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Universität Tübingen

1. Bahmani, Hamed. Neural correlates of perceptual transitions during binocular flash suppression .

Degree: 2018, Universität Tübingen

Neural correlates of visual awareness have been attracting scientists’ interest for decades. A central question for many students has been at which stage of brain processing the resolution of perceptual ambiguities occurs. Discovering which aspects of neural activity underlie our subjective percepts and not simply the sensory input has also fascinated many researchers for a long time. Bistable and multistable perception phenomena demonstrated great experimental potential to address this question in primary visual cortex (V1) and multiple higher cortical areas including temporal and prefrontal cortices in humans and macaques. However, the role of single neurons in parietal cortical areas in perceptual transitions has not been explored in macaques by the time of this work. Also, the role that area V1 plays in perception has been a subject of debate, as the magnitude of perceptual modulations differed substantially in single-cell and imaging studies. In this thesis, we took a step further and explored the role of parietal visual areas in perceptual transitions during binocular flash suppression (BFS). We also searched for another coding scheme in V1 in addition to firing rate modulation, which may be responsible for larger modulations observed in human studies. Furthermore, we compared the extent to which neurons in V1 modulate by perception under anesthetized conditions and compared with awake passively fixating animals during the BFS paradigm in order to highlight the possible role of task in this controversy. For the first set of experiments, we recorded extracellular activity from visual units in lateral intraparietal area (LIP) of the macaque brain under the conditions of BFS. We found that LIP neurons exhibit two type of responses to the perceptual changes, possibly responsible for two distinct underlying processes: a fast transient component that is a good candidate of feedback carrying higher order visual information to the early cortical circuits, and a tonic response, which is moderately modulated by perception and becomes selective to the visual stimuli by manipulating reward size. Next, we analyzed a large dataset of single- and multi-unit activity in V1 concurrently recorded with the local field potentials (LFP) during BFS stimulation. We found that spike-field coherence (SFC) in V1 was correlated with subjective perception. Of particular interest, this correlation was also found in the absence of significant modulations in firing rate. We conjectured that SFC plays a leading role in initiating the competition in V1. Finally, we analyzed comparable spiking data collected during anesthesia and awake passive fixation conditions from four macaque monkeys and showed that the modulation of firing rates in V1 upon perceptual suppression during BFS is comparable in both conditions. We concluded that active engagement in a task is critical to boost firing rate modulations in V1 to the level reported in human studies. Taken together, our work confirms that a distributed network of cortical regions is responsible for… Advisors/Committee Members: Keliris, Georgios A. (Prof. Dr.) (advisor).

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Bahmani, H. (2018). Neural correlates of perceptual transitions during binocular flash suppression . (Thesis). Universität Tübingen. Retrieved from http://hdl.handle.net/10900/72429

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Bahmani, Hamed. “Neural correlates of perceptual transitions during binocular flash suppression .” 2018. Thesis, Universität Tübingen. Accessed January 15, 2019. http://hdl.handle.net/10900/72429.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Bahmani, Hamed. “Neural correlates of perceptual transitions during binocular flash suppression .” 2018. Web. 15 Jan 2019.

Vancouver:

Bahmani H. Neural correlates of perceptual transitions during binocular flash suppression . [Internet] [Thesis]. Universität Tübingen; 2018. [cited 2019 Jan 15]. Available from: http://hdl.handle.net/10900/72429.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Bahmani H. Neural correlates of perceptual transitions during binocular flash suppression . [Thesis]. Universität Tübingen; 2018. Available from: http://hdl.handle.net/10900/72429

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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