Organization in the auditory sector of the cat's thalamic reticular nucleus

Abstract

This study describes the organization of cells in the thalamic reticular nucleus (TRN) that project to the auditory part of the cat's dorsal thalamus. Injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) and fluorescent dyes were made into the medial geniculate complex (MG). The resultant retrograde labelling in the TRN was analyzed. Injections of WGA-HRP into the ventral (MGv), dorsal (MGd), or medial (MGm) nuclei of the MG label zones of cells that are restricted to a caudoventral sector of the TRN. In reconstructions, these zones resemble "slabs" that are elongated in the dorsoventral and oblique rostrocaudal dimensions of the nucleus. In comparisons of the zones of labelling in the TRN following tracer injections into different nuclei of the MG, inner and caudal cells project to the pars lateralis of the MGv (MGvl) or to the MGd, and outer and rostral cells project to the pars ovoidea of the MGv (MGvo) or to the MGm. Thus, cells projecting to the MGvl or MGd or to the MGvo or MGm occupy overlapping territories. Double injections of different fluorescent dyes into selected pairs of MG nuclei result in reticular cells that are labelled from either both nuclei or only one or the other nucleus in each pair. These results indicate that the projections of cells in the auditory sector of the TRN to the MGvl or MGvo or to the MGd or MGm are topographically organized. Furthermore, projections to more than one MG nucleus can arise from single reticular cells.

Slow Oscillation in Non-Lemniscal Auditory Thalamus

“…The TRN neurons extend dendrites within the thin reticular sheet, which enable them to receive projections from a wide cortical region, and project to widespread areas in the ventroposterior nucleus of the thalamus (Liu et al, 1995). These, together with the results of other studies, lead to the reasonable conclusion that the control of the thalamus via the TRN is widespread (Jones, 1975(Jones, , 1985Ohara et al, 1980;Yen et al, 1985;Liu et al, 1995;Bourassa et al, 1995;Cox et al, 1997;Crabtree, 1998;Crabtree and Isaac, 2002).…”

Stimulus-Specific Adaptation in the Gerbil Primary Auditory Thalamus Is the Result of a Fast Frequency-Specific Habituation and Is Regulated by the Corticofugal System

“…Metabotropic receptors, however, such as the GABA B receptor with its potassium conductance have a longer time constant and are plausible candidates in the MGB (Tennigkeit et al, 1998(Tennigkeit et al, , 1999Schwarz et al, 2000). Because GABAergic interneurons are missing in the rodent vMGB (Winer and Larue, 1996;Arcelli et al, 1997), the cortex could act via the GABAergic projection neurons from the TRN (Crabtree, 1998;Winer et al, 1999) as demonstrated recently . The axonal projection pattern of TRN cells as described in the rat (Kimura et al, 2007) is well suited to Figure 11 A (bottom).…”

Prefrontal Projections to the Thalamic Reticular Nucleus form a Unique Circuit for Attentional Mechanisms

“…In rats, cats, rabbits, and primates, cortical and thalamic afferents in TRN are topographically organized (Crabtree and Killackey, 1989;Cicirata et al, 1990;Conley and Diamond, 1990;Cornwall et al, 1990;Crabtree, 1992aCrabtree, ,b, 1996Crabtree, , 1998Crabtree, , 1999Lozsadi, 1994Lozsadi, , 1995Ilinsky et al, 1999). Along the rostrocaudal axis, centroposterior loci in TRN are respectively linked with the somatosensory, visual, and auditory cortices and their associated thalamic nuclei.…”