Delayed maturation of receptive field center/surround mechanisms in V2

Abstract

Neurons in the adult visual cortex are capable of integrating signals over a large area that surrounds their classic receptive field (RF), and this ability of cortical neurons is thought to be intimately involved in perceptual binding. It is not known, however, at what age these long-range signal interactions emerge. Here, we report that qualitatively adult-like center͞surround interactions are already present in the primary visual cortex as early as postnatal day 14 in macaque monkeys. However, the RF surrounds of visual area 2 (V2) neurons were largely absent until 4 weeks of age and, as late as 8 weeks of age, center͞surround signal interactions in V2 neurons were immature. Our results suggest that the cortical circuits underlying the RF center͞surround of individual neurons mature considerably later in V2 than in the primary visual cortex and give critical evidence for the hypothesis that the functional maturation of the primate visual brain proceeds in a hierarchical manner.monkey ͉ postnatal development ͉ primary visual cortex ͉ long-range signal interaction ͉ cortical circuits

Development of Temporal Response Properties and Contrast Sensitivity of V1 and V2 Neurons in Macaque Monkeys

“…The spatial response properties of neurons in monkey V1 are far more mature near birth Rust et al 2002;Zhang et al 2005) than previously thought (Blakemore and Vital-Durand 1981). As early as 1 wk of age, V1 neurons are well tuned to stimulus orientation, spatial frequency, and binocular spatial phase disparity and, by 4 wk of age, qualitatively adultlike tuning is present for these response properties .…”

“…The center-surround receptive-field (RF) organization of the majority of V1 neurons is adultlike by 2 wk of age. However, the maturation of the RF centers and surrounds of V2 neurons is substantially delayed relative to that in V1 (Zhang et al 2005). These previous studies have begun to provide evidence for the aforementioned hypothesis of visual system development.…”

“…However, these investigators concluded that the neural limits imposed on these functions in infant monkeys are likely to reside beyond the LGN, i.e., in V1 or beyond. Very little is known about the normal development of the temporal response properties or the contrast sensitivity of V1 neurons (Rust et al 2002;Zhang et al 2005) and absolutely nothing is known about the maturation of these response properties in extrastriate neurons. In this study, we examined the temporal frequency tuning, response timing, and contrast sensitivity of V2 neurons at 2, 4, and 8 wk of age and compared them to those in V1 to determine whether V2 and/or V1 neurons are involved in setting limits on the development of temporal contrast sensitivity.…”

“…An emerging view on primate vision development is that the neural mechanisms that support normal maturation may reflect differential development in at least two parts of our visual brain: 1) the "low-level mechanisms" [e.g., lateral geniculate nucleus (LGN) and V1] that functionally mature relatively early and 2) the "mid-or high-level mechanisms" (e.g., visual cortices beyond V1), where functional maturation is progressively delayed in a hierarchical order (Barone et al 1996;Batardiere et al 2002;Kiorpes and Movshon 2004b;Zhang et al 2005).…”

Development of visually evoked cortical activity in infant macaque monkeys studied longitudinally with fMRI

“…Thus, an obvious and important question to address is, what is the sequence of development of higher visual cortical areas in relation to primary visual cortex? A few studies have attempted to investigate this question at the single-neurone level in nonhuman primates [4][5][6][7][8]. These studies show on balance later development of extrastriate and inferotemporal visual areas.…”