Whither the hypercolumn?

Abstract

Among the crowning achievements of Hubel and Wiesel's highly influential studies on primary visual cortex is the description of the cortical hypercolumn, a set of cortical columns with functional properties spanning a particular parameter space. This fundamental concept laid the groundwork for the notion of a modular sensory cortex, canonical cortical circuits and an understanding of visual field coverage beyond simple retinotopy. Surprisingly, the search for and description of analogous hypercolumnar organizations in other cortical areas to date has been limited. In the present work, we have applied the hypercolumn concept to the functional organization of the second visual area, V2. We found it important to separate out the original definition of the hypercolumn from other associated observations and concepts, not all of which are applicable to V2. We present results indicating that, as in V1, the V2 hypercolumns for orientation and binocular interaction (disparity) run roughly orthogonal to each other. We quantified the 'nearest neighbour' periodicities for the hypercolumns for ocular dominance, orientation, colour and disparity, and found a marked similarity in the periodicities of all of these hypercolumns, both across hypercolumn type and across visual areas V1 and V2. The results support an underlying common mechanism that constrains the anatomical extent of hypercolumn systems, and highlight the original definition of the cortical hypercolumn.

Distinct Functional Organizations for Processing Different Motion Signals in V1, V2, and V4 of Macaque

“…functional domains for disparity are located in V2 thick stripes (Livingstone and Hubel, 1988;Ts'o et al, 2001Ts'o et al, , 2009Chen et al, 2008), where direction-selective domains were also found (Figs. 2 E, 8).…”

“…Drifting sine-wave gratings are the most popular visual stimuli used to map cortical orientation domains (Grinvald et al, 1986;Ts'o et al, 1990;Blasdel, 1992;Khaytin et al, 2008;Ts'o et al, 2009;Lu et al, 2010;Pan et al, 2012), whereas stimuli such as visual noise and dots are widely used to dissect the motion processing system (Mackay, 1965;Nakayama and Tyler, 1981;Britten et al, 1992;Snowden et al, 1992). In this study, to maximally remove non-motion related cues, we employed lowpass filtered FNS, whose global translation was varied only in the direction, speed, and axis of motion.…”

Attentional Modulation of fMRI Responses in Human V1 Is Consistent with Distinct Spatial Maps for Chromatically Defined Orientation and Contrast

“…However, classification in V2 is complicated by the presence of domains within the thin stripes sensitive to low spatial frequency temporal luminance modulations (Wang et al, 2007). In addition, despite the apparently larger spatial extent of the stripes compared to the V1 blobs, careful analysis shows that the spatial periodicity of the V1 and V2 color domains is very similar (Ts’o et al, 2009). It is not clear, therefore, that classification performance in V2 should surpass that in V1.…”

Early transformations in odor representation

“…For example, whereas primary visual cortex (V1) inherits a basic retinotopic organization, additional maps of orientation, spatial frequency, ocular dominance, and other higher-order attributes of the visual scene also are embedded into its cortical architecture [17, 38]. Decorrelation and related tuning operations in V1 are performed with respect to higher-order visual stimulus attributes rather than retinotopy per se – e.g., the regulation of orientation selectivity [89].…”