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Temporal and spatial properties of shape processing in the human visual cortex : combined fMRI and MEG adaptation; Zeitliche und räumliche Eigenschaften in der Objektverarbeitung im visuellen Cortex des Menschen : kombinierte fMRI und MEG-Adaptationsstudien

Huberle, Elisabeth
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Relevância na Pesquisa
Recent studies have shown that global information about shapes is processed in both early ventral (i.e. V1, V2, Vp, V4) and higher occipitotemporal visual areas (i.e. Lateral Occipital Complex/LOC). However, the temporal and spatial properties of shape processing across visual areas in the human brain are largely unknown. The present thesis addressed this question in a combined fMRI and MEG study, that made use of the complimentary spatial and temporal resolution of the two techniques. An event-related adaptation paradigm was applied, in which lower neural responses are observed for two identical than two different consecutivelypresented stimuli. The stimuli were shapes, that consisted of collinear Gabor elements. To investigate the temporal properties of shape processing, the interstimulus interval between the two consecutively-presented stimuli was manipulated (ISI: 100 vs. 400 msec). The results showed adaptation for both the short and the long ISI in the LOC, but only for the short ISI in early visual areas. Further, the spatial properties (Local vs. Global) were tested by changes in the local orientation of the Gabor elements or different global changes. Strong fMRI adaptation effects to local changes were observed in early visual areas (V1...