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Martijn E. Wokke, H. Steven Scholte, Victor A.F. Lamme; Opposing dorsal/ventral stream dynamics during figure-ground segregation. Journal of Vision 2013;13(9):1260. doi: 10.1167/13.9.1260.
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© ARVO (1962-2015); The Authors (2016-present)
The visual system has been commonly subdivided into two segregated visual processing streams: The dorsal pathway processes mainly spatial information, whereas the ventral pathway specializes in object perception. Recent findings, however, indicate that different forms of interaction (cross-talk) exist between the dorsal and the ventral stream. Here, we used transcranial magnetic stimulation (TMS) and concurrent electroencephalographic (EEG) recordings to explore these interactions between the dorsal and ventral stream during visual perception. In two separate experiments we used rTMS and single pulse TMS to disrupt processing in the dorsal (V5/HMT+) and the ventral (Lateral Occipital area) stream during a motion-defined figure discrimination task. Interestingly, we presented stimuli that made it possible to differentiate between relatively low-level (figure boundary detection) from higher-level (surface segregation) processing steps during visual perception. Results show that disruption of V5/HMT+ impaired performance related to surface segregation; this effect was mainly found when V5/HMT+ was perturbed in an early time window (100 ms) after stimulus presentation. Surprisingly, disruption of the Lateral Occipital area resulted in increased performance scores and enhanced neural correlates of surface segregation. This facilitatory effect was also mainly found in an early time window (100 ms) after stimulus presentation. These results suggest a "push-pull" interaction in which dorsal and ventral extrastriate areas are being recruited or inhibited depending on stimulus category and task demands.
Meeting abstract presented at VSS 2013
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