Remapping for visual stability

Abstract

Visual perception is based on both incoming sensory signals and information about ongoing actions. Recordings from single neurons have shown that corollary discharge signals can influence visual representations in parietal, frontal and extrastriate visual cortex, as well as the superior colliculus (SC). In each of these areas, visual representations are remapped in conjunction with eye movements. Remapping provides a mechanism for creating a stable, eye-centred map of salient locations. Temporal and spatial aspects of remapping are highly variable from cell to cell and area to area. Most neurons in the lateral intraparietal area remap stimulus traces, as do many neurons in closely allied areas such as the frontal eye fields the SC and extrastriate area V3A. Remapping is not purely a cortical phenomenon. Stimulus traces are remapped from one hemifield to the other even when direct cortico-cortical connections are removed. The neural circuitry that produces remapping is distinguished by significant plasticity, suggesting that updating of salient stimuli is fundamental for spatial stability and visuospatial behaviour. These findings provide new evidence that a unified and stable representation of visual space is constructed by redundant circuitry, comprising cortical and subcortical pathways, with a remarkable capacity for reorganization.

Visual stability

“…But what is new in Cavanagh et al's proposal is to challenge the entire idea of dynamic receptive fields by suggesting that attention moves but receptive fields stay fixed. It does seem difficult, initially, to reconcile their proposal with all of the research showing receptive field shifts (see reviews in [20,21,23]). Another departure in their proposal is the claim that attentional pointers represent only a spatial location (in retinal coordinates), not objects or their features.…”

“…Remapping in the frontal eye fields (FEF), for example, has been linked to the development of a predictive map of the expected consequences of the saccade [21,26] while remapping in the posterior parietal cortex has been linked to post-saccadic updating of visual working memory [27]. Two of the articles in this special issue [20,21] review the recent attempts to directly link remapping circuits to behaviour by disrupting the flow of information within the primate brain. These pioneering studies are a first step in understanding the how and why of remapping.…”

“…The change in the spatial profile of the receptive fields of neurons around the time of saccades is called 'remapping' [20][21][22], since the spatial map of the receptive field is temporarily altered. The neurophysiological evidence for remapping is discussed in detail in several of the reviews in this theme issue [20,21,23]. A number of studies which explore the pattern of remapping neurons in the brain, including the proportion of neurons that show remapping in different brain regions and the potential pathways that underlie remapping, are beginning to shed light on this process.…”

“…In many ways, neurophysiology has led the way in re-framing the issue of visual stability in terms of dynamic changes in the receptive fields of neurons (see [20,21]). The change in the spatial profile of the receptive fields of neurons around the time of saccades is called 'remapping' [20][21][22], since the spatial map of the receptive field is temporarily altered. The neurophysiological evidence for remapping is discussed in detail in several of the reviews in this theme issue [20,21,23].…”

Spatiotopic coding and remapping in humans

“…We (and many others) suggest that the reason for this is that the information integrated from one fixation to the next is information about features-such as motion and form-not light elements or pixels. As other reviews in this issue point out [16][17][18][19][20][21], the process is not like 'sticking postage stamps on a tailor's dummy', integrating detailed 'snapshots' within a trans-saccadic buffer with an external metric. This would suggest that very early stages of analysis, such as V1, should not be spatiotopic, while higher centres responsible for motion and form (including middle temporal (MT) and medial superior temporal (MST) areas) might be spatiotopic.…”