Connections of the lateral and medial divisions of the goldfish telencephalic pallium

Abstract

Biotinylated dextran amine and fluorescent carbocyanine dye (DiI) were used to examine connections of the lateral (Dl) and medial (Dm) divisions of the goldfish pallium. Besides numerous intrinsic telencephalic connections to Dl and Dm, major ascending projections to these pallial divisions arise in the preglomerular complex of the posterior tuberculum, rather than in the dorsal thalamus. The rostral subnucleus of the lateral preglomerular nucleus receives auditory input via the medial pretoral nucleus, lateral line input via the ventrolateral toral nucleus, and visual input via the optic tectum, and it projects to both Dl and Dm. The anterior preglomerular nucleus and caudal subnucleus of the lateral preglomerular nucleus receive auditory input via the central toral nucleus and project to Dm. This pallial division also receives chemosensory information via the medial preglomerular nucleus. The central posterior (CP) nucleus, which receives both auditory and visual inputs, also projects to Dm and is the only dorsal thalamic nucleus projecting to the pallium. Thus, both Dl and Dm clearly receive multisensory inputs. Major projections of CP and projections of all other dorsal thalamic nuclei are to the subpallium, however. Descending projections of Dl are primarily to the preoptic area and the caudal hypothalamus, whereas descending projections of Dm are more extensive and particularly heavy to the anterior tuber and nucleus diffusus of the hypothalamus. The topography and connections of Dl are remarkably similar to those of the hippocampus of tetrapods, whereas the topography and connections of Dm are similar to those of the amygdala.

L-histidine reduces inhibitory avoidance in Carassius auratus submitted to cerebellar ablation

“…Similar findings have been reported in several other studies (10,11,17,18). Thus, we believe that the results for the fish in the A-SAL and S-SAL groups were opposite in terms of memory consolidation of the inhibitory avoidance task due to the absence of cerebellar modulation in limbic structures in the ablation group, especially in the MP, which is thought to be homologous to the amygdala (29)(30)(31).…”

“…The lateral pallium is associated with spatial and temporal memory, and appears to be homologous to the hippocampus of vertebrates, while the medial pallium (MP) is related to emotional memory and has been suggested to be homologous to the amygdala of mammals (28,29). Furthermore, recent studies have demonstrated the existence of connections between the cerebellum and the MP in goldfish and other teleost fish (30,31).…”

Evolution of the forebrain — revisiting the pallium

“…This organization led early comparative anatomists to the view that the telencephalon in teleosts EDITORIAL was entirely subpallial. But as was the case for birds, studies on molecular and hodological features of the forebrain in these fishes have led to the realization that pallial-equivalent cell groups are present despite the location of these groups below the ventricle (Wullimann and Mueller, 2004;Yamamoto et al, 2007;Northcutt, 2006;Nieuwenhuys, 2009;Mueller et al, 2011HarveyGirard et al, 2012Ganz et al, 2012). Recent hodological, neurochemical, and molecular studies suggest that lampreys also possess pallial and subpallial homologues (Murakami et al, 2001;Stephenson-Jones et al, 2012;Sugahara et al, 2013).…”

“…As is the case for birds, teleosts have two major pallial regions, lateral and medial, that receive sensory inputs from the diencephalon Ito, 2005, 2008;Northcutt, 2006). One hypothesis considers the lateral part to be homologous to the hippocampus while the medial part would represent the claustroamygdaloid complex (Northcutt, 2006).…”

“…As is the case for birds, teleosts have two major pallial regions, lateral and medial, that receive sensory inputs from the diencephalon Ito, 2005, 2008;Northcutt, 2006). One hypothesis considers the lateral part to be homologous to the hippocampus while the medial part would represent the claustroamygdaloid complex (Northcutt, 2006). A contravening hypothesis considers both the lateral and medial sensory recipient zones to be homologous to components of the neocortex, and perhaps only to its layer IV (Yamamoto et al, 2007;Ito and Yamamoto, 2009).…”