Continuous Updating of Visuospatial Memory in Superior Colliculus during Slow Eye Movements

Abstract

Highlights d Visual neurons in monkey SC retain target location during pursuit eye movements d These responses are continuously updated in gaze-centered coordinates d This response is modulated by attention and/or target

Object files across eye movements: Previous fixations affect the latencies of corrective saccades

“…Additionally, IOR may be elicited by location more than by object identity (Bichot & Schall, 2002), which seems to be supported by neurophysiological studies. The superior colliculus is critically involved in executing saccades and (disengaging) spatial attention (Dash, Yan, Wang, & Crawford, 2015; Ferreira, Araujo, Matsumoto, Ono, & Nishijo, 2015; Sapir, Soroker, Berger, & Henik, 1999; Wurtz & Goldberg, 1972). As such, activity in the superior colliculus has been shown to reflect IOR (Dorris, Klein, Everling, & Munoz, 2002; Fecteau, Bell, & Munoz, 2004), which is supported by lesion studies showing that IOR is not generated in patients with a lesioned superior colliculus (Sapir et al, 1999).…”

Vision: A Moving Hill for Spatial Updating on the Fly

“…The study by Dash et al [5] speaks directly to the distinction. Prior to this work, almost all that was known about the neural mechanisms of spatial updating derived from studies employing saccades [1–4,6–11], the extremely rapid, highly stereotyped, and discrete eye movements used to sample a visual scene one fixation at a time.…”

“…In contrast, virtually nothing was known about how the brain updates the representations of remembered visual goals when movements are continuous, as in the case of the smooth pursuit eye movements that would be enlisted to track a fly’s path in space. As described below, by cleverly adapting the key features of a transsaccadic remapping task for use with smooth pursuit eye movements, Dash et al [5] may have revealed a critical neural foundation for this capability.…”

“…The highly stereotyped and quantal nature of saccades lends well to this because the motor command is a good predictor of the upcoming gaze displacement. As noted by Dash et al [5], however, pursuit movements offer no such foreknowledge; generally speaking, they are neither stereotyped nor of predetermined metrics and thus provide no such future gaze anchoring point for updating the spatial representations of remembered visual goals. So what implications does the distinction between discrete and continuous movements have for spatial performance and the neural mechanisms of spatial updating?…”

“…A study by Dash et al [5] reported in this issue of Current Biology highlights the intersection of these processes by revealing a novel neural substrate for maintaining a moment-by-moment account of where past viewed objects are with respect to one’s present gaze. In demonstrating a heretofore unrecognized dynamism within a well-known midbrain ‘visual’ topography, the findings provide the first glimpse into a putative neural mechanism for spatial updating on a continuous time scale.…”