How do functional maps in primary visual cortex vary with eccentricity?

Abstract

It is important to understand whether functional maps of primary visual cortex (V1) are organized differently at the representation of different eccentricities. By using optical imaging of intrinsic signals, we compared the maps of orientation and spatial frequency (SF) preference between central (0-3 degrees ) and paracentral (4-8 degrees ) V1 in the prosimian bush baby (Otolemur garnetti). No differences related to eccentricity were found for orientation selectivity or magnitude between central and paracentral V1. We found, however, that cardinal orientations were overrepresented in central but not in paracentral V1 and that isoorientation domain size tended to be smaller in the central representation. We demonstrated that spatial frequency was represented continuously across V1, and that the map of SF preference exhibited eccentricity-dependent variations, with more territory devoted to higher SFs in central than in paracentral V1. Although there were no spatial relationships between orientation domains and cytochrome oxidase (CO) blobs or interblobs, CO blobs tended to prefer lower SFs than interblobs. Taken together with previous research, our data indicate that functional domains in V1 show eccentricity-related differences in organization and also support the idea that different maps (with or without specific geometrical relationships) are organized for adequate coverage of each feature in visual space.

Quantification of Optical Images of Cortical Responses for Inferring Functional Maps

“…The main aim of this study was to empirically determine the general scope of applicability of these methods to optical images and their limitations thereof. We also tested the resolving power of these methods by applying them to the problem of mapping spatiotemporal frequency preferences across the surface of the primary visual cortex (Basole et al 2003;Bonhoeffer et al 1995;Hubener et al 1997;Issa et al 2000;Khaytin et al 2008;Shoham et al 1997;Sirovich and Uglesich 2004;Xu et al 2007).…”

“…For instance, computational modeling of the results of Hubel and Wiesel (1963) suggested a "pinwheel" pattern of arrangement for orientation maps (Braitenberg and Braitenberg 1979). Optical imaging has visibly demonstrated the existence of orientation pinwheels in cortical areas with orderly orientation maps (Bartfeld and Grinvald 1992;Blasdel 1992a,b;Bonhoeffer and Grinvald 1991;Bosking et al 1997;Crair et al 1997;Hubener et al 1997;Rao et al 1997;Xu et al 2004Xu et al , 2005Xu et al , 2007. Optical imaging has also shown that orientation pinwheels and high orientation gradient sites tend to lie near the centers of ocular dominance columns in cats and primates (Blasdel and Salama 1986;Bartfeld and Grinvald 1992;Crair et al 1997;Hubener et al 1997;Obermayer and Blasdel 1993;Xu et al 2004Xu et al , 2005Yu et al 2005) largely in agreement with computational models proposed for the formation of cortical feature maps (Farley et al 2007;Obermayer et al 1990;Swindale 1991Swindale , 2004Yu et al 2005).…”

“…For example, different imaging studies have suggested different patterns of organization for spatiotemporal frequency preferences across the primary visual cortex of cats, prosimians, and monkeys (Bonhoeffer et al 1995;Everson et al 1998;Hubener et al 1997;Issa et al 2000;Khaytin et al 2008;Shoham et al 1997;Sirovich and Uglesich 2004;Xu et al 2007). Early optical-imaging studies concluded that only two distinct spatiotemporal frequency domains exist, one corresponding to high spatial frequency (SF) and low temporal frequency (TF) and the other corresponding to low SF and high TF (Bonhoeffer et al 1995;Hubener et al 1997;Shoham et al 1997).…”

“…The main aim of this study was to empirically determine the general scope of applicability of these methods to optical images and their limitations thereof. We also tested the resolving power of these methods by applying them to the problem of mapping spatiotemporal frequency preferences across the surface of the primary visual cortex (Basole et al 2003;Bonhoeffer et al 1995;Hubener et al 1997;Issa et al 2000;Khaytin et al 2008;Shoham et al 1997;Sirovich and Uglesich 2004;Xu et al 2007).Optical imaging of intrinsic signals and voltage-sensitive dyes in vivo has made it possible to test models of cortical organization that could not be easily tested earlier (reviewed by Bonhoeffer and Grinvald 1996). For instance, computational modeling of the results of Hubel and Wiesel (1963) suggested a "pinwheel" pattern of arrangement for orientation maps (Braitenberg and Braitenberg 1979).…”

On the Specific Role of the Occipital Cortex in Scene Perception

“…A large number of neurophysiological studies performed on cats [79,80], primates [6,[81][82][83][84] and humans [16][17][18] have mapped representations of the different spatial frequencies in retinotopic areas. Using retinotopic encoding with achromatic sinusoidal gratings, Sasaki and collaborators [17] have, in particular, shown that LSF are mapped in occipital areas in accordance with the cortical representation of the peripheral visual field, whereas HSF are mapped in accordance with the central visual field.…”