RESUMO
The thalamus is a deep cerebral structure that is crucial for proper neurological functioning as it transmits signals from nearly all pathways in the body. Insult to the thalamus can, therefore, result in complex syndromes involving sensation, cognition, executive function, fine motor control, emotion, and arousal, to name a few. Specific territories in the thalamus that are supplied by deep cerebral arteries have been shown to correlate with clinical symptoms. The aim of this review is to enhance our understanding of the arterial anatomy of the thalamus and the complications that can arise from lesions to it by considering the functions of known thalamic nuclei supplied by each vascular territory.
Assuntos
Artéria Basilar/anatomia & histologia , Infarto Encefálico/fisiopatologia , Círculo Arterial do Cérebro/anatomia & histologia , Artéria Cerebral Posterior/anatomia & histologia , Tálamo/irrigação sanguínea , Núcleos Anteriores do Tálamo/anatomia & histologia , Núcleos Anteriores do Tálamo/irrigação sanguínea , Núcleos Anteriores do Tálamo/fisiologia , Corpos Geniculados/anatomia & histologia , Corpos Geniculados/irrigação sanguínea , Corpos Geniculados/fisiologia , Humanos , Núcleos Laterais do Tálamo/anatomia & histologia , Núcleos Laterais do Tálamo/irrigação sanguínea , Núcleos Laterais do Tálamo/fisiologia , Núcleo Mediodorsal do Tálamo/anatomia & histologia , Núcleo Mediodorsal do Tálamo/irrigação sanguínea , Núcleo Mediodorsal do Tálamo/fisiologia , Pulvinar/anatomia & histologia , Pulvinar/irrigação sanguínea , Pulvinar/fisiologia , Tálamo/anatomia & histologia , Tálamo/fisiologia , Núcleos Ventrais do Tálamo/anatomia & histologia , Núcleos Ventrais do Tálamo/irrigação sanguínea , Núcleos Ventrais do Tálamo/fisiologiaRESUMO
In this study, two circadian related centers, the suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) were evaluated in respect to their cytoarchitecture, retinal afferents and chemical content of major cells and axon terminals in the rock cavy (Kerodon rupestris), a Brazilian rodent species. The rock cavy SCN is innervated in its ventral portion by terminals from the predominantly contralateral retina. It also contains vasopressin, vasoactive intestinal polypeptide and glutamic acid decarboxilase immunoreactive cell bodies and neuropeptide Y, serotonin and enkephalin immunopositive fibers and terminals and is marked by intense glial fibrillary acidic protein immunoreactivity. The IGL receives a predominantly contralateral retinal projection, contains neuropeptide Y and nitric oxide synthase-producing neurons and enkephalin immunopositive terminals and is characterized by dense GFAP immunoreactivity. This is the first report examining the neural circadian system in a crepuscular rodent species for which circadian properties have been described. The results are discussed comparing with what has been described for other species and in the context of the functional significance of these centers.
Assuntos
Corpos Geniculados/anatomia & histologia , Corpos Geniculados/metabolismo , Roedores/anatomia & histologia , Roedores/metabolismo , Núcleo Supraquiasmático/anatomia & histologia , Núcleo Supraquiasmático/metabolismo , Animais , Ritmo Circadiano , Imuno-Histoquímica , Masculino , Neurônios/metabolismo , Fotomicrografia , Retina/anatomia & histologia , Retina/metabolismo , Vias Visuais/anatomia & histologia , Vias Visuais/metabolismoRESUMO
We investigated in young rats the effects of malnutrition on the main structures of the circadian timing system: retina, hypothalamic suprachiasmatic nuclei (SCN), thalamic intergeniculate leaflet, retinohypothalamic- and geniculohypothalamic tracts. Control rats were born from mothers fed a commercial diet since gestation, and malnourished rats from mothers fed a multideficient diet since gestation (GLA group) or lactation (LA group). After weaning, pups received the same diet as their mothers, and were analysed at postnatal days 27, 30-33 and 60-63. Brain sections were processed to visualise in the SCN neuropeptide Y immunoreactivity and terminal labeling after intraocular tracer injections. Nissl staining was used to assess cytoarchitectonic boundaries of the SCN and cell features in retinal whole mounts. Cell counts, morphometric and densitometric analysis were performed. Compared with controls, the total retinal surface was reduced and the topographical distribution of retinal ganglion cells was altered in malnourished rats, with changes in their density. Alterations were also detected in the SCN dimensions in the GLA and LA groups at one and two postnatal months, as well as in the SCN portion occupied by the retinal input in the GLA group at days 30-33, but not in the NPY-containing geniculohypothalamic tract. The present data point to subtle changes, with a low and differential vulnerability to early malnutrition, of structures involved in circadian timing regulation. Furthermore, the present findings suggest that the altered circadian rhythmicity previously documented in malnourished rats cannot be ascribed to impaired development of the retino- and geniculohypothalamic projections to the SCN.
Assuntos
Encéfalo/patologia , Corpos Geniculados/patologia , Desnutrição/patologia , Retina/patologia , Núcleo Supraquiasmático/patologia , Fatores Etários , Animais , Animais Recém-Nascidos , Peso Corporal/fisiologia , Encéfalo/citologia , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Contagem de Células/métodos , Tamanho Celular , Feminino , Corpos Geniculados/anatomia & histologia , Corpos Geniculados/crescimento & desenvolvimento , Corpos Geniculados/metabolismo , Imuno-Histoquímica/métodos , Lactação , Masculino , Vias Neurais/crescimento & desenvolvimento , Vias Neurais/patologia , Neurônios/metabolismo , Neurônios/patologia , Neuropeptídeo Y/metabolismo , Tamanho do Órgão/fisiologia , Ratos , Ratos Wistar , Retina/citologia , Retina/crescimento & desenvolvimento , Retina/metabolismo , Fatores Sexuais , Coloração e Rotulagem/métodos , Núcleo Supraquiasmático/crescimento & desenvolvimento , Núcleo Supraquiasmático/metabolismoRESUMO
After performing eye enucleations or restricted lesions in the superior colliculus or the pulvinar nucleus, the degeneration patterns provoked by these procedures were analyzed by means of the Nissl and the Fink-Heimer methods in 30 specimens of Octodon degus. The pulvinar or lateroposterior nucleus can be subdivided into 3 regions (rostrolateral, rostromedial and caudal), on the basis of cytoarchitecture, tectofugal afferent and efferent connections to the cerebral cortex. In addition, this nucleus projects to the ipsilateral tail of the caudate nucleus and the nucleus lateralis dorsalis of the thalamus, which has been shown to project over the cingulate cortex in this animal 43. These findings support the possibility that the pulvinar may have an important role visuo-limbic interactions, by way of its connections with the nucleus lateralis dorsalis. Another highly interesting finding from the phylogenetic point of view is that the organization of the pulvinar in the Octodon degus is remarkably similar to that of the inferior pulvinar described for the owl monkey 46. Furthermore, the fact that the organization of the retino-tecto-thalamo-cortical pathways described in the grey squirrel 54 and in the tree shrew 33 is strikingly similar to those found in the Octodon degus, a semi-fossorial South American rodent that has evolved in isolation from the two former species for about 40 million years, makes it impossible to explain the organization of this pathway by advocating convergent evolution, due to environmental pressures determined by arboreal life, as postulated by kaas et al 39.
Assuntos
Retina/anatomia & histologia , Roedores/anatomia & histologia , Colículos Superiores/anatomia & histologia , Telencéfalo/anatomia & histologia , Núcleos Talâmicos/anatomia & histologia , Animais , Gânglios da Base/anatomia & histologia , Núcleo Caudado/anatomia & histologia , Dominância Cerebral/fisiologia , Corpos Geniculados/anatomia & histologia , Sistema Límbico/anatomia & histologia , Degeneração Neural , Nervo Óptico/anatomia & histologia , Sinapses/ultraestrutura , Lobo Temporal/anatomia & histologia , Córtex Visual/anatomia & histologia , Vias Visuais/anatomia & histologiaRESUMO
Retinofugal projections in the blind cave fish A. hubbsi and in the highly visual A. mexicanus were studied with both reduced silver and autoradiographic methods. Contrary to what has been reported for other teleosts, ipsilateral, as well as the generally accepted contralateral, projections were found in A. mexicanus. Bilateral retinofugal projections were traced to the dorsolateral thalamic nucleus and area pretectalis. Contralateral projections were traced to the lateral geniculate nucleus, nucleus pretectalis, accessory optic nucleus, nucleus corticalis, nucleus opticus hypothalamicus and the superficial layers of the optic tectum (strata opticum, fibrosum and griseum superficiale, and the cellular zone of griseum centrale). Retinal efferents in the blindfish, A. hubbsi, are sparse and totally crossed. Areas receiving a retinal projection include nucleus opticus hypothalamicus, lateral geniculate and the superficial layers of the medial third of the optic tectum. Preliminary behavioral studies are described and discussed in relation to the possible visual potential of this teleost.