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Steven R. Holloway, Michael K. McBeath; Anatomically-driven Visual Neural Model Assessments Predict Temporal Thresholds Associated with the Dorsal and Ventral Systems. Journal of Vision 2014;14(10):52. doi: 10.1167/14.10.52.
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© ARVO (1962-2015); The Authors (2016-present)
An abundance of evidence supports functional anatomical specialization of cortical visual pathways. This suggests that we should be able to measure the functional processing characteristics of a specific neural pathway by emphasizing the characteristics of a stimulus that corresponds to known response characteristics of that system and by limiting those stimulus characteristics not related to the system in question. Using neural pathway models that specify distinct and measurable stimulus characteristics as a guide, we created classes of stimuli that varied in shape, presentation speed, relative brightness, edge distinctiveness, and color. This allowed us to develop and test several within-subject objective measures that are associated with recent neural anatomical models of dorsal and ventral visual pathways that predict distinct levels of temporal information processing. In the first study, baseline flicker thresholds were compared against a shape-recognition task that targeted ventral stream processing and against an apparent motion measure that targeted dorsal stream processing . For both tests, we developed objective measures in which participants identified the correct directionality of stimulus change. We found that thresholds for shape recognition were significantly slower than those for apparent motion, supporting the contention that the shape-assessment measure was consistent with ventral processing and distinct from dorsal processing. The second study compared a shape-defined-by-motion recognition task across ten speeds and three colors. We predicted three levels of temporal processing corresponding to each color condition and compared performance with a static control that presented the same information and conditions but without motion. Thresholds for shape recognition differed significantly by color and matched predicted levels of performance. Furthermore, crossover points between motion and static control conditions exhibited a consistency despite differences in shape-recognition performance. Overall, our findings support the contention that the two visual systems have distinct temporal processing rates but share information at a higher cortical level.
Meeting abstract presented at VSS 2014
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