Can ambient odors influence the recognition of emotional words? A behavioral and event-related potentials study

Odor context can affect the recognition of facial expressions. However, there is no evidence to date that odor can regulate the processing of emotional words conveyed by visual words. An emotional word recognition task was combined with event-related potential technology. Briefly, 49 adults were randomly divided into three odor contexts (pleasant odor, unpleasant odor, and no odor) to judge the valence of emotional words (positive, negative, and neutral). Both behavioral and Electroencephalography (EEG) data were collected. Both the pleasant odor and unpleasant odor contexts shortened the response time of the subjects to emotional words. In addition, negative words induced greater amplitudes of early posterior negativity (EPN) and late positive potential (LPP) than the positive and neutral words. However, the neutral words induced a larger N400 amplitude than the positive and negative words. More importantly, the processing of emotional words was found to be modulated by external odor contexts. For example, during the earlier (P2) processing stages, pleasant and unpleasant odor contexts induced greater P2 amplitudes than the no odor context. In the unpleasant odor context, negative words with the same odor valence induced greater P2 amplitudes than the positive words. During the later (N400) stages, various regions of the brain regions exhibited different results. For example, in the left and right frontal areas of the brain, exposure to positive words in a pleasant odor context resulted in a smaller N400 amplitude than exposure to neutral words in the same context. Meanwhile, in the left and right central regions, emotional words with the same valence as pleasant or unpleasant odor contexts elicited the minimum N400 amplitude. Individuals are very sensitive to emotional information. With deeper processing, different cognitive processes are reflected and they can be modulated by external odors. In the early and late stages of word processing, both pleasant and unpleasant odor contexts exhibited an undifferentiated dominance effect and could specifically modulate affectively congruent words.     

Corticospinal Excitability Preceding the Grasping of Emotion-Laden Stimuli

Evolutionary theories posit that emotions prime organisms for action. This study examined whether corticospinal excitability (CSE) is modulated by the emotional valence of a to-be-grasped stimulus. CSE was estimated based on the amplitude of motor evoked potentials (MEPs) elicited using transcranial magnetic stimulation (TMS) and recorded on the first dorsal interosseous (FDI) muscle. Participants were instructed to grasp (ACTION condition) or just look at (NO-ACTION condition) unpleasant, pleasant and neutral stimuli. TMS pulses were applied randomly at 500 or 250 ms before a go signal. MEP amplitudes were normalized within condition by computing a ratio for the emotion-laden stimuli by reference to the neutral stimuli. A divergent valence effect was observed in the ACTION condition, where the CSE ratio was higher during the preparation to grasp unpleasant compared to pleasant stimuli. In addition, the CSE ratio was lower for pleasant stimuli during the ACTION condition compared to the NO-ACTION condition. Altogether, these results indicate that motor preparation is selectively modulated by the valence of the stimulus to be grasped. The lower CSE for pleasant stimuli may result from the need to refrain from executing an imminent action.     

Preparing to Grasp Emotionally Laden Stimuli

Background

Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding nature of movements’ outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence.

Methodology/Principal Findings

The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude.

Conclusions/Significance

We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact.     

Gaze differences in processing pictures with emotional content

The International Affective Picture System (IAPS) is a set of standardized emotionally evocative color photographs developed by NIMH Center for Emotion and Attention at the University of Florida. It contains more than 900 emotional pictures indexed by emotional valence, arousal and dominance. However, when IAPS pictures were used in studying emotions with the event-related potentials, the results have shown a great deal of variation and inconsistency. In this research arousal and dominance of pictures were controlled while emotional valence was manipulated as 3 categories, pleasant, neutral and unpleasant pictures. Two experiments were conducted with an eye-tracker in order to determine to what the participants turn their gaze. Participants were 25 psychology students with normal vision. Every participant saw all pictures in color and same pictures in black/white version. This makes 200 analyzed units for color pictures and 200 for black and white pictures. Every picture was divided into figure and ground. Considering that perception can be influenced by color, edges, luminosity and contrast and since all those factors are collapsed on the pictures in IAPS, we compared color pictures with same black and white pictures. In first eye-tracking IAPS research we analyzed 12 emotional pictures and showed that participants have higher number of fixations for ground on neutral and unpleasant pictures and for figure on pleasant pictures. Second experiment was conducted with 4 sets of emotional complementary pictures (pleasant/unpleasant) which differ only on the content in the figure area and it was shown that participants were more focused on the figure area than on the ground area. Future ERP (event related potential) research with IAPS pictures should take into consideration these findings and to either choose pictures with blank ground or adjust pictures in the way that ground is blank. For the following experiments suggestion is to put emotional content in the figure area and to use different non complementary pictures to see if there is difference between different emotional categories.     

Effect of alexithymia on the event-related theta-synchronization of human EEG during reception of emotional visual stimuli

The 62-channel EEG was recorded while control non-alexithymic (n = 21) and alexithymic (n = 20) participants viewed sequentially presented neutral, pleasant and unpleasant pictures and subjectively rated them after each presentation. The event-related synchronization (ERS) to these stimuli was assessed in the theta-1 (4-6 Hr) and theta-2 (6-8 Hz) frequency bands. The obtained findings indicate that alexithymia influences perception of only emotional stimuli. In the upper theta over anterior cortical regions alexithymia vs control individuals in response to both pleasant and unpleasant stimuli manifested decreased left hemisphere ERS in the early test period of 0-200 ms along with enhanced ERS in response to negative vs positive and neutral stimuli in the right hemisphere at 200-600 ms after stimulus onset. The findings provide the first EEG evidence that alexithymia construct, associated with a cognitive deficit in initial evaluation of emotion, is indexed by disrupted early frontal synchronization in the upper theta band that can be best interpreted to reflect disregulation during appraisal of emotional stimuli.     

Self-Reported Trait Mindfulness and Affective Reactivity: A Motivational Approach Using Multiple Psychophysiological Measures

As a form of attention, mindfulness is qualitatively receptive and non-reactive, and is thought to facilitate adaptive emotional responding. One suggested mechanism is that mindfulness facilitates disengagement from an affective stimulus and thereby decreases affective reactivity. However, mindfulness has been conceptualized as a state, intervention, and trait. Because evidence is mixed as to whether self-reported trait mindfulness decreases affective reactivity, we used a multi-method approach to study the relationship between individual differences in self-reported trait mindfulness and electrocortical, electrodermal, electromyographic, and self-reported responses to emotional pictures. Specifically, while participants (N = 51) passively viewed pleasant, neutral, and unpleasant IAPS pictures, we recorded high-density (128 channels) electrocortical, electrodermal, and electromyographic data to the pictures as well as to acoustic startle probes presented during the pictures. Afterwards, participants rated their subjective valence and arousal while viewing the pictures again. If trait mindfulness spontaneously reduces general emotional reactivity, then for individuals reporting high rather than low mindfulness, response differences between emotional and neutral pictures would show relatively decreased early posterior negativity (EPN) and late positive potential (LPP) amplitudes, decreased skin conductance responses, and decreased subjective ratings for valence and arousal. High mindfulness would also be associated with decreased emotional modulation of startle eyeblink and P3 amplitudes. Although results showed clear effects of emotion on the dependent measures, in general, mindfulness did not moderate these effects. For most measures, effect sizes were small with rather narrow confidence intervals. These data do not support the hypothesis that individual differences in self-reported trait mindfulness are related to spontaneous emotional responses during picture viewing.     

Predicting the Valence of a Scene from Observers’ Eye Movements

Multimedia analysis benefits from understanding the emotional content of a scene in a variety of tasks such as video genre classification and content-based image retrieval. Recently, there has been an increasing interest in applying human bio-signals, particularly eye movements, to recognize the emotional gist of a scene such as its valence. In order to determine the emotional category of images using eye movements, the existing methods often learn a classifier using several features that are extracted from eye movements. Although it has been shown that eye movement is potentially useful for recognition of scene valence, the contribution of each feature is not well-studied. To address the issue, we study the contribution of features extracted from eye movements in the classification of images into pleasant, neutral, and unpleasant categories. We assess ten features and their fusion. The features are histogram of saccade orientation, histogram of saccade slope, histogram of saccade length, histogram of saccade duration, histogram of saccade velocity, histogram of fixation duration, fixation histogram, top-ten salient coordinates, and saliency map. We utilize machine learning approach to analyze the performance of features by learning a support vector machine and exploiting various feature fusion schemes. The experiments reveal that ‘saliency map’, ‘fixation histogram’, ‘histogram of fixation duration’, and ‘histogram of saccade slope’ are the most contributing features. The selected features signify the influence of fixation information and angular behavior of eye movements in the recognition of the valence of images.     

The effect of emotion and personality on olfactory perception

It is well established that both the emotional tone of sensory stimuli and the personality characteristics of an individual can bias sensory perception. What has largely been unexplored is whether the current emotional state of an individual has a similar effect, and how it works together with other factors. Here we carry out a comprehensive study to examine how olfactory perception is affected by the emotional tone of the stimuli, and the personality and current emotional state of the individual. Subjects reported experiencing happiness, sadness, negativity/hostility and neutrality when exposed to corresponding emotionally themed video clips, and in each case, smelled a suprathreshold pleasant, an unpleasant and a neutral odorant. The time taken for the subject to detect each odorant and the olfactory intensity were recorded. We found that women detected the pleasant odorant faster than the neutral one. In addition, personality modulated reaction time and olfactory intensity, such that neurotic and anxious individuals were selectively biased toward affective rather than neutral odorants. Finally, current emotional state augmented intensity in men but not in women, and differentially influenced the response time. These findings provided new insights into the effects of emotion and personality on olfactory perception.     

Emotional stimulation alters olfactory sensitivity and odor judgment

Emotions have a strong influence on the perception of visual and auditory stimuli. Only little is known about the relation between emotional stimulation and olfactory functions. The present study investigated the relationship between the presentation of affective pictures, olfactory functions, and sex. Olfactory performance was assessed in 32 subjects (16 male). Olfactory sensitivity was significantly reduced following unpleasant picture presentation for all subjects and following pleasant picture presentation for male subjects only. Pleasantness and intensity ratings of a neutral suprathreshold odor were related to the valence of the pictures: After unpleasant picture presentation, the odor was rated as less pleasant and more intense, whereas viewing positive pictures induced a significant increase in reported odor pleasantness. We conclude that inducing a negative emotional state reduces olfactory sensitivity. A relation to functional deviations within the primary olfactory cortices is discussed.     

Remembering the Object You Fear: Brain Potentials during Recognition of Spiders in Spider-Fearful Individuals

In the present study we investigated long-term memory for unpleasant, neutral and spider pictures in 15 spider-fearful and 15 non-fearful control individuals using behavioral and electrophysiological measures. During the initial (incidental) encoding, pictures were passively viewed in three separate blocks and were subsequently rated for valence and arousal. A recognition memory task was performed one week later in which old and new unpleasant, neutral and spider pictures were presented. Replicating previous results, we found enhanced memory performance and higher confidence ratings for unpleasant when compared to neutral materials in both animal fearful individuals and controls. When compared to controls high animal fearful individuals also showed a tendency towards better memory accuracy and significantly higher confidence during recognition of spider pictures, suggesting that memory of objects prompting specific fear is also facilitated in fearful individuals. In line, spider-fearful but not control participants responded with larger ERP positivity for correctly recognized old when compared to correctly rejected new spider pictures, thus showing the same effects in the neural signature of emotional memory for feared objects that were already discovered for other emotional materials. The increased fear memory for phobic materials observed in the present study in spider-fearful individuals might result in an enhanced fear response and reinforce negative beliefs aggravating anxiety symptomatology and hindering recovery.     

Dissociation of neural representation of intensity and affective valuation in human gustation

We used a 2 x 2 factorial design to dissociate regions responding to taste intensity and taste affective valence. Two intensities each of a pleasant and unpleasant taste were presented to subjects during event-related fMRI scanning. The cerebellum, pons, middle insula, and amygdala responded to intensity irrespective of valence. In contrast, valence-specific responses were observed in anterior insula/operculum extending into the orbitofrontal cortex (OFC). The right caudolateral OFC responded preferentially to pleasant compared to unpleasant taste, irrespective of intensity, and the left dorsal anterior insula/operculuar region responded preferentially to unpleasant compared to pleasant tastes equated for intensity. Responses best characterized as an interaction between intensity and pleasantness were also observed in several limbic regions. These findings demonstrate a functional segregation within the human gustatory system. They also show that amygdala activity may be driven by stimulus intensity irrespective of valence, casting doubt upon the notion that the amygdala responds preferentially to negative stimuli.     

Comparative analysis of changes in short EEG segments during music perception based on event-related synchronization/desynchronization and wavelet synchronicity

The goal of the pilot study was to analyze the characteristics of changes in short EEG segments recorded from 32 sites during perception of musical melodies by healthy subjects depending on logical (recognition) and emotional (pleasant/unpleasant) estimation of the melody. For this purpose, the changes in event-related synchronization/desynchronization and the indices of wavelet synchrony of EEG responses were compared in 31 healthy subjects (18 to 60 years old). It has been shown that melody recognition during logical estimation of music is accompanied by event-related desynchronization in the left frontal-parietal-temporal area. Emotional estimation of a melody is characterized by event-related synchronization in the left frontal-temporal area for pleasant melodies, desynchronization in the temporal area for unpleasant melodies, and desynchronization in the occipital area for melodies inducing no emotional response. The analysis of EEG wavelet synchronization characterizing reactive changes in the interaction between cortical areas shows that the most distinct topographic differences are associated with the type of music processing: logical (familiar/unfamiliar) or emotional (pleasant/unpleasant). The changes in interhemispheric connections between the associative cortical areas (central, frontal, temporal) are greater during emotional estimation, while the changes in inter- and intrahemispheric connections between the projection areas of the acoustic analyzer (temporal area) are greater during logical estimation. It is assumed that the revealed event-related synchronization/desynchronization is most likely to reflect the activation component of musical fragment estimation, whereas wavelet analysis provides insight into the character of musical stimulus processing.     

Auditory-olfactory integration: congruent or pleasant sounds amplify odor pleasantness

Even though we often perceive odors while hearing auditory stimuli, surprisingly little is known about auditory-olfactory integration. This study aimed to investigate the influence of auditory cues on ratings of odor intensity and/or pleasantness, with a focus on 2 factors: "congruency" (Experiment 1) and the "halo/horns effect" of auditory pleasantness (Experiment 2). First, in Experiment 1, participants were presented with congruent, incongruent, or neutral sounds before and during the presentation of odor. Participants rated the odors as being more pleasant while listening to a congruent sound than while listening to an incongruent sound. In Experiment 2, participants received pleasant or unpleasant sounds before and during the presentation of either a pleasant or unpleasant odor. The hedonic valence of the sounds transferred to the odors, irrespective of the hedonic tone of the odor itself. The more the participants liked the preceding sound, the more pleasant the subsequent odor became. In contrast, the ratings of odor intensity appeared to be little or not at all influenced by the congruency or hedonic valence of the auditory cue. In conclusion, the present study for the first time provides an empirical demonstration that auditory cues can modulate odor pleasantness.     

Influence of Affective Stimuli on Leg Power Output and Associated Neuromuscular Parameters during Repeated High Intensity Cycling Exercises

The aim of this study was to examine the impact of emotional eliciting pictures on neuromuscular performance during repetitive supramaximal cycling exercises (RSE). In a randomized order, twelve male participants were asked to perform five 6-s cycle sprints (interspaced by 24 s of recovery) on a cycle ergometer in front of neutral, pleasant or unpleasant pictures. During each RSE, mean power output (MPO) and electromyographic activity [root mean square (RMS) and median frequency (MF)] of the vastus lateralis and vastus medialis muscles were analyzed. Neuromuscular efficiency (NME) was calculated as the ratio of MPO to RMS. Higher RMS (232.17 ± 1.17 vs. 201.90 ± 0.47 μV) and MF (68.56 ± 1.78 vs. 64.18 ± 2.17 Hz) were obtained in pleasant compared to unpleasant conditions (p < 0.05). This emotional effect persisted from the first to the last sprint. Higher MPO was obtained in pleasant than in unpleasant conditions (690.65 ± 38.23 vs. 656.73 ± 35.95 W, p < 0.05). However, this emotional effect on MPO was observed only for the two first sprints. NME decreased from the third sprint (p < 0.05), which indicated the occurrence of peripheral fatigue after the two first sprints. These results suggested that, compared with unpleasant pictures, pleasant ones increased the neuromuscular performance during RSE. Moreover, the disappearance of the beneficial effect of pleasant emotion on mechanical output from the third sprint appears to be due to peripheral fatigue.     

The ‘Positive Effect’ Is Present in Older Chinese Adults: Evidence from an Eye Tracking Study

The ''Positive Effect'' is defined as the phenomenon of preferential cognitive processing of positive affective information, and avoidance or dismissal of negative affective information in the social environment. The ‘Positive Effect’ is found for older people compared with younger people in western societies and is believed to reflect a preference for positive emotional regulation in older adults. It is not known whether such an effect is Universal, and in East Asian cultures, there is a highly controversial debate concerning this question. In the current experiment we explored whether Chinese older participants showed a ''Positive Effect'' when they inspected picture pairs that were either a positive or a negative picture presented with a neutral picture, or a positive and negative picture paired together. The results indicated that both groups of participants showed an attentional bias to both pleasant (more processing of) and unpleasant pictures (initial orienting to) when these were paired with neutral pictures. When pleasant and unpleasant pictures were paired together both groups showed an initial orientation bias for the pleasant picture, but the older participants showed this bias for initial orienting and increased processing measures, providing evidence of a ‘Positive Effect’ in older Chinese adults.     

Autonomic Effects of Music in Health and Crohn's Disease: The Impact of Isochronicity,Emotional Valence,and Tempo

BackgroundMusic can evoke strong emotions and thus elicit significant autonomic nervous system (ANS) responses. However, previous studies investigating music-evoked ANS effects produced inconsistent results. In particular, it is not clear (a) whether simply a musical tactus (without common emotional components of music) is sufficient to elicit ANS effects; (b) whether changes in the tempo of a musical piece contribute to the ANS effects; (c) whether emotional valence of music influences ANS effects; and (d) whether music-elicited ANS effects are comparable in healthy subjects and patients with Crohn´s disease (CD, an inflammatory bowel disease suspected to be associated with autonomic dysfunction).MethodsTo address these issues, three experiments were conducted, with a total of n = 138 healthy subjects and n = 19 CD patients. Heart rate (HR), heart rate variability (HRV), and electrodermal activity (EDA) were recorded while participants listened to joyful pleasant music, isochronous tones, and unpleasant control stimuli.ResultsCompared to silence, both pleasant music and unpleasant control stimuli elicited an increase in HR and a decrease in a variety of HRV parameters. Surprisingly, similar ANS effects were elicited by isochronous tones (i.e., simply by a tactus). ANS effects did not differ between pleasant and unpleasant stimuli, and different tempi of the music did not entrain ANS activity. Finally, music-evoked ANS effects did not differ between healthy individuals and CD patients.ConclusionsThe isochronous pulse of music (i.e., the tactus) is a major factor of music-evoked ANS effects. These ANS effects are characterized by increased sympathetic activity. The emotional valence of a musical piece contributes surprisingly little to the ANS activity changes evoked by that piece.     

Pain and Pessimism: Dairy Calves Exhibit Negative Judgement Bias following Hot-Iron Disbudding

Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, but emotional states are difficult to directly assess in animals. Researchers have assessed pain using behavioural and physiological measures, but these approaches are limited to understanding the arousal rather than valence of the emotional experience. Cognitive bias tasks show that depressed humans judge ambiguous events negatively and this technique has been applied to assess emotional states in animals. However, limited research has examined how pain states affect cognitive processes in animals. Here we present the first evidence of cognitive bias in response to pain in any non-human species. In two experiments, dairy calves (n = 17) were trained to respond differentially to red and white video screens and then tested with unreinforced ambiguous colours in two or three test sessions before and two sessions after the routine practice of hot-iron disbudding. After disbudding calves were more likely to judge ambiguous colours as negative. This ‘pessimistic’ bias indicates that post-operative pain following hot-iron disbudding results in a negative change in emotional state.     

Characteristics of electroencephalographic responses induced by a pleasant and an unpleasant odor

More than sensory stimuli, odorous stimuli were employed to facilitate the evocation of emotional responses in the present study. The odor-stimulated emotion was evaluated by investigating specific features of encephalographic (EEG) responses produced thereof. In this study, the concentrations of the same odor were altered; viz., the changes in odor-induced emotional level were compared with the concurrently monitored EEG response features. In addition, we performed the mental task to evoke the arousal state of the brain and investigated the resemblance of response characteristics of the resting state to the post-mental task resting state. Subjects having no abnormalities in the sense of smell included 12 male undergraduate and graduate students (age range: 22-26 years). Experiment I involved 2 types of odors that induced favorable odorous stimuli (pleasant induction); test-solutions were either diluted 150 (easily perceptible odorous sensation) or 500 (slightly perceptible odorous stimuli) times. Experiment II had 2 types of odors that evoked unfavorable odorous stimuli (unpleasant induction), and test-solutions with dilution rates similar to those of pleasant induction were prepared. Odorless distilled water was used as the control in both experiments. From results of rating the odorous stimuli of our compounds used, the candidates were respectively found to be appropriate in inducing the pleasant and unpleasant smell sensations. The analyses of EEG responses on inducing pleasant and unpleasant smell sensations revealed that the EEG activities of the left frontal region were enhanced. This finding may establish the hypothesis of a relationship prevailing between the positive approach-related emotion evoked by the visual sensation and the left hemisphere (Davidson, 1992; Tomarken et al., 1989). In other words, it can be interpreted that the negative withdrawal-related emotion may be associated with activities of the right hemisphere. However, this hypothesis may not be applicable to the unpleasant odors, as the unpleasant emotions are activated by the unpleasant odors not only in the bilateral frontal regions but also over an extensive area of the brain. As such, the pleasant emotions are evoked in the left frontal brain region while the unpleasant emotions are incited in the bilateral frontal and extensive regions in the brain with the odorous stimuli. Moreover, intrinsic EEG activities in response to the pleasant and unpleasant inputs were not observed after performing the mental tasks. In other words, EEG responses reflecting central nervous system activities elevated by loading of the mental tasks as a result of exposure to the pleasant and unpleasant odors may not apparently be observed.     

“Disorganized in time”: Impact of bottom-up and top-down negative emotion generation on memory formation among healthy and traumatized adolescents

“Travelling in time,” a central feature of episodic memory is severely affected among individuals with Post Traumatic Stress Disorder (PTSD) with two opposite effects: vivid traumatic memories are unorganized in temporality (bottom-up processes), non-traumatic personal memories tend to lack spatio-temporal details and false recognitions occur more frequently that in the general population (top-down processes). To test the effect of these two types of processes (i.e. bottom-up and top-down) on emotional memory, we conducted two studies in healthy and traumatized adolescents, a period of life in which vulnerability to emotion is particularly high. Using negative and neutral images selected from the international affective picture system (IAPS), stimuli were divided into perceptual images (emotion generated by perceptual details) and conceptual images (emotion generated by the general meaning of the material). Both categories of stimuli were then used, along with neutral pictures, in a memory task with two phases (encoding and recognition). In both populations, we reported a differential effect of the emotional material on encoding and recognition. Negative perceptual scenes induced an attentional capture effect during encoding and enhanced the recollective distinctiveness. Conversely, the encoding of conceptual scenes was similar to neutral ones, but the conceptual relatedness induced false memories at retrieval. However, among individuals with PTSD, two subgroups of patients were identified. The first subgroup processed the scenes faster than controls, except for the perceptual scenes, and obtained similar performances to controls in the recognition task. The second subgroup group desmonstrated an attentional deficit in the encoding task with no benefit from the distinctiveness associated with negative perceptual scenes on memory performances. These findings provide a new perspective on how negative emotional information may have opposite influences on memory in normal and traumatized individuals. It also gives clues to understand how intrusive memories and overgeneralization takes place in PTSD.     

Time window for cognitive activity involved in emotional processing

Background

From previous studies it is becoming evident that the processing of unpleasant stimuli occurs early (0 to 300 ms); however, it is not clear how cognitive processing related to pleasant/unpleasant emotions occurs at later time windows (≥300 ms). On the other hand, as evident from the previous reports, BIS and BAS personality traits are strongly associated with unpleasant and pleasant responses, respectively. Therefore, in the present study, we aim to identify the time window involved in human pleasant/unpleasant emotional processing by investigating ERP components correlated with BIS/BAS personality traits.

Methods

Twenty-nine men took part in the study and recording ERP during presented sounds. BIS/BAS score was calculated using the Japanese edition of the BIS/BAS questionnaire.

Results

Significant correlation was not observed between BIS and BAS scores. A significant and positive correlation was observed between N100 amplitude and BIS score. A positive correlation was found between BAS fun seeking subscale score and LPP amplitude. Our findings did not contradict previous study results.

Conclusions

Our results suggest that the processing of unpleasant emotions takes place early on, since N100 response was larger in high BIS subjects who are known to be sensitive to unpleasant emotions. LPP was larger in high BAS subjects who are known to be sensitive to pleasant emotions. The LPP was considered to be augmented because the ACC activity level during pleasant emotions reflected on LPP.