Detection of Chlamydia pneumoniae in a collection of captive snakes and response to treatment with marbofloxacin.

In a collection of 58 snakes comprising predominantly Eurasian vipers in Switzerland, five snakes died unexpectedly during hibernation from 2009 to 2012. In one snake, organisms resembling chlamydiae were detected by immunohistochemistry in multiple histiocytic granulomas. Real-time quantitative PCR and microarray analysis were used to determine the presence of Chlamydia pneumoniae in tissue samples and cloacal/choanal swabs from snakes in the collection; 8/53 (15.1%) of the remaining snakes were positive. Although one infected snake had suppurative periglossitis, infection with C. pneumoniae did not appear to be associated with specific clinical signs in snakes. Of seven snakes treated with 5 mg/kg marbofloxacin IM once daily, five became PCR negative for C. pneumoniae following treatment, whereas one animal remained positive and one snake was lost to follow-up.

Negative emotional stimuli enhance vestibular processing

Recent studies have shown that vestibular stimulation can influence affective processes. In the present study, we examined whether emotional information can also modulate vestibular perception. Participants performed a vestibular discrimination task on a motion platform while viewing emotional pictures. Six different picture categories were taken from the International Affective Picture System: mutilation, threat, snakes, neutral objects, sports and erotic pictures. Using a Bayesian hierarchical approach we were able to show that vestibular discrimination improved when participants viewed emotionally negative pictures (mutilation, threat, snake) when compared to neutral objects. There was no difference in vestibular discrimination while viewing emotionally positive compared to neutral pictures. We conclude that some of the mechanisms involved in the processing of vestibular information are also sensitive to emotional content. Emotional information signals importance and mobilizes the body for action. In case of danger, a successful motor response requires precise vestibular processing. Therefore, negative emotional information improves processing of vestibular information.

Negative emotional stimuli enhance vestibular processing

Recent studies have shown that vestibular stimulation can influence affective processes. In the present study, we examined whether emotional information can also modulate vestibular perception. Participants performed a vestibular discrimination task on a motion platform while viewing emotional pictures. Six different picture categories were taken from the International Affective Picture System: mutilation, threat, snakes, neutral objects, sports and erotic pictures. Using a Bayesian hierarchical approach we were able to show that vestibular discrimination improved when participants viewed emotionally negative pictures (mutilation, threat, snake) when compared to neutral objects. There was no difference in vestibular discrimination while viewing emotionally positive compared to neutral pictures. We conclude that some of the mechanisms involved in the processing of vestibular information are also sensitive to emotional content. Emotional information signals importance and mobilizes the body for action. In case of danger, a successful motor response requires precise vestibular processing. Therefore, negative emotional information improves processing of vestibular information.

Brain systems underlying encounter expectancy bias in spider phobia.

Spider-phobic individuals are characterized by exaggerated expectancies to be faced with spiders (so-called encounter expectancy bias). Whereas phobic responses have been linked to brain systems mediating fear, little is known about how the recruitment of these systems relates to exaggerated expectancies of threat. We used fMRI to examine spider-phobic and control participants while they imagined visiting different locations in a forest after having received background information about the likelihood of encountering different animals (spiders, snakes, and birds) at these locations. Critically, imagined encounter expectancies modulated brain responses differently in phobics as compared with controls. Phobics displayed stronger negative modulation of activity in the lateral prefrontal cortex, precuneus, and visual cortex by encounter expectancies for spiders, relative to snakes or birds (within-participants analysis); these effects were not seen in controls. Between-participants correlation analyses within the phobic group further corroborated the hypothesis that these phobia-specific modulations may underlie irrationality in encounter expectancies (deviations of encounter expectancies from objective background information) in spider phobia; the greater the negative modulation a phobic participant displayed in the lateral prefrontal cortex, precuneus, and visual cortex, the stronger was her bias in encounter expectancies for spiders. Interestingly, irrationality in expectancies reflected in frontal areas relied on right rather than left hemispheric deactivations. Our data accord with the idea that expectancy biases in spider phobia may reflect deficiencies in cognitive control and contextual integration that are mediated by right frontal and parietal areas.

Visual avoidance in phobia: particularities in neural activity, autonomic responding, and cognitive risk evaluations.

We investigated the neural mechanisms and the autonomic and cognitive responses associated with visual avoidance behavior in spider phobia. Spider phobic and control participants imagined visiting different forest locations with the possibility of encountering spiders, snakes, or birds (neutral reference category). In each experimental trial, participants saw a picture of a forest location followed by a picture of a spider, snake, or bird, and then rated their personal risk of encountering these animals in this context, as well as their fear. The greater the visual avoidance of spiders that a phobic participant demonstrated (as measured by eye tracking), the higher were her autonomic arousal and neural activity in the amygdala, orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and precuneus at picture onset. Visual avoidance of spiders in phobics also went hand in hand with subsequently reduced cognitive risk of encounters. Control participants, in contrast, displayed a positive relationship between gaze duration toward spiders, on the one hand, and autonomic responding, as well as OFC, ACC, and precuneus activity, on the other hand. In addition, they showed reduced encounter risk estimates when they looked longer at the animal pictures. Our data are consistent with the idea that one reason for phobics to avoid phobic information may be grounded in heightened activity in the fear circuit, which signals potential threat. Because of the absence of alternative efficient regulation strategies, visual avoidance may then function to down-regulate cognitive risk evaluations for threatening information about the phobic stimuli. Control participants, in contrast, may be characterized by a different coping style, whereby paying visual attention to potentially threatening information may help them to actively down-regulate cognitive evaluations of risk.

Evidence for an encounter expectancy bias in fear of spiders.

Whereas research has demonstrated that phobic or fearful individuals overestimate the likelihood of incurring aversive consequences from an encounter with feared stimuli, it has not yet been systematically investigated whether these individuals also overestimate the likelihood (i.e., the frequency) of such encounters. In the current study, spider-fearful and control participants were presented with background information that allowed them to estimate the overall likelihood that different kinds of animals (spiders, snakes, or birds) would be encountered. Spider-fearful participants systematically overestimated the likelihood of encountering a spider with respect to the likelihood of encountering a snake or a bird. No such expectancy bias was observed in control participants. The results thus strengthen our idea that there indeed exist two different types of expectancy bias in high fear and phobia that can be related to different components of the fear response. A conscientious distinction and examination of these two types of expectancy bias are of potential interest for therapeutic applications.

Negative Emotional Stimuli Enhance Vestibular Processing

Recent studies have shown that vestibular stimulation can influence affective processes. In the present study, we examined whether emotional information can also modulate vestibular perception. Participants performed a vestibular discrimination task on a motion platform while viewing emotional pictures. Six different picture categories were taken from the International Affective Picture System: mutilation, threat, snakes, neutral objects, sports, and erotic pictures. Using a Bayesian hierarchical approach, we were able to show that vestibular discrimination improved when participants viewed emotionally negative pictures (mutilation, threat, snake) when compared to neutral/positive objects. We conclude that some of the mechanisms involved in the processing of vestibular information are also sensitive to emotional content. Emotional information signals importance and mobilizes the body for action. In case of danger, a successful motor response requires precise vestibular processing. Therefore, negative emotional information improves processing of vestibular information.