Lateral division of the lateral posterior region: Connections with area 18 in cats

Abstract

To establish the topography of the lateral division of the lateral posterior region (LP1) projections to area 18, up to five different anatomical tracers were injected in separate rostrocaudal locations in area 18 of four adult cats, and patterns of retrogradely labeled LP1 cells were identified. LP1 inputs to area 18 arose from both caudal and rostral nuclei and were topological, organized in patterns that indicate that lower visual space is represented anteroventrally, and more central and upper visual space is represented caudodorsally. In the caudal LP1 nucleus, patches of labeled cells formed bands that ran parallel to the medial and lateral LPI borders and encompassed medial portions of the nucleus. In rostral LP1, the patches of labeled cells formed clusters giving the connections with area 18 a more modular appearance, and were nearer the lateral LP1 border. Injections made nearest area centralis representations in area 18 labeled more neurons than injections in cortex representing more peripheral visual space. Also, neighboring injections in area 18 labeled overlapping patches of cells, but no double-labeled cells were observed. These findings are consistent with previous conclusions based on electrophysiological mapping studies, that two retinotopically organized nuclei constitute LP1.

Parallel feedback pathways in visual cortex of cats revealed through a modified rabies virus

“…Area 18, however, shows more dorsal stream specificity in that the majority of neurons are highly direction selective (Hubel and Wiesel, 1965;Dreher and Cottee, 1975), signifying a clear contribution to motion processing (see more below). However, area 18 is connected not only to higher order areas in the lateral suprasylvian sulcus such as PMLS and PLLS, but also to area 21a (Symonds and Rosenquist, 1984a;Sherk, 1986;Grant and Shipp, 1991;Pospichal et al, 1996;Stewart et al, 2000). It has been suggested that PMLS and 21a are part of the dorsal and ventral streams, respectively, because they are relatively more involved in motion (PMLS) or form (21a) processing (Dreher et al, 1996a,b;Wang and Dreher, 1996;Wang et al, 2007;Villeneuve et al, 2009).…”

Postnatal development of the LP-Pulvinar complex

“…Кластерную организацию ядра LPl ранее демонстрировали при изучении его кортикопетальных проекций, поскольку нейроны, инициирующие эти проекции, образовывали регулярные группы (Berson, Graybiel 1983;Raczkowski, Rosenquist 1983;Pospichal et al 1996). У животных группы «Трейсирование», использованных в нашей работе, нейроны ядра LPl, ретроградно Рис.…”