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Biomedical subjects

R J Sutherland

Publications and source records attributed to R J Sutherland.

At least 73 records · Page 4Linked to original sources
PubMed1982

The dorsal diencephalic conduction system: a review of the anatomy and functions of the habenular complex.

The first part of this paper is an attempt to sketch an outline of the anatomy of the dorsal diencephalic conduction system by reviewing experimental evidence establishing the afferent and efferent connections of the habenular complex. This system provides an alternative to the descending medial forebrain bundle for the conduction of information from the limbic forebrain to limbic midbrain areas. The second part is a critical examination of experiments using ablation or electrical and chemical stimulation techniques which are concerned with the behavioural functions of the habenular complex. The habenula has been shown to play an important role in a diverse set of behavioural systems, which include olfaction, ingestion, mating, endocrine function, aversive motivation, and brain stimulation. Anatomical and behavioural support is presented for the view that the dorsal diencephalic conduction system provides an opportunity for interaction of activity in motivational systems with movement systems in the striatum and midbrain.

Animals↗
PubMed1982

Dissociation of the contributions of the prefrontal cortex and dorsomedial thalamic nucleus to spatially guided behavior in the rat.

Rats with lesions of the medial frontal cortex or dorsomedial nucleus of the thalamus (MD) were studied in two spatial localization tasks: the Morris water task and the 8-arm radial arm maze. Rats with medial frontal lesions failed to learn to swim from different locations to a hidden platform located at a specific place in a large tank (Morris task) and were impaired at learning the location of reward in the radial arm maze. Rats with MD lesions were not impaired at spatial orientation in either task. The results provide the first unequivocal evidence of a spatial orientation deficit following frontal lesions and lend support to the notion that the frontal cortex forms part of a 'spatial mapping system'. The results suggest that although MD is the major afferent to the frontal cortex, it does not provide necessary spatially-relevant input.

Afferent Pathways↗
PubMed1982

Cholinergic receptor blockade impairs spatial localization by use of distal cues in the rat.

Spatial localization was studied in the Morris water maze. The task required rats to escape from cool water (made opaque by milk) by finding a submerged, invisible platform located at a fixed place within the room. The start point was varied randomly, and there was no local cues to indicate the position of the platform. After training, the platform was moved. Rats subjected to central cholinergic receptor blockade with atropine sulfate were compared with normal rats and rats receiving peripheral cholinergic blockade with atropine methylnitrate. The controls for the use of search strategies, as compared with spatial mapping, were a group of blind rats and a group of rats for which the platform was moved from trial to trial. Measures of escape latency, swim distance, initial heading error, posttrial rearing on the platform, and search strategy after platform displacement revealed that the control rats and the atropine methylnitrate rats used a spatial mapping strategy to locate the platform. The atropine sulfate treated rats adopted a search strategy like that of the blind rats and the rats for which the platform was randomly moved: Their escape latency and swimming distance decreased across trials, including reversal trials, but their initial heading errors remained unchanged. The results support the idea that central cholinergic systems are important for spatial mapping, which demands the use of distal visual cues, but not for spatial localization, which requires other search strategies and possibly the use of proximal tactile, kinesthetic, and visual cues. Consistent with this idea, certain features of the atropine sulfate treated rats' behavior also suggested a novel explantation for some aspects of atropine stereotypies.

Animals↗
PubMed1981

Self-stimulation of the habenular complex in the rat.

The rewarding effect of habenular stimulation was studied in 65 rats. The animals learned to bar press for electrical stimulation of the medial or lateral habenular nucleus or the fasciculus retroflexus, but not the surrounding thalamic nuclei. The response rates were moderate and steady and not influenced by food or water deprivation. Habenular self-stimulation was significantly facilitated by placing lesions in the ipsilateral anterior part of the medial forebrain bundle (MFB). Similarly, MFB self-stimulation was enhanced by ipsilateral habenular lesions. Lesions centered in the region of median raphe nucleus suppressed habenular self-stimulation for more than 4 wk. Self-stimulation of median raphe was not affected by habenular lesions. The results show that habenular stimulation can produce a rewarding effect by exciting neurons in the region of the raphe nuclei but apparently without requiring the participation of the well-known MFB reward system.

Animals↗