Threat Of Electric Shock Research Articles

Does attachment in adolescence predict neural responses to handholding in adulthood? A functional magnetic resonance imaging study.

Early life experiences, including attachment-related experiences, inform internal working models that guide adult relationship behaviors. Few studies have examined the association between adolescent attachment and adult relationship behavior on a neural level. The current study examined attachment in adolescence and its associations with neural correlates of relationship behaviors in adulthood. 85 participants completed the Adult Attachment Interview (AAI) at age 14. Ten years later, at age 24, participants underwent functional brain image when participants were under the threat of electric shock alone, holding the hand of a stranger, or their partner. We found that adolescents who were securely attached at age 14 showed increased activation in regions commonly associated with cognitive, affective, and reward processing when they held the hand of their partner and stranger compared to being alone. Adolescents with higher preoccupied attachment scores showed decreased activation in similar regions only during the stranger handholding condition compared to being alone. These findings suggest that adolescent attachment predicts adult social relationship behaviors on a neural level, in regions largely consistent with previous literature. Broadly, this study has implications for understanding long-term links between attachment and adult relationship behaviors and has potential for informing intervention.

Infection with an acanthocephalan helminth reduces anxiety-like behaviour in crustacean host

Trophically transmitted heteroxenous parasites of diverse clades can decrease or reverse antipredator behaviours in their intermediate hosts, thereby increasing their chances of reaching their final hosts. Such behavioural alterations could result from compromised cognitive abilities affecting fear- or more generally stress-related neurophysiological pathways. We tested this hypothesis in a key model system in the study of parasitic manipulation, the fish acanthocephalan parasite Pomphorhynchus tereticollis and its intermediate crustacean host Gammarus fossarum, using the ‘threat of electric shock’ paradigm. We exposed uninfected and infected G. fossarum to chronic and/or acute electric shock programs at two different intensities (voltage), and then quantified their sheltering behaviour as a proxy for anxiety-like state. Infected gammarids did not express anxiety-like response to electric shocks, while uninfected gammarids hid more when exposed to acute treatments, and when exposed to the high intensity chronic treatment. Interestingly, the lack of response in infected gammarids depended on parasite developmental stage. Our results support the hypothesis that this acanthocephalan parasite impacts the general anxiety-like circuitry of their intermediate host. Further studies are needed to investigate whether it involves inappropriate processing of information, impaired integration, or altered activation of downstream pathways initiating behavioural action.

Threat Sensitivity is Related to Enhanced Contingent Negative Variation Amplitude During an Attention Network Test Under Threat of Shock

Threat sensitivity is a heritable trait that reflects fearful tendencies in a variety of contexts and is considered a vulnerability factor for anxiety psychopathology. The contingent negative variation (CNV) is a negative-going event-related potential component that is elicited following the presentation of warning stimuli. It is thought to reflect cortical activity governing anticipation and preparation. The current study investigated the relationship between threat sensitivity and CNV amplitude during an attention network test (ANT) under threat of electric shock.

Instructed threat enhances threat perception in faces.

Anxiety can boost the detection of potential threats in many ways. There is evidence that one and the same facial expression can be perceived differently depending on whether it is seen in a neutral or in a threatening situation. The present study investigated how aversive anticipation influences the accuracy of facial emotion recognition and the perceived emotional intensity of faces that had their objective emotional intensity manipulated. Forty-three participants categorized and rated the intensity of morphed faces (20%, 40%, 60%, and 80%) of fearful, angry, and happy expressions. Differently colored picture frames indicated either threat of electric shock or safety. Threat of shock enhanced the categorization accuracy specifically for fearful faces. During threat, 80% fearful and happy faces, and all levels of angry faces (20%-80%) were rated as more intense. In addition, we found that more trait-anxious individuals more frequently erroneously categorized neutral faces as fearful. Thus, state anxiety enhanced accurate fear categorization and boosted the perceived intensity of emotional faces, whereas trait anxiety led to a biased threat perception in nonthreatening faces. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Towards a neuroscience-based theory of personality: within-subjects dissociation of human brain activity during pursuit and goal conflict.

As demonstrated by neuroimaging data, the human brain contains systems that control responses to threat. The revised Reinforcement Sensitivity Theory of personality predicts that individual differences in the reactivity of these brain systems produce anxiety and fear-related personality traits. Here we discuss some of the challenges in testing this theory and, as an example, present a pilot study that aimed to dissociate brain activity during pursuit by threat and goal conflict. We did this by translating the Mouse Defense Test Battery for human fMRI use. In this version, dubbed the Joystick Operated Runway Task (JORT), we repeatedly exposed 24 participants to pursuit and goal conflict, with and without threat of electric shock. The runway design of JORT allowed the effect of threat distance on brain activation to be evaluated independently of context. Goal conflict plus threat of electric shock caused deactivation in a network of brain areas that included the fusiform and middle temporal gyri, as well as the default mode network core, including medial frontal regions, precuneus and posterior cingulate gyrus, and laterally the inferior parietal and angular gyri. Consistent with earlier research, we also found that imminent threat activated the midbrain and that this effect was significantly stronger during the simple pursuit condition than during goal conflict. Also consistent with earlier research, we found significantly greater hippocampal activation during goal conflict than pursuit by imminent threat. In conclusion, our results contribute knowledge to theories linking anxiety disorders to altered functioning in defensive brain systems and also highlight challenges in this research domain.

Visuocortical changes during a freezing-like state in humans

An adaptive response to threat requires optimized detection of critical sensory cues. This optimization is thought to be aided by freezing - an evolutionarily preserved defensive state of immobility characterized by parasympathetically mediated fear bradycardia and regulated by the amygdala-periaqueductal grey (PAG) circuit. Behavioral observations in humans and animals have suggested that freezing is also a state of enhanced visual sensitivity, particularly for coarse visual information, but the underlying neural mechanisms remain unclear. We induced a freezing-like state in healthy volunteers using threat of electrical shock and measured threat-related changes in both stimulus-independent (baseline) and stimulus-evoked visuocortical activity to low-vs. high-spatial frequency gratings, using functional MRI. As measuring immobility is not feasible in MRI environments, we used fear bradycardia and amygdala-PAG coupling in inferring a freezing-like state. An independent functional localizer and retinotopic mapping were used to assess the retinotopic specificity of visuocortical modulations. We found a threat-induced increase in baseline (stimulus-independent) visuocortical activity that was retinotopically nonspecific, which was accompanied by increased connectivity with the amygdala. A positive correlation between visuocortical activity and fear bradycardia (while controlling for sympathetic activation), and a concomitant increase in amygdala-PAG connectivity, confirmed the specificity of these findings for the parasympathetically dominated freezing-like state. Visuocortical responses to gratings were retinotopically specific, but did not differ between threat and safe conditions across participants. However, individuals who exhibited better discrimination of low-spatial frequency stimuli showed reduced stimulus-evoked V1 responses under threat. Our findings suggest that a defensive state of freezing involves an integration of preparatory defensive and perceptual changes which may be regulated by a common mechanism involving the amygdala.

Cognitive trait anxiety, stress and effort interact to predict inhibitory control

ABSTRACTFew studies have focussed on the link between anxiety and inhibitory control in the absence of stimulus-driven external threat. This two-part experiment examined the interactions between (1) somatic trait anxiety, somatic situational stress (i.e. threat of electric shock), and effort, and (2) cognitive trait anxiety, cognitive situational stress (i.e. ego-threat instructions), and effort, on inhibitory processes using a Go-No-Go paradigm. Trait anxiety was operationalised using questionnaire scores and effort was operationalised using a visual analogue scale. Performance effectiveness was measured using the d′ parameter from signal detection theory and processing efficiency was indexed by the ratio of d′ to response time on correct trials. Results indicated that somatic trait anxiety and stress did not predict effectiveness or efficiency. Cognitive trait anxiety and stress were associated with both inhibitory effectiveness and efficiency deficits; however, contrary to expectations these deficits were evident at higher rather than lower mental effort. Results suggest a distinction between how somatic and cognitive anxiety manifest on tasks involving inhibitory control.

Attentional Biases in Processing Emotional Facial Expressions: Effects of State Anxiety, Trait Anxiety and Awareness

The effect of state anxiety and trait anxiety on selective attention for threatening, neutral and happy schematic faces was investigated. A student sample was assigned to high trait anxious (HTA) or low trait anxious (LTA) groups using questionnaire scores and state anxiety was manipulated through the threat of electric shock. Stimulus materials were presented both outside (using a backward masking procedure) and within awareness. A novel version of a probe classification task was developed to assess performance when distracting information and the central task were spatially separated. For the masked trials, the LTA group were slower to identify the status of the probe on happy face trials relative to threat face trials in the shock safe condition, and slower on threat face trials relative to happy face trials in the shock threat condition. For the HTA group, performance on the probe status task was unaffected by shock condition status or item valence for the masked exposures. During the unmasked exposure trials neither trait anxiety status, item valence nor shock condition affected response latencies to the probes. Results are interpreted with respect to contemporary models of attention and anxiety.

Prefrontal inhibition of threat processing reduces working memory interference

Bottom-up processes can interrupt ongoing cognitive processing in order to adaptively respond to emotional stimuli of high potential significance, such as those that threaten wellbeing. However it is vital that this interference can be modulated in certain contexts to focus on current tasks. Deficits in the ability to maintain the appropriate balance between cognitive and emotional demands can severely impact on day-to-day activities. This fMRI study examined this interaction between threat processing and cognition; 18 adult participants performed a visuospatial working memory (WM) task with two load conditions, in the presence and absence of anxiety induction by threat of electric shock. Threat of shock interfered with performance in the low cognitive load condition; however interference was eradicated under high load, consistent with engagement of emotion regulation mechanisms. Under low load the amygdala showed significant activation to threat of shock that was modulated by high cognitive load. A directed top-down control contrast identified two regions associated with top-down control; ventrolateral PFC and dorsal ACC. Dynamic causal modeling provided further evidence that under high cognitive load, top-down inhibition is exerted on the amygdala and its outputs to prefrontal regions. Additionally, we hypothesized that individual differences in a separate, non-emotional top-down control task would predict the recruitment of dorsal ACC and ventrolateral PFC during top-down control of threat. Consistent with this, performance on a separate dichotic listening task predicted dorsal ACC and ventrolateral PFC activation during high WM load under threat of shock, though activation in these regions did not directly correlate with WM performance. Together, the findings suggest that under high cognitive load and threat, top-down control is exerted by dACC and vlPFC to inhibit threat processing, thus enabling WM performance without threat-related interference.

Risk‐avoidant decision making increased by threat of electric shock

Threat cues elicit defensive reactions mediated by limbic brain circuitry that is also implicated in risk-sensitive decision making. Building upon research looking at stress effects on decision making, a gambling task was administered to 65 healthy adults, comparing decision making on trials on which a red screen background signalled threat of shocks against trials when shocks could not occur. The threat cues elicited increased electrodermal activity and a sustained decrease in heart rate, consistent with defensive vigilance. The threat condition was associated with risk-avoidant choices, on trials where the risky option involved moderate losses and when choosing between options involving only losses. These effects were not explained by changes in latency. Threat exerts immediate effects on decision making and physiological arousal, biasing subjects towards safer alternatives, potentially through a magnified processing of loss information.

The effect of induced anxiety on cognition: threat of shock enhances aversive processing in healthy individuals

Individuals with anxiety disorders demonstrate altered cognitive performance including (1) cognitive biases towards negative stimuli (affective biases) and (2) increased cognitive rigidity (e.g., impaired conflict adaptation) on affective Stroop tasks. Threat of electric shock is frequently used to induce anxiety in healthy individuals, but the extent to which this manipulation mimics the cognitive impairment seen in anxiety disorders is unclear. In this study, 31 healthy individuals completed an affective Stroop task under safe and threat-of-shock conditions. We showed that threat (1) enhanced aversive processing and abolished a positive affective bias but (2) had no effect on conflict adaptation. Threat of shock thus partially models the effects of anxiety disorders on affective Stroop tasks. We suggest that the affective state of anxiety-which is common to both threat and anxiety disorders-modulates the neural inhibition of subcortical aversive processing, whilst pathologies unique to anxiety disorders modulate conflict adaptation.

Hydrocortisone suppression of the fear-potentiated startle response and posttraumatic stress disorder

This study examined the effects of oral administration of 20mg hydrocortisone on baseline and fear-potentiated startle in 63 male veterans with or without PTSD. The procedure was based on a two-session, within-subject design in which acoustic startle eyeblink responses were recorded during intervals of threat or no threat of electric shock. Results showed that the magnitude of the difference between startle responses recorded during anticipation of imminent shock compared to "safe" periods was reduced after hydrocortisone administration relative to placebo. This effect did not vary as a function of PTSD group nor were there were any significant group differences in other indices startle amplitude. Findings suggest that the acute elevations in systemic cortisol produced by hydrocortisone administration may have fear-inhibiting effects. This finding may have implications for understanding the role of hypothalamic-pituitary-adrenal (HPA)-axis function in vulnerability and resilience to traumatic stress.

Selective attention for masked and unmasked emotionally toned stimuli: Effects of trait anxiety, state anxiety, and test order

We investigated selective attention for masked and unmasked, threat, and positively valenced words, in high trait anxious (HTA) and low trait anxious (LTA) individuals using the emotional Stroop colour-naming task. State anxiety was varied within participants through the threat of electric shock. To investigate whether the sequencing of the state anxiety manipulation affected colour-naming latencies, the ordering of the shock threat and shock safe conditions was counterbalanced across participants. The results indicated that the ordering of the state anxiety manipulation moderated masked and unmasked threat bias effects. Specifically, relative to LTA individuals, HTA individuals showed a threat interference effect, but this effect was limited to those who performed under the threat of shock in the later stages of the experiment. Irrespective of exposure mode and state anxiety status, all individuals showed interference for threat in the early stages of the experiment, relative to a threat facilitation effect in the later stages of the experiment. For the unmasked trials alone, the data also revealed a significant threat interference effect for the HTA group relative to the LTA group in the shock threat condition, and this effect was evident irrespective of shock threat order. The results are discussed with respect to the automatic nature of emotional processing in anxiety.

Selective attention for masked and unmasked threatening words in anxiety: Effects of trait anxiety, state anxiety and awareness

We investigated the effects of awareness on selective attention for masked and unmasked verbal threat material using a computerised version of the emotional Stroop. Participants were assigned to the high trait anxious (HTA) and low trait anxious (LTA) groups on the basis of questionnaire scores, and state anxiety was manipulated within participants through the threat of electric shock. To investigate the effects of awareness on responses to threat, the mode of exposure was blocked such that half the participants received masked trials before the unmasked trials, whereas the other half received the reverse order. The results revealed that there was no difference between the HTA and LTA groups in responses to threat for those who received the masked trials before the unmasked trials. However, when unmasked trials were presented before the masked trials HTA individuals were significantly slower to respond to both masked and unmasked threat words compared to the LTA group, and these effects were not further modified by participants' state anxiety status. The results are discussed in terms of the automatic nature of threat processing in anxiety.

Neural and behavioural responses to threat in men with a history of serious violence and schizophrenia or antisocial personality disorder

Background Contemporary theories and evidence implicate defective emotion regulation in violent behaviour. The two psychiatric illnesses most implicated in violence are schizophrenia and antisocial personality disorder (APD). This study examined behavioural and brain abnormalities in violent men with schizophrenia or APD during anticipatory fear. Method Fifty-three men [14 non-violent healthy controls, 13 with schizophrenia and a history of serious violence (VSZ), 13 with schizophrenia without a history of violence (SZ), 13 with APD and a history of serious violence] underwent blood-oxygenation-level-dependent fMRI during an experiment involving repeated presentations of ‘safe’ and ‘threat of electric shock’ conditions and provided ratings of shock anticipation and fear. Schizophrenia patients did not have co-morbid APD. Results VSZ participants reported the highest, and APD participants the lowest, level of shock anticipation and fear, with intermediate ratings by SZ and healthy participants. The violent, relative to non-violent, groups showed altered activity modulation in occipital and temporal regions, from early to latter parts of threat periods. Additionally, VSZ patients displayed exaggerated whereas APD patients showed attenuated thalamic-striatal activity during latter threat periods. Conclusions Aberrant activity in occipital and temporal regions when exposed to sustained visual threat cues is associated with a predisposition to violence in both schizophrenia and APD. This common biological deficit, however, appears to arise from dissimilar behavioural mechanisms related to differences in the strength of aversive conditioning and behavioural response to sustained threat cues (enhanced in VSZ; attenuated in APD), also reflected in opposite patterns of alternations in thalamic-striatal activity, in these two disorders.

Attention bias in nicotine withdrawal and under stress.

Drug motivation models postulate that attention biasing toward smoking-related cues is a cognitive mechanism supporting continued or renewed drug use, and they predict that drug use history, deprivation, and distress should modulate the extent of this bias. The present study used the modified Stroop paradigm to extend past research regarding attention biasing toward smoking and unpleasant, pleasant, and neutral words among adult nonsmokers and daily smokers. Both nonsmokers and smokers showed differential attention toward unpleasant and pleasant cues, particularly pleasant cues, but did not show a unique bias toward smoking-related stimuli. Results suggested that, among smokers, nicotine deprivation and exogenous stress (threat of electric shock) have a nonadditive effect on attention toward pleasant cues but no effect on attention to smoking cues specifically. Similarly, instructing smokers that they would have an opportunity to smoke did not significantly increase the bias of nicotine-deprived smokers' attention toward smoking-related cues, relative to arousing unpleasant and pleasant cues. Overall, results suggest that smokers' attention may be biased toward both smoking-related and other salient cues when deprived of nicotine and anticipating an opportunity to smoke. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

Effects of threat of electric shock and diazepam on the N1/P2 auditory-evoked potential elicited by low-intensity auditory stimuli

The acoustic startle response includes rapid muscular contractions elicited by loud sounds; it may be measured in humans as the electromyographic response of the orbicularis oculi muscle. Enhancement of this response during exposure to threat of electric shock (fear- potentiated startle) is a widely used model of human anxiety. A problem with the use of the startle reflex in studies of human anxiety is the aversiveness of startle-eliciting sounds, which may, in some subjects, exceed the aversiveness of the electric shock itself. We have recently found that the long-latency N1/P2 auditory-evoked potential elicited by loud sounds is subject to fear potentiation. However, it is not known whether N1/P2 potentials elicited by low-intensity sounds, which do not elicit the startle response, are also subject to fear potentiation. This study examined the susceptibility of the N1/P2 potential elicited by low-intensity sounds to fear potentiation, and the effect of the anxiolytic diazepam on the N1/P2 potential in the absence and presence of threat of electric shock. Fifteen male volunteers (18-43 years) participated in three sessions in which they received placebo, diazepam 5 mg and diazepam 10 mg according to a double-blind protocol. Sixty minutes after treatment, auditory-evoked potentials were elicited by 40 ms 1 kHz tones 5, 10, 15, 20 and 25 dB[A] above a background of 70 dB[A]. Recording sessions consisted of eight alternating 2 min THREAT and SAFE blocks; unpredictable shocks (1.8 mA, 50 ms) were delivered to the subject's wrist in THREAT blocks (1-4 shocks per block). The amplitude of the N1/P2 potential increased monotonically as a function of stimulus intensity. The responses were significantly greater during THREAT blocks than during SAFE blocks (fear potentiation). Diazepam attenuated the responses in both the SAFE and THREAT conditions. Fear potentiation of the N1/P2 potential was significantly reduced by diazepam. Diazepam reduced subjective alertness and lowered critical flicker fusion frequency, a measure of arousal. The results suggest that fear potentiation of the N1/P2 potential is not simply a manifestation of the fear-potentiated startle response. The use of low-intensity stimuli may be advantageous in studies of fear potentiation in humans.

Selective processing of masked and unmasked verbal threat material in anxiety: Influence of an immediate acute stressor

Attentional biases for threat were investigated using a computerised version of the emotional Stroop task. The study examined the influence of state and trait anxiety by employing a student sample assigned to high trait anxious (HTA; n=32) or low trait anxious (LTA; n=32) groups on the basis of questionnaire scores, and state anxiety was manipulated within participants through the threat of electric shock. Threatening words that were either unrelated (e.g., cancer, danger) or related to the threat of shock (e.g., electrocute, shock) were presented to participants both within and outside of awareness. In the latter condition a backward masking procedure was used to prevent awareness and exposure thresholds between the target and mask were individually set for each participant. For unmasked trials the HTA group showed significant interference in colour naming for all threat words relative to control words when performing under the threat of shock, but not in the shock safe condition. For the masked trials, despite chance performance in being able to identify the lexical status of the items, HTA participants showed facilitated colour naming for all threat words relative to control items when performing under threat of shock, but this effect was not evident in the shock safe condition. Neither valence of the items nor the threat of shock influenced colour naming latencies in either exposure mode for the LTA group.

Lack of effect of laboratory-provoked anxiety on plasma homovanillic acid concentration in normal subjects

The present study was undertaken to investigate if acute anxiety can affect plasma concentrations of homovanillic acid (pHVA). Since elevated pHVA levels have been associated with severity of schizophrenic symptoms, the results of this study will help determine if the pHVA elevations are directly related to psychosis or if anxiety is also a contributory factor. Anxiety was provoked in 10 young normal subjects by a combined paradigm of mental arithmetic task and threat of electrical shock. A significant increase in self-ratings of anxiety, blood pressure, and plasma levels of norepinephrine, 3-methoxy-4-hydroxyphenylethyleneglycol and growth hormone indicated that the paradigm used was effective in provoking anxiety; however, anxiety did not affect pHVA concentrations. The results may support the notion that increased pHVA levels in severely ill schizophrenic patients are related to the schizophrenic pathophysiology rather than to anxiety.

Acoustic startle and anticipatory anxiety in humans: Effects of monaural right and left ear stimulation

The startle reflex elicited by binaural acoustic startle stimuli is potentiated by the threat of electric shock. The present study explored the lateralization of this fear-potentiated startle reflex effect using acoustic startle stimuli delivered binaurally or monaurally to the left or right ear and recorded from the left and right orbicularis oculi muscles. Consistent with previous results, the acoustic startle to binaural stimulation was potentiated during the anticipation of shock. This effect was also present for monaural stimulation but was greater when startle stimuli were delivered to the right than to the left ear. The results are discussed in terms of hemispheric lateralization during shock anticipation.