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W Fries

Publications and source records attributed to W Fries.

At least 73 records · Page 4Linked to original sources
PubMed1981

The distribution of pontine projection cells in visual and association cortex of the cat: an experimental study with horseradish peroxidase.

The projections from the visual and association areas of the cat's neocortex to the pons were investigated with horseradish peroxidase as retrograde tracer. Small injections were made into the pars basalis of the pons, along its entire rostrocaudal extent. The cortical areas considered were areas 17, 18, 19, 20, 21, and the lateral suprasylvian areas (LSA); the posterior (PMSA), and the anterior middle suprasylvian association area (AMSA), the anterior lateral association area (ALA) and the anterior suprasylvian association area (ASA). A pontine projection was found for all the areas investigated; however, areas differ in the relative strength of their projection, in their intraareal distribution of projection cells, and in the location of their projection zones within the pons. A low to moderate density of projection cells is seen in the areas 17, 18, 19, 20, 21, and in PMSA. The posterior part of LSA contains only a few projection cells, whereas in more anterior parts of LSA the density of projection cells is moderate to high. A relatively dense distribution of projection cells also appears in AMSA, ALA, and ASA. In those areas which are retinotopically organized (17, 18, 19, LSA) the representation of the center of gaze contains far fewer projection cells than the representation of peripheral vision. In the association areas the distribution of projection cells appears even. The projection zones from areas 17, 18, and 19 overlap with the zones from LSA in the anterior half of the basal pons. The projection zones from areas 20 and 21 and from ALA and ASA are located in the middle third and the projection zones from PMSA and AMSA spread throughout the entire rostrocaudal extent of the basal pons. Our findings indicate that efferent impulses from the visual cortical areas and from the association areas on the middle suprasylvian gyrus are relayed to the cerebellum exclusively via the basal pontine nuclei. The findings further suggest that the visual corticopontine projections carry a map of the visual field in which the cortical magnification factor is reduced.

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PubMed1980

A function of the corpus callosum in the Siamese cat.

Recordings were made from 180 single cells, or cell clusters, in the Clare-Bishop area of two Siamese cats. In one cat, the corpus callosum had been sectioned prior to recording and all cells were driven by the contralateral eye exclusively. In the other recordings were made before and after callosal section. Before callosal section, most cells were binocularly driven but dominated by the contralateral eye. There were striking examples of binocular interaction and some cells could only be activated by simultaneous binocular stimulation. After callosal section, cells were driven by the contralateral eye only. The same experiment performed in a normal cat revealed no change in binocularity following section of the corpus callosum. We conclude that one of the functions of the corpus callosum in the Siamese cat is to generate binocular neurons.

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PubMedDate not supplied

Inputs from motor and premotor cortex to the superior colliculus of the macaque monkey.

In retrograde studies of corticotectal projections in the monkey using horseradish peroxidase (HRP), projections of the frontal lobes were found to originate not only from the frontal eye fields and prefrontal association cortex but also from both motor and premotor cortex. Even small HRP injections into the superficial layers of the superior colliculus yielded labelled cells in the agranular cortex (area 6) of the anterior bank of the arcuate sulcus. After large collicular injections affecting all layers, labelled cells were found in both motor and premotor cortex. This projection appeared to be topographically organized. Injections into the anterolateral parts of the superior colliculus labelled cells that were distributed within the presumed finger-hand--arm-shoulder representation, whereas after more caudal injections labelled cells occurred more in the presumed arm-trunk representation. The supplementary motor cortex was not found to contain labelled cells. The corticotectal cells in the motor cortex differed from those in the premotor cortex in their size distribution; the former being small, the latter both small and large. The functional significance of the motor and premotor input into the superior colliculus for sensory, and particularly visual, guidance of movements is discussed in view of a collicular role in the extrapersonal space representation and of its possible participation in steering arm and hand movements.

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PubMedDate not supplied

Effects of jejunoileal bypass on oxalate and mineral metabolism in rats.

OBJECTIVE: To reassess the effects of jejunoileal bypass on the gastrointestinal absorption and bone metabolism of certain minerals in rats, and to see if jejunoileal bypass in rats was a suitable model in which to study formation of calcium oxalate renal stones. DESIGN: Controlled study. SETTING: Division of Experimental Surgery, University of Erlangen, Germany. MATERIAL: 43 male Sprague-Dawley rats. INTERVENTION: 23 rate underwent jejunoileal bypass, and 20 laparotomy, with transsection and anastomosis of the jejunum and ileotomy and suture (sham operation). RESULTS: Rats that had undergone jejunoileal bypass ate less and gained less weight than those that had had sham operations. Absorption of calcium and phosphorus from the intestine was impaired, but that of magnesium was unchanged. Absorption of oxalate from the small intestine was unchanged, but that from the colon was increased. There were no signs of hyperoxaluria or urolithiasis. Serum mineral homeostasis was not affected by jejunoileal bypass nor were bone volume, density, or mineral concentrations. Serum concentrations of parathyroid hormone and 1,25-dihydroxycholecalciferol remained low, suggesting that jejunoileal bypass might have induced some calcium flux towards the vascular space. CONCLUSIONS: Jejunoileal bypass halts weight increase in rats; the model may be helpful in elucidating associations between enteric factors and calciotropic hormones, and several metabolic features that are altered by jejunoileal bypass in man are not altered in rats.

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