Search PubMed⌕ Search

Biomedical subjects

R B Illing

Publications and source records attributed to R B Illing.

At least 37 records · Page 2Linked to original sources
PubMed1993

Distribution of cytochrome oxidase in layers IV and V of the striate cortex in neonate monkeys.

The uniformly dense staining for cytochrome oxidase (CO) in layer IV of area 17 in adult monkeys has been described as developing from a bilaminar pattern in neonates being composed of a broad CO band in layer IV alpha and a narrow CO band attributed to the innermost zone of layer IV beta. Here we present evidence, in the neonate marmoset monkey, for the narrow CO band to be localized in the outermost rim of layer V, designated as sublayer Va.

Aging↗
PubMed1993

More modules.

Explore the source record for details and available documents.

Animals↗
PubMed1992

Association of efferent neurons to the compartmental architecture of the superior colliculus.

The superior colliculus is a layered structure in the mammalian midbrain serving multimodal sensorimotor integration. Its intermediate layers are characterized by a compartmental architecture. These compartments are apparent through the clustering of terminals of major collicular afferents, which in many instances match the heterogeneous distribution of tissue components such as acetylcholinesterase, choline acetyltransferase, substance P, and parvalbumin. The present study was undertaken to determine whether efferent cells observe this compartmental architecture. It was found that subpopulations of both descending and ascending collicular efferents originate from perikarya situated in characteristic positions relative to the collicular compartments defined by elevated acetylcholinesterase activity and that their dendrites appear to be specifically coordinated with the heterogeneous environment. With the specific interlocking of afferent and efferent neurons through spatially distinguished neural networks, the compartmental architecture apparently constitutes an essential element for the determination of information flow in the superior colliculus.

Acetylcholinesterase↗
PubMed1992

Similarities and differences between cholinergic systems in the superior colliculus of guinea pig and rat.

We studied the distribution of acetylcholinesterase activity and choline acetyltransferase immunoreactivity in the superior colliculus of the guinea pig and the albino rat, using enzyme histochemical and immunohistochemical methods. Choline acetyltransferase-like immunoreactivity was localized in the neuropil throughout the colliculi, but the density of the immunoreactive neuropil varied among layers as well as between species. In the intermediate collicular layers the pattern of choline acetyltransferase immunoreactivity was closely matched by the distribution of acetylcholinesterase activity in guinea pig and rat, confirming our previous findings in the cat. Furthermore, in the guinea pig, but not in the rat, choline acetyltransferase-like immunoreactivity was localized in a prominent population of perikarya of the superficial gray layer.

Acetylcholinesterase↗
PubMed1991

Delineation of the striate cortex, and the striate-peristriate projections in the guinea pig.

The size and position of the guinea pig area 17 were determined by transneuronal labeling after intraocular injections of 3H-proline or WGA-HRP. Area 17 occupies a large region of the occipital cortex located between two shallow fissures, the fissura sagittalis lateralis and the lateral groove. Area 17 extends for about 6 mm rostral from the occipital pole of the hemisphere, and encroaches occipitally for more than 1 mm upon the ventromedial surface of the hemisphere; the lateral width is up to 4.5 mm. Single injections of WGA-HRP into area 17 produced eight patches of transported tracer which formed the same general pattern in the peristriate cortex, regardless of the position of the injection within the visual field representation of area 17. Two of these patches were found in anteromedial peristriate cortex; three patches were distributed anterolateral and lateral of area 17; and three patches were located in posterolateral peristriate cortex. For several reasons, each of these patches was interpreted as representing a single striate projection onto a separate peristriate area. Comparison of these results with published findings indicates that the parcellation of the peristriate cortex into a variety of different areas, the pattern formed by these areas around area 17, and their reciprocal connections with area 17 follow a common plan in all hitherto studied terrestrial Old World and New World rodents. Lucifer Yellow injections into striate cells projecting to one of the recipient areas (AM) indicated that the pyramidal cells of this set of striate neurons are characterized by a short apical dendrite, and that the basal dendrites of the layer V pyramidal cells branch more profusely than those of the layer III pyramids.

Animals↗
PubMed1990

Parvalbumin in rat superior colliculus.

Parvalbumin-like immunoreactivity (PA-LI) has been studied in sections of the superior colliculus (SC) of the rat and its distribution compared to the patterns of acetylcholinesterase (AChE) and cytochrome oxidase (CO) staining. In the intermediate layers it was found that PA-LI is spatially associated with AChE only in the medial part of the SC, but assumes a complementary distribution further laterally. There was a positive correlation between PA-LI and CO. We conclude that the patterns of PA-LI and CO are not systematically related to collicular input known to be associated with the AChE-rich zones, but may reflect adherence to channel separation beyond the terminal fields of clustered afferents.

Acetylcholinesterase↗
PubMed1990

A subtype of cerebellar Golgi cells may be cholinergic.

In cerebellar sections of the feline brain processed for choline acetyltransferase-like immunoreactivity, a population of distinctly stained cells was discovered in the granular layer of the cortex in both vermis and hemispheres. Their position and morphology qualify them as Golgi cells, but their density indicated that they comprise less than 5% of all cerebellar Golgi cells. Varicose immunoreactive fiber nets in all cortical layers also contribute to seemingly widespread cholinergic systems in the cerebellar cortex.

Animals↗
PubMed1990

Choline acetyltransferase-like immunoreactivity in the superior colliculus of the cat and its relation to the pattern of acetylcholinesterase staining.

Choline acetyltransferase, the biosynthetic enzyme for acetylcholine, is thought to be a marker for cholinergic neurons. This report presents an analysis of the pattern of choline acetyltransferase-like immunoreactivity in the superior colliculus of the cat. A dense network of highly varicose immunoreactive fibers pervaded the superficial gray and optical layer. The density of the fiber network in the superficial layers was heterogeneous, forming a mosaic pattern with a period of about 400 microns. The antigen was also located in numerous small perikarya embedded in this network. This neuronal population reached a density of 2,000 cells/mm3 of the superficial gray layer and suggested the presence of a substantial cholinergic system originating in the superior colliculus. A detailed comparison was made between the pattern of choline acetyltransferase-like immunoreactivity and the distribution of acetylcholinesterase activity. By comparisons of adjacent sections, both staining patterns were found to be similar in all collicular layers. In particular, the compartmental distribution of immunoreactivity in the intermediate collicular layers seemed to mimic the pattern of acetylcholinesterase staining. A double-staining technique demonstrated a near-perfect correlation between the two patterns. In conclusion, there was no indication of heightened acetylcholinesterase activity without an associated elevation in choline acetyltransferase-like immunoreactivity throughout the superior colliculus. In this part of the brain, the presence of the putative cholinergic terminals could fully account for the distribution of acetylcholinesterase activity.

Acetylcholinesterase↗
PubMed1990

Release of met-enkephalin and its modulation through acetylcholine receptors in the rabbit superior colliculus.

This report presents evidence for the depolarization-dependent release of met-enkephalin from the superior colliculus of the rabbit. Collicular tissue was placed in superfusion chambers and met-enkephalin accumulation in the superfusate was measured by radioimmunoassay. Exposure to high potassium concentrations (30 mM and 56 mM) increased met-enkephalin release. This is the fourth transmitter shown to be released from collicular tissue. Furthermore, we have obtained the first evidence that suggests that met-enkephalin release is susceptible to muscarinic modulation. While the depolarization-dependent release of met-enkephalin was depressed in the presence of atropine (1 microM), hexamethonium (100 microM) did not block the increase of met-enkephalin release induced by high potassium.

Animals↗
PubMed1989

The mosaic of the uncrossed retinal projection in the superior colliculus of the cat.

The uncrossed retinocollicular projection in the cat was labeled by axonal transport of horseradish peroxidase from the eye and visualized in tangential sections through the superior colliculus. The terminals of this pathway are distributed in clusters and form a mosaic pattern rather than stripes in the superficial collicular layers. It is suggested that the periodicity of this pattern relates to the smallest receptive field diameters across the visual field.

Animals↗
PubMed1989

Macro square wave jerks in a rhesus monkey: physiological and anatomical findings in a case of selective impairment of attentive fixation.

An otherwise normal female rhesus monkey executed large saccadic eye movements (macro square wave jerks) when required to attentively fixate a small visual target (fixation point). The jerks were observed exclusively in this specific testing situation. They occurred periodically at a frequency of 2.04 + - 0.18 Hz to the right side with an amplitude of 23.5 deg. Direction of the jerks was about 3-4 degrees downward from horizontal. These parameters remained constant throughout the several months of daily recording. No jerks were executed during periods when the behaviourally important target was absent or substituted by another, behaviourally non-relevant visual stimulus. The monkey could perform normal visually guided saccades as well as smooth pursuit eye movements, but with the jerks always superimposed, when the monkey paid attention to the visual target. Histologic inspection of the brain revealed the presence of an incapsulated nematode in the cortex of lobulus simplex of the right cerebellar hemisphere, i.e., in a region involved in oculomotor control.

Animals↗
PubMed1988

Spatial relation of the acetylcholinesterase-rich domain to the visual topography in the feline superior colliculus.

The superior colliculus (SC) of the cat shows a prominent compartmentalized organization at the level of its intermediate layers. The mosaic of these compartments is apparent in the pattern of acetylcholinesterase (AChE) staining. Patches of high AChE-activity are sharply set off from surrounding areas in the caudal SC while they are less distinct anteriorly. The rostral part lacks such obvious compartments. Thus, a structural reorganization apparently cuts across the topographical representations spread out in the SC. In order to test if this compartmental gradient relates to the topographic maps of the colliculus, retinotopic landmarks were visualized in the superficial layers by labeling the retinotectal pathway. In the SC ipsilateral to the eye injected with horseradish peroxidase (HRP) a paucity of labeling indicated the zone representing the ipsilateral visual half-field. Serial reconstructions of collicular sections, cut longitudinally or tangentially, revealed that the non-compartmentalized part of the intermediate layers corresponds to the representation of the ipsilateral visual half-field in the layers above, while an intricate mosaic array of compartments prevail in tectal zones related to the representation of the contralateral visual half-field.

Acetylcholinesterase↗
PubMed1987

Evidence for a neurotransmitter function of acetylcholine in rabbit superior colliculus.

Acetylcholinesterase staining and studies on the uptake of [3H]choline into the subsequent efflux of tritium from collicular slices were carried out in order to provide evidence for a neurotransmitter function of acetylcholine in rabbit superior colliculus. Acetylcholinesterase staining was dense and homogeneous in superficial layers whereas the staining was arranged in patches with slightly higher density caudally than rostrally in the intermediate layers. The accumulation of tritium in slices incubated with [3H]choline depended on time, temperature and concentration, and was inhibited by hemicholinium-3. Accumulation was slightly higher in caudal than in rostral slices. Electrical stimulation enhanced tritium outflow from slices preincubated with [3H]choline. Tetrodotoxin and a low calcium medium inhibited the evoked overflow whereas hemicholinium-3 caused an enhancement. Oxotremorine decreased the evoked overflow; atropine prevented this effect. The opioids [D-Ala2, MePhe4, Glycol5]enkephalin, [D-Ala2, D-Leu5]enkephalin and ethylketocyclazocine caused an inhibition. The effects of the latter two agonists were antagonized by naloxone. The GABAB-receptor-agonist (-)-baclofen decreased the evoked overflow at lower concentrations than GABA, whereas the GABAA-receptor-agonist muscimol was ineffective. Serotonin produced an inhibition which was prevented by metitepin, alpha- and beta-adrenoceptor as well as dopamine-receptor ligands caused no change. It is concluded that in the rabbit superior colliculus the pattern of acetylcholinesterase staining is comparable, but not identical to the distribution in other species. The accumulation of [3H]choline, as well as the tetrodotoxin-sensitive and calcium-dependent overflow of tritium upon electrical stimulation (reflecting presumably release of [3H]acetylcholine) indicate that acetylcholine has a neurotransmitter function in this tissue. The release of [3H]acetylcholine was modulated by various transmitter substances and related compounds. The pattern of modulation of release differed from the pattern in other cholinergically innervated tissues.

Acetylcholine↗
PubMed1986

Complementary and non-matching afferent compartments in the cat's superior colliculus: innervation of the acetylcholinesterase-poor domain of the intermediate gray layer.

Three tectal afferent-fiber systems were experimentally labeled in the cat to learn how their distributions within the superior colliculus were related to the prominent compartments of high acetylcholinesterase activity found in the intermediate gray layer. Presumptive somatic sensory afferents were labeled by injections of horseradish peroxidase-wheatgerm agglutinin conjugate placed at the bulbospinal junction and in the ventral anterior ectosylvian cortex corresponding to somatic sensory area SIV. Vision-related afferents were labeled by injections of the same tracer substance into the lateral suprasylvian visual area. In each animal, a single type of injection was made and a detailed study was carried out to compare the patterns of anterograde labeling and acetylcholinesterase staining in serially adjoining sections through the superior colliculus. Fibers labeled by the three types of injection were distributed in clusters that resembled the acetylcholinesterase-positive patches in the intermediate gray layer. In no case, however, were the afferent-fiber clusters in register with the histochemically defined patches. Instead, the innervations derived from the bulbospinal junction, anterior estosylvian sulcus and lateral suprasylvian visual area all formed patchworks within the acetylcholinesterase-poor domain of the intermediate gray layer. In some instances, the afferent-fiber clusters and enzyme-positive patches appeared to have complementary distributions. In other instances, the afferent-fiber clusters seemed to be arranged in the acetylcholinesterase-poor parts of the intermediate layer in a fashion independent of, but not significantly overlapping, the acetylcholinesterase-positive patches. Not all of the space between the acetylcholinesterase-positive patches was taken up by any one of the afferent-fiber systems labeled. The complementary and non-matching distribution of these afferent systems in relation to the acetylcholinesterase-rich patches of the intermediate gray layer stands in contrast to the spatial registration of two other tectal afferent systems with the zones of high acetylcholinesterase activity. Both nigrotectal and frontotectal afferents converge on the acetylcholinesterase-positive patches. We conclude that afferent systems projecting to the intermediate gray layer can be divided into at least two groups: those innervating the acetylcholinesterase-rich compartments and those avoiding them.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1985

Convergence of afferents from frontal cortex and substantia nigra onto acetylcholinesterase-rich patches of the cat's superior colliculus.

The patterns of distribution of frontotectal and nigrotectal fibers were studied with the anterograde horseradish peroxidase method in the cat. Direct serial-section comparisons were made between the afferent-fiber patterns and the compartmentalized arrangements of acetylcholinesterase staining within the intermediate and deep collicular layers. Many of the patches of high acetylcholinesterase activity in the intermediate gray layer proved to be zones in which labeled frontotectal and nigrotectal fibers converged. These acetylcholinesterase-rich patches may thus represent sites at which functional influences from the basal ganglia and frontal cortex are coordinated. In the deeper tiers of the intermediate gray layer and layers ventral to it, there were also zones of heightened and diminished acetylcholinesterase staining. Much of this histochemical patterning was reflected in the arrangement of fibers labeled by large rostromedial frontal injections, but these deeper tiers were not strongly labeled after more lateral frontal injections or after injections placed in the substantia nigra. The deeper parts of the acetylcholinesterase-positive gridwork in the superior colliculus are thus distinct from its upper tier of acetylcholinesterase-positive patches. We conclude that the compartmentalized patterning of dense acetylcholinesterase staining in the intermediate and deep collicular layers represents a mosaic architecture to which collicular afferent circuitry is tightly related. This gridwork may serve to set up functional domains within which different aspects of collicular processing are accommodated.

Acetylcholinesterase↗
PubMed1981

The retinal projection to the thalamus in the cat: a quantitative investigation and a comparison with the retinotectal pathway.

The projection of cat retinal ganglion cells to the thalamus was examined using the method of retrograde axonal transport of horseradish peroxidase (HRP). After the injection site was determined physiologically, HRP was applied by one of three methods: iontophoretic injection of minimal amounts, single pressure injections and multiple pressure injections. Iontophoretic injections into single laminae of the dorsal part of the lateral geniculate nucleus (LGNd) revealed that laminae A and A1 receive almost exclusively axon terminals from alpha and beta cells. Single pressure injections elucidated the retinotopic organization of the LGNd. Multiple injections lead to HRP uptake in the whole LGNd including parts of adjacent thalamic nuclei and revealed that at least 77% of all retinal ganglion cells project to the thalamus. This pathway is made up of all alpha cells, all beta cells and almost half of the gamma cells. The thalamus receives its visual input predominantly from the ipsilateral temporal and the contralateral nasal retina; some alpha cells were also labeled in the contralateral temporal retina. The shape of the decussation line was analyzed and its width was found to be proportional to the average ganglion cell spacing along the dorsoventral axis of the retina. From a comparison of the retinothalamic and retinotectal pathways, an estimate of the number of cells with bifurcating axons could be given. The axons of all alpha cells, 10% of the beta cells, and every second gamma cell bifurcate; this amounts to 30% of the retinal ganglion cells.

Animals↗
PubMed1981

Morphology and mosaic of on- and off-beta cells in the cat retina and some functional considerations.

The beta type of ganglion cell can be subdivided in Golgi-stained whole mounts of the cat retina according to the branching level of the dendritic tree in the inner plexiform layer. The dendritic branching level of on-beta cells is nearer to the cell body; that of off-beta cells is about 10 micrometers further outwards. After horseradish peroxidase (HRP) injection into the lateral geniculate nucleus all beta cells were labelled. In this way it is shown that about 55% of all ganglion cells, irrespective of retinal topography, are beta cells. The spatial distribution of on- and off-beta cells was studied from the HRP-labelled material. On-beta cells form a lattice with regular inter-cell spacings; off-beta cells are also regularly arrayed. The two lattices are superimposed independently of each other. Beta cells are commonly assumed to be associated with the resolution of fine detail in the cat vision system. The mosaic of beta cells imposes some constraints and permits some predictions to be made with respect to the cat's visual discrimination.

Animals↗