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Biomedical subjects

D Miceli

Publications and source records attributed to D Miceli.

At least 37 records · Page 2Linked to original sources
PubMed1987

The primary optic system in a microphthalmic snake (Calabaria reinhardti).

The retinal projections in the microphthalmic snake Calabaria reinhardti were investigated by means of the radioautographic method following intraocular injections of [3H]proline. The results demonstrated the existence of a general pattern of organization of the primary visual system comparable to that observed in macrophthalmic snakes. However, most of the primary optic centers appeared reduced and showed varying signs of atrophy, whereas others were completely absent. Elsewhere, the ipsilateral visual component appeared as well developed as that found in macrophthalmic snakes. The evolutionary significance of the differential microphthalmic pattern of organization of the primary visual system is discussed.

Animals↗
PubMed1987

Extratelencephalic projections of the avian visual Wulst. A quantitative autoradiographic study in the pigeon Columbia livia.

The efferent projections of the pigeon visual Wulst upon the diencephalon and mesencephalon were investigated using the autoradiographic technique following the combined injection of [3H] proline and [3H] leucine into the rostral hyperstriatum accessorium. Repeated measures of silver grain densities were performed bilaterally in different brain structures using a computer-assisted system of image analysis. The density values were compared (Mann-Whitney U-Test) with those recorded in three homolateral control structures (tractus opticus, n. rotundus, n. pretectalis principalis) and in corresponding contralateral areas and nuclei. The data showed ipsilateral projections from the visual Wulst and via the tractus septomesencephalicus upon the dorsal thalamus (n.: dorsolateralis anterior superficialis parvocellularis), ventral thalamus (n.: intercalatus, ventrolateralis, geniculatus lateralis pars ventralis--GLv), pretectum (n.: superficialis synencephali, geniculatus pretectalis, griseus tectalis, pretectalis: diffusus, pars lateralis and pars medialis, area pretectalis) as well as to the nucleus of the basal optic root, n. spiriformis medialis and optic tectum (layer 2-4, 6, 7, 12 and 13). Crossed projections were observed to pass through the supraoptic decussation and the posterior commissure, however only the contralateral n. GLv was found to be significantly labeled. Interspecies variations in the organization of descending visual Wulst projections, related to the terminal distribution and relative size of the crossed components may be linked to differences in the degree of overlap of the binocular fields. Correspondingly, this may reflect the degree of bilateralization upon the Wulst of direct input from the visual thalamus.

Animals↗
PubMed1987

Distribution of visual callosal projection neurons in the siamese cat: an HRP study.

In this experiment we studied the distribution of callosal cells in various visual cortical areas of both common and siamese cats using the HRP method. The results showed that the most notable difference between the two strains concerned the primary visual areas. Indeed, labeling in areas 17 and 18 was significantly lower in siamese cats and only a few scattered cells were encountered at the 17/18 border. In general, the number of callosal cells forming interhemispheric connections within areas 17, 18 and the 17/18 border was dramatically reduced in the siamese. For all other visual areas (19, lateral suprasylvian subdivisions, 20 a, b and 21 a, b) the distribution was comparable for both species. A study of the laminar distribution indicated that, for common and siamese cats, medium and large pyramidal cells were mainly concentrated in layers III and IV whereas in deeper layers we found a mixture of small pyramidal and fusiform neurons.

Animals↗
PubMed1986

The anatomical organization of retinal projections in the shark Scyliorhinus canicula with special reference to the evolution of the selachian primary visual system.

The retinal projections of the shark Scyliorhinus canicula were investigated using both the degeneration technique after eye removal and the radioautographic method following the intraocular injection of various tritiated tracers (proline, leucine, fucose, adenosine). The results showed contralateral projection via different optic tract components (TOM, AOT, TOm, TOl, ROVm, RODm) to various areas and nuclei of the hypothalamus (NSC), thalamus (NODLAT, NODMAT, NTTOM, NOVT, NODPT), pretectum (NOPC, NOCPd, NOCPv), tectum (SFGS, SGI) and mesencephalic tegmentum (AOTMd, NOTMv). Ipsilateral retinal projections were found to arborize within 7 distinct zones at the hypothalamic (NSC), thalamo-pretectal (NODLAT, NTTOM, NOVT, NOPC, NOCpd) and tectal (SFGS) levels. A comparison of the data with those previously obtained in different species of elasmobranchs and batoids indicate the existence of a common and consistent pattern of organization of the primary visual system in all selachians. Many of the discrepancies reported in studies on the organization of selachian retinal projection may be listed to methodological differences and/or interspecies variations in the cytoarchitecture of the different visual centers. Moreover, a comparison of the primary visual system of more primitive squalomorph sharks with that of the more advanced galeomorph sharks and batoids suggests that this system evolved through an increase in the neuronal density of the target structures and transformations in the dendritic configurations of the postsynaptic neurons rather than through an increase in the total number of projection zones.

Animals↗
PubMed1986

[Course of the degeneration of the primary visual system in albino quails with glaucoma].

In the quail, a sex-linked albino mutation is associated with buphthalmic glaucoma. This progressive disorder is detectable 3 to 6 months after hatching. Its development leads to a degeneration of retinal projection according to a relatively orderly sequence progressing from the tegmentum to the tectum and from the pretectum to the thalamus. We suggest that the degeneration of visual axons might be produced by mechanical compression resulting from an increase in intraocular pressure.

Albinism↗
PubMed1985

A comparative radioautographic study of the bidirectional axonal and transcellular transport of different amino acids and sugars in the lamprey visual system.

Following recent radioautographic evidence for the bidirectional axonal transport of [3H]proline from the eye of Lampetra fluviatilis, the present study examined the anterograde and/or retrograde labeling properties of 11 other amino acids and two sugars after intraocular injections of these tritiated substances in the lamprey. The intraocular injections of aspartic acid, glutamic acid, gamma-aminobutyric acid, arginine, phenylalanine, fucose and acetyl glucosamine resulted in a weak labeling of the primary visual centers: there was no evidence of either the transcellular transport of these tracers or the retrograde labeling of the retinopetal neurons. The primary visual system was found to be heavily labeled 24 h after eye injections of alanine, leucine, glycine, lysine, serine and valine. Among the latter only glycine produced a retrograde somatic labeling of retinopetal neurons. With a longer survival period (7 days), a specific transneuronal labeling was also noted after glycine injections. The significance of the differential uptake and transport of these different tracers in the lamprey visual system and possible mechanisms involved in the axonal retrograde transport of [3H]glycine and [3H]proline in the centrifugal pathways are discussed.

Acetylglucosamine↗
PubMed1985

Intracortical connections of the anterior ectosylvian and lateral suprasylvian visual areas in the cat.

Intra- and interhemispheric connections between the anterior ectosylvian visual area (AEV) and other visual cortical areas including the lateral suprasylvian (LSS) were examined in the cat using the retrograde double-label fluorescence technique. The areal and laminar distributions of labeled neurons were mapped following injections of different tracers: Evans Blue (EB), Fast Blue (FB) and Nuclear Yellow (NY) made separately into AEV and LSS of the same or opposite hemispheres. The results indicated: (1) reciprocal and bilateral AEV-LSS connections stemming from layers V and VI in addition to a predominant efferent LSS projection upon AEV from both layer III and the posterior lateral (PLLS) subdivision of LSS; (2) homotopic interhemispheric connections to AEV arising from layers III, V and VI and from layers III and V of ipsilateral areas 20 and 21a; (3) differential laminar distributions of the cell populations projecting to the two cortical sites injected including neurons in layer III of LSS which project to contralateral LSS and AEV of either hemisphere via collateral axon branching (double-labeled). The anatomical findings support the functional similarities between AEV and LSS and the possible role of AEV in interhemispheric transfer of visual information is discussed.

Animals↗
PubMed1985

An anatomical study of ipsilateral retinal projections in the quail using radioautographic, horseradish peroxidase, fluorescence and degeneration techniques.

The topographical organization of ipsilateral retinal projections was investigated in the pigmented quail using different anatomical tracing techniques. The orthograde labeling patterns were examined after intraocular injections of tritiated tracers (autoradiography), horseradish peroxidase (HRP) either alone or combined with wheat germ agglutinin (WGA), the fluorescent tracer rhodamine beta-isothiocyanate (RITC) and after unilateral retinal ablations using degeneration methods where the material was observed at both light and electron microscope levels. The different techniques provided extremely variable results with regard to demonstrating ipsilateral retinal projections. Whereas the latter could not be revealed in the radioautographic preparations, the results derived using the degeneration and HRP methods were fragmentary. The RITC method was found to be the most effective and made it possible to accurately define the different ipsilateral optic contingents and their terminal arborizations within various thalamic, pretectal and tegmentomesencephalic centers. The contradictory data in the literature regarding the existence of ipsilateral retinal projections in various avian species may be explained by differences in methodology based upon the relative degrees of resolution offered by the different techniques.

Animals↗
PubMed1985

Telencephalic afferent projections from the diencephalon and brainstem in the pigeon. A retrograde multiple-label fluorescent study.

The sites of origin of ascending projections to the telencephalon in the pigeon (Columba livia) were studied by means of the retrograde fluorescence technique following the injection of various tracers (Evans Blue, Fast Blue, Nuclear Yellow) concomitantly into different regions of topographically distinct areas of one hemisphere: hyperstriatum (HY), ectostriatum-paleostriatum (EP), posterior neostriatum (PN). The distribution of retrograde neuronal labeling observed within diencephalic and midbrain structures revealed systems providing unique projections to either a single or a multiple combination of the different telencephalic sites sampled. Single projections to HY arise from numerous dorsal thalamic nuclei including: ipsilaterally-dorsolateralis anterior pars medialis, dorsointermedius posterior, dorsomedialis anterior and posterior and bilaterally-dorsolateralis anterior and superficialis parvocellularis. Single ipsilateral projections upon either the ectostriatum or the caudal neostriatum arise from the nucleus (n.) rotundus/n. triangularis complex and the n. ovoidalis respectively. Multiple ipsilateral afferents to both HY and the neostriatum intermedium stem from rostral and caudal portions of the n. dorsolateralis posterior respectively, whereas the n. subrotundus projects to all of the telencephalic sites examined. Within midbrain/caudal brainstem regions, the area ventralis-Tsai sends afferents to HY and EP and multiple projections upon the latter in addition to the PN site originate in ipsilateral: zona perinervus oculomotorius, the lateral and medial mesencephalic reticular formation, n. tegmenti pedunculo-pontinus pars compacta and bilateral: zona peri-fasciculus longitudinalis medialis, substantia grisea centralis, n. locus coeruleus, n. annularis, n. linearis caudalis. In the case of the latter structures, the multiple-label procedure also made it possible to demonstrate differential distributions of the component populations of neurons whose axons terminate within distinct telencephalic sites and those which display multiple projections via collateral axon branching. Various neuronal systems projecting to the avian telencephalon are compared to those of other vertebrates and possible homologies in telencephalic afferent organization are discussed.

Afferent Pathways↗
PubMed1984

An anatomical and electrophysiological study of the centrifugal visual system in the lamprey (Lampetra fluviatilis).

The centrifugal visual system of the lamprey Lampetra fluviatilis was investigated using various neurohistophysical methods: intraocular injections of [3H]adenosine, fluorescent tracer (Evans Blue) and the iontophoretic deposit of HRP on the optic nerve. Retrogradely labeled neurons were identified bilaterally within the nucleus M5 of Schober and contralaterally in the reticular mesencephalic area (RMA). Comparison of the various orthograde and retrograde labeling results indicated that the neurons of M5 and RMA were labeled via retrograde axonal transport of the different tracers in the retinopetal system and not by orthograde transneuronal processes or from extraretinal pathways. Part of the anatomical data regarding RMA as a site of origin of the centrifugal visual system was confirmed using electrophysiological techniques involving evoked potential and unit cell recordings in RMA following electrical stimulation of the optic nerve. The experiments were performed in the curarized animal under conditions of either normal blood circulation, perfusions of adapted physiological saline, or with a solution known to block chemical synaptic transmission. Various electrophysiological criteria, including the results obtained during the conditions of reversible chemical synaptic blockade, indicated that the responses in RMA reflect an antidromic process. The anatomical organization of the centrifugal visual system in the lamprey is compared to that found in different gnathostome vertebrate species. Several hypotheses concerning the marked interspecies differences related either to the number and the topographical location of the centrifugal neurons as well as the evolution of this system are advanced.

Animals↗
PubMed1984

[New findings on the organization of retinal projections in the Scyliorhinus canicula shark. Radioautographic study].

The retinal projections of the shark Scyliorhinus canicula were re-examined using the radioautographic method following the intraocular injection of tritiated tracers. New primary visual centers were identified. Overall 12 distinct sites of termination of contralateral optic endings were found distributed within five levels of the brain (hypothalamus, thalamus, pretectum, tectum and mesencephalic tegmentum). Furthermore the presence of a small ipsilateral retinal projection was demonstrated attaining the hypothalamic thalamo:pretectal and tectal levels. These new data broaden our understanding of the organization of the primary visual system in Scyliorhinus as defined previously using the degeneration technique.

Animals↗
PubMed1983

Hyperstriatal-tectal projections in the pigeon (Columba livia) as demonstrated by the retrograde double-label fluorescence technique.

Hyperstriatal-tectal connections were investigated in the pigeon by mapping retrogradely labeled neurons in the hyperstriatum following the injection of different fluorescent tracers (Fast Blue, Nuclear Yellow, Evans Blue) either bilaterally or unilaterally into distinct portions of the tectum. The projections were found to arise from the hyperstriatum accessorium (HA) of the Wulst, were essentially ipsilateral and topographically organized with respect to the dorsoventral and lateromedial plane of HA. No double-labeled neurons which would indicate bilateral axon branching via collaterals were observed. Some interspecies differences in the organization of the avian hyperstriatal-tectal pathways are discussed.

Animals↗
PubMed1983

Orthograde axonal and transcellular transport of different fluorescent tracers in the primary visual system of the rat.

The differential labeling properties of various fluorescent tracers injected intraocularly were investigated using as a model the rat primary visual system. All of the tracers tested (Fast Blue, FB; True Blue, TB; Nuclear Yellow, NY; bisbenzimide, BB; Evans Blue, EB; propidium iodide, PI) produced a retrograde neuronal labeling of oculomotor neurons. However, no such labeling was observed in the medial pretectal nucleus (NPM) considered to be the site of origin of the rat centrifugal visual pathway. Orthograde transport within the axons of the optic tract and their terminal arborizations were visualized directly with FB and TB. No evidence of EB or PI orthograde transport was demonstrated. Furthermore, FB, TB, NY and BB displayed varying degrees of leakage from the optic axons and terminals into the extracellular space, there to be taken up by glial (FB, TB, NY, BB) and neuronal (NY, BB) somas of the primary optic system or in adjacent structures including NPM (BB). The neuronal labeling with NY or BB does not result from the retrograde axonal transport but appears to involve an orthograde transneuronal process transport. Some limitations in the use of different fluorescent tracers for determining neuronal connections are discussed.

Animals↗
PubMed1983

Efferent projections of the visual Wulst upon the nucleus of the basal optic root in the pigeon.

Efferent projections of the visual Wulst upon the nucleus of the basal optic root (nBOR) were investigated using various neuroanatomical approaches: optical and EM orthograde degeneration methods (following visual Wulst ablation), radioautographic and HRP techniques (following injection of various tracers within the visual Wulst). The radioautographic and electron microscope degeneration experiments clearly demonstrated a visual Wulst projection upon the ipsilateral nBORl and the lateral portions of nBORd and nBORp. The pigeon's hyperstriato-nBOR projection is compared to a similar descending visual cortico-accessory optic pathway in mammals and its possible role in the control of oculomotor function is discussed.

Animals↗
PubMed1983

Decrease in ethanol consumption by naloxone in naive and dependent rats.

Acute effects of the opiate antagonist, naloxone, on alcohol intake have been examined and compared in naive and behaviorally dependent rats. In naive rats the aversion to an 8% alcohol solution exhibited in a 30 min presentation was selectively augmented by an IP administration of naloxone (1 mg/kg) 30 min before a morning drinking session. In other rats, behavioral dependence was established by 15 days of IG administration of intoxicating doses of alcohol. This dependence was exhibited by a sustained preference for ethanol for 6 days. Naloxone (1 mg/kg) abolishes the acquired preference for ethanol tested during an 8 hour day time presentation. These effects of naloxone on alcohol intake in ethanol naive and dependent rats are interpreted in relation to a general non-specific action of naloxone on preferred or aversive flavoured solutions.

Alcohol Drinking↗
PubMed1983

[Structures of telencephalic projection in the pigeon. Identification by marking with horseradish peroxidase].

The sites of origin of afferents to the telencephalon in the pigeon were investigated using the HRP technique (TMB). Following large multiple injections of the enzyme into the cerebral hemisphere, peroxidase-positive neurons were identified at diencephalic levels: ipsilaterally in DLM, DMA, DLP, DIP, DMP, Rt, Ov, SRt and SCE/SCI; bilaterally in DLA and SPC. At mesencephalic and posterior brainstem levels, HRP-labeled neurons were found: ipsilaterally in AVT, ZpNIII, ICo, FRM, FRL, TP and SCv; bilaterally in GCt, ZpFLM, neurons were found: ipsilaterally in AVT, ZpNIII, ICo, FRM, FRL, TP and SCv; bilaterally in GCt, ZpFLM, Annul, LoC, LC and PrV. Smaller injections of HRP into different regions of the telencephalon demonstrated, for some of the latter structures, either single or multiple projections upon topographically distinct subdivisions.

Afferent Pathways↗
PubMed1982

Thalamo-hyperstriatal projections in the pigeon (Columbia livia) as demonstrated by retrograde double-labeling with fluorescent tracers.

Thalamo-hyperstriatal projections were studied in the pigeon by retrograde thalamic labeling following bilateral injections of different combinations of fluorescent substances (Fast Blue, Evans Blue, Nuclear Yellow) into the hyperstriatum. The distribution of single and double-labeled neurons within the thalamic nuclei dorsolateralis anterior and superficialis parvocellularis indicated the presence of distinct functional sub-regions containing neuronal populations providing ascending projections which were either ipsilateral, contralateral or bilateral via collateral axon branching.

Animals↗