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Biomedical subjects

B L Guthrie

Publications and source records attributed to B L Guthrie.

23 records · Page 2Linked to original sources
PubMed1985

Selective retrograde transneuronal transport of wheat germ agglutinin-conjugated horseradish peroxidase in the oculomotor system.

The fate of wheat germ agglutinin-conjugated horseradish peroxidase (WGA/HRP) subsequent to its uptake and retrograde axonal transport in abducens motoneurons of the monkey was studied using histochemical localization of WGA/HRP reaction product and light microscopy. Injections of WGA/HRP into monkey lateral rectus muscles produced a pattern of labelled motoneurons like that obtained with native HRP. In contrast to the native HRP data, WGA/HRP injections consistently labelled additional neuronal populations in the ipsilateral medial vestibular nucleus and contralateral dorsal medullary reticular formation. These regions correspond to those containing neurons known to make inhibitory synaptic contact with abducens motoneurons. No labelled neurons were observed in regions which contain excitatory premotor neurons. These data are consistent with the notion of retrograde transneuronal transport of WGA/HRP to premotor neurons. The specificity of the transneuronal exchange is indicated by the finding that only certain populations of premotor neurons were labelled. The precise manner by which preferential transneuronal transport of WGA/HRP is attained remains to be determined.

Abducens Nerve↗
PubMed1983

Corollary discharge provides accurate eye position information to the oculomotor system.

The saccadic system accurately compensates for perturbations of eye position produced by microstimulation of the superior colliculus. This requires that information about the stimulation-induced change in eye position be provided by an extraretinal source--either proprioceptive endings in extraocular muscles or a centrally generated corollary discharge. It is shown that compensation remains intact after elimination of extraocular muscle proprioception, demonstrating that corollary discharge provides accurate eye position information.

Animals↗
PubMed1976

Size and distribution of movement fields in the monkey superior colliculus.

A gradient of response magnitude was observed across the movement fields (the range of eye movements which alter the discharge frequency of a nueron) of neurons in the intermediate and deeper layers of the superior colliculus. A vigorous discharge preceded movements with a particular direction and amplitude but reduced responses preceded movements which deviated from this direction and/or amplitude. Movement field size is a function of the amplitude of the optimal movement. Neurons discharging prior to small saccades have small and sharply tuned fields. Neurons discharging prior to large saccades have large movement fields and tuning is relatively coarse. Movement fields are topographically organized within the superior colliculus. Neurons discharging prior to small saccades are located anteriorly; neurons firing before large saccades are found caudally. Neurons near the midline discharge prior to up movements and neurons located laterally fire before downward movements. Movement fields of superior colliculus neurons are also characterized by a temporal gradient. The interval between spike discharge and the onset of a saccade is greater for movements near the center of the movement field than for movements to the periphery of the field. Results are interpreted as supporting the foveation hypothesis of superior colliculus function. It is suggested that precise saccadic movements are not produced by the discharge of a small population of finely tuned neurons but result from the weighted sum of the simultaneous movement tendencies produced by the activity of a large population of less finely tuned neurons.

Animals↗
PubMedDate not supplied

Bilateral cholesterol granulomas of the temporal bone.

Cholesterol granulomas of the temporal bone without clinical symptoms of chronic otitis media may result from an indolent inflammatory process caused by a congenitally blocked group of air cells. A unique case of giant bilateral cholesterol granulomas of the temporal bone is presented to support this theory. Management allowed bilateral surgical removal with hearing preservation. The differentiation between cholesterol granuloma, giant cholesterol cyst and other lesions of the temporal bone is discussed. The presumed pathogenesis of this condition is reviewed.

Bone Diseases↗