Personality modulates the effects of emotional arousal and valence on brain activation

The influence of personality on the neural correlates of emotional processing is still not well characterized. We investigated the relationship between extraversion and neuroticism and emotional perception using functional magnetic resonance imaging (fMRI) in a group of 23 young, healthy women. Using a parametric modulation approach, we examined how the blood oxygenation level dependent (BOLD) signal varied with the participants' ratings of arousal and valence, and whether levels of extraversion and neuroticism were related to these modulations. In particular, we wished to test Eysenck's biological theory of personality, which links high extraversion to lower levels of reticulothalamic-cortical arousal, and neuroticism to increased reactivity of the limbic system and stronger reactions to emotional arousal. Individuals high in neuroticism demonstrated reduced sustained activation in the orbitofrontal cortex (OFC) and attenuated valence processing in the right temporal lobe while viewing emotional images, but an increased BOLD response to emotional arousal in the right medial prefrontal cortex (mPFC). These results support Eysenck's theory, as well as our hypothesis that high levels of neuroticism are associated with attenuated reward processing. Extraversion was inversely related to arousal processing in the right cerebellum, but positively associated with arousal processing in the right insula, indicating that the relationship between extraversion and arousal is not as simple as that proposed by Eysenck.     

Differences in neural activity when processing emotional arousal and valence in autism spectrum disorders

Individuals with autism spectrum disorders (ASD) often have difficulty recognizing and interpreting facial expressions of emotion, which may impair their ability to navigate and communicate successfully in their social, interpersonal environments. Characterizing specific differences between individuals with ASD and their typically developing (TD) counterparts in the neural activity subserving their experience of emotional faces may provide distinct targets for ASD interventions. Thus we used functional magnetic resonance imaging (fMRI) and a parametric experimental design to identify brain regions in which neural activity correlated with ratings of arousal and valence for a broad range of emotional faces. Participants (51 ASD, 84 TD) were group‐matched by age, sex, IQ, race, and socioeconomic status. Using task‐related change in blood‐oxygen‐level‐dependent (BOLD) fMRI signal as a measure, and covarying for age, sex, FSIQ, and ADOS scores, we detected significant differences across diagnostic groups in the neural activity subserving the dimension of arousal but not valence. BOLD‐signal in TD participants correlated inversely with ratings of arousal in regions associated primarily with attentional functions, whereas BOLD‐signal in ASD participants correlated positively with arousal ratings in regions commonly associated with impulse control and default‐mode activity. Only minor differences were detected between groups in the BOLD signal correlates of valence ratings. Our findings provide unique insight into the emotional experiences of individuals with ASD. Although behavioral responses to face‐stimuli were comparable across diagnostic groups, the corresponding neural activity for our ASD and TD groups differed dramatically. The near absence of group differences for valence correlates and the presence of strong group differences for arousal correlates suggest that individuals with ASD are not atypical in all aspects of emotion‐processing. Studying these similarities and differences may help us to understand the origins of divergent interpersonal emotional experience in persons with ASD. Hum Brain Mapp 37:443–461, 2016. © 2015 Wiley Periodicals, Inc.     

An affective circumplex model of neural systems subserving valence, arousal, and cognitive overlay during the appraisal of emotional faces

Increasing evidence supports the existence of distinct neural systems that subserve two dimensions of affect--arousal and valence. Ten adult participants underwent functional magnetic resonance imaging during which they were presented a range of standardized faces and then asked, during the scan, to rate the emotional expressions of the faces along the dimensions of arousal and valence. Lower ratings of arousal accompanied greater activity in the amygdala complex, cerebellum, dorsal pons, and right medial prefrontal cortex (mPFC). More negative ratings of valence accompanied greater activity in the dorsal anterior cingulate (dACC) and parietal cortices. Extreme ratings of valence (highly positive and highly negative ratings) accompanied greater activity in the temporal cortex and fusiform gyrus. Building on an empirical literature which suggests that the amygdala serves as a salience and ambiguity detector, we interpret our findings as showing that a face rated as having low arousal is more ambiguous and a face rated as having extreme valence is more personally salient. This explains how both low arousal and extreme valence lead to greater activation of an ambiguity/salience system subserved by the amygdala, cerebellum, and dorsal pons. In addition, the right medial prefrontal cortex appears to down-regulate individual ratings of arousal, whereas the fusiform and related temporal cortices seem to up-regulate individual assessments of extreme valence when individual ratings are studied relative to group reference ratings for each stimulus. The simultaneous assessment of the effects of arousal and valence proved essential for the identification of neural systems contributing to the processing of emotional faces.     

Similar patterns of cardiovascular response during emotional activation as a function of affective valence and arousal and gender

OBJECTIVE: Laboratory studies of emotion-induced cardiovascular responses have been conducted predominantly with a specific affects approach rather than a dimensional approach. The purpose of this study was to apply the principles of the Circumplex Model of Affect (i.e., valence and arousal) to investigate cardiovascular reactivity during emotional activation in men and women. METHODS: Forty-two healthy university students (mean age = 19.45, 52% women, 58% Caucasian) engaged in personally relevant recall tasks that varied as a function of valence and arousal. Self-reported valence and arousal, systolic and diastolic blood pressure (SBP and DBP, respectively), heart rate (HR), preejection period (PEP), stroke index (SI), cardiac index (CI), and total peripheral resistance (TPR) were measured during baseline and task periods. RESULTS: Cardiovascular responses were found to be largely comparable across the recall tasks and were characterized by significant increases in blood pressure, HR, and TPR, and decreases in SI (Ps < .001). In addition, SBP during negative valence tasks was significantly higher than during positive valence tasks (P < .03), and PEP lengthened more during low as compared to high arousal tasks (P < .03). CONCLUSIONS: These results highlight the similarity of hemodynamic adjustments during the verbal expression of emotion across gender and the dimensions of valence and arousal. The overall response pattern suggests alpha-adrenergically mediated sympathetic activation and vagal withdrawal.     

Nonconscious emotional processing involves distinct neural pathways for pictures and videos

Facial expressions are known to impact observers' behavior, even when they are not consciously identifiable. Relying on visual crowding, a perceptual phenomenon whereby peripheral faces become undiscriminable, we show that participants exposed to happy vs. neutral crowded faces rated the pleasantness of subsequent neutral targets accordingly to the facial expression's valence. Using functional magnetic resonance imaging (fMRI) along with psychophysiological interaction analysis, we investigated the neural determinants of this nonconscious preference bias, either induced by static (i.e., pictures) or dynamic (i.e., videos) facial expressions. We found that while static expressions activated primarily the ventral visual pathway (including task-related functional connectivity between the fusiform face area and the amygdala), dynamic expressions triggered the dorsal visual pathway (i.e., posterior partietal cortex) and the substantia innominata, a structure that is contiguous with the dorsal amygdala. As temporal cues are known to improve the processing of visible facial expressions, the absence of ventral activation we observed with crowded videos questions the capacity to integrate facial features and facial motions without awareness. Nevertheless, both static and dynamic facial expressions activated the hippocampus and the orbitofrontal cortex, suggesting that nonconscious preference judgments may arise from the evaluation of emotional context and the computation of aesthetic evaluation.     

Cross-modal emotional attention: emotional voices modulate early stages of visual processing

Emotional attention, the boosting of the processing of emotionally relevant stimuli, has, up to now, mainly been investigated within a sensory modality, for instance, by using emotional pictures to modulate visual attention. In real-life environments, however, humans typically encounter simultaneous input to several different senses, such as vision and audition. As multiple signals entering different channels might originate from a common, emotionally relevant source, the prioritization of emotional stimuli should be able to operate across modalities. In this study, we explored cross-modal emotional attention. Spatially localized utterances with emotional and neutral prosody served as cues for a visually presented target in a cross-modal dot-probe task. Participants were faster to respond to targets that appeared at the spatial location of emotional compared to neutral prosody. Event-related brain potentials revealed emotional modulation of early visual target processing at the level of the P1 component, with neural sources in the striate visual cortex being more active for targets that appeared at the spatial location of emotional compared to neutral prosody. These effects were not found using synthesized control sounds matched for mean fundamental frequency and amplitude envelope. These results show that emotional attention can operate across sensory modalities by boosting early sensory stages of processing, thus facilitating the multimodal assessment of emotionally relevant stimuli in the environment.     

Common neural substrates for the control and effects of visual attention and perceptual bistability

Behavioral studies have suggested that bistable figure perception is mediated by spatial attention. We tested this hypothesis using event-related functional MRI. During central fixation, two tilted squares containing coherently moving dots were presented in the left and right hemifields. In the attention condition, participants were occasionally cued to shift attention between the squares. In the perception condition, corresponding corners of the squares were connected by horizontal lines producing a perceptually bistable Necker cube figure. Observers reported which of the two faces appeared 'forward' in depth; cues elicited voluntary perceptual reversals. Attending to either square during the attention condition or perceiving either square as forward during the perception condition yielded increased activity in contralateral visual areas. Furthermore, voluntary shifts of attention and voluntary shifts in perceptual configuration were associated with common activity in the posterior parietal cortex, part of the frontoparietal attentional control network. These results support the hypothesis that voluntary shifts in perceptual bistability are mediated by spatial attention.     

Neural correlates of emotional recognition memory in schizophrenia: effects of valence and arousal

Schizophrenia patients are often impaired in their memory for emotional events compared with healthy subjects. Investigations of the neural correlates of emotional memory in schizophrenia patients are scarce in the literature. The present study aimed to compare cerebral activations in schizophrenia patients and healthy controls during memory retrieval of emotional images that varied in both valence and arousal. In a study with functional magnetic resonance imaging, 37 schizophrenia patients were compared with 37 healthy participants while performing a yes/no recognition paradigm with positive, negative (differing in arousal intensity) and neutral images. Schizophrenia patients performed worse than healthy controls in all experimental conditions. They showed less cerebral activation in limbic and prefrontal regions than controls during retrieval of negatively valenced stimuli, but had a similar pattern of brain activation compared with controls during retrieval of positively valenced stimuli (particularly in the high arousal condition) in the cerebellum, temporal lobe and prefrontal cortex. Both groups demonstrated increased brain activations in the high relative to low arousing conditions. Our results suggest atypical brain function during retrieval of negative pictures, but intact functional circuitry of positive affect during episodic memory retrieval in schizophrenia patients. The arousal data revealed that schizophrenia patients closely resemble the control group at both the behavioral and neurofunctional level.     

Cortical activity patterns in ADHD during arousal, activation and sustained attention

Objective

The goal of the present study is to test whether there are Attention-Deficit Hyperactivity Disorder (ADHD)-related differences in brain electrical activity patterns across arousal, activation and vigilance states.

Method

The sample consists of 80 adults (38 with ADHD and 42 non-ADHD controls) who were recruited for a family study on the genetics of ADHD. Patterns of cortical activity were measured using electroencephalography (EEG) during baseline and sustained attention conditions and compared according to ADHD diagnostic status. Cortical activity was examined separately for the first, middle, and last 5-min of the sustained attention task to assess whether patterns differed over time and according to ADHD status.

Results

In frontal and parietal regions, patterns of activation in the alpha (8-10 Hz) range differed according to ADHD status, indicating increased cortical arousal among ADHD subjects. Beta power (13-14 and 17-18 Hz) also differed between ADHD and controls, indicating increased cortical activation is associated with ADHD. Behavioral performance on the sustained attention task did not differ significantly by diagnosis. EEG correlates of cognitive performance differed significantly ADHD diagnosis and were primarily in frontal regions. Brain activation patterns recorded during the sustained attention task suggest that the ADHD group exhibited significantly increased cortical activation at the end of the task when compared to controls.

Conclusions

Adults with ADHD may have different neural organization primarily in frontal regions which results in the need for continually high levels of cortical activation to maintain sustained attention.     

Luminance and spatial attention effects on early visual processing

Event-related potentials (ERPs) were recorded from healthy subjects in response to unilaterally flashed high and low luminance bar stimuli presented randomly to left and right field locations. Their task was to covertly and selectively attend to either the left or right stimulus locations (separate blocks) in order to detect infrequent shorter target bars of either luminance. Independent of attention, higher stimulus luminance resulted in higher ERP amplitudes for the posterior N95 (80–110 ms), occipital P1 (110–140 ms), and parietal N1 (130–180 ms). Brighter stimuli also resulted in shorter peak latency for the occipital N1 component (135–220 ms); this effect was not observed for the N1 components over parietal, central or frontal regions. Significant attention-related amplitude modulations were obtained for the occipital P1, occipital, parietal and central N1, the occipital and parietal P2, and the parietal N2 components; these components were larger to stimuli at the attended location. In contrast to the relatively short latencies of both spatial attention and luminance effects, the first interaction between luminance and spatial attention effects was observed for the P3 component to the target stimuli (350–750 ms). This suggests that interactions of spatial attention and stimulus luminance previously reported for reaction time measures may not reflect the earliest stages of sensory/perceptual processing. Differences in the way in which luminance and attention affected the occipital P1, occipital N1 and parietal N1 components suggest dissociations among these ERPs in the mechanisms of visual and attentional processing they reflect. Nonetheless, scalp current density mappings of the attention effects throughout the latency ranges of the P1 and N1 components show the most prominent attention-related activity to be in lateral occipital scalp areas. Such a pattern is consistent with the spatially selective filtering of information into the ventral stream of visual processing which is reponsible for complex feature analysis and object identification.     

The effects of emotional valence on hemispheric processing of metaphoric word pairs

Recent theories of metaphor comprehension discuss the cognitive substrates involved in processing metaphors. However, the role of valence perception during metaphor comprehension has received little attention. The present study aims to examine the effect of emotional valence on metaphor processing, as well as the interaction between this effect and hemispheric differences. Metaphoric, literal, and meaningless word pairs were presented to 43 participants who performed a semantic judgment task. Results showed that processing of metaphors with negative valence was faster when done in the right hemisphere as compared with the left hemisphere. These findings indicate that emotional valence interacts with cognitive processes of metaphor comprehension. We discuss valence with respect to the class inclusion model and the fine versus coarse semantic coding model of metaphor processing.     

Remembering emotional experiences: the contribution of valence and arousal

Emotional experiences can be described by two factors: valence (how negative or positive) and arousal (how calming or exciting). Although both dimensions appear to influence memory, they may do so via distinct mechanisms. The amygdala likely plays a specific role in modulating memory for arousing experiences, whereas non-amygdalar networks may be instrumental in enhancing memory for non-arousing positive or negative events.     

The influence of gender and emotional valence of visual cues on FMRI activation in humans

Emotional neuroscience maps neurocircuits associated with the processing of affective stimuli. To assess gender differences in brain activation elicited by affective stimuli, we used pictures from the International Affective Picture System in a functional magnetic resonance imaging (fMRI) study. Ten male and ten female age-matched healthy volunteers were included and viewed affectively negative versus positive pictures, which were presented in an event related design. There was a significant interaction between valence of emotional stimuli and gender in the sublenticular extended amygdala (SLEA) and the rostral anterior cingulate. fMRI activation in these regions was stronger for negative compared to positive cues in women. In men fMRI activation was independent of stimulus valence. These results suggest to take gender differences into account when emotional paradigms are tested in functional brain imaging.     

Intermodal auditory, visual, and tactile attention modulates early stages of neural processing

We used event-related potentials (ERPs) and gamma band oscillatory responses (GBRs) to examine whether intermodal attention operates early in the auditory, visual, and tactile modalities. To control for the effects of spatial attention, we spatially coregistered all stimuli and varied the attended modality across counterbalanced blocks in an intermodal selection task. In each block, participants selectively responded to either auditory, visual, or vibrotactile stimuli from the stream of intermodal events. Auditory and visual ERPs were modulated at the latencies of early cortical processing, but attention manifested later for tactile ERPs. For ERPs, auditory processing was modulated at the latency of the Na (29 msec), which indexes early cortical or thalamocortical processing and the subsequent P1 (90 msec) ERP components. Visual processing was modulated at the latency of the early phase of the C1 (62-72 msec) thought to be generated in the primary visual cortex and the subsequent P1 and N1 (176 msec). Tactile processing was modulated at the latency of the N160 (165 msec) likely generated in the secondary association cortex. Intermodal attention enhanced early sensory GBRs for all three modalities: auditory (onset 57 msec), visual (onset 47 msec), and tactile (onset 27 msec). Together, these results suggest that intermodal attention enhances neural processing relatively early in the sensory stream independent from differential effects of spatial and intramodal selective attention.     

Dissociable neural effects of stimulus valence and preceding context during the inhibition of responses to emotional faces

Socially appropriate behavior requires the concurrent inhibition of actions that are inappropriate in the context. This self‐regulatory function requires an interaction of inhibitory and emotional processes that recruits brain regions beyond those engaged by either processes alone. In this study, we isolated brain activity associated with response inhibition and emotional processing in 24 healthy adults using event‐related functional magnetic resonance imaging (fMRI) and a go/no‐go task that independently manipulated the context preceding no‐go trials (ie, number of go trials) and the valence (ie, happy, sad, and neutral) of the face stimuli used as trial cues. Parallel quadratic trends were seen in correct inhibitions on no‐go trials preceded by increasing numbers of go trials and associated activation for correct no‐go trials in inferior frontal gyrus pars opercularis, pars triangularis, and pars orbitalis, temporoparietal junction, superior parietal lobule, and temporal sensory association cortices. Conversely, the comparison of happy versus neutral faces and sad versus neutral faces revealed valence‐dependent activation in the amygdala, anterior insula cortex, and posterior midcingulate cortex. Further, an interaction between inhibition and emotion was seen in valence‐dependent variations in the quadratic trend in no‐go activation in the right inferior frontal gyrus and left posterior insula cortex. These results suggest that the inhibition of response to emotional cues involves the interaction of partly dissociable limbic and frontoparietal networks that encode emotional cues and use these cues to exert inhibitory control over the motor, attention, and sensory functions needed to perform the task, respectively. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.     

Differential amygdala activation to negative and positive emotional pictures during an indirect task

The role of the amygdala for the processing of valence and arousal is a matter of debate. Using event-related functional magnetic resonance imaging, we tested valence-specific amygdala effects during attentional distraction. Subjects attended to a matching task in the foreground of neutral pictures, and of negative and positive pictures matched for arousal. Negative pictures elicited stronger amygdala activation than neutral or positive pictures, suggesting valence-specific amygdala responses under attentional load.     

Fear activation and distraction during the emotional processing of claustrophobic fear

We tested several hypotheses derived from the emotional processing theory of fear reduction by manipulating claustrophobic participants' focus of attention during in vivo exposure. Sixty participants displaying marked claustrophobic fear were randomized to one of four exposure conditions. Each participant received a total of 30-min of self-guided exposure 2-weeks after pretreatment testing. One group attended to threatening words and images during exposure (TW) and was compared to a control group that attended to neutral words and images (NW). A third group performed a demanding cognitive load task--a modified Seashore Rhythm Test during exposure (SR) and was compared to an exposure only (EO) control group. Contrary to prediction, the threat word manipulation was not associated with lower levels of fear following treatment. Consistent with prediction, the distraction manipulation resulted in less fear reduction at post-treatment. Treatment process analyses revealed that the negative effects of distraction on treatment outcome manifested early as slower between-trial habituation. These results and their relevance to emotional processing theory are discussed.     

Electrophysiological correlates of semantic processing during encoding of neutral and emotional pictures in patients with ADHD

The current study investigated the relevance of semantic processing and stimulus salience for memory performance in young ADHD patients and healthy control participants. 18 male ADHD patients and 15 healthy control children and adolescents participated in an ERP study during a visual memory paradigm with two different encoding tasks requiring either perceptual or semantic processing of neutral and emotional pictures. ADHD patients and healthy controls both showed a more negative slow-wave in response to task cues signalling semantic as compared to perceptual stimulus processing. In contrast to ADHD patients, healthy control children showed a larger increase in memory performance for deeply processed neutral pictures which was accompanied by a more positive mid-latency ERP component (so-called P300) after stimulus onset. Our results demonstrate that ADHD patients succeeded in allocating neural resources in preparation of different task demands. However, this increase in preparatory activation to the semantic task cue did not suffice to support successful processing and encoding of neutral stimuli to the same extent as in healthy controls. These findings provide evidence that ADHD patients show deficits in translating pre-stimulus mobilization of neural resources to successful memory formation in the absence of salient stimulus material.     

Effects of social and emotional context on neural activation and synchrony during movie viewing

Sharing emotional experiences impacts how we perceive and interact with the world, but the neural mechanisms that support this sharing are not well characterized. In this study, participants (N = 52) watched videos in an MRI scanner in the presence of an unfamiliar peer. Videos varied in valence and social context (i.e., participants believed their partner was viewing the same (joint condition) or a different (solo condition) video). Reported togetherness increased during positive videos regardless of social condition, indicating that positive contexts may lessen the experience of being alone. Two analysis approaches were used to examine both sustained neural activity averaged over time and dynamic synchrony throughout the videos. Both approaches revealed clusters in the medial prefrontal cortex that were more responsive to the joint condition. We observed a time‐averaged social‐emotion interaction in the ventromedial prefrontal cortex, although this region did not demonstrate synchrony effects. Alternatively, social‐emotion interactions in the amygdala and superior temporal sulcus showed greater neural synchrony in the joint compared to solo conditions during positive videos, but the opposite pattern for negative videos. These findings suggest that positive stimuli may be more salient when experienced together, suggesting a mechanism for forming social bonds.     

Common basal extrastriate areas for the semantic processing of words and pictures.

OBJECTIVE: The recognition potential (RP) is an electrophysiological brain response which is sensitive to the semantic processing of meaningful stimuli. In this study we attempt to elucidate the topography and neural origin of the RP evoked by pictures and to compare it with the RP evoked by words. METHODS: Words, pictures, Chinese characters and control stimuli were presented to 20 subjects following the rapid stream stimulation procedure. The activity was recorded using 60 cephalic electrodes. RESULTS: We found a RP displaying its maximal amplitude at the left inferior parieto-occipital electrode (PO7) for words and at the right homologue electrode (PO8) for pictures and Chinese characters. Both the amplitude and the latency of the RP were larger in the case of words. A profile analysis indicated that the neural generators of the RP were common regardless of the type of stimulus, and a dipole analysis placed them about the lingual gyrus. CONCLUSIONS: Words and pictures share the same neural generators for the RP despite of subtle differences in lateralization. This is interpreted as an index of a multimodal semantic processing in basal extrastriate areas.