Effects of diazepam on approach, self-reported fear and psychophysiological responses in snake phobics

Modality of fear cues affects acoustic startle potentiation but not heart-rate response in patients with dental phobia

The acoustic startle response (SR) has consistently been shown to be enhanced by fear-arousing cross-modal background stimuli in phobics. Intra-modal fear-potentiation of acoustic SR was rarely investigated and generated inconsistent results. The present study compared the acoustic SR to phobia-related sounds with that to phobia-related pictures in 104 dental phobic patients and 22 controls. Acoustic background stimuli were dental treatment noises and birdsong and visual stimuli were dental treatment and neutral control pictures. Background stimuli were presented for 4 s, randomly followed by the administration of the startle stimulus. In addition to SR, heart-rate (HR) was recorded throughout the trials. Irrespective of their content, background pictures elicited greater SR than noises in both groups with a trend for phobic participants to show startle potentiation to phobia-related pictures but not noises. Unlike controls, phobics showed HR acceleration to both dental pictures and noises. HR acceleration of the phobia group was significantly positively correlated with SR in the noise condition only. The acoustic SR to phobia-related noises is likely to be inhibited by prolonged sensorimotor gating.

Behavioral correlates of anxiety

The tripartite model of anxiety includes three response domains: cognitive (most often identified by self report), behavioral, and physiological. Each is suggested to bring a separate element of response characteristics and, in some cases, potentially independent underlying mechanisms to the construct of anxiety. In this chapter, commonly used behavioral correlates of anxiety in human research, including startle reflex, attentional bias, and avoidance tasks, as well as future tasks using virtual reality technology will be discussed. The focus will be in evaluating their translational utility supported by (1) convergent validity with other measures of anxiety traits or anxiety disorders, (2) their use in identifying neural and genetic mechanisms of anxiety, and (3) ability to predict treatment efficacy.

Is eye to eye contact really threatening and avoided in social anxiety?--An eye-tracking and psychophysiology study

The effects of direct and averted gaze on autonomic arousal and gaze behavior in social anxiety were investigated using a new paradigm including animated movie stimuli and eye-tracking methodology. While high, medium, and low socially anxious (HSA vs. MSA vs. LSA) women watched animated movie clips, in which faces responded to the gaze of the participants with either direct or averted gaze, their eye movements, heart rate (HR) and skin conductance responses (SCR) were continuously recorded. Groups did not differ in their gaze behavior concerning direct vs. averted gaze, but high socially anxious women tended to fixate the eye region of the presented face longer than MSA and LSA, respectively. Furthermore, they responded to direct gaze with more pronounced cardiac acceleration. This physiological finding indicates that direct gaze may be a fear-relevant feature for socially anxious individuals in social interaction. However, this seems not to result in gaze avoidance. Future studies should examine the role of gaze direction and its interaction with facial expressions in social anxiety and its consequences for avoidance behavior and fear responses. Additionally, further research is needed to clarify the role of gaze perception in social anxiety.

Short-term full kindling of the amygdala dissociates natural and periaqueductal gray-evoked flight behaviors of the rat

Panic attacks present a high comorbidity with agoraphobia, separation anxiety and generalized anxiety disorder. Nevertheless, while panic attacks have been frequently equated to fear, the relationship of panic disorder with specific phobias remains uncertain. The combination of experimental models of panic and phobias could but afford valuable information about both the comorbidity and causation of these disorders. As it regards, while the defensive behaviors produced by stimulation of dorsal periaqueductal gray matter (DPAG) resemble a panic attack, resistance to capture (RC) behaviors that ensue the kindling of the amygdala (AMY) are reminiscent of a phobic reaction. Therefore, this study examined the thresholds of DPAG-evoked panic-like behaviors in rats showing RC behaviors. Rats bearing electrodes in the DPAG and right AMY were subjected to either the full- (Kin-F) or sham- (Kin-S) kindling of AMY. RC behaviors were evaluated throughout both kindling procedures. Thresholds of DPAG-evoked defensive behaviors were recorded before and after the kindling. Moreover, performances of Kin-F and Kin-S rats in the elevated plus-maze were compared to those of intact controls. Data showed that Kin-F and Kin-S rats perform similarly in the elevated plus-maze, thereby making AMY-kindled rats unlikely as a model of generalized anxiety disorder. On the other hand, whereas the RC is characterized by a marked facilitation of natural freezing and flight behaviors, DPAG-evoked freezing (immobility and exophthalmus) and flight (galloping) behaviors were unexpectedly attenuated. Data suggest that RC is mediated by circuits distinct from those of DPAG-evoked defensive behaviors. Consequently, panic and phobic attacks may be mediated by different mechanisms as well.

Attention, heart rate, and startle response during exposure to trauma-relevant pictures: a comparison of recent trauma victims and patients with posttraumatic stress disorder

Victims of a recent trauma were compared with posttraumatic stress disorder (PTSD) patients and healthy controls to assess whether a specific anxiety response and an attentional bias were evident initially or only in chronic PTSD. Heart rate (HR) and startle response were measured, and a dot-probe task was carried out using trauma-relevant pictures. Severely affected recent trauma victims and chronic PTSD patients showed HR acceleration to trauma-related material, which was the only significant group difference. A bias away from trauma-related material was related to severity of intrusions in recent trauma victims, and the bias toward trauma-related material increased with amplitude of the HR response in PTSD patients. A specific anxiety reaction is present initially in severely affected trauma victims.

A two-dimensional neuropsychology of defense: fear/anxiety and defensive distance

We present in this paper a picture of the neural systems controlling defense that updates and simplifies Gray's "Neuropsychology of Anxiety". It is based on two behavioural dimensions: 'defensive distance' as defined by the Blanchards and 'defensive direction'. Defensive direction is a categorical dimension with avoidance of threat corresponding to fear and approach to threat corresponding to anxiety. These two psychological dimensions are mapped to underlying neural dimensions. Defensive distance is mapped to neural level, with the shortest defensive distances involving the lowest neural level (periaqueductal grey) and the largest defensive distances the highest neural level (prefrontal cortex). Defensive direction is mapped to separate parallel streams that run across these levels. A significant departure from prior models is the proposal that both fear and anxiety are represented at all levels. The theory is presented in a simplified form that does not incorporate the interactions that must occur between non-adjacent levels of the system. It also requires expansion to include the dimension of escapability of threat. Our current development and these proposed future extensions do not change the core concepts originally proposed by Gray and, we argue, demonstrate their enduring value.

Phobia-relevant illusory correlations: the role of phobic responsivity

The authors investigated the role of phobic responsivity in the generation of phobia-relevant illusory correlations. As a means of disentangling the contributions of prior fear and elicited fear responses, half of a group of phobic women received 1 mg alprazolam (n = 21), and half received a placebo (n = 22). A group of nonfearful women (n = 24) was included to control for prior fear per se. Participants were exposed to slides of spiders, weapons, and flowers that were randomly paired with a shock, a siren, or nothing. Postexperimental covariation estimates and on-line outcome expectancies were assessed. Irrespective of both prior and elicited fear, participants postexperimentally overassociated spiders and shock. Yet, only women with spider phobia displayed a persisting fear-confirming expectancy bias. This bias was similar for the placebo and alprazolam groups. Thus, the bias appeared to be due to preexisting phobogenic beliefs, whereas phobic responsivity played a negligible role.

Functional neuroanatomy of visually elicited simple phobic fear: additional data and theoretical analysis

We investigated central nervous system correlates of simple phobic fear. Regional cerebral blood flow (rCBF) was measured using positron emission tomography (PET) in eight volunteers with symptomatic spider phobia that were exposed to visual phobogenic and neutral stimuli. Diazepam (0.1 mg/kg body weight i.v.) or placebo was administered under double-blind conditions after initial PET scans. The PET scans were then repeated. The presence of fear was confirmed by rating procedures and increased number of nonspecific electrodermal fluctuations and by higher heart rate during phobic than during neutral stimulation. Phobic as compared to neutral stimulation elevated the regional to whole brain (relative) CBF in the secondary visual cortex but reduced relative rCBF in the hippocampus, prefrontal, orbitofrontal, temporopolar, and posterior cingulate cortex. Diazepam treatment did not affect the relative rCBF or the subjective or physiological fear indices. The observed rCBF pattern replicates our previous findings in snake phobics (M. Fredrikson et al. [1993] Psychophysiology, 30, 127-131; G. Wik et al. [1993] Psychiatry Research (Neuroimaging), 50, 15-24) and indicates that fear and anxiety affect cortical areas outside the classic limbic system areas.

Endorphins stimulate approach behaviour, but do not reduce subjective fear. A pilot study

The present study explored whether endorphins have a short-term influence on behavioural approach to a phobic object and on the experience of fear. In a double-blind design, spider phobics (n = 30) received a placebo, a low dose (25 mg) or a high dose (100 mg) of naltrexone, an endorphin blocker. Approach to a spider appeared to be negatively influenced by the endorphin blocker, but subjective fear was not significantly related to it. The findings support the view that endorphin release during anxiety stimulates courageous behaviour, but does not directly reduce the experience of fear.

The measurement and mismeasurement of ophidiophobia in analogue research: a procedural review

The adequacy of current paper-and-pencil measures of ophidiophobia (fear of snakes) was analyzed by reviewing the subject selection procedures in 24 published articles with the restriction that the procedures involve some form of self-report. The sample characteristics and selection procedures of these studies were reviewed in detail. We conclude that the recommendations and conclusions of these studies should not be accepted due to limited generalizability. Paper-and-pencil measures are excellent initial selection devices, but cannot stand alone in selecting ophidiophobics from the general population.

Effect of a beta-adrenergic blocking agent on dental anxiety

The effect of propranolol was studied on 23 dental phobics in a double-blind, placebo-controlled clinical trial involving actual dental treatment. The subjects were selected because they showed high physiological reactivity in the dental situation. Twelve subjects received the test drug and 11 subjects received the placebo at individualized doses of either 80 or 120 mg. A significant difference in self-reported anxiety at the injection phase of treatment and less overall pain intensity and aversiveness were observed for the propranolol as compared with the placebo group. No differences were detected for behavior ratings. Beta-adrenergic blocking agents may have utility for reducing anxiety in individuals fearful of dental treatment.