The Journal of comparative neurology
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A population of ascending interneurones with cell bodies in the metathoracic ganglion of the locust is described. Interneurones are characterised by their morphology (revealed by intracellular cobalt injection) and by their physiological responses to afferent stimulation. All interneurones have their somata in the ventral cortex of the ganglion, in an area just posterior to the medial tracheae. ⋯ Interneurones with restricted branching patterns have restricted receptive fields. The position of the ventral branching reflects the position of the receptive field on the leg. An interneurone with a receptive field restricted to the femur has ventral branches in an anterior position in the ganglion; an interneurone with a receptive field restricted to the tarsus has ventral branches in a more posterior position.
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The organization of the thalamic projections to the ventral striatum in the rat was studied by placing injections of the retrograde tracer cholera toxin subunit B in the ventral striatum and small deposits of the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) in individual midline and intralaminar thalamic nuclei. In order to provide a complete map of the midline and intralaminar thalamostriatal projections, PHA-L injections were also made in those parts of the intralaminar nuclei that project to the dorsal striatum. The relationship of thalamic afferent fibres with the compartmental organization of the ventral striatum was assessed by combining PHA-L tracing and enkephalin immunohistochemistry. ⋯ The lateral part of the parafascicular nucleus projects to the most lateral part of the caudate-putamen, whereas projections from the medial part of this nucleus terminate in the medial part of the caudate-putamen and in the dorsolateral part of the nucleus accumbens. Furthermore, a rostral to caudal gradient in a midline or intralaminar nucleus corresponds to a dorsal to ventral and rostral to caudal gradient in the striatum. In the ventral striatum, thalamic afferent fibres in the "shell" region of the nucleus accumbens avoid areas of high cell density and weak enkephalin immunoreactivity.(ABSTRACT TRUNCATED AT 400 WORDS)