No robust differences in fear conditioning between patients with fear-related disorders and healthy controls.

Fear conditioning and extinction serve as a dominant model for the development and maintenance of pathological anxiety, particularly for phasic fear to specific stimuli or situations. The validity of this model would be supported by differences in the physiological or subjective fear response between patients with fear-related disorders and healthy controls, whereas the model's validity would be questioned by a lack of such differences. We derived pupillometry, skin conductance response and startle electromyography as well as unconditioned stimulus expectancy in a two-day fear acquisition, immediate extinction and recall task and compared an unmedicated group of patients (n = 73) with phobias or panic disorder and a group of patients with posttraumatic stress disorder (PTSD, n = 21) to a group of carefully screened healthy controls (n = 35).

Measuring the conditioned response: A comparison of pupillometry, skin conductance, and startle electromyography.

In human fear conditioning studies, different physiological readouts can be used to track conditioned responding during fear learning. Commonly employed readouts such as skin conductance responses (SCR) or startle responses have in recent years been complemented by pupillary readouts, but to date it is unknown how pupillary readouts relate to other measures of the conditioned response. To examine differences and communalities among pupil responses, SCR, and startle responses, we simultaneously recorded pupil diameter, skin conductance, and startle electromyography in 47 healthy subjects during fear acquisition, extinction, and a recall test on 2 consecutive days.

Disentangling reward anticipation with simultaneous pupillometry / fMRI.

The reward system may provide an interesting intermediate phenotype for anhedonia in affective disorders. Reward anticipation is characterized by an increase in arousal, and previous studies have linked the anterior cingulate cortex (ACC) to arousal responses such as dilation of the pupil. Here, we examined pupil dynamics during a reward anticipation task in forty-six healthy human subjects and evaluated its neural correlates using functional magnetic resonance imaging (fMRI).

Multi-echo EPI of human fear conditioning reveals improved BOLD detection in ventromedial prefrontal cortex.

Standard T weighted functional magnetic resonance imaging (fMRI) performed with echo-planar imaging (EPI) suffers from signal loss in the ventromedial prefrontal cortex (vmPFC) due to macroscopic field inhomogeneity. However, this region is of special interest to affective neuroscience and psychiatry. The Multi-echo EPI (MEPI) approach has several advantages over EPI but its performance against EPI in the vmPFC has not yet been examined in a study with sufficient statistical power using a task specifically eliciting activity in this region.

Neural correlates of pupil dilation during human fear learning.

Background: Fear conditioning and extinction are prevailing experimental and etiological models for normal and pathological anxiety. Pupil dilations in response to conditioned stimuli are increasingly used as a robust psychophysiological readout of fear learning, but their neural correlates remain unknown. We aimed at identifying the neural correlates of pupil responses to threat and safety cues during a fear learning task.

Spontaneous pupil dilations during the resting state are associated with activation of the salience network.

Resting state functional magnetic resonance imaging (rs-fMRI) is increasingly applied for the development of functional biomarkers in brain disorders. Recent studies have revealed spontaneous vigilance drifts during the resting state, involving changes in brain activity and connectivity that challenge the validity of uncontrolled rs-fMRI findings. In a combined rs-fMRI/eye tracking study, the pupil size of 32 healthy subjects after 2h of sleep restriction was recorded as an indirect index for activity of the locus coeruleus, the brainstem's noradrenergic arousal center.