Michela Balconi

EEG correlates (event-related desynchronization) of emotional face elaboration: A temporal analysis

An EEG frequency band analysis was conducted, in order to explore the significance of brain oscillations (delta, theta, alpha and beta) for emotional face comprehension during different post-stimulus time intervals (50-150; 150-250; 250-350; and 350-450 ms). The study was conducted on twenty adults who looked at emotional (happy, sad, angry, fearful) or neutral faces. The results showed that motivational significance of the stimulus can modulate the power synchronization (event-related desynchronization (ERD) decrease) within the frequency band of delta and theta. We propose that delta and theta respond to variations in processing stage of emotional face: whereas, delta reflects updating of the stimulus, theta responds to the emotional significance of face. The findings revealed that emotional discrimination by theta is observable mainly within 150-250 time interval and that it is more distributed on anterior regions, whereas delta is maximally synchronized within 250-350 interval and more posteriorly distributed for all the stimulus type. Finally, a right-hemisphere dominance was found for theta during emotional face comprehension.

Brain oscillations and BIS/BAS (behavioral inhibition/activation system) effects on processing masked emotional cues. ERS/ERD and coherence measures of alpha band

Alpha brain oscillation modulation was analyzed in response to masked emotional facial expressions. In addition, behavioural activation (BAS) and behavioural inhibition systems (BIS) were considered as an explicative factor to verify the effect of motivational significance on cortical activity. Nineteen subjects were submitted to an ample range of facial expressions of emotions (anger, fear, surprise, disgust, happiness, sadness, and neutral). The results demonstrated that anterior frontal sites were more active than central and posterior sites in response to facial stimuli. Moreover, right-side responses varied as a function of emotional types, with an increased right-frontal activity for negative emotions. Finally, whereas higher BIS subjects generated a more right hemisphere activation for some negative emotions (such as fear, anger, and surprise), Reward-BAS subjects were more responsive to positive emotion (happiness) within the left hemisphere. Valence and potential threatening power of facial expressions were considered to elucidate these cortical differences.

BIS/BAS, cortical oscillations and coherence in response to emotional cues.

The present study explored the effect of the individual differences related to BIS and BAS (Behavioural Inhibition and Activation System) on brain oscillations, in response to appetitive and aversive emotional stimuli. EEG cortical measures (delta, theta, alpha, and gamma) were recorded, during viewing IAPS figures, that varied in terms of pleasantness and arousal. Withdrawal (BIS system) and appetitive (BAS system) behaviour showed opposite patterns of subjective responses. Also, a specific frontal network was found to be responsive to the relevance of emotional cues. Moreover an increased response for high arousing (negative and positive) stimuli in comparison with low arousing and neutral stimuli was found within the left and right frontal areas. Specifically delta and theta band have a significant role in monitoring the attentional significance of emotions. Finally, the effects of subjective evaluation and individual differences were discussed at light of the two-dimensional model of emotion processing, that is the valence and the arousing power of emotional cues.

Appetitive vs. defensive responses to emotional cues. Autonomic measures and brain oscillation modulation.

The present study explored the effect of the subjective evaluation and the individual differences related to BIS and BAS (Behavioural Inhibition and Activation System) on autonomic measures and brain oscillations, in response to appetitive and aversive emotional stimuli. Multiple measures were recorded, such as psychophysiological (skin conductance response, heart rate, and electromyography) and frequency bands (delta, theta, alpha, and gamma), during viewing IAPS figures, that varied in terms of pleasantness (appetitive vs. aversive) and arousing power (high vs. low intensity). Both BIS and BAS measures were significant in modulating behavioural, autonomic and brain oscillations responses. Withdrawal (BIS system) and appetitive (BAS system) behaviour showed opposite patterns of responses by the subjects. Also, frontal cortical site response was more significant than other sites. Nevertheless, no specific lateralization effect was found as a function of BIS/BAS dichotomy. Moreover, autonomic variables and frequency band modulations were found to be effected by valence and arousal rating per se, with an increased response for high arousing and negative or positive stimuli in comparison with low arousing and neutral stimuli. The effects of subjective evaluation and individual differences were discussed at light of coping activity model of emotion comprehension.

What hemodynamic (fNIRS), electrophysiological (EEG) and autonomic integrated measures can tell us about emotional processing

Due to its fast temporal evolution and its representation and integration among complex and widespread neural networks, the emotion perception process should preferably be examined by means of multimethodological approach. Indeed the indubitable vantage of acquiring both the autonomic (arousal-related) and the central (cortical-related) activities stands in the possibility to better elucidate the reciprocal interplay of the two compartments. In the present study EEG (frequency band analysis), systemic SCR and heart rate (HR) were all recorded simultaneously with hemodynamic (NIRS, Near-Infrared Spectroscopy) measurements as potential biological markers of emotions, related to both central and peripheral systems. These multiple measures were then related to the self-report correlates, that is the subjective appraisal in term of valence (positive vs. negative) and arousal (high vs. low) by using SAM rating. Twenty subjects were submitted to emotional cues processing (IAPS) when fNIRS, frequency bands (alpha, beta, delta, theta), SCR and HR were recorded. As shown by O2Hb increasing within the right hemisphere, the contribution of prefrontal cortex was elucidated, by pointing out a relevant lateralization effect (more right-PFC activity) induced by the specific valence (negative) of the emotional patterns. Secondly, EEG activity (mainly low-frequency theta and delta bands) was intrinsically associated with the cortical hemodynamic responsiveness to the negative emotional patterns, within the right side. Finally SCR increased mainly in response to negative patterns, and the autonomic behavior was related to explicit (SAM) and cortical (NIRS; EEG) activity. The intrinsic relationships between these three different levels are discussed.

FRN and P300 ERP effect modulation in response to feedback sensitivity. The contribution of punishment-reward system (BIS/BAS) and Behaviour Identification of action

Disruption of the sense of being effective and causally determinant in performing an action was explored in the present research by inducing an erroneous external spatial feedback in response to the subjects behaviour. ERPs were recorded from fifteen subjects when they were receiving mismatching/matching feedback information on direction. In addition, subjective sensitivity to the external cues was monitored by Behavioural Inhibition System (BIS) and Behavioural Activation System (BAS) measures, as well as Behaviour Identification process was tested by Behavior Identification Form (BIF). One negative ERP deflections of higher amplitude was revealed in concomitance to false feedback, peaking at about 210ms post-stimulus, more central-posteriorly localized. We supposed that it may represent feedback-error system of which activity might be reflected in FRN, deputed to monitor the unattended feedback furnished by an external system. Moreover, a P3b effect was also observed in great measure for false spatial feedback, more posteriorly (Pz) distributed. According to the context-updating hypothesis, the P3b may reflect the revision of the mental model of the context. BIS showed to be more sensitive to both veridical and false feedback that increased FRN, whereas higher-BAS and BAS-Reward measures revealed an increased proactive attitude to external feedback (higher P3b). Finally, low-level of action representation explained FRN amplitude more than high-level one.

Event‐related oscillations (EROs) and event‐related potentials (ERPs) comparison in facial expression recognition

The study aims to explore the significance of event-related potentials (ERPs) and event-related brain oscillations (EROs) (delta, theta, alpha, beta, gamma power) in response to emotional (fear, happiness, sadness) when compared with neutral faces during 180-250 post-stimulus time interval. The ERP results demonstrated that the emotional face elicited a negative peak at approximately 230 ms (N2). Moreover, EEG measures showed that motivational significance of face (emotional vs. neutral) could modulate the amplitude of EROs, but only for some frequency bands (i.e. theta and gamma bands). In a second phase, we considered the resemblance of the two EEG measures by a regression analysis. It revealed that theta and gamma oscillations mainly effect as oscillation activity at the N2 latency. Finally, a posterior increased power of theta was found for emotional faces.

In the face of emotions: event-related potentials in supraliminal and subliminal facial expression recognition.

Is facial expression recognition marked by specific event-related potentials (ERPs) effects? Are conscious and unconscious elaborations of emotional facial stimuli qualitatively different processes? In Experiment 1, ERPs elicited by supraliminal stimuli were recorded when 21 participants viewed emotional facial expressions of four emotions and a neutral stimulus. Two ERP components (N2 and P3) were analyzed for their peak amplitude and latency measures. First, emotional face-specificity was observed for the negative deflection N2, whereas P3 was not affected by the content of the stimulus (emotional or neutral). A more posterior distribution of ERPs was found for N2. Moreover, a lateralization effect was revealed for negative (right lateralization) and positive (left lateralization) facial expressions. In Experiment 2 (20 participants), 1-ms subliminal stimulation was carried out. Unaware information processing was revealed to be quite similar to aware information processing for peak amplitude but not for latency. In fact, unconscious stimulation produced a more delayed peak variation than conscious stimulation.

Detection of the facial expression of emotion and self-report measures in empathic situations are influenced by sensorimotor circuit inhibition by low-frequency rTMS

BACKGROUND Empathic responses to facial cues are a main social competency. Both appraisal processes (facial emotion detection) and self-perceived empathy (empathic responsiveness) in response to emotional faces are thought to be related to empathic behavior, although no systematic analysis has been performed to assess their relationship. OBJECTIVES The current research explored the contribution of the frontal sensorimotor system to facial detection and self-reported empathic measures by using repetitive transcranial magnetic stimulation (rTMS) to produce a temporary disruption of this specific cortical site. METHODS Eighteen subjects were asked to detect facial expression of emotions (anger, fear, happiness, and neutrality) and to evaluate their empathic responsiveness to these facial cues. A 5-second rTMS (1 Hz, inhibition paradigm) pulse was delivered before the stimulus onset. RESULTS Error rates and response times (RTs) increased when brain activity was disrupted, specifically in response to anger and fear. Self-reported measures showed a concomitant decreased empathic response when the frontal sensorimotor system was deactivated. CONCLUSIONS The ability to monitor emotional cues and the behavioral empathic responsiveness to emotional situations was shown to be partially compromised in the case of frontal activity disruption, highlighting the main role of the sensorimotor system for empathic social skills.

Consciousness and emotional facial expression recognition: subliminal/supraliminal stimulation effect on N200 and P300 ERPs

Abstract. In this study we analyze whether facial expression recognition is marked by specific event-related potential (ERP) correlates and whether conscious and unconscious elaboration of emotional facial stimuli are qualitatively different processes. ERPs elicited by supraliminal and subliminal (10 ms) stimuli were recorded when subjects were viewing emotional facial expressions of four emotions or neutral stimuli. Two ERP effects (N2 and P3) were analyzed in terms of their peak amplitude and latency variations. An emotional specificity was observed for the negative deflection N2, whereas P3 was not affected by the content of the stimulus (emotional or neutral). Unaware information processing proved to be quite similar to aware processing in terms of peak morphology but not of latency. A major result of this research was that unconscious stimulation produced a more delayed peak variation than conscious stimulation did. Also, a more posterior distribution of the ERP was found for N2 as a function of emot...