TY - JOUR T1 - Parallel Streams to Interconnected Networks: Organization and Reorganization of Cortical Processing During Visual Perception and Action JF - bioRxiv DO - 10.1101/609487 SP - 609487 AU - Dipanjan Ray AU - Nilambari Hajare AU - Dipanjan Roy AU - Arpan Banerjee Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/04/16/609487.abstract N2 - Dual stream theory of visual processing posits that two distinct neural pathways of specific functional significance originate from primary visual areas and reaches the inferior temporal and posterior parietal areas. However, there are several unresolved questions concerning the fundamental aspects of this theory. For example, is the functional dissociation between ventral and dorsal stream input or output based? Is the dual stream rigid or adaptable to changes? What are the nature of the interactions between ventral and dorsal streams? We addressed these questions using fMRI recordings on healthy human volunteers when they perform perception and action tasks involving color, face, and position stimuli. fMRI scans were repeated after seven practice sessions to investigate the effects of neuroplasticity. Brain mapping analysis supports an input-based functional specialihation and existence of context-dependent neuroplasticity in dual stream areas. Intriguingly, premotor cortex activation was observed in position perception task and distributed deactivated regions showing decrease in BOLD activity during task performance compared to baseline was observed in all perception tasks. Dynamic causal modelling (DCM) analysis of cortical activations and deactivations during perception tasks indicates that the brain dynamics in dorsal and ventral stream areas could be interpreted within the framework of predictive coding. DCM analysis also reveals an inhibitory influence from dorsal to ventral stream regions while performing goal-directed action. Effectively, the network level findings point towards the existence of more intricate context-driven functional networks selective of “what” and “where” information processing and likely breakdown of the parallel architecture underlying processing of visual information.Significant Statenent The present work addressed several gaps in the visual dual stream theory. The study supported an input-based functional specialihation in the dual stream, however, the dominant dual stream theories could not explain the pattern of BOLD activations and deactivations in entirety. Using network metrics we could establish the mechanism of predictive coding as a guiding principle to interpret the brain dynamics in dorsal and ventral stream areas. Effective connectivity analysis during action tasks revealed the inhibitory influence of dorsal areas on to ventral stream processing and demonstrated that this influence consolidated over training. Overall, the study pointed towards the existence of more intricate context-driven functional networks and likely breakdown of the parallel architecture underlying processing of visual information. ER -