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The fear of somatic sensations is highly relevant in the etiology and maintenance of various disorders. Nevertheless, little is known about this fear of body symptoms and many questions are yet unanswered. Especially physiological studies on interoceptive threat are rare. Therefore, the present thesis investigated defensive mobilization, autonomic arousal, and brain activation during the anticipation of, exposure to, and recovery from unpleasant body sensations. Symptoms were provoked using a standardized hyperventilation procedure in a sample of high (and as controls: low) anxiety sensitive individuals - a population high at risk for developing a panic disorder and high in fear of internal body symptoms.
In study one, anxious apprehension was investigated during anticipation of interoceptive threat (somatic sensations evoked by hyperventilation) and exteroceptive threat (electric shock). Symptom reports, autonomic arousal, and defensive mobilization assessed by the startle eyeblink response were analyzed. Extending the knowledge on anticipation of interoceptive threat, study two investigated the neural networks activated during anxious apprehension of unpleasant body sensations. Symptom reports and startle response data were collected during a learning session after which participants high and low in fear of somatic symptoms attended a fMRI session anticipating threat (hyperventilation – learned to provoke unpleasant symptoms) or safety (normal breathing). Study three examined the actual exposure to internal body symptoms, investigating symptoms reports, autonomic arousal, and the startle eyeblink response during guided breathing (hyperventilation and, as a non-provocative comparison condition, normoventilation) and during recovery. And finally, study four addressed changes in the defensive mobilization during repeated interoceptive exposure via a hyperventilation procedure. High and low anxiety sensitive persons went through two guided hyperventilation and normoventilation procedures that were spaced one week apart while symptom reports, breathing parameters, and startle response magnitudes were measured.
In study one it was demonstrated that the anticipation of exteroceptive threat led to a defensive and autonomic mobilization in high and low anxiety sensitive individuals, while during interoceptive threat only high anxiety sensitive participants were characterized by a potentiated startle response and autonomic activation. Imaging data of study two revealed that 1) during anticipation of hyperventilation all participants were characterized by an increased activation of a fear network consisting of anterior insula/ orbitofrontal cortex and rostral parts of the dorsal anterior cingulate cortex/ dorsomedial prefrontal cortex, 2) high fear individuals showed higher anxious apprehension than low fear controls during the entire context (safe and threat conditions), indexed by an overall stronger activation of the described network, and 3) while low fear controls learned that (undisclosed to all participants) in the fMRI scanner the threat cue was not followed by an unpleasant hyperventilation task, high fear participants continued to show stronger fear network activation to this cue. In study three it was demonstrated, that the hyperventilation procedure led to a marked increase in somatic symptoms and to autonomic arousal. While high and low anxiety sensitive groups did not differ during hyperventilation, in the early recovery only high anxiety sensitive individuals showed defensive mobilization, indicated by potentiated startle response magnitudes, and increased autonomic arousal after hyperventilation as compared to after normoventilation. Substantiating these findings, in study four all participants reported more symptoms during hyperventilation than during normoventilation, in both sessions. Nevertheless, only high anxiety sensitive participants displayed a potentiation of startle response magnitudes after the first hyper- vs. normoventilation. One week later, when the exercise was repeated this potentiation was no longer present and thus both groups no longer differed in their defensive mobilization. Even more, the number of reported baseline symptoms decreased from session one to session two in the high-AS group. While high anxiety sensitive persons reported increased baseline anxiety symptoms in session one, groups did not anymore differ in session two.
These data indicate that the standardized hyperventilation procedure is a valid paradigm to induce somatic symptoms. Moreover, it induces anxious apprehension especially in persons highly fearful of internal body symptoms. The repetition of interoceptive exposure, however, reduces associated fear in highly fearful individuals. Thus, this paradigm might provide an innovative method to study anxious apprehension and also treatment effects in patients with panic disorder. The present findings are integrated and discussed in the light of the current literature.
Two decades of research indicate that visual processing is typically enhanced for items that are in the space near the hands (near-hand space). Enhanced attention and cognitive control have been thought to be responsible for the observed effects, amongst others. As accumulating experimental evidence and recent theories of dual-tasking suggest an involvement of cognitive control and attentional processes during dual tasking, dual-task performance may be modulated in the near-hand space. Therefore, we performed a series of three experiments that aimed to test if the near-hand space affects the shift between task-component processing in two visual-manual tasks. We applied a Psychological Refractory Period Paradigm (PRP) with varying stimulus-onset asynchrony (SOA) and manipulated stimulus-hand proximity by placing hands either on the side of a computer screen (near-hand condition) or on the lap (far-hand condition). In Experiment 1, Task 1 was a number categorization task (odd vs. even) and Task 2 was a letter categorization task (vowel vs. consonant). Stimulus presentation was spatially segregated with Stimulus 1 presented on the right side of the screen, appearing first and then Stimulus 2, presented on the left side of the screen, appearing second. In Experiment 2, we replaced Task 2 with a color categorization task (orange vs. blue). In Experiment 3, Stimulus 1 and Stimulus 2 were centrally presented as a single bivalent stimulus. The classic PRP effect was shown in all three experiments, with Task 2 performance declining at short SOA while Task 1 performance being relatively unaffected by task-overlap. In none of the three experiments did stimulus-hand proximity affect the size of the PRP effect. Our results indicate that the switching operation between two tasks in the PRP paradigm is neither optimized nor disturbed by being processed in near-hand space.
In the present study, we investigated whether inter-individual differences in vagally mediated heart rate variability (vmHRV) would be associated with inter-individual differences in empathy and alexithymia. To this end, we determined resting state HF-HRV in 90 individuals that also completed questionnaires assessing inter-individual differences in empathy and alexithymia. Our categorical and dimensional analyses revealed that inter-individual differences in HF-HRV were differently associated with inter-individual differences in empathy and alexithymia. We found that individuals with high HF-HRV reported more empathy and less alexithymia than individuals with low HF-HRV. Moreover, we even found that an increase in HF-HRV was associated with an increase in empathy and a decrease in alexithymia across all participants. Taken together, these findings indicate that individuals with high HF-HRV are more empathetic and less alexithymic than individuals with low HF-HRV. These differences in empathy and alexithymia may explain why individuals with high HF-HRV are more successful in sharing and understanding the mental and emotional states of others than individuals with low HF-HRV.
Das Ziel der vorliegenden Studie bestand darin, einen möglichen Einfluss des Darbietungsmodus auf die Leistung von Vorschulkindern in einer Aufgabe zur Theory of Mind (ToM) zu überprüfen. Dazu wurden die Leistungen von 94 Kindern zwischen 3 und 5 Jahren in einer klassischen Ortsverlagerungsaufgabe zum Verständnis falscher Überzeugungen (Wimmer & Perner, 1983) untersucht. Den Kindern wurde die Originalgeschichte entweder live oder als Videofilm präsentiert. Erstmalig konnte ein signifikanter Effekt des Darbietungsmodus in einer Aufgabe zur ToM nachgewiesen werden. Dieser ergab sich in der Altersgruppe der 4-Jährigen. Unabhängig vom Darbietungsmodus antworteten 3-Jährige überzufällig falsch und 5-Jährige überzufällig korrekt. Der nachgewiesene Effekt des Darbietungsmodus wird auf dem Hintergrund bereits bestehender Theorien zum so genannten Videodefiziteffekt (VDE) diskutiert.
Recent research suggests that the P3b may be closely related to the activation of the locus coeruleus-norepinephrine (LC-NE) system. To further study the potential association, we applied a novel technique, the non-invasive transcutaneous vagus nerve stimulation (tVNS), which is speculated to increase noradrenaline levels. Using a within-subject cross-over design, 20 healthy participants received continuous tVNS and sham stimulation on two consecutive days (stimulation counterbalanced across participants) while performing a visual oddball task. During stimulation, oval non-targets (standard), normal-head (easy) and rotated-head (difficult) targets, as well as novel stimuli (scenes) were presented. As an indirect marker of noradrenergic activation we also collected salivary alpha-amylase (sAA) before and after stimulation. Results showed larger P3b amplitudes for target, relative to standard stimuli, irrespective of stimulation condition. Exploratory post hoc analyses, however, revealed that, in comparison to standard stimuli, easy (but not difficult) targets produced larger P3b (but not P3a) amplitudes during active tVNS, compared to sham stimulation. For sAA levels, although main analyses did not show differential effects of stimulation, direct testing revealed that tVNS (but not sham stimulation) increased sAA levels after stimulation. Additionally, larger differences between tVNS and sham stimulation in P3b magnitudes for easy targets were associated with larger increase in sAA levels after tVNS, but not after sham stimulation. Despite preliminary evidence for a modulatory influence of tVNS on the P3b, which may be partly mediated by activation of the noradrenergic system, additional research in this field is clearly warranted. Future studies need to clarify whether tVNS also facilitates other processes, such as learning and memory, and whether tVNS can be used as therapeutic tool.