The Representation of Orientation in Macaque V2: Four Stripes Not Three

Abstract

Area V2 of macaque monkeys is traditionally thought to consist of 3 distinct functional compartments with characteristic cortical connections and functional properties. Orientation selectivity is one property that has frequently been used to distinguish V2 stripes, however, this receptive field property has been found in a high percentage of neurons across V2 compartments. Using quantitative intrinsic cortical imaging, we derived maps of preferred orientation, orientation selectivity, and orientation gradient in thin stripes, thick stripes, and interstripes in area V2. Orientation-selective responses were found in each V2 stripe, but the magnitude and organization of orientation selectivity differed significantly from stripe to stripe. Remarkably, the 2 pale stripes flanking each cytochrome oxidase dense stripe differed significantly in their representation of orientation resulting in their distinction as type-I and type-II interstripes. V2 orientation maps are characterized by clockwise and anticlockwise "orientation pinwheels", but unlike V1, they are not homogeneously distributed across V2. Furthermore, V2 stripes contain large-scale sequences of preferred orientation. These analyses demonstrate that V2 consists of 4 distinct functional compartments; thick stripes and type-II interstripes, which are strongly orientation selective and thin stripes and type-I interstripes, which are significantly less selective for orientation and exhibit larger orientation gradient magnitudes.

Spatial frequency representation in V2 and V4 of macaque monkey

“…Thus, SF preference differences vary uniquely within V2 (see Figure 7M ). The differences in SF preference between the regions on the two sides of a thin stripe (see Figure 7K and L , thin stripe location: around the peaks of the black lines) may correlate to the reported two types (medial vs. lateral) of pale stripes in V2 ( Felleman et al, 2015 ).…”

Columnar organization of mid-spectral and end-spectral hue preferences in human visual cortex

“…This dichotomous end-vs. mid-spectral model has been supported by single unit recording in area V2 (Yoshioka and Dow, 1996; Yoshioka et al, 1996), in which segregated pathways are well-known based on histological (cytochrome oxidase) staining (Hubel and Livingstone, 1987; Tootell and Hamilton, 1989; Peterhans and von der Heydt, 1993; Vanduffel et al, 2002; Kaskan et al, 2009; Felleman et al, 2015). Specifically, a significant response was reported to mid-spectral hues within the thick-type (but not thin-type) stripes in macaque V2 (Yoshioka and Dow, 1996).…”

Specificity of V1–V2 orientation networks in the primate visual cortex

“…Pale stripes are further distinguished into two types (Roe & Ts'o 1995; Shipp & Zeki 2002; Federer et al 2009, 2013; Felleman et al 2014). Pale stripes associated with thick stripes (lying lateral to thick stripes, Type II) receive input from layer 4B in V1, exhibit greater orientation selectivity, smaller receptive fields with smaller scatter, and larger orientation domains with smoothly changing orientation preference across the stripe.…”