Visual response properties of cortical inputs to an extrastriate cortical area in the cat

Abstract

The existence of multiple areas of extrastriate visual cortex raises the question of how the response properties of each area are derived from its visual input. This question was investigated for one such area in the cat, referred to here as the Clare-Bishop area (Hubel & Wiesel, 1969); it is the region of lateral suprasylvian cortex that receives input from area 17. A novel approach was used, in which kainic acid was injected locally into the Clare-Bishop area, making it possible to record directly from afferent inputs.The response properties of the great majority of a sample of 424 presumed afferents resembled cells in areas 17 and 18. Thus, a systematic comparison was made with cells from area 17's upper layers, the source of its projection to the Clare-Bishop area (Gilbert & Kelly, 1975), to see whether these afferents had distinctive properties that might distinguish them from cells projecting to areas 18 or 19. Some differences did emerge: (1) The smallest receptive fields typical of area 17 were relatively scarce among afferents. (2) Direction-selective afferents were more abundant than were such cells in area 17. (3) End-stopped afferents were extremely rare, although end-stopped cells were common in area 17's upper layers.Despite these differences, afferents were far more similar in their properties to cells in areas 17 and 18 than to cells in the Clare-Bishop area. Compared to the latter, afferents showed major discrepancies in receptive-field size, in direction selectivity, in end-stopping, and in ocular dominance distribution. These differences seem most likely to stem from circuitry intrinsic to the Clare-Bishop area.

Processing of form and motion in area 21a of cat visual cortex

“…Indeed, the proportion of neurons which could be excited by visual stimuli presented through either eye is substantially higher in area 21a than in areas 17 and 18 (cf. Hubel & Wiesel, 1962, 1965Dreher & Cottee, 1975;Kato et al, 1978;Ferster, 1981;LeVay & Voigt, 1988;Sherk, 1989Sherk, , 1990. Furthermore, in our recent study (Wang et al, 1991) in which we varied systematically (using Risley biprisms) the degree of superimposition of the receptive fields revealed by stimulation of either eye, we have found that close to 15% of area 21a neurons are "obligate binocular cells" which do not respond to monocular stimulation of either eye (cf.…”

“…Dreher, 1986). It is also worth pointing out that, among the cells which provide principal associational input to area 21a, simple cells are relatively scarce in laminae 2 and 3 of area 17 (Hubel & Wiesel, 1962;Sherk, 1989), although they are fairly common in these layers in area 18 (Ferster, 1981).…”

“…Finally, the present study indicates that binocular neurons in area 21a, unlike those in areas 17 and 18, tend to be class 4 cells, that is, cells dominated by the ipsilateral eye (cf. Hubel & Wiesel, 1962, 1965Katoetal., 1978;Skottun& Freeman, 1984;Sherk, 1989Sherk, , 1990.…”

Cytoarchitectural differences are a key determinant of laminar projection origins in the visual cortex

“…It arises predominantly from segregated populations of supragranular layer cells (Fig. 7, Boyd and Matsubara, 1999;Shipp and Grant, 1991), the majority (∼70%) of which exhibit some degree of directional-selectivity, a higher proportion than among all cells (∼55%) residing in the upper layers of area 17 (Sherk, 1989), suggesting that the projection contributes to the role of area PMLS in motion perception (Lomber et al, 1996;Rudolph and Pasternak, 1996) and its preponderance (∼ 80-90%) of direction-selective neurons (Spear and Baumann, 1975). Indeed, selective removal of the projection by unilateral lesion of area 17 has been reported to reduce the proportion and degree of directionselectivity among PMLS cells for both simple (Spear, 1988) and complex (Ouellette et al, 2007) motion stimuli.…”

Reciprocal projections of cat extrastriate cortex: I. distribution and morphology of neurons projecting from posterior medial lateral suprasylvian sulcus to area 17

“…However, to say that these neuronal morphologies are similar is not to say that they are identical; even within a cortical area, the morphology of neurons projecting to one cortical area may differ from those projecting to another cortical area (Einstein and Fitzpatrick, 1991). Indeed, the functional types differ as well (Bullier et al, 1988;Sherk, 1989). However, both feedforward and feedback projections share the essential features of a broad distribution of neuronal morphologies and, most likely, functional types from across layers 2-6, with little integration of multilaminar input at the level of a single neuron.…”