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Investigating the interplay of the human attentional and vestibular systems using transcranial magnetic stimulation
Investigating the interplay of the human attentional and vestibular systems using transcranial magnetic stimulation
The aim of this doctoral thesis was to investigate the relationship between the processing of vestibular information, on the one hand, and higher cognitive functions such as visual (spatial) attention and perceptual decision making, on the other. In order to draw causal inference about the role of specific cortical regions in this interplay, two experimental studies were conducted which combined psychophysical task designs using verticality judgment tasks with transcranial magnetic stimulation (TMS). The first study employed a simultaneous TMS-EEG approach to examine the role of the right intraparietal sulcus (IPS) within the dorsal parietal cortex in verticality judgments – a cortical area that has repeatedly been associated with both the visual attention and vestibular systems. Facilitatory effects of right IPS TMS on the bias of verticality perception were reported and mirrored by EEG results, which pointed to a normalization of individual perceptual biases reflected in a fronto-central ERP component following the stimulation. In contrast, no effects of left IPS TMS on either behavioural or electrophysiological measures were observed and right IPS TMS did not modulate performance in a control task that used the same set of stimuli (vertical Landmark task). These findings point to a causal role of the right IPS in the neuronal implementation of upright perception and strengthen the notion of vestibular-attentional coupling. In the second study verticality judgments had to be made under different levels of perceptual demand to address the question of how perceptual decision making interacts with vestibular processing. Stimuli adapted from those used in the first study were presented in a visual search setting, which required perceptual and response switches, in a way that varied attentional demands. This task was combined with offline theta-burst TMS applied to the dorsal medial frontal cortex (dMFC). The dMFC has been found to crucially contribute to perceptual decision making and is connected to core parts of the vestibular cortical network. Analysis of distinct features of behavioural performance before as compared to following dMFC TMS revealed a specific involvement of the dMFC in establishing the precision and accuracy of verticality judgments, particularly under conditions of high perceptual load. In summary, the results of the two studies support the idea of a functional link between the processing of vestibular information, (spatial) attention, and perceptual decision making, giving rise to higher vestibular cognition. Moreover, they suggest that on a cortical level this interplay is achieved within a network of multimodal processing regions such as the parietal and frontal cortices.
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Willacker, Lina
2020
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Willacker, Lina (2020): Investigating the interplay of the human attentional and vestibular systems using transcranial magnetic stimulation. Dissertation, LMU München: Graduate School of Systemic Neurosciences (GSN)
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Abstract

The aim of this doctoral thesis was to investigate the relationship between the processing of vestibular information, on the one hand, and higher cognitive functions such as visual (spatial) attention and perceptual decision making, on the other. In order to draw causal inference about the role of specific cortical regions in this interplay, two experimental studies were conducted which combined psychophysical task designs using verticality judgment tasks with transcranial magnetic stimulation (TMS). The first study employed a simultaneous TMS-EEG approach to examine the role of the right intraparietal sulcus (IPS) within the dorsal parietal cortex in verticality judgments – a cortical area that has repeatedly been associated with both the visual attention and vestibular systems. Facilitatory effects of right IPS TMS on the bias of verticality perception were reported and mirrored by EEG results, which pointed to a normalization of individual perceptual biases reflected in a fronto-central ERP component following the stimulation. In contrast, no effects of left IPS TMS on either behavioural or electrophysiological measures were observed and right IPS TMS did not modulate performance in a control task that used the same set of stimuli (vertical Landmark task). These findings point to a causal role of the right IPS in the neuronal implementation of upright perception and strengthen the notion of vestibular-attentional coupling. In the second study verticality judgments had to be made under different levels of perceptual demand to address the question of how perceptual decision making interacts with vestibular processing. Stimuli adapted from those used in the first study were presented in a visual search setting, which required perceptual and response switches, in a way that varied attentional demands. This task was combined with offline theta-burst TMS applied to the dorsal medial frontal cortex (dMFC). The dMFC has been found to crucially contribute to perceptual decision making and is connected to core parts of the vestibular cortical network. Analysis of distinct features of behavioural performance before as compared to following dMFC TMS revealed a specific involvement of the dMFC in establishing the precision and accuracy of verticality judgments, particularly under conditions of high perceptual load. In summary, the results of the two studies support the idea of a functional link between the processing of vestibular information, (spatial) attention, and perceptual decision making, giving rise to higher vestibular cognition. Moreover, they suggest that on a cortical level this interplay is achieved within a network of multimodal processing regions such as the parietal and frontal cortices.