Feedforward and feedback processes in vision

Hierarchical processing is key to understanding vision. The visual system consists of hierarchically organized distinct anatomical areas functionally specialized for processing different aspects of a visual object (Felleman and Van Essen, 1991). These visual areas are interconnected through ascending feedforward projections, descending feedback projections, and projections from neural structures at the same hierarchical level (Lamme et al., 1998). Even though accumulating evidence suggests that these three projections play fundamentally different roles in perception, their distinct functional roles in visual processing are still subject to debate (Lamme and Roelfsema, 2000). The focus of this Research Topic was the roles of feedforward and feedback projections in vision. In fact, our motivation to edit this Research Topic was threefold: (i) to provide current views on the functional roles of feedforward and feedback projections for the perception of specific visual features, (ii) to invite recent views on how these functional roles contribute to the distinct modes of visual processing, (iii) to provide recent methodological views to identify distinct functional roles of feedforward and feedback projections and corresponding neural signatures. As summarized below, these aims are largely achieved thanks to fourteen contributions to this issue.