Refine
Document Type
- Article (15)
Language
- English (15)
Has Fulltext
- yes (15)
Is part of the Bibliography
- no (15)
Keywords
- - (8)
- emotion recognition (2)
- empathy (2)
- social cognition (2)
- vagus nerve (2)
- EEG (1)
- P300 (1)
- alexithymia (1)
- anxiety disorders (1)
- attentive immobility (freezing) (1)
Institute
Publisher
- Frontiers Media S.A. (5)
- Frontiers (3)
- Nature Publishing Group (1)
- Oxford Universitxy Press (1)
- S. Karger AG (1)
- SAGE Publications (1)
- Sage (1)
- Springer Nature (1)
Abstract
During fear conditioning, a cue (CS) signals an inevitable distal threat (US) and evokes a conditioned response that can be described as attentive immobility (freezing). The organism remains motionless and monitors the source of danger while startle responses are potentiated, indicating a state of defensive hypervigilance. Although in animals vagally mediated fear bradycardia is also reliably observed under such circumstances, results are mixed in human fear conditioning. Using a single‐cue fear conditioning and extinction protocol, we tested cardiac reactivity and startle potentiation indexing low‐level defensive strategies in a fear‐conditioned (n = 40; paired presentations of CS and US) compared with a non‐conditioned control group (n = 40; unpaired presentations of CS and US). Additionally, we assessed shock expectancy ratings on a trial‐by‐trial basis indexing declarative knowledge of the previous contingencies. Half of each group underwent extinction under sham or active transcutaneous vagus nerve stimulation (tVNS), serving as additional proof of concept. We found stronger cardiac deceleration during CS presentation in the fear learning relative to the control group. This learned fear bradycardia was positively correlated with conditioned startle potentiation but not with declarative knowledge of CS‐US contingencies. TVNS abolished differences in heart rate changes between both groups and removed the significant correlation between late cardiac deceleration and startle potentiation in the fear learning group. Results suggest, fear‐conditioned cues evoke attentive immobility in humans, characterized by cardiac deceleration and startle potentiation. Such defensive response pattern is elicited by cues predicting inevitable distal threat and resembles conditioned fear responses observed in rodents.
Individual responses to behavioral treatment of anxiety disorders vary considerably, which requires a better understanding of underlying processes. In this study, we examined the violation and change of threat beliefs during exposure. From 8,484 standardized exposure records of 605 patients with different anxiety disorders, learning indicators were derived: expectancy violation as mismatch between threat expectancy before exposure and threat occurrence, expectancy change as difference between original and adjusted expectancy after exposure, and prediction-error learning rate as extent to which expectancy violation transferred into change. Throughout sessions, high threat expectancy but low occurrence and adjusted expectancy indicated successful violation and change of threat beliefs by exposure. Expectancy violation, change, and learning rate substantially varied between patients. Not expectancy violation itself, but higher learning rate and expectancy change predicted better treatment outcome. Successful exposure thus requires expectancy violation to induce actual expectancy change, supporting learning from prediction error as transdiagnostic mechanism underlying successful exposure therapy.
The ventromedial prefrontal cortex (vmPFC) mediates the inhibition of defensive responses upon encounters of cues, that had lost their attribute as a threat signal via previous extinction learning. Here, we investigated whether such fear extinction recall can be facilitated by anodal transcranial direct current stimulation (tDCS). Extinction recall was tested twenty-four hours after previously acquired fear was extinguished. Either anodal tDCS or sham stimulation targeting the vmPFC was applied during this test. After stimulation ceased, we examined return of fear after subjects had been re-exposed to aversive events. Fear was assessed by reports of threat expectancy and modulations of autonomic (skin conductance, heart rate) and protective reflex (startle potentiation) measures, the latter of which are mediated by subcortical defense circuits. While tDCS did not affect initial extinction recall, it abolished the return of startle potentiation and autonomic components of the fear response. Results suggest hierarchical multi-level vmPFC functions in human fear inhibition and indicate, that its stimulation might immunize against relapses into pathological subcortically mediated defensive activation.
Structural integrity of the insula and emotional facial recognition performance following stroke
(2023)
The role of the human insula in facial emotion recognition is controversially discussed, especially in relation to lesion-location-dependent impairment following stroke. In addition, structural connectivity quantification of important white-matter tracts that link the insula to impairments in facial emotion recognition has not been investigated. In a case–control study, we investigated a group of 29 stroke patients in the chronic stage and 14 healthy age- and gender-matched controls. Lesion location of stroke patients was analysed with voxel-based lesion-symptom mapping. In addition, structural white-matter integrity for tracts between insula regions and their primarily known interconnected brain structures was quantified by tractography-based fractional anisotropy. Our behavioural analyses showed that stroke patients were impaired in the recognition of fearful, angry and happy but not disgusted expressions. Voxel-based lesion mapping revealed that especially lesions centred around the left anterior insula were associated with impaired recognition of emotional facial expressions. The structural integrity of insular white-matter connectivity was decreased for the left hemisphere and impaired recognition accuracy for angry and fearful expressions was associated with specific left-sided insular tracts. Taken together, these findings suggest that a multimodal investigation of structural alterations has the potential to deepen our understanding of emotion recognition impairments after stroke.
Chills are emotional peaks especially in response toward acoustic stimuli. In the present study, we examined facial expressions associated with pleasant and unpleasant chill experiences during music and harsh sounds by measuring electromyographic activity from facial corrugator and zygomatic muscles. A rubber bulb could be pressed by the participants to report chill intensities. During harsh sounds, increased activation of both corrugator and zygomatic muscle was observed. Zygomatic muscle activity was even more pronounced when a chill experience was reported during such sounds. In contrast, pleasant chill experiences during music were associated with slightly increased corrugator activity compared with absent chills. Our data suggest that harsh sounds produce a painful facial expression that is even intensified when a chill experience is reported. Increased corrugator activity during chills toward music might refer to states of being moved. The results are discussed in the light of a proposed role of the chill in regulating social behavior. Our results suggest that recording facial muscle activity can be a valuable method for the examination of pleasant and unpleasant peak emotions induced by acoustic stimuli.