger than or smaller than a “standard” common fraction (1/5). Behavioral results indicated that under both conditions, participants mentally processed the fractions componentially in terms of their constituent parts rather than holistically in terms of the numerical value of the fraction as a whole. The data provided by the event-related potentials (ERPs) demonstrated electrophysiological correlates of the componential processing of common fractions in the simple condition, as reflected in the latency and amplitude of P3. However, in contrast to what the behavioral data showed, there was no strong electrophysiological evidence to indicate that common fractions were accessed componentially in the complex condition. In addition, the complex condition was linked to longer latency and more negative amplitude of N2 over the frontal scalp than the simple condition, which could be attributed to the fact that the comparison of fractions in the complex condition involved task switching and thus was more taxing on cognitive control than the simple condition.     

Restraint stress has no effect on morphine-induced inhibition of gastrointestinal transit in the rat

Stress in the rat has been reported to enhance the analgesic and thermic effects of opioids, drug effects that are mediated centrally. We examined whether this stress-induced enhancement of response to opioids could also be demonstrated for a drug effect mediated largely in the periphery, morphine-induced inhibition of gastrointestinal transit. Restrained (stressed) and unrestrained (unstressed) rats were injected with saline or morphine and then administered orally a charcoal suspension; after sacrifice, the distance the charcoal traveled through the intestine was determined. After the administration of saline, restrained rats had significantly lower gastrointestinal transit than did unstressed rats; however, both groups were comparably sensitive to inhibition of gastrointestinal transit by morphine.     

Influence of acute stress on response inhibition in healthy men: An ERP study

The current study investigated the influence of acute stress and the resulting cortisol increase on response inhibition and its underlying cortical processes, using EEG. Before and after an acute stressor or a control condition, 39 healthy men performed a go/no‐go task while ERPs (N2, P3), reaction times, errors, and salivary cortisol were measured. Acute stress impaired neither accuracy nor reaction times, but differentially affected the neural correlates of response inhibition; namely, stress led to enhanced amplitudes of the N2 difference waves (N2d, no‐go minus go), indicating enhanced response inhibition and conflict monitoring. Moreover, participants responding to the stressor with an acute substantial rise in cortisol (high cortisol responders) showed reduced amplitudes of the P3 of the difference waves (P3d, no‐go minus go) after the stressor, indicating an impaired evaluation and finalization of the inhibitory process. Our findings indicate that stress leads to a reallocation of cognitive resources to the neural subprocesses of inhibitory control, strengthening premotor response inhibition and the detection of response conflict, while concurrently diminishing the subsequent finalization process within the stream of processing.     

Effect of neuropeptide Y on behavior and on the time course of the brain noradrenalin level

Laboratory of General Physiology of Functional Systems, P. K. Anokhin Research Institute of Normal Physiology, Academy of Medical Sciences of the USSR, Moscow. Institute of Pathophysiology, Szeged Medical University, Hungary. (Presented by Academician of the Academy of Medical Sciences of the USSR I. P. Ashmarin). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 8, pp. 132–135, August, 1989.     

An ERP study on the effect of self-relevant possessive pronoun

The present study examined the electrophysiological correlates of the psychological processing of possessive pronouns such as “wo de” (Chinese for “my”/“mine”) and “ta de” (Chinese for “his”) using a three-stimulus oddball paradigm. Sixteen participants were visually presented the stimuli (possessive pronouns, small circle and big circle). The results showed that, relative to non-self-relevant possessive pronoun “ta de”, self-relevant possessive pronoun “wo de” elicited a significantly larger P300 amplitude independently. The present study suggested that the self-relevant possessive pronoun was psychologically important to human beings.     

Understanding the subliminal affective priming effect of facial stimuli: an ERP study

The subliminal affective priming was studied by recording event-related potential (ERP) to ambiguous neutral faces preceded by 20 ms positive or negative prime faces. Behavioral results showed that positive and negative prime faces led to valance-consistent biases in affective judgments of ambiguous neutral faces. ERP data showed that subliminal primes differentially influenced N100, N300 and vertex positive potential (VPP), with larger amplitudes in negative priming trials. These results support the conclusion that the early perceptual analysis of targets, as well as evaluation and selection of targets, is affected by subliminal affective information.     

The different time courses of reading different levels of Chinese characters: An ERP study

The dual route processing was generally accepted in the reading of alphabetic languages, which suggests alphabetic words can be read by either addressed pathway or assembled pathway. However, it was still unclear whether there was a particular ‘dual route mechanism’ during reading Chinese characters. In our previous fMRI study, the result showed that there might be a particular ‘dual route mechanism’, and its addressed pathway was similar between Chinese and English, whereas for the need of spatial analysis, the assembled pathway of Chinese was different from that of English which involved grapheme-to-phoneme correspondences. The present study, using event-related potential, which provide more temporal information, aimed to further support our previous view, and peered inside the different time courses of reading different types of Chinese characters. It was found that reading high frequency Chinese characters increased the N170 component which was believed to enhance attention to the addressed pathway in the left occipital–temporal area. Pseudo Chinese characters could be read by a particular assembled pathway, which caused the largest amplitude of P320 component in the right occipital–temporal area, which considered as a key brain area for radical analysis.     

Dissociable effects of psychopathic traits on cortical and subcortical visual pathways during facial emotion processing: An ERP study on the N170

This study examined the relation between psychopathic traits and the brain response to facial emotion by analyzing the N170 component of the ERP. Fifty‐four healthy participants were assessed for psychopathic traits and exposed to images of emotional and neutral faces with varying spatial frequency content. The N170 was modulated by the emotional expressions, irrespective of psychopathic traits. Fearless dominance was associated with a reduced N170, driven by the low spatial frequency components of the stimuli, and dependent on the tectopulvinar visual pathway. Conversely, coldheartedness was related to overall enhanced N170, suggesting mediation by geniculostriate processing. Results suggest that different dimensions of psychopathy are related to distinct facial emotion processing mechanisms and support the existence of both amygdala deficits and compensatory engagement of cortical structures for emotional processing in psychopathy.     

An anatomical study on the lingual–facial trunk

Purpose  We quantified variations of the lingual artery origin, measured the lingual artery origin distance from clinical relevant landmarks and compared the lingual artery diameters with normal and variable origin. Methods  Forty-two formalin fixed male cadavers were bilaterally evaluated. Measurements were performed with the aid of an electronic digital caliper. Results  The origin distances from the common carotid artery bifurcation was 1.05 ± 0.11 and 1.02 ± 0.11 cm for the right and left lingual arteries respectively with no differences compared to the lingual–facial trunks. The diameters of the lingual arteries were 0.25 ± 0.01 and 0.26 ± 0.01 cm for the right and left sides, respectively, while the lingual–facial trunks showed diameters of 0.21 ± 0.02 and 0.24 ± 0.02 cm for the right and left sides, respectively. Conclusions  The present study adds information on the lingual artery diameter and its anatomical relation to clinically useful landmarks.     

Sleep homeostasis in the rat: Simulation of the time course of EEG slow-wave activity

According to the two-process model of sleep regulation, a homeostatic Process S increases during waking and declines during sleep. For humans, the time course of S has been derived from the changes in EEG slow-wave activity (SWA; spectral power density in the 0.75–4.0 Hz range) during sleep. We tested the applicability of the model to sleep in the rat. The simulation was based on the vigilance states for consecutive 8-s epochs of a 96-h experiment in 9 animals. The level of S was made to decrease in epochs of non-REM sleep (NREMS), and to increase in epochs of waking or REM sleep according to exponential functions. By optimizing the initial value and the time constants of S, a close fit between the hourly values of SWA in NREMS and of S was obtained. The biphasic time course of SWA during baseline, its enhancement in the initial recovery period after 24-h sleep deprivation, and its subsequent prolonged undershoot were present in the simulation. We conclude that sleep homeostasis as conceptualized in the two-process model may be a general property of mammalian sleep.     

Speaking one's second language under time pressure: An ERP study on verbal self-monitoring in German–Dutch bilinguals

This study addresses how verbal self-monitoring and the Error-Related Negativity (ERN) are affected by time pressure when a task is performed in a second language as opposed to performance in the native language. German–Dutch bilinguals were required to perform a phoneme-monitoring task in Dutch with and without a time pressure manipulation. We obtained an ERN following verbal errors that showed an atypical increase in amplitude under time pressure. This finding is taken to suggest that under time pressure participants had more interference from their native language, which in turn led to a greater response conflict and thus enhancement of the amplitude of the ERN. This result demonstrates once more that the ERN is sensitive to psycholinguistic manipulations and suggests that the functioning of the verbal self-monitoring system during speaking is comparable to other performance monitoring, such as action monitoring.     

Effects of prior experience with dehydration and water on the time course of dehydration-induced drinking in weanling rats

Although cellular dehydration increases oral responding and swallowing of orally infused water in rats as young as 2 days old, it is not until well after the time of weaning that dehydration stimulates immediate water-seeking and initiation of drinking in situations where the water source must be approached voluntarily. Recent work has shown that the goal-directed appetitive sequence for drinking-orienting, approaching, and initiating contact with water-matures much later than the more precocial oral licking and swallowing behaviors, and normally comes to be elicited by dehydration only after post-weaning experience with dry food. In the current experiments we evaluate some critical features of post-weaning experience with dehydration and drinking, and find that prior experience with initiating drinking while dehydrated, but not experience with dehydration nor water per se, alters the time course of water intake during a subsequent hydrational challenge. The effects of experience are manifested as an increased proportion of water consumed in the early portion of the test, rather than a general increase in total consumption. These findings are consistent with the interpretation that prior experience is necessary for the coordination of water-oriented appetitive behaviors that lead to the initiation and maintenance of drinking bouts, and provide further evidence for an associative learning account of the acquisition of dehydration-induced drinking.