@phdthesis{Stegmann2021,
  author    = {Stegmann, Yannik},
  title     = {Electrocortical mechanisms of sustained attention during the acquisition and interaction of conditioned fear and anxiety},
  doi       = {10.25972/OPUS-23770},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-237700},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Adapting defensive behavior to the characteristics of a threatening situation is a fundamental function of the brain. Particularly, threat imminence plays a major role for the organization of defensive responses. Acute threat prompts phasic physiological responses, which are usually associated with an intense feeling of fear. In contrast, diffuse and potentially threatening situations elicit a sustained state of anxious apprehension. Detection of the threatening stimulus defines the key event in this framework, initiating the transition from potential to acute threat. Consequently, attention to threat is crucial for supporting defensive behavior. The functions of attention are finely tuned to the characteristics of a threatening situation. Potential threat is associated with hypervigilance, in order to facilitate threat detection. Once a threatening stimulus has been identified, attention is selectively focused on the source of danger. Even though the concepts of selective attention and hypervigilance to threat are well established, evidence for their neural correlates remain scarce. Therefore, a major goal of this thesis is to elucidate the neural correlates of selective attention to acute threat and hypervigilance during potential threat. A second aim of this thesis is to provide a mechanistic account for the interaction of fear and anxiety. While contemporary models view fear and anxiety as mutually exclusive, recent findings for the neural networks of fear and anxiety suggest potential interactions. In four studies, aversive cue conditioning was used to induce acute threat, while context conditioning served as a laboratory model of potential threat. To quantify neural correlates of selective attention and hypervigilance, steady-state visual evoked potentials (ssVEPs) were measured as an index of visuocortical responding. Study 1 compared visuocortical responses to acute and potential threat for high versus low trait-anxious individuals. All individuals demonstrated enhanced electrocortical responses to the central cue in the acute threat condition, suggesting evidence for the neural correlate of selective attention. However, only low anxious individuals revealed facilitated processing of the contexts in the potential threat condition, reflecting a neural correlate of hypervigilance. High anxious individuals did not discriminate among contexts. These findings contribute to the notion of aberrational processing of potential threat for high anxious individuals. Study 2 and 3 realized orthogonal combinations of cue and context conditioning to investigate potential interactions of fear and anxiety. In contrast to Study 1 and 2, Study 3 used verbal instructions to induce potentially threatening contexts. Besides ssVEPs, threat ratings and skin conductance responses (SCRs) were recorded as efferent indices of defensive responding. None of these studies found further evidence for the neural correlates of hypervigilance and selective attention. However, results for ratings and SCRs revealed additive effects of fear and anxiety, suggesting that fear and anxiety are not mutually exclusive, but interact linearly to organize and facilitate defensive behavior. Study 4 tested ssVEPs to more ecologically valid forms of context conditioning, using flickering video stimuli of virtual offices to establish context representations. Contrary to expectations, results revealed decreased visuocortical responses during sustained presentations of anxiety compared to neutral contexts. A disruption of ssVEP signals eventually suggests interferences by continuously changing video streams which are enhanced as a function of motivational relevance. In summary, this thesis provided evidence for the neural correlates of attention only for isolated forms of fear and anxiety, but not for their interaction. In contrast, an additive interaction model of fear and anxiety for measures of defensive responding offers a new perspective on the topography of defensive behavior.},
  subject      = {Furcht},
  language  = {en}
}
@phdthesis{Ahrens2020,
  author    = {Ahrens, Lea Marlen},
  title     = {The Role of Attentional Control and Fear Acquisition and Generalization in Social Anxiety Disorder},
  doi       = {10.25972/OPUS-17162},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171622},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {Although Social Anxiety Disorder (SAD) is one of the most prevalent mental disorders, still little is known about its development and maintenance. Cognitive models assume that deviations in attentional as well as associative learning processes play a role in the etiology of SAD. Amongst others, deficits in inhibitory attentional control as well as aberrations during fear generalization, which have already been observed in other anxiety disorders, are two candidate mechanisms that might contribute to the onset and retention of SAD. However, a review of the literature shows that there is a lack of research relating to these topics. Thus, the aim of the present thesis was to examine in which way individuals with SAD differ from healthy controls regarding attentional control and generalization of acquired fear during the processing of social stimuli. Study 1 tested whether impairment in the inhibitory control of attention is a feature of SAD, and how it might be influenced by emotional expression and gaze direction of an interactional partner. For this purpose, individuals with SAD and healthy controls (HC) participated in an antisaccade task with faces displaying different emotional expressions (angry, neutral and happy) and gaze directions (direct and averted) serving as target stimuli. While the participants performed either pro- or antisaccades in response to the peripherally presented faces, their gaze behavior was recorded via eye-tracking, and ratings of valence and arousal were obtained. Results revealed that both groups showed prolonged latencies and increased error rates in trials with correct anti- compared to prosaccades. However, there were no differences between groups with regard to response latency or error rates, indicating that SAD patients did not exhibit impairment on inhibitory attentional control in comparison to HC during eye-tracking. Possible explanations for this finding could be that reduced inhibitory attentional control in SAD only occurs under certain circumstances, for example, when these individuals currently run the risk of being negatively evaluated by others and not in the mere presence of phobic stimuli, or when the cognitive load of a task is so high that it cannot be unwound by compensatory strategies, such as putting more effort into a task. As not only deviations in attentional, but also associative learning processes might be pathogenic markers of SAD, these mechanisms were further addressed in the following experiments. Study 2 is the first that attempted to investigate the generalization of conditioned fear in patients with SAD. To this end, patients with SAD and HC were conditioned to two neutral female faces serving as conditioned stimuli (CS+: reinforced; CS-: non-reinforced) and a fearful face paired with a loud scream serving as unconditioned stimulus (US). Fear generalization was tested by presenting morphs of the two faces (GS: generalization stimuli), which varied in their similarity to the original faces. During the whole experiment, self-report ratings, heart rate (HR) and skin conductance responses (SCR) were recorded. Results demonstrated that SAD patients rated all stimuli as less pleasant and more arousing, and overestimated the occurrence of the US compared to HC, indicating a general hyperarousal in individuals with SAD. In addition, ratings and SCR indicated that both groups generalized their acquired fear from the CS+ to intermediate GSs as a function of their similarity to the CS+. However, except for the HR data, which indicated that only SAD patients but not HC displayed a generalization response in this measure, most of the results did not support the hypothesis that SAD is characterized by overgeneralization. A plausible reason for this finding could be that overgeneralization is just a key characteristic of some anxiety disorders and SAD is not one of them. Still, other factors, such as comorbidities in the individuals with SAD, could also have had an influence on the results, which is why overgeneralization was further examined in study 3. The aim of study 3 was to investigate fear generalization on a neuronal level. Hence, high (HSA) and low socially anxious participants (LSA) underwent a conditioning paradigm, which was an adaption of the experimental design used study 2 for EEG. During the experiment, steady-state visually evoked potentials (ssVEPs) and ratings of valence and arousal were recorded. Analyses revealed significant generalization gradients in all ratings with highest fear responses to the CS+ and a progressive decline of these reactions with increasing similarity to the CS-. In contrast, the generalization gradient on a neuronal level showed highest amplitudes for the CS+ and a reduction in amplitude to the most proximal, but not distal GSs in the ssVEP signal, which might be interpreted as lateral inhibition in the visual cortex. The observed dissociation among explicit and implicit measures points to different functions of behavioral and sensory cortical processes during fear generalization: While the ratings might reflect an individual's consciously increased readiness to react to threat, the lateral inhibition pattern in the occipital cortex might serve to maximize the contrast among stimuli with and without affective value and thereby improve adaptive behavior. As no group differences could be observed, the finding of study 2 that overgeneralization does not seem to be a marker of SAD is further consolidated. In sum, the conducted experiments suggest that individuals with SAD are characterized by a general hyperarousal during the exposition to disorder-relevant stimuli as indicated by enhanced arousal and reduced valence ratings of the stimuli compared to HC. However, the hypotheses that reduced inhibitory attentional control and overgeneralization of conditioned fear are markers of SAD were mostly not confirmed. Further research is required to elucidate whether they only occur under certain circumstances, such as high cognitive load (e.g. handling two tasks simultaneously) or social stress (e.g. before giving a speech), or whether they are not characteristics of SAD at all. With the help of these findings, new interventions for the treatment of SAD can be developed, such as attentional bias modification or discrimination learning.},
  subject      = {Sozialangst},
  language  = {en}
}
@phdthesis{Brill2019,
  author    = {Brill, Michael},
  title     = {Spontaneous eye blinks as an alternative measure for spatial presence experiences},
  edition   = {1. Auflage},
  publisher = {W{\"u}rzburg University Press},
  address   = {W{\"u}rzburg},
  isbn      = {978-3-95826-094-8},
  doi       = {10.25972/WUP-978-3-95826-095-5},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167898},
  school      = {W{\"u}rzburg University Press},
  pages     = {xvi, 265},
  year      = {2019},
  abstract  = {Spatial presence, a state in which media users temporarily overlook the mediated nature of their media use experience, is frequently assessed by means of post-session self-report scales. However, such methods have methodical limitations, for example concerning measurement of dynamic fluctuations in presence during media use. Consequently, researchers have tested several approaches that try to infer subjective experiences of spatial presence from objectively measurable indicators. The present doctoral thesis examines aspects of temporal structure in spontaneous eye-blink behavior. Cognitive processes—and especially attention—are seen as essential antecedents of presence experiences. Because such cognitive processes influence timing of spontaneous eye-blinks, it is tested if the degree of stimulus-dependent structure in spontaneous eye-blink behavior is related to presence self-report scores. To address this research question, the thesis first establishes a theoretical framework, including theorizing and empirical findings on presence, on related media use phenomena, spontaneous eye-blink behavior, and subjective and objective approaches for presence assessment. Then, three experiments are presented that examine the relation between self-reported presence, and amount of stimulus-dependent structure in blinking behavior. Three different methods for quantification of stimulus-dependent structure are tested in different media environments, and are related to an established presence scale. Discussion of the experimental findings leads, on the one hand, to fundamental questions on the presence concept and on the understanding of stimulus-dependent structure in spontaneous eye-blink behavior. On the other hand, interpretation of the results emphasizes the necessity for methods with appropriate temporal resolution, that consider both media events and user behavior.},
  subject      = {Lidschlag},
  language  = {en}
}
@phdthesis{Sareen2011,
  author    = {Sareen, Preeti},
  title     = {Visual attention in Drosophila melanogaster},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69616},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {There is such vast amount of visual information in our surroundings at any time that filtering out the important information for further processing is a basic requirement for any visual system. This is accomplished by deploying attention to focus on one source of sensory inputs to the exclusion of others (Luck and Mangun 2009). Attention has been studied extensively in humans and non human primates (NHPs). In Drosophila, visual attention was first demonstrated in 1980 (Wolf and Heisenberg 1980) but this field remained largely unexplored until recently. Lately, however, studies have emerged that hypothesize the role of attention in several behaviors but do not specify the characteristic properties of attention. So, the aim of this research was to characterize the phenomenon of visual attention in wild-type Drosophila, including both externally cued and covert attention using tethered flight at a torque meter. Development of systematic quantifiable behavioral tests was a key aspect for this which was not only important for analyzing the behavior of a population of wild-type flies but also for comparing the wild-type flies with mutant flies. The latter would help understand the molecular, genetic, and neuronal bases of attention. Since Drosophila provides handy genetic tools, a model of attention in Drosophila will serve to the greater questions about the neuronal circuitry and mechanisms involved which might be analogous to those in primates. Such a model might later be used in research involving disorders of attention. Attention can be guided to a certain location in the visual field by the use of external cues. Here, using visual cues the attention of the fly was directed to one or the other of the two visual half-fields. A simple yet robust paradigm was designed with which the results were easily quantifiable. This paradigm helped discover several interesting properties of the cued attention, the most substantial one being that this kind of external guidance of attention is restricted to the lower part of the fly's visual field. The guiding cue had an after-effect, i.e. it could occur at least up to 2 seconds before the test and still bias it. The cue could also be spatially separated from the test by at least 20° and yet attract the attention although the extent of the focus of attention (FoA) was smaller than one lower visual half-field. These observations excluded the possibility of any kind of interference between the test and the cue stimuli. Another interesting observation was the essentiality of continuous visibility of the test stimulus but not the cue for effective cuing. When the contrast of the visual scene was inverted, differences in response frequencies and cuing effects were observed. Syndirectional yaw torque responses became more frequent than the antidirectional responses and cuing was no longer effective in the lower visual field with inverted contrast. Interestingly, the test stimulus with simultaneous displacement of two stripes not only effectuated a phasic yaw torque response but also a landing response. A 50 landing response was produced in more than half of the cases whenever a yaw torque response was produced. Elucidation of the neuronal correlates of the cued attention was commenced. Pilot experiments with hydroxyurea (HU) treated flies showed that mushroom bodies were not required for the kind of guidance of attention tested in this study. Dopamine mutants were also tested for the guidance of attention in the lower visual field. Surprisingly, TH-Gal4/UAS-shits1 flies flew like wild-type flies and also showed normal optomotor response during the initial calibration phase of the experiment but did not show any phasic yaw torque or landing response at 18 °C, 25 °C or 30 °C. dumb2 flies that have almost no D1 dopamine receptor dDA1 expression in the mushroom bodies and the central complex (Kim et al. 2007) were also tested and like THGal4/ UAS-shits1 flies did not show any phasic yaw torque or landing response. Since the dopamine mutants did not show the basic yaw torque response for the test the role of dopamine in attention could not be deduced. A different paradigm would be needed to test these mutants. Not only can attention be guided through external cues, it can also be shifted endogenously (covert attention). Experiments with the windows having oscillating stripes nicely demonstrated the phenomenon of covert attention due to the production of a characteristic yaw torque pattern by the flies. However, the results were not easily quantifiable and reproducible thereby calling for a more systematic approach. Experiments with simultaneous opposing displacements of two stripes provide a promising avenue as the results from these experiments showed that the flies had a higher tendency to deliver one type of response than when the responses would be produced stochastically suggesting that attention increased this tendency. Further experiments and analysis of such experiments could shed more light on the mechanisms of covert attention in flies.},
  subject      = {Visuelle Aufmerksamkeit},
  language  = {en}
}
@phdthesis{Gerdes2008,
  author    = {Gerdes, Antje B. M.},
  title     = {Preferential Processing of Phobic Cues : Attention and Perception in Spider Phobic Patients},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-28684},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {Cognitive views of the psychopathology of anxiety propose that attentional biases toward threatening information play a substantial role in the disorders' etiology and maintenance. For healthy subjects, converging evidence show that threatening stimuli attract attention and lead to enhanced activation in visual processing areas. It is assumed that this preferential processing of threat occurs at a preattentive level and is followed by fast attentional engagement. High-anxious individuals show augmented tendencies to selectively attend toward fear-relevant cues (Mathews, 1990) and exhibit elevated neural processing of threatening cues compared to non-anxious individuals (Dilger et al., 2003). Regarding attentional biases in high-anxious subjects, it remains unanswered up to now whether initial engagement of attention toward threat or difficulties to disengage from threat is an underlying mechanism. Furthermore, little is known whether the preferential (attentive) processing of threatening cues does influence perceptional outcomes of anxious subjects. In order to directly study separate components of attentional bias the first study of this dissertation was a combined reaction time and eye-tracking experiment. Twenty one spider phobic patients and 21 control participants were instructed to search for a neutral target while ignoring task-irrelevant abrupt-onset distractor circles which contained either a small picture of a spider (phobic), a flower (non-phobic, but similar to spiders in shape), a mushroom (non-phobic, and not similar to spiders in shape), or small circles with no picture. As expected, patients' reaction times to targets were longer on trials with spider distractors. However, analyses of eye movements revealed that this was not due to attentional capture by spider distractors; patients more often fixated on all distractors with pictures. Instead, reaction times were delayed by longer fixation durations on spider distractors. This result does not support automatic capture of attention by phobic cues but suggests that phobic patients fail to disengage attention from spiders. To assess whether preferential processing of phobic cues differentially affects visual perception in phobic patients compared to healthy controls, the second study of this dissertation used a binocular rivalry paradigm, where two incompatible pictures were presented to each eye. These pictures cannot be merged to a meaningful percept and temporarily, one picture predominates in conscious perception whereas the other is suppressed. 23 spider phobic patients and 20 non-anxious control participants were shown standardized pictures of spiders or flowers, each paired with a neutral pattern under conditions of binocular rivalry. Their task was to continuously indicate the predominant percept by key presses. Analyses show that spider phobic patients perceived the spider picture more often and longer as dominant compared to non-anxious control participants. Thus, predominance of phobic cues in binocular rivalry provides evidence that preferential processing of fear-relevant cues in the visual system actually leads to superior perception. In combination both studies support the notion that phobic patients process phobic cues preferentially within the visual system resulting in enhanced attention and perception. At early stages of visual processing, this is mainly reflected by delayed attentional disengagement and across time, preferential processing leads to improved perception of threat cues.},
  subject      = {Phobie},
  language  = {en}
}