RESUMO
The projection of cortical areas 17, 18, and 19 onto the laminar part of the dorsal lateral geniculate nucleus was investigated with degeneration methods and with the autoradiographic axon tracing method. In agreement with previous accounts, degenerating cortical axons stained by the Nauta method were restricted to laminae A, A1, C and to the interlaminar zones. In contrast, adjacent sections stained with the Fink-Heimer method showed fine dust like degeneration throughout all of the laminae of the nucleus. Comparisons of Fink-Heimer degeneration resulting from lesions of area 17 with that resulting from lesions of areas 18 and 19 further suggested that the area ) projection is heavier and more uniform than the projections from areas 18 and 19. Autoradiographic tracing of axons after intracortical injections of 3H-proline provided detailed demonstrations of the cortical projection patterns that confirmed the Fink-Heimer results. Following restricted injections of areas 17 or 18 the termination zones in the dorsal lateral geniculate nucleus consisted of columns of labeled tissue oriented perpendicular to the laminae of the nucleus. Area 17 was found to project heavily and uniformly throughout all of the laminae of the nucleus. The projection from area 18 also extended throughout all of the laminae of the nucleus, but was sparser and less uniformly distributed than that from area 17. Projections from area 18 distributed more heavily to the interlaminar zones and to lamina C than to laminae A, A1 C1, C2 or C3. A projection from area 19 to laminae C1, C2 and C3 was also demonstrated autoradiographically.
Assuntos
Córtex Cerebral/anatomia & histologia , Corpos Geniculados/anatomia & histologia , Animais , Mapeamento Encefálico , Gatos , Vias NeuraisRESUMO
Electrophysiological mapping criteria were employed to identify visual areas 20a, 20b, 21a, 21b, PMLS, AMLS, ALLS, PLLS, DLS, VLS, and PS in the cat, and to guide placement of tracer deposits. Anterograde tracer methods were used to study the corticostriatal projections of these extrastriate visual areas. The experiments demonstrate that all 11 extrastriate areas send projections to two distinct regions within the striatum, an extensive longitudinal zone within the caudate nucleus, and a more compact region within the posterolateral putamen. Cortical visual projections to the putamen terminate in relatively compact sheets or slabs, and appear to overlap extensively, while those to the caudate nucleus are irregularly patchy and more widely dispersed. Retrograde tracer deposits into the visual recipient zone of the caudate nucleus reveal substantial convergence of other cortical inputs to this same domain. Aspects of visuotopic organization are preserved in the visual projections to both the putamen and the caudate nucleus, but unequivocal retinotopic organization could not be inferred from the available material. Ten of the eleven extrastriate visual area also project topographically onto the visual zone of the claustrum. Area PS does not appear to contribute to the corticoclaustral projections. Five of the extrastriate visual areas (ALLS, PLLS, DLS, VLS, PS) also send sparse projections to the amygdaloid complex.
Assuntos
Tonsila do Cerebelo/citologia , Gânglios da Base/citologia , Corpo Estriado/citologia , Córtex Visual/citologia , Vias Visuais/citologia , Tonsila do Cerebelo/fisiologia , Animais , Gânglios da Base/fisiologia , Mapeamento Encefálico , Gatos , Corpo Estriado/fisiologia , Eletrofisiologia , Neurônios/fisiologia , Transmissão Sináptica , Córtex Visual/fisiologia , Vias Visuais/fisiologiaRESUMO
The distribution of cortical projections from areas 17, 18 and 19 to the lateral thalamus, pretectum, and superior colliculus was investigated with the autoradiographic tracing method. Cortical areas 17, 18 and 19 were demonstrated to project retinotypically and in register upon the dorsal lateral geniculate nucleus, medial interlaminar nucleus, lateral zone of the lateral posterior complex, nucleus of the optic tract and superior colliculus. Area 19 was shown to project retinotopically upon the pulvinar nucleus. Clear retinotopic organization was not demonstrable in the projections of areas 17, 18 and 19 to the reticular complex of the thalamus and ventral lateral geniculate nucleus, or in the projection of area 19 to the anterior pretectal nucleus. The cortical projections were employed to define the retinotopic organization of the nucleus of the optic tract, pulvinar nucleus, and later zone of the lateral posterior complex. The cortical projections show the vertical meridian to be represented caudally, with the lower visual field represented laterally, and the upper visual field medially, within the nucleus of the optic tract. The projections of area 19 to the pulvinar nucleus demonstrate the lower visual field to be represented rostrally and the upper field caudally in this mucleus; the vertical meridian to be represented at the lateral border and the visual field periphery to be represented at the medial border of the pulvinar nucleus. Cortical projections to the lateral zone of the lateral posterior complex demonstrate the lower visual field to be represented rostrally and the upper visual field caudally; the vertical meridian to be represented at the medial limit and the visual field periphery at the lateral border of the termination zones. On the basis of the experimental findings a new terminology is introduced for the feline lateral posterior complex. Divisions are proposed which correspond to zones with demonstrably distinct afferent input. The pulvinar nucleus is defined by the distribution of projections from area 19. Three flanking divisions are defined within the lateral posterior complex; a lateral division recipient of projections from area 17, 18 and 19, and interjacent division recipient of projections of the superficial layers of the superior colliculus, and a medial division flanking the tectorecipient zone medially.
Assuntos
Colículos Superiores/citologia , Tálamo/citologia , Córtex Visual/citologia , Vias Visuais/citologia , Animais , Gatos , Corpos Geniculados/citologia , Formação Reticular/citologia , Retina/citologiaRESUMO
The organization of the cat's lateral posterior complex was reevaluated and its cytoarchitecture described. Analysis of visual representations within the complex confirmed that the pulvinar, lateral zone (LPL), and interjacent zone (LPi) correspond to separate representations of the visual field and established that the zones exhibit heterogeneous connections as a result of retinotopic interconnections with extrastriate areas which represent varying amounts of the visual field. A common system of visual representation extending through layers with differing anatomical connections was identified within zone LPL. The concept of an "isorepresentation cord" was introduced to describe these variable correspondences between sensory representations and connectional relationships. Isorepresentation cords are conceived as holding in common representation of a common locus on a sensory surface without functioning as a unit with respect to connections. Visual representations within the lateral posterior complex consist of many such cords arranged in orderly array. Zone LPm (medial) was also delineated more accurately on the basis of its connections with the ectosylvian visual area. Analysis of termination patterns which occupy boundary regions adjacent to and between the principal zones further established the existence of a collection of cell groups which form a thin, irregular shell investing the principal zones. The identification of these additional cell groups and the recognition of connectional heterogeneity within the principal zones of the complex made it possible to identify and describe the subtle cytoarchitectural differences which characterize the subdivisions of the lateral posterior complex and their boundaries with adjoining nuclear groups. The present findings are discussed with respect to the functions of the lateral posterior complex in interconnecting cortical visual and visuomotor areas, and with respect to the conceptual issues raised by variable correspondences between sensory representations and connectional relationships within thalamus.
Assuntos
Tálamo/anatomia & histologia , Córtex Visual/anatomia & histologia , Animais , Autorradiografia , Transporte Axonal , Gatos , Peroxidase do Rábano Silvestre , Especificidade de Órgãos , Prolina , Tálamo/citologia , Trítio , Córtex Visual/citologia , Vias Visuais/fisiologiaRESUMO
Golgi methods were used to study class V cells within the cat visual thalamus. Counterstaining was combined with Golgi staining to assess the distribution of dendrites relative to cytoarchitectural boundaries. Class V cells were encountered within all laminae of the lateral geniculate nucleus, the medial interlaminar nucleus, and the lateral posterior complex. The cells possess medium-sized perikarya and smooth and varicose or moniliform dendrites. Dendritic appendages are sparse and occur as single or serial swellings on thin processes. Many class V cells exhibit large, sparse dendritic arbors which span laminar or nuclear borders; dendrites were seen to lie within and to cross the interlaminar zones of the lateral geniculate nucleus, and extend beyond this nucleus into the perigeniculate nucleus and medial interlaminar nucleus. Class V cells of the lateral posterior complex send dendrites into the external medullary lamina. Indirect evidence favors the interpretation that the class V cells are thalamo-cortical relay cells.
Assuntos
Neurônios/fisiologia , Tálamo/fisiologia , Animais , Axônios/fisiologia , Axônios/ultraestrutura , Gatos , Corantes , Dendritos/fisiologia , Dendritos/ultraestrutura , Histocitoquímica , Tálamo/ultraestrutura , Fixação de Tecidos , Vias Visuais/fisiologia , Vias Visuais/ultraestruturaRESUMO
The distribution of corticothalamic projections from lateral suprasylvian areas AMLS, PMLS, ALLS, and PLLS was investigated with the autoradiographic method. Areas AMLS and PMLS were both found to project retinotopically upon the medial interlaminar nucleus and the lateral and pulvinar zones of the lateral posterior complex, as well as to the ventral lateral geniculate nucleus, intralaminar nuclei, and thalamic reticular complex. Retinotopic projections to the dorsal lateral geniculate nucleus were demonstrated from PMLS but not AMLS, and projections to zona incerta were demonstrated from AMLS but not PMLS. Areas PLLS and ALLS were both found to project retinotopically upon the interjacent zone of the lateral posterior complex, as well as to the intermediate and suprageniculate divisions of the posterior nuclear group, the magnocellular division of the medial geniculate complex, the thalamic reticular complex, and central lateral nucleus. Area ALLS was also found to project onto the dorsal division of the medial geniculate complex and lateral division of the posterior nuclear group. Differences between the four cortical areas in the pattern and density of their thalamic projections supports the parcellation of these areas as proposed by Palmer et al. ('78). The projection patterns of areas PMLS, AMLS, PLLS, and ALLS were found to respect the boundaries of the zones of the lateral posterior complex, which had been identified and defined previously (Updyke, '77), and the results thus support the hypothesis that these zones are the functional units of organization of visual traffic between the cat's extrastriate visual areas.
Assuntos
Córtex Cerebral/anatomia & histologia , Núcleos Talâmicos/anatomia & histologia , Vias Visuais/anatomia & histologia , Animais , Mapeamento Encefálico , GatosRESUMO
The organization of extrastriate visual areas of the cat's posterior suprasylvian sulcus and gyrus was studied with electrophysiological mapping methods. Analysis of retinotopic organization confirmed the presence of dorsal lateral and ventral lateral suprasylvian (DLS, VLS) visual areas (Palmer et al., '78, J. Comp. Neurol. 177:237-256) and demonstrated new features of organization. Areas DLS and VLS occupy the upper two-thirds of the posterior suprasylvian sulcus, with DLS wholly confined to the upper bank and VLS straddling the sulcal fundus. Both areas contain a partial representation of the lower quadrant of the visual field. A narrow strip of visually responsive cortex (periauditory belt) was identified adjoining DLS on the posterior ectosylvian gyrus; its organization and extent were not explored in detail. The organization of the posterior suprasylvian areas (PS) (Updyke, '82, Soc. Neurosci. Abst. 8:810) was explored in detail. Area PS lies inferior to areas VLS and 21b in the lower third of the posterior suprasylvian sulcus and gyrus, extending onto the fusiform gyrus. PS contains a partial representation of the lower quadrant of the visual field. It shares a representation of horizontal meridian with area 21b and a representation of central gaze with area VLS. Analysis of the PS/20 border region indicates that the representation of the lower quadrant periphery is common to the borders of PS, 20a, and 20b rather than lying internal to areas 20a and 20b as suggested by Tusa and Palmer ('80, J. Comp. Neurol. 193:147-164).
Assuntos
Retina/fisiologia , Córtex Visual/fisiologia , Animais , Mapeamento Encefálico , Gatos , Potenciais Evocados Visuais , Campos Visuais , Vias Visuais/fisiologiaRESUMO
Electrophysiological mapping methods were employed to systematically study the retinotopic organization within the cat's lateral posterior complex (LP). Visual responses were recorded in all the major subdivisions of the LP as well as in several adjoining cell groups. Specifically, separate representations of the visual field were identified for pulvinar, zones LP1-c, LP1-r, LPi, and LPm. Partial representations of the visual field were also evident in the geniculate wing, subdivisions of the lateral posterior shell, the inferior division of the posterior nuclear group, the suprageniculate nucleus, and the central lateral nucleus. Sufficient mapping observations were made to define the internal organization of major visual representations. Additionally, there was a very close correspondence between the mapping observations when they were compared with the cytoarchitectural criteria for recognizing functional cell groups (Updyke: J. Comp. Neurol. 219:143-181, '83).
Assuntos
Mapeamento Encefálico , Encéfalo/anatomia & histologia , Gatos/anatomia & histologia , Retina/anatomia & histologia , Animais , Encéfalo/fisiologia , Gatos/fisiologia , Eletrofisiologia , Retina/fisiologia , Percepção Visual/fisiologiaRESUMO
Retrograde transport studies have shown that widespread areas of the cerebral cortex project upon the superior colliculus. In order to explore the organization of these extensive projections, the anterograde autoradiographic method has been used to reveal the distribution and pattern of corticotectal projections arising from 25 cortical areas. In the majority of experiments, electrophysiological recording methods were used to characterize the visual representation and cortical area prior to injection of the tracer. Our findings reveal that seventeen of the 25 cortical areas project upon some portion of the superficial layers (stratum zonale, stratum griseum superficiale, and stratum opticum, SO). These cortical regions include areas 17, 18, 19, 20a, 20b, 21a, 21b, posterior suprasylvian area (PS), ventral lateral suprasylvian area (VLS), posteromedial lateral suprasylvian area (PMLS), anteromedial lateral suprasylvian area (AMLS), anterolateral lateral suprasylvian area (ALLS), posterolateral lateral suprasylvian area (PLLS), dorsolateral lateral suprasyvian area (DLS), periauditory cortex, cingulate cortex, and the visual portion of the anterior ectosylvian sulcus. While some of these corticotectal projections target all superficial laminae and sublaminae, others are more discretely organized in their laminar-sublaminar distribution. Only the corticotectal projections arising from areas 17 and 18 are exclusively related to the superficial layers. The remaining 15 pathways innervate both the superficial and intermediate and/or deep layers. The large intermediate gray layer (stratum griseum intermedium; SGI) receives projections from almost every cortical area; only areas 17 and 18 do not project ventral to SO. All corticotectal projections to SGI vary in their sublaminar distribution and in their specific pattern of termination. The majority of these projections are periodic, or patchy, and there are elaborate (double tier, bridges, or streamers) modes of distribution. We have attempted to place these findings into a conceptual framework that emphasizes that the SGI consists of sensory and motor domains, both of which contain a mosaic of connectionally distinct afferent compartments (Illing and Graybiel, '85, Neuroscience 14:455-482; Harting and Van Lieshout, '91, J. Comp. Neurol. 305:543-558). Corticotectal projections to the layers ventral to SGI, (stratum album intermediale, stratum griseum profundum, and stratum album profundum) arise from thirteen cortical areas. While an organizational plan of these deeper projections is not readily apparent, the distribution of several corticotectal inputs reveals some connectional parcellation.
Assuntos
Gatos/anatomia & histologia , Córtex Cerebral/anatomia & histologia , Colículos Superiores/anatomia & histologia , Animais , Transporte Biológico/fisiologia , Giro do Cíngulo/anatomia & histologia , Vias Neurais/anatomia & histologia , Córtex Somatossensorial/anatomia & histologiaRESUMO
By using multiple-unit recording techniques, we explored the visual responsiveness of regions of cortex in and around the area described by others as the cat's "frontal eye fields" (Schlag J, Schlag-Rey M [1970] Brain Res 22:1-13; Guitton D, Mandl G [1978] Brain Res 149:295-312; Pigarev IN [1984] Neirofiziologiia 16:761-766). Our exploration included most of the cat's motor areas (subdivisions of areas 4 and 6) as well as prefrontal and prelimbic regions. Visual responses were routinely obtained from portions of each of the areas we explored, including prefrontal and prelimbic cortex. The qualitative characteristics of visual responses appeared to vary with cytoarchitectonic area. With few exceptions, receptive fields in these areas were large (most exceeding 2,500 deg2) and included the area centralis. Such large fields and inclusion of central vision at nearly all sites precluded retinotopic organization and prevented delineating distinct visual field representations. The most reliable and robust visual activity was observed on the ventral bank of the cruciate sulcus in area 6aalpha. The regions reported to correspond to the "frontal eye fields" did not exhibit any unique visual properties that distinguished them from surrounding areas. The widespread distribution of visually driven activity we observed is consistent with the known pattern of both cortical and subcortical inputs to this broad region of cortex. The observation of visually responsive activity across broad regions of cortex that is nominally motor is consistent with recent studies involving awake animals.
Assuntos
Mapeamento Encefálico , Gatos/fisiologia , Lobo Frontal/fisiologia , Sistema Límbico/fisiologia , Córtex Pré-Frontal/fisiologia , Campos Visuais/fisiologia , Animais , Processamento de Imagem Assistida por ComputadorRESUMO
A technique is described for dark-field and light--dark-field illumination of autoradiographic preparations for photomacrogra. A right-angle prism is employed as a substrate through which illumination is introduced to the specimen. The technique permits uniform illumination of large fields of view, and also minimizes the image-degrading effects of chromatic dispersion and excessive noncoherent scatter which are often associated with conventional dark-field illumination.
Assuntos
Autorradiografia/métodos , Encéfalo/anatomia & histologia , Aumento da Imagem/métodos , Fotomicrografia/métodos , Animais , Autorradiografia/instrumentação , Gatos , Aumento da Imagem/instrumentação , Fotomicrografia/instrumentaçãoRESUMO
The autoradiographic technique was used to examine the projection from the digit and wrist area of the precentral gyrus to the putamen in two macaque monkeys. Motor responses elicited by intracortical microstimulation were mapped to guide selection of the site of injection of isotope. Additionally, an electrophysiological study of the activity of putamen neurons during voluntary movements of the distal arm in an awake monkey was performed prior to the anatomical study in one of the animals. Two major findings resulted from this study. Firstly, the area of representation of the digits and wrist in area 4 gives rise to a substantial projection to the putamen. The distribution of terminals consisted of a simple pattern of clusters at anterior levels of the putamen. At caudal levels in the putamen, the clusters merged into a single diagonal band of label. This basic pattern was found to be virtually identical in the two monkeys. Secondly, the location of neurons in the putamen which were activated during voluntary movements of the distal arm was closely associated with the terminal distribution of fibers from the digit and wrist zone of area 4. These data provide strong evidence to support the idea that the putamen is concerned with motor function of distal muscles of the arm, and that the topographic characteristics of the corticoputamen projection are closely related to the physiological properties of individual neurons in the putamen.
Assuntos
Córtex Motor/anatomia & histologia , Putamen/anatomia & histologia , Animais , Braço , Mapeamento Encefálico , Vias Eferentes/anatomia & histologia , Dedos/inervação , Macaca fascicularis , Macaca mulatta , Movimento , Músculos/inervação , Putamen/fisiologia , Punho/inervaçãoRESUMO
The retinofugal pathways of normal and albino axolotls have been studied by tracing the transport of radioactive materials after tritiated proline was injected into one eye. The pathways demonstrated by this method include crossed projections to the diencephalon, pretectum, and tectum, and a small component that goes to the midbrain tegmentum in the basal optic root. Ipsilaterally, radioactive label was found in all of the same cerebral regions, but in much smaller quantities. Although on the basis of earlier fiber degeneration studies most of the label could be interpreted as evidence for direct retinofugal pathways, some of the label, especially that in the ipsilateral tectum, does not correspond to a known pathway and may represent a small new component or have been produced by transneuronal transport mechanisms. The pattern of labeling was the same in the albino as in the normally pigmented axolotls. Thus, it appears that the abnormality of the chiasmatic pathway, which has been found in albinos of many different mammalian species, does not occur in axolotls.
Assuntos
Albinismo/veterinária , Ambystoma/anatomia & histologia , Vias Visuais/anatomia & histologia , Albinismo/patologia , Animais , Quiasma Óptico/patologia , Retina/patologia , Colículos Superiores/patologiaRESUMO
The projection patterns from different visual areas of the parieto-occipital cortex to the claustrum were studied autoradiographically in cats. When [3H]proline was injected into 17, 18, 19 or Clare-Bishop areas, the label was transported to an area restricted to the dorsal and caudal parts of the claustrum without any suggestion of retinotopic organization. Injection in each of these visual areas resulted in individual patterns of projection but with overlapping fields of termination, a pattern similar to corticocaudate projection. When injected into area 7, a region shown to have neurons involved in visuomotor mechanisms, the label was transported to the same area as that of the visual projection. These and other findings suggest that claustrum may be reciprocally and topographically connected with the cerebral cortex.
Assuntos
Gânglios da Base/anatomia & histologia , Córtex Visual/anatomia & histologia , Animais , Autorradiografia , Transporte Axonal , Gatos , Prolina , Técnicas EstereotáxicasRESUMO
Cortical projections to the nuclei of the cat's accessory optic system were demonstrated by anterograde transport and degeneration methods. Areas 21a, 21b, AMLS and PMLS were found to project to the medial, lateral and dorsal terminal accessory optic nuclei. Selective projections from area PLLS to the lateral terminal nucleus and from areas 17 and 18 to the medial terminal nucleus were noted. No terminal labeling was detected following injections of areas ALLS, DLS, 20a, 20b, 19, 7 or the splenial visual area. The accessory optic system has been implicated in the control of optokinetic nystagmus. Additional evidence supports a role for ipsilateral visual cortical projections in mediating optokinetic pursuit in the naso-temporal direction under monocular conditions. Thus the visual cortical projections we describe may partially underlie the observed functional laterality of monocularly elicited optokinetic pursuit in the cat. The present results further indicate that suprasylvian areas AMLS, PMLS and 21 are the cortical regions primarily responsible for descending visual influences on the cat's accessory optic nuclei.
Assuntos
Vias Aferentes/fisiologia , Córtex Visual/fisiologia , Animais , Autorradiografia , Transporte Axonal , Gatos , Degeneração Neural , Prolina/metabolismo , Retina/fisiologia , TrítioRESUMO
Because of the potential value of evoked potential methods in evaluating striatal organization, a study was made to examine the reliability of evoked potentials in demonstrating the fine topographic details of the corticostriatal projection in comparison with the autoradiographic fiber-tracing method. The present data indicate a close relation between the distribution of striatal evoked potentials to electrical stimulation of a specific site in the motor cortex and the distribution of axon terminals emanating from that same cortical site in the same animal.
Assuntos
Axônios/fisiologia , Córtex Cerebral/fisiologia , Corpo Estriado/fisiologia , Terminações Nervosas/fisiologia , Transmissão Sináptica , Animais , Autorradiografia , Gatos , Potenciais EvocadosRESUMO
The present study uses immunocytochemical techniques to determine whether cholinergic basal forebrain neurons in the cat are in a position to receive a homogeneous pattern of inputs, or if specific immunocytochemically defined afferent systems are localized to only selected regions of the basal forebrain. Monoclonal antibodies against choline acetyltransferase (ChAT) were used to identify the location of putative cholinergic neurons which are known to project to the cerebral cortex. In addition, polyclonal antibodies against substance P (SP) or enkephalin (Enk) were used on either adjacent or on the same histological sections reacted for ChAT to identify the neuropeptide plexuses that provide input to the basal forebrain. ChAT-immunoreactive (ChAT-IR) perikarya were located throughout the vertical limb, genu and horizontal limb of the diagonal band of Broca. ChAT-IR neurons also were located within the substantia innominata (SI), within the peripallidal zone around the globus pallidus, and were intercalated within the internal capsule. Enk-IR and SP-IR were used to determine the distribution of putative peptidergic terminals within the basal forebrain. Extensive Enk-IR and SP-IR terminal label was localized within the globus pallidus and the surrounding peripallidal zones, as well as within the SI, whereas the components of the diagonal band of Broca demonstrated negligible Enk-IR and SP-IR label. These data predict that the subdivisions of the cholinergic basal forebrain in the cat do not share a uniform afferent system, and only selective portions of this cholinergic system are in an anatomical position to receive a major direct input from the identified subcortical peptidergic afferents. The segregation of afferents has important consequences in the selective control of cortical function by the cholinergic basalocortical pathway.
Assuntos
Colina O-Acetiltransferase/metabolismo , Encefalinas/metabolismo , Prosencéfalo/metabolismo , Substância P/metabolismo , Animais , Gatos , Imuno-Histoquímica , Neuropeptídeos/metabolismo , Distribuição TecidualRESUMO
Blocks of neural tissue were processed by a modified Golgi-Kopsch procedure and by the rapid Golgi method. Following the impregnation, the blocks were embedded in celloidin, sectioned at 100 micrometer, and collected in 70% alcohol. The sections were then processed as follows: 1) rinsed in distilled water; 2) substituted with 0.4M sodium bromide for five minutes; 3) reduced in Kodak D-19 developer; and 4) treated in 0.5M sodium thiosulfate. The silver chromate deposits within the impregnated cells are converted successively to silver bromide and to reduced silver by this procedure. Sections so treated resist decomposition of the Golgi impregnation, and they may be counterstained with conventional aqueous cresyl violet to demonstrate the cytoarchitecture of the Golgi-impregnated tissue.
Assuntos
Tecido Nervoso/anatomia & histologia , Coloração e Rotulagem , Animais , Gatos , Cromatos , Haplorrinos , Vison , Prata , Córtex Visual/anatomia & histologiaRESUMO
Anterograde transport methods reveal an extensive thalamostriate projection from the extrageniculate visual thalamus. These projections distribute to approximately the same regions of the striatum innervated by the corticostriate projections from over a dozen higher visual cortical areas [visual-recipient sector; Updyke, B.V. (1993) J. Comp. Neurol., 327, 159-193.]. Like their cortical counterparts, the thalamostriate projections to the caudate distribute in a patchy manner that suggests potential overlap or intermingling spatial relationships between the two major afferents. All of the visually related thalamic nuclei projecting to the striatum receive ascending signals from the superior colliculus, suggesting that the constraints placed upon tectal processing by striatonigral control have important consequences for central perceptuomotor processing at the striatal and cortical levels.