Representation of shape, space, and attention in monkey cortex
Authors: Sidney R Lehky
Margaret E Sereno
Anne B Sereno
Journal: Cortex (2020)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Executive function; Human disorders; Population coding; Sensorimotor function; Visual cortex.
Affiliations: Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA. Electronic address: ., Computational Neurobiology Laboratory, The Salk Institute, La Jolla, CA, USA., Department of Psychology, University of Oregon, Eugene, OR, USA.

Abstract:  Attentional deficits are core to numerous developmental, neurological, and psychiatric disorders. At the single-cell level, much knowledge has been garnered from studies of shape and spatial properties, as well as from numerous demonstrations of attentional modulation of those properties. Despite this wealth of knowledge of single-cell responses across many brain regions, little is known about how these cellular characteristics relate to population level representations and how such representations relate to behavior; in particular, how these cellular responses relate to the representation of shape, space, and attention, and how these representations differ across cortical areas and streams. Here we will emphasize the role of population coding as a missing link for connecting single-cell properties with behavior. Using a data-driven intrinsic approach to population decoding, we show that both 'what' and 'where' cortical visual streams encode shape, space, and attention, yet demonstrate striking differences in these representations. We suggest that both pathways fully process shape and space, but that differences in representation may arise due to their differing functions and input and output constraints. Moreover, differences in the effects of attention on shape and spatial population representations in the two visual streams suggest two distinct strategies: in a ventral area, attention or task demands modulate the population representations themselves (perhaps to expand or enhance one part at the expense of other parts) while in a dorsal area, at a population representation level, attention effects are weak and nearly non-existent, perhaps in order to maintain veridical representations needed for visuomotor control. We show that an intrinsic approach, as opposed to theory-driven and labeled approaches, is useful for understanding how representations develop and differ across brain regions. Most importantly, these approaches help link cellular properties more tightly with behavior, a much-needed step to better understand and interpret cellular findings and key to providing insights to improve interventions in human disorders. 

Retracted: No

PubPeer comments:
  We argue that the visual propertiesu201cshapeu201dandu201clocationu201d are independently elaborated in each of the two streams. This is in contrast to the widespread interactionist viewpoint, in which a complete representation of an image requires cross-talk or inter-stream communication between different streams. Under our viewpoint, what distinguishes the dorsal and ventral stream are not specializations for the different propertiesu201cshapeu201dandu201clocationu201din the two streams. Rather, what distinguishes them are the ways that shape and location are differently and independently constructed within each stream to achieve particular functions. From the point of view of someone familiar with the nature of perceptual experience, the idea that  shape and  location can be  independently elaborated (or even  interact as independent factors) doesn t ring true. In perception, shape and location are inextricably linked. Perceived shape structures space and creates the impression of relative location and distance. And, as is the case for true, physical shape, true physical location of objects, at least in relative terms, are a potential but not a necessary outcome of perceptual processes. This is self-evident in the case of pictorial perception. With pictures we may create extremely powerful illusions of depth. There is nothing remotely accurate about the illusions these create. Even 3D environments, such as the Ames room, create inaccurate perceptions of shape (of the room) and relative location (of the walls and people). I don t know how to integrate statements such as  having large receptive field diameters produce metrically accurate representations of physical space, whereas smaller receptive fields degrade the accuracy of spatial representations... with what I know about perception. How do models constructed on the basis of  metric accuracy relate to perceptual processes that may or may not produce accurate representations, and for which the information relating to either shape or location (i.e. the retinal stimulation) is identical? ,