MMN responses during implicit processing of changes in emotional prosody: an ERP study using Chinese pseudo-syllables

In this study, we tested the underlying mechanisms of early emotional prosody perception, especially examined whether change detection in oddball paradigm was caused by emotional category and physical properties. Using implicit oddball paradigms, the current study manipulated the cues for detecting deviant stimuli from standards in three conditions: the simultaneous changes in emotional category and physical properties (EP condition), change in emotional category alone (E condition), and change in physical properties alone (P condition). ERP results revealed that physical property change increased brain responses to deviant stimuli in the EP than in the E condition at early stage 90–160 ms, suggesting that physical property change of emotional sounds can also be detected at the early stage. At the later stage 160–260 ms, the simultaneous and respective changes in emotional category and physical properties were reliably detected, and the sum of the brain responses to the corresponding changes in E and P conditions was equal to the brain responses to the simultaneous changes in EP condition. Source analysis further revealed that stimuli-driven regions (inferior parietal lobule), temporal and frontal cortices were activated at early stage, while only frontal cortices for higher cognitive processing were activated at later stage. These findings suggest that emotional prosody changes in physical properties and emotion category are perceived as domain-general change information in emotional prosody perception.     

An Event-Related Potential Study on the Effects of Cannabis on Emotion Processing

The effect of cannabis on emotional processing was investigated using event-related potential paradigms (ERPs). ERPs associated with emotional processing of cannabis users, and non-using controls, were recorded and compared during an implicit and explicit emotional expression recognition and empathy task. Comparisons in P3 component mean amplitudes were made between cannabis users and controls. Results showed a significant decrease in the P3 amplitude in cannabis users compared to controls. Specifically, cannabis users showed reduced P3 amplitudes for implicit compared to explicit processing over centro-parietal sites which reversed, and was enhanced, at fronto-central sites. Cannabis users also showed a decreased P3 to happy faces, with an increase to angry faces, compared to controls. These effects appear to increase with those participants that self-reported the highest levels of cannabis consumption. Those cannabis users with the greatest consumption rates showed the largest P3 deficits for explicit processing and negative emotions. These data suggest that there is a complex relationship between cannabis consumption and emotion processing that appears to be modulated by attention.     

Dissociation of Neural Substrates of Response Inhibition to Negative Information between Implicit and Explicit Facial Go/Nogo Tasks: Evidence from an Electrophysiological Study

Background

Although ample evidence suggests that emotion and response inhibition are interrelated at the behavioral and neural levels, neural substrates of response inhibition to negative facial information remain unclear. Thus we used event-related potential (ERP) methods to explore the effects of explicit and implicit facial expression processing in response inhibition.

Methods

We used implicit (gender categorization) and explicit emotional Go/Nogo tasks (emotion categorization) in which neutral and sad faces were presented. Electrophysiological markers at the scalp and the voxel level were analyzed during the two tasks.

Results

We detected a task, emotion and trial type interaction effect in the Nogo-P3 stage. Larger Nogo-P3 amplitudes during sad conditions versus neutral conditions were detected with explicit tasks. However, the amplitude differences between the two conditions were not significant for implicit tasks. Source analyses on P3 component revealed that right inferior frontal junction (rIFJ) was involved during this stage. The current source density (CSD) of rIFJ was higher with sad conditions compared to neutral conditions for explicit tasks, rather than for implicit tasks.

Conclusions

The findings indicated that response inhibition was modulated by sad facial information at the action inhibition stage when facial expressions were processed explicitly rather than implicitly. The rIFJ may be a key brain region in emotion regulation.     

The contribution of sound intensity in vocal emotion perception: behavioral and electrophysiological evidence

Although its role is frequently stressed in acoustic profile for vocal emotion, sound intensity is frequently regarded as a control parameter in neurocognitive studies of vocal emotion, leaving its role and neural underpinnings unclear. To investigate these issues, we asked participants to rate the angry level of neutral and angry prosodies before and after sound intensity modification in Experiment 1, and recorded electroencephalogram (EEG) for mismatching emotional prosodies with and without sound intensity modification and for matching emotional prosodies while participants performed emotional feature or sound intensity congruity judgment in Experiment 2. It was found that sound intensity modification had significant effect on the rating of angry level for angry prosodies, but not for neutral ones. Moreover, mismatching emotional prosodies, relative to matching ones, induced enhanced N2/P3 complex and theta band synchronization irrespective of sound intensity modification and task demands. However, mismatching emotional prosodies with reduced sound intensity showed prolonged peak latency and decreased amplitude in N2/P3 complex and smaller theta band synchronization. These findings suggest that though it cannot categorically affect emotionality conveyed in emotional prosodies, sound intensity contributes to emotional significance quantitatively, implying that sound intensity should not simply be taken as a control parameter and its unique role needs to be specified in vocal emotion studies.     

Features of temporal dynamics of oscillatory brain activity during creative problem solving in young and elderly adults

Considering evidence from psychological research, successful aging is accompanied by long-term preservation of creative potential despite slowing of mental processes; however, the neurophysiological mechanisms that ensure the maintenance of those abilities are unclear. In this study, we compared temporal dynamics of changes induced by divergent task electrical activity (event-related spectral perturbations, ERSP) in a wide range of EEG frequencies in the younger (YA, N = 80, 22.6 ± 3 years) and older (OA, N = 80, 63.4 ± 6.7 years) age groups. The groups were sex-matched. EEG was recorded while participants performed the “alternate uses task”. The time ranges 200–400, 400–600 and 600–800 ms after stimulus presentation were analyzed. It was found that task performance was associated with distinct patterns of ERSP changes in the θ and α₃ rhythms in young and elderly subjects. The elderly subjects exhibited smaller θ-desyn-chronization of anterior brain areas at the initial stage of creative thinking as compared to young participants. The gradient of fronto-parietal activation was unchanged during the entire interval of analysis in the elderly subjects, whereas it was observed in young adults in the interval 200–400 ms only. Decrease in desynchronization of the parieto-occipital area in the α₃ rhythm in the interval 600–800 ms in elderly subjects was revealed, and it resulted in disappearance of differences between parietal and fronto-temporal areas, while they were preserved in the young group. Significant correlations between ERSP in the α₃ band and originality, in the β₁ band and solution rate were obtained in old adults exclusively. Identified age-related changes in oscillatory activity may be the basis of different strategies in solving creative task in young and elderly adults.     

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.     

Asymmetric Engagement of Amygdala and Its Gamma Connectivity in Early Emotional Face Processing

The amygdala has been regarded as a key substrate for emotion processing. However, the engagement of the left and right amygdala during the early perceptual processing of different emotional faces remains unclear. We investigated the temporal profiles of oscillatory gamma activity in the amygdala and effective connectivity of the amygdala with the thalamus and cortical areas during implicit emotion-perceptual tasks using event-related magnetoencephalography (MEG). We found that within 100 ms after stimulus onset the right amygdala habituated to emotional faces rapidly (with duration around 20–30 ms), whereas activity in the left amygdala (with duration around 50–60 ms) sustained longer than that in the right. Our data suggest that the right amygdala could be linked to autonomic arousal generated by facial emotions and the left amygdala might be involved in decoding or evaluating expressive faces in the early perceptual emotion processing. The results of effective connectivity provide evidence that only negative emotional processing engages both cortical and subcortical pathways connected to the right amygdala, representing its evolutional significance (survival). These findings demonstrate the asymmetric engagement of bilateral amygdala in emotional face processing as well as the capability of MEG for assessing thalamo-cortico-limbic circuitry.     

情绪面孔对听觉通道短时距内隐知觉的影响

时间知觉是人类的一项基本能力.日常生活经验表明时间知觉容易受到情绪的影响.但是在前人的研究中,这些影响往往伴随着主动注意和外显的运动反应.这里关注的是不伴随主动注意和外显运动反应的内隐时间知觉是否受到情绪面孔的影响.被试在主动完成一个由情绪面孔组成的视觉辨别任务的同时,被动地听一系列声音刺激.声音刺激的刺激启动异步时间(stimulus onset asynchrony,SOA)中,80%是标准SOA(800ms),20%是偏差SOA(400,600 ms).对频繁出现的标准SOA和偶尔出现的偏差SOA诱发的事件相关电位(event-related potential,ERP)进行记录.2个短的偏差SOA(400和600ms)引发了2个变化相关的ERP成分:失匹配负波(the mismatch negativity,MMN)和P3a.代表对无规律变化早期检测的MMN波幅受到了情绪面孔的影响.与愉快和中性面孔相比,恐惧面孔降低了MMN波幅.对于400ms偏差SOA,与恐惧面孔和中性面孔相比,愉快面孔增加了P3a波幅.该ERP研究提示听觉通道的内隐时间知觉受到情绪面孔的影响,恐惧面孔降低了内隐时间知觉的准确性.     

Affective pictures processing is reflected by an increased long-distance EEG connectivity

Analysis of affective picture processing by means of EEG has invaded the literature. The methodology of event-related EEG coherence is one of the essential methods used to analyze functional connectivity. The aims of the present study are to find out the long range EEG connectivity changes in perception of different affective pictures and analyze gender differences in these long range connected networks. EEGs of 28 healthy subjects (14 female) were recorded at 32 locations. The participants passively viewed emotional pictures (IAPS, unpleasant, pleasant, neutral). The long-distance intra-hemispheric event-related coherence was analyzed for delta (1–3.5 Hz), theta (4–7.5 Hz), and alpha (8–13 Hz) frequency ranges for F₃–T₇, F₄–T₈, F₃–TP₇, F₄–TP₈, F₃–P₃, F₄–P₄, F₃–O₁, F₄–O₂, C₃–O₁, C₄–O₂ electrode pairs. Unpleasant pictures elicited significantly higher delta coherence values than neutral pictures (p < 0.05), over fronto-parietal, fronto-occipital, and centro-occipital electrode pairs. Furthermore, unpleasant pictures elicited higher theta coherence values than pleasant (p < 0.05) and neutral pictures (p < 0.05). The present study showed that female subjects had higher delta (p < 0.05) and theta (p < 0.05) coherence values than male subjects. This difference was observed more for emotional pictures than for neutral pictures. This study showed that the brain connectivity was higher during emotional pictures than neutral pictures. Females had higher connectivity between different parts of the brain than males during emotional processes. According to these results, we may comment that increased valence and arousal caused increased brain activity. It seems that not just single sources but functional networks were also activated during perception of emotional pictures.     

Implicit Processing of Visual Emotions Is Affected by Sound-Induced Affective States and Individual Affective Traits

The ability to recognize emotions contained in facial expressions are affected by both affective traits and states and varies widely between individuals. While affective traits are stable in time, affective states can be regulated more rapidly by environmental stimuli, such as music, that indirectly modulate the brain state. Here, we tested whether a relaxing or irritating sound environment affects implicit processing of facial expressions. Moreover, we investigated whether and how individual traits of anxiety and emotional control interact with this process. 32 healthy subjects performed an implicit emotion processing task (presented to subjects as a gender discrimination task) while the sound environment was defined either by a) a therapeutic music sequence (MusiCure), b) a noise sequence or c) silence. Individual changes in mood were sampled before and after the task by a computerized questionnaire. Additionally, emotional control and trait anxiety were assessed in a separate session by paper and pencil questionnaires. Results showed a better mood after the MusiCure condition compared with the other experimental conditions and faster responses to happy faces during MusiCure compared with angry faces during Noise. Moreover, individuals with higher trait anxiety were faster in performing the implicit emotion processing task during MusiCure compared with Silence. These findings suggest that sound-induced affective states are associated with differential responses to angry and happy emotional faces at an implicit stage of processing, and that a relaxing sound environment facilitates the implicit emotional processing in anxious individuals.     

The time course of the influence of valence and arousal on the implicit processing of affective pictures

In the current study, we investigated the time course of the implicit processing of affective pictures with an orthogonal design of valence (negative vs. positive) by arousal (low vs. high). Previous studies with explicit tasks suggested that valence mainly modulates early event-related potential (ERP) components, whereas arousal mainly modulates late components. However, in this study with an implicit task, we observed significant interactions between valence and arousal at both early and late stages over both parietal and frontal sites, which were reflected by three different ERP components: P2a (100-200 ms), N2 (200-300 ms), and P3 (300-400 ms). Furthermore, there was also a significant main effect of arousal on P2b (200-300 ms) over parieto-occipital sites. Our results suggest that valence and arousal effects on implicit affective processing are more complicated than previous ERP studies with explicit tasks have revealed.     

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.     

Frontal EEG Activation Asymmetry Reflects Cognitive Biases in Anxiety: Evidence from an Emotional Face Stroop Task

Electroencephalography (EEG) has been extensively used in studies of the frontal asymmetry of emotion and motivation. This study investigated the midfrontal EEG activation, heart rate and skin conductance during an emotional face analog of the Stroop task, in anxious and non-anxious participants. In this task, the participants were asked to identify the expression of calm, fearful and happy faces that had either a congruent or incongruent emotion name written across them. Anxious participants displayed a cognitive bias characterized by facilitated attentional engagement with fearful faces. Fearful face trials induced greater relative right frontal activation, whereas happy face trials induced greater relative left frontal activation. Moreover, anxiety specifically modulated the magnitude of the right frontal activation to fearful faces, which also correlated with the cognitive bias. Therefore, these results show that frontal EEG activation asymmetry reflects the bias toward facilitated processing of fearful faces in anxiety.     

The Insular Cortex: Relationship to Skin Conductance Responses to Facial Expression of Emotion in Temporal Lobe Epilepsy

The insula plays an important role both in emotion processing and in the generation of epileptic seizures. In the current study we examined thickness of insular cortices and bilateral skin conductance responses (SCR) in healthy subjects in addition to a small number of patients with temporal lobe epilepsy. SCR measures arousal and is used to assess non-conscious responses to emotional stimuli. We used two emotion tasks, one explicitly about emotion and the other implicit. The explicit task required judgments about emotions being expressed in photographs of faces, while the implicit one required judgments about the age of the people in the photographs. Patients and healthy differed in labeling neutral faces, but not other emotions. They also differed in their SCR to emotions, though the profile depended on which hand the recordings were from. Finally, we found relationships between the thickness of the insula and SCR to each task: in the healthy group the thickness of the left insula was related to SCR to the emotion-labeling task; in the patient group it was between the thickness of the right insula and SCR in the age-labeling task. These patterns were evident only for the right hand recordings, thus underscoring the importance of bilateral recordings.     

Individual Differences in Detecting Rapidly Presented Fearful Faces

Rapid detection of evolutionarily relevant threats (e.g., fearful faces) is important for human survival. The ability to rapidly detect fearful faces exhibits high variability across individuals. The present study aimed to investigate the relationship between behavioral detection ability and brain activity, using both event-related potential (ERP) and event-related oscillation (ERO) measurements. Faces with fearful or neutral facial expressions were presented for 17 ms or 200 ms in a backward masking paradigm. Forty-two participants were required to discriminate facial expressions of the masked faces. The behavioral sensitivity index d'' showed that the detection ability to rapidly presented and masked fearful faces varied across participants. The ANOVA analyses showed that the facial expression, hemisphere, and presentation duration affected the grand-mean ERP (N1, P1, and N170) and ERO (below 20 Hz and lasted from 100 ms to 250 ms post-stimulus, mainly in theta band) brain activity. More importantly, the overall detection ability of 42 subjects was significantly correlated with the emotion effect (i.e., fearful vs. neutral) on ERP (r = 0.403) and ERO (r = 0.552) measurements. A higher d'' value was corresponding to a larger size of the emotional effect (i.e., fearful – neutral) of N170 amplitude and a larger size of the emotional effect of the specific ERO spectral power at the right hemisphere. The present results suggested a close link between behavioral detection ability and the N170 amplitude as well as the ERO spectral power below 20 Hz in individuals. The emotional effect size between fearful and neutral faces in brain activity may reflect the level of conscious awareness of fearful faces.     

Implicit Binding of Facial Features During Change Blindness

Change blindness refers to the inability to detect visual changes if introduced together with an eye-movement, blink, flash of light, or with distracting stimuli. Evidence of implicit detection of changed visual features during change blindness has been reported in a number of studies using both behavioral and neurophysiological measurements. However, it is not known whether implicit detection occurs only at the level of single features or whether complex organizations of features can be implicitly detected as well. We tested this in adult humans using intact and scrambled versions of schematic faces as stimuli in a change blindness paradigm while recording event-related potentials (ERPs). An enlargement of the face-sensitive N170 ERP component was observed at the right temporal electrode site to changes from scrambled to intact faces, even if the participants were not consciously able to report such changes (change blindness). Similarly, the disintegration of an intact face to scrambled features resulted in attenuated N170 responses during change blindness. Other ERP deflections were modulated by changes, but unlike the N170 component, they were indifferent to the direction of the change. The bidirectional modulation of the N170 component during change blindness suggests that implicit change detection can also occur at the level of complex features in the case of facial stimuli.     

Seeing emotion with your ears: emotional prosody implicitly guides visual attention to faces

Interpersonal communication involves the processing of multimodal emotional cues, particularly facial expressions (visual modality) and emotional speech prosody (auditory modality) which can interact during information processing. Here, we investigated whether the implicit processing of emotional prosody systematically influences gaze behavior to facial expressions of emotion. We analyzed the eye movements of 31 participants as they scanned a visual array of four emotional faces portraying fear, anger, happiness, and neutrality, while listening to an emotionally-inflected pseudo-utterance (Someone migged the pazing) uttered in a congruent or incongruent tone. Participants heard the emotional utterance during the first 1250 milliseconds of a five-second visual array and then performed an immediate recall decision about the face they had just seen. The frequency and duration of first saccades and of total looks in three temporal windows ([0-1250 ms], [1250-2500 ms], [2500-5000 ms]) were analyzed according to the emotional content of faces and voices. Results showed that participants looked longer and more frequently at faces that matched the prosody in all three time windows (emotion congruency effect), although this effect was often emotion-specific (with greatest effects for fear). Effects of prosody on visual attention to faces persisted over time and could be detected long after the auditory information was no longer present. These data imply that emotional prosody is processed automatically during communication and that these cues play a critical role in how humans respond to related visual cues in the environment, such as facial expressions.     

Event-related Potential Study of the Effects of Emotional Facial Expressions on Task Performance in Euthymic Bipolar Patients

There appears to be a significant disconnect between symptomatic and functional recovery in bipolar disorder (BD). Some evidence points to interepisode cognitive dysfunction. We tested the hypothesis that some of this dysfunction was related to emotional reactivity in euthymic bipolar subjects may effect cognitive processing. A modification of emotional gender categorization oddball task was used. The target was gender (probability 25%) of faces with negative, positive, and neutral emotional expression. The experiment had 720 trials (3 blocks × 240 trials each). Each stimulus was presented for 150 ms, and the EEG/ERP responses were recorded for 1,000 ms. The inter-trial interval was varied in 1,100–1,500 ms range to avoid expectancy effects. Task took about 35 min to complete. There were 9 BD and 9 control subjects matched for age and gender. Reaction time (RT) was globally slower in BD subjects. The centro-parietal amplitudes at N170 and N200, and P200 and P300 were generally smaller in the BD group compared to controls. Latency was shorter to neutral and negative targets in BD. Frontal P200 amplitude was higher to emotional negative facial non-targets in BD subjects. The frontal N200 in response to positive facial emotion was less negative in BD subjects. The frontal P300 of BD subjects was lower to emotionally neutral targets. ERP responses to facial emotion in BD subjects varied significantly from normal controls. These variations are consistent with the common depressive symptomology seen in long term studies of bipolar subjects.     

Circadian and homeostatic modulation of the attentional blink

An important property of attention is the limitation to process new information after responding to a stimulus. This property of attention can be evaluated by the Attentional Blink (AB), a phenomenon that consists of a failure to detect the second of two targets when the interval between them is 200–500 ms. The aim of the present work is to determine the possible existence of time awake (homeostatic changes) and time of day (circadian rhythm) variations in the AB. Eighteen undergraduate students, 11 men and 7 women, age = 18.06 ± 1.16 years, participated voluntarily in this research. They were recorded in a constant routine protocol during 29 h, in which rectal temperature was recorded every minute, while subjective sleepiness and responses to a Rapid Serial Visual Presentation (RSVP) task, to measure the AB, were recorded every hour. Homeostatic and circadian variations in all parameters of the RSVP task were observed, including changes in the capacity to process a new stimulus (Target 1 accuracy), a second stimulus occurring in a short interval after the first (Target 2 accuracy at lag 2, 200 ms) and to process another successive independent stimulus (Target 2 accuracy at lag 8, 800 ms). The acrophase of these parameters occurred with a phase delay of 2 h compared to the circadian rhythm of rectal temperature. The AB magnitude, an index of the AB, showed a decline with time awake, but no variations with time of day. In conclusion, there are homeostatic and circadian variations in the capacity to process any incoming information, especially in tasks with brief duration stimuli presented at a high frequency.     

Effect of high dose cytosine arabinoside on quantitative EEG in patients with acute myeloid leukemia

Background EEG activity is considered an index of functional state of brain. Chemotherapy (CT), used for non-central nervous system (CNS) cancer, can cross the blood brain barrier and contribute to changes in the functional state of brain that can alter background EEG activity. Quantitative EEG (qEEG) is superior to conventional EEG in the detection of subtle alterations of EEG background activity and for this reason, the use of qEEG might assist the clinician in evaluating the possible effect of CT on the CNS. The nucleoside analog cytosine arabinoside (Ara-C) is one of the milestone chemotherapeutic agents used for treatment of acute myeloid leukemia (AML). Our observational study evaluates the possible effect of Ara-C on the qEEG of patients with AML, without CNS involvement. We conducted an observational study on newly diagnosed AML patients without CNS involvement, undergoing treatment with Ara-C to analyze the possible effect of Ara-C high doses on EEG background activity using qEEG analyses. A total of nine AML patients, 5 with Ara-C i.v. high dose (≥3 g/m² die), 4 with standard dose (100 mg/m² die) underwent qEEG (at rest, during hyperpnoea, mental arithmetic task and blocking reaction). We compared the EEG background activity of the two groups at baseline and after 6 months. Statistical analysis showed no significant differences between the two groups in mean relative power for all frequency bands, at rest and during hyperpnoea, mental arithmetic task and blocking reaction. Our data indicate that high dose Ara-C i.v. did not induce significant changes on EEG background activity in our patients. Future research in this area could include prospective studies that would combine qEEG and neuropsychological testing to assess the impact of CT on brain functions.