Horizontal projections of area 17 in Cebus monkeys: metric features, and modular and laminar distribution

Abstract

Metric features and modular and laminar distributions of intrinsic projections of area 17 were studied in Cebus apella. Anterogradely and retrogradely labeled cell appendages were obtained using both saturated pellets and iontophoretic injections of biocytin into the operculum. Laminar and modular distributions of the labeled processes were analyzed using Nissl counterstaining, and/or cytochrome oxidase and/or NADPH-diaphorase histochemistry. We distinguished three labeled cell types: pyramidal, star pyramidal and stellate cells located in supragranular cortical layers (principally in layers IIIa, IIIb α, IIIb ß and IIIc). Three distinct axon terminal morphologies were found, i.e., Ia, Ib and II located in granular and supragranular layers. Both complete and partial segregation of group I axon terminals relative to the limits of the blobs of V1 were found. The results are compatible with recent evidence of incomplete segregation of visual information flow in V1 of Old and New World primates.

S1 to S2 hind- and forelimb projections in the agouti somatosensory cortex: Axon fragments morphological analysis

“…This implies in incomplete reconstructions from which only metric features that do not depend on the order of the segments are suitable for analysis. As previously recommended elsewhere (Amorim and Picanco-Diniz, 1997;Gomes-Leal et al, 2002;Rocha et al, 2007) we have done similar choice in the present morphometric analysis, providing consistent quantitative data through density values in [ ( ) T D $ F I G ] , and field area (E) of axon trees of the S1 to S2 somatosensory ipsilateral projections in the agouti. Significant distinctions between axon fragments Types I and II (left column) and between hind and forelimb (right column) are indicated by asterisk (two-tailed Student's t-test, p < 0.05).…”

Precise visuotopic organization of the blind spot representation in primate V1

“…This result corroborates our working hypothesis that long-range collinear interactions in V1 constitute the anatomical substrate for the completion phenomena we observe. V1 horizontal connections, for example, give rise to specialized circuits, which shape the direction and orientation tuning of the neurons by linking columns with similar response properties ( Amorim and Picanco-Diniz 1997 , Bosking et al 1997 ; Buzas et al 1998 , 2001 ; Crook et al 1996 , 1997 , 1998 ; de Amorim and Picanco-Diniz 1996 , Kisvarday et al 1997 , 2000 ; Sincich and Blasdel 2001 ). In this way, neurons inside the BSR would receive long-distance input (up to ∼8 mm, see Calford et al 2003 ; Chino et al 1995 ; Gilbert et al 1996 ) from neurons with similar response properties located outside the BSR, explaining the relevance of collinear flanks to the active completion process.…”

GABA-induced inactivation of Cebus apella V2 neurons: effects on orientation tuning and direction selectivity

“…V2 is a belt of cortex located in the opercular region of the occipital pole in front of V1. It is limited posteriorly by V1, except in the most anterior region of the calcarine sulcus, which borders the area of prostriata of Sanides ( 14 , 21 ). V2 is limited anteriorly by V3 except at the representation of the fovea region at the lateral surface between the lunate sulcus and the inferior occipital sulcus, where V2 borders V4 21 ).…”

“…We studied the receptive field properties of V2 neurons before and after the inactivation of a small portion of area V2 in the capuchin monkey ( Cebus apella ). Several aspects of the visual system of this New World monkey, including the thalamic organization ( 16 - 18 ), intrinsic circuitry of V1 ( 19 - 21 ), and topographical characteristics of areas V1, V2, MT, and V4 ( 14 , 22 - 25 ) have been studied for almost two decades, making this monkey a suitable experimental model for this study. In addition, we recently studied the effect of GABA inactivation of visual area MT ( 26 ), visual area V4 ( 27 ), and previously (2004) the pulvinar ( 28 ) on the direction and orientation selectivity of V2 neurons.…”