Two Visual Pathways in Primates Based on Sampling of Space: Exploitation and Exploration of Visual Information

Abstract

Evidence is strong that the visual pathway is segregated into two distinct streams—ventral and dorsal. Two proposals theorize that the pathways are segregated in function: The ventral stream processes information about object identity, whereas the dorsal stream, according to one model, processes information about either object location, and according to another, is responsible in executing movements under visual control. The models are influential; however recent experimental evidence challenges them, e.g., the ventral stream is not solely responsible for object recognition; conversely, its function is not strictly limited to object vision; the dorsal stream is not responsible by itself for spatial vision or visuomotor control; conversely, its function extends beyond vision or visuomotor control. In their place, we suggest a robust dichotomy consisting of a ventral stream selectively sampling high-resolution/focal spaces, and a dorsal stream sampling nearly all of space with reduced foveal bias. The proposal hews closely to the theme of embodied cognition: Function arises as a consequence of an extant sensory underpinning. A continuous, not sharp, segregation based on function emerges, and carries with it an undercurrent of an exploitation-exploration dichotomy. Under this interpretation, cells of the ventral stream, which individually have more punctate receptive fields that generally include the fovea or parafovea, provide detailed information about object shapes and features and lead to the systematic exploitation of said information; cells of the dorsal stream, which individually have large receptive fields, contribute to visuospatial perception, provide information about the presence/absence of salient objects and their locations for novel exploration and subsequent exploitation by the ventral stream or, under certain conditions, the dorsal stream. We leverage the dichotomy to unify neuropsychological cases under a common umbrella, account for the increased prevalence of multisensory integration in the dorsal stream under a Bayesian framework, predict conditions under which object recognition utilizes the ventral or dorsal stream, and explain why cells of the dorsal stream drive sensorimotor control and motion processing and have poorer feature selectivity. Finally, the model speculates on a dynamic interaction between the two streams that underscores a unified, seamless perception. Existing theories are subsumed under our proposal.

Goal-Directed Behavior under Variational Predictive Coding: Dynamic organization of Visual Attention and Working Memory

“…2). Inspired by the two stream hypothesis proposed in [14], [15], the dorsal visuomotor stream network receives peripheral visual information and the ventral visuomotor stream network receives central visual information, but both receive the same motor input. The size and location of the attentional focus for central vision vary continuously over time in response to changing environments and goals.…”

Characterization of Feedback Neurons in the High-Level Visual Cortical Areas That Project Directly to the Primary Visual Cortex in the Cat

“…It is widely assumed for a long time that visual perception is formed step by step in a feedforward mode from the retina to LGN, then to the primary visual cortex (V1), and finally to higher-order visual cortical areas (Hubel and Wiesel, 1968 ; Hirsch, 2003 ; Herzog and Clarke, 2014 ). Different types of visual information are processed through segregated pathways of ventral and dorsal streams in the visual cortex of primates and cats (Tong et al, 2011 ; Sheth and Young, 2016 ). Generally, the ventral stream, from V1 to V3 and then to V4, processes information of object form and identity, whereas the dorsal stream, from V1 to V2 and then to V5 (MT), is responsible for the processing of object location and movement (Sheth and Young, 2016 ).…”

Psychophysical evaluation of individual low-level feature influences on visual attention

“…Distinct eye movement behavior is presented to be dependent as well for saccade length, pupil dilation and eye vergence [Privitera et al, 2014] [Miura et al, 2001] [Fallah and Reynolds, 2012] [Wang et al, 2014] [Puig et al, 2013]. All of these factors should be considered in future visual attention modeling considering their relationships with the two-stream hypothesis [VanEssen and Gallant, 1994] [Bell et al, 2013] [Trevarthen, 1968] [Sheth and Young, 2016] in order to specify the experimental conditions for a better evaluation of uniquely bottom-up visual attention.…”