Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DIENCEPHALON”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed1989

Narcolepsy associated with lesions of the diencephalon.

Although symptomatic narcolepsy, or narcolepsy due to identifiable brain lesions, was once thought to be common, there are few well-documented reported cases since the discovery of the association of REM sleep abnormalities with narcolepsy. Even fewer such reports have been accompanied by human leukocyte antigen (HLA) testing. We report 3 patients who fulfill criteria for symptomatic narcolepsy, 1 with a craniopharyngioma, the 2nd with a hypothalamic syndrome of unknown etiology, and the 3rd with obstructive hydrocephalus and a sarcoid granuloma in the region of the 3rd ventricle. The first 2 were positive for HLA-DR2 while the 3rd was negative for the HLA-DR2 and HLA-DQwl antigens. These findings suggest that diencephalic lesions can be associated with signs and symptoms of narcolepsy that are clinically indistinguishable from those of idiopathic narcolepsy, and that the HLA-DR2 antigen is not required in all cases of symptomatic narcolepsy.

Adult↗
PubMed2003

Engrailed and Fgf8 act synergistically to maintain the boundary between diencephalon and mesencephalon.

Specification of the forebrain, midbrain and hindbrain primordia occurs during gastrulation in response to signals that pattern the gastrula embryo. Following establishment of the primordia, each brain part is thought to develop largely independently from the others under the influence of local organizing centers like the midbrain-hindbrain boundary (MHB, or isthmic) organizer. Mechanisms that maintain the integrity of brain subdivisions at later stages are not yet known. To examine such mechanisms in the anterior neural tube, we have studied the establishment and maintenance of the diencephalic-mesencephalic boundary (DMB). We show that maintenance of the DMB requires both the presence of a specified midbrain and a functional MHB organizer. Expression of pax6.1, a key regulator of forebrain development, is posteriorly suppressed by the Engrailed proteins, Eng2 and Eng3. Mis-expression of eng3 in the forebrain primordium causes downregulation of pax6.1, and forebrain cells correspondingly change their fate and acquire midbrain identity. Conversely, in embryos lacking both eng2 and eng3, the DMB shifts caudally into the midbrain territory. However, a patch of midbrain tissue remains between the forebrain and the hindbrain primordia in such embryos. This suggests that an additional factor maintains midbrain cell fate. We find that Fgf8 is a candidate for this signal, as it is both necessary and sufficient to repress pax6.1 and hence to shift the DMB anteriorly independently of the expression status of eng2/eng3. By examining small cell clones that are unable to receive an Fgf signal, we show that cells in the presumptive midbrain neural plate require an Fgf signal to keep them from following a forebrain fate. Combined loss of both Eng2/Eng3 and Fgf8 leads to complete loss of midbrain identity, resulting in fusion of the forebrain and the hindbrain primordia. Thus, Eng2/Eng3 and Fgf8 are necessary to maintain midbrain identity in the neural plate and thereby position the DMB. This provides an example of a mechanism needed to maintain the subdivision of the anterior neural plate into forebrain and midbrain.

Animals↗
PubMed2001

Emx2 directs the development of diencephalon in cooperation with Otx2.

The vertebrate brain is among the most complex biological structures of which the organization remains unclear. Increasing numbers of studies have accumulated on the molecular basis of midbrain/hindbrain development, yet relatively little is known about forebrain organization. Nested expression among Otx and Emx genes has implicated their roles in rostral brain regionalization, but single mutant phenotypes of these genes have not provided sufficient information. In order to genetically determine the interaction between Emx and Otx genes in forebrain development, we have examined Emx2(-/-)Otx2(+/-) double mutants and Emx2 knock-in mutants into the Otx2 locus (Otx2(+/Emx2)). Emx2(-/-)Otx2(+/-) double mutants did not develop diencephalic structures such as ventral thalamus, dorsal thalamus/epithalamus and anterior pretectum. The defects were attributed to the loss of the Emx2-positive region at the three- to four-somite stage, when its expression occurs in the laterocaudal forebrain primordia. Ventral structures such as the hypothalamus, mammillary region and tegmentum developed normally. Moreover, dorsally the posterior pretectum and posterior commissure were also present in the double mutants. In contrast, Otx2(+/Emx2) knock-in mutants displayed the majority of these diencephalic structures; however, the posterior pretectum and posterior commissure were specifically absent. Consequently, development of the dorsal and ventral thalamus and anterior pretectum requires cooperation between Emx2 and Otx2, whereas Emx2 expression is incompatible with development of the commissural region of the pretectum.

Animals↗
PubMed1976

[The effect of low-frequency stimulation of the diencephalon on the topogram of cortical potentials in freely moving rabbits].

The spatio-temporal organization of the cortical potentials in rabbits was investigated by means of comparison of successive electroencephalotopograms. This systemic organization was characterized by the potentials' sagittal gradient and its inversion within the 4-6/sec range due to higher amplitudes in the frontal cortical areas, - during natural transition from the active to passive behavior as well as after low-frequency stimulation of the thalamic midline nuclei and of the hypothalamic supraoptic area. Single stimuli applied to the structures under study ordinarily prevented any obvious active behavioral periods, although entailed no long-lasting changes in the rest-activity dynamics.

Animals↗