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At least 1,369 records · Page 76Linked to original sources
PubMed1983

Changes in [3H]muscimol binding in substantia nigra, entopeduncular nucleus, globus pallidus, and thalamus after striatal lesions as demonstrated by quantitative receptor autoradiography.

A quantitative autoradiographic technique for measuring the binding of [3H]muscimol to central nervous system GABA receptors is described using tritium-sensitive film. [3H]Muscimol binding was studied in primary and secondary striatal projection areas of rat brain following kainic acid lesions of the striatum. Seven days after the lesion, binding affinities in the striatum and its projection areas were not altered significantly. There was a loss of [3H]muscimol receptors in the striatum. Receptors increased in numbers in the ipsilateral globus pallidus (19%), entopeduncular nucleus (22%), and substantia nigra pars reticulata (38%). [3H]Muscimol binding was decreased in the ipsilateral anteroventrolateral and ventromedial (8%) thalamic nuclei. [3H]Muscimol binding in other brain areas (layer IV of the cerebral cortex, central gray, superior colliculus, and stratum moleculare of hippocampus) was not affected. The findings suggest that a loss of striatal innervation resulted in increased numbers of GABA receptors in striatal projection sites. It is further suggested that loss of inhibitory striatal inputs to neurons in the entopeduncular nucleus and substantia nigra pars reticulata may activate GABAergic projections to thalamus and thus result in decreased numbers of thalamic GABA receptors.

Animals↗
PubMed1983

Multiple opiate binding sites in the central nervous system of the rabbit. Large predominance of a mu subtype in the cerebellum and characterization of a kappa subtype in the thalamus.

We have compared the binding characteristics of [3H]etorphine, a nonselective mu-, delta-, and kappa-opiate agonist, with those of [3H]Tyr-D-Ala-Gly-MePhe-NH(CH2)2OH ([3H]DAGO), a selective mu-agonist, in rabbit cerebellar and thalamic membranes. We have also examined the ability of various unlabeled opioid ligands to compete with the binding of [3H]etorphine in the two preparations. In cerebellar membranes, [3H]DAGO(Kd = 0.7 nM) labels slightly fewer sites than does [3H]etorphine (Kd = 0.06 nM): 0.18 versus 0.24 pmole/mg of protein. In addition, competition studies indicate that up to 75% of the [3H]etorphine binding sites in this preparation display (a) high apparent affinity for unlabeled DAGO and (b) higher apparent affinity for morphine, the prototypical mu-agonist, than for Tyr-D-Ala-Gly-Phe-D-Leu (DADL), a delta-agonist. Together, these results suggest that the rabbit cerebellum contains a very high proportion (0.7-0.8) of mu-opiate binding sites. In thalamic membranes, [3H]DAGO (Kd = 1.1 nM) labels considerably fewer sites than does [3H]etorphine (Kd = 0.08 nM): 0.09 versus 0.27 pmole/mg of protein. In this preparation, the competition curves of DAGO and of DADL resolve binding of [3H]etorphine into two components. The first component accounts for 40-50% of total binding and reflects the interaction of [3H]etorphine with mu-opiate binding sites. The second component (up to 50% of total binding) is unaffected in the presence of DADL at concentrations (1-10 microM) that rule out binding of [3H]etorphine to mu- and delta-opiate binding sites. It disappears readily in the presence of very low concentrations (Ki less than 1 nM) of benzomorphan opiates (bremazocine, cyclazocine, and ethylketocyclazocine) yet it is relatively insensitive to inhibition by mu- and delta-agonists. This second component may therefore reflect [3H]etorphine's interaction with a kappa-opiate binding site. The kappa-opiate binding site is assayed for as that site which binds [3H]etorphine (0.5 nM) in the presence of either DADL (2 microM) or 10 microM of another enkephalin: Tyr-D-Ser-Gly-Phe-Leu-Thr. We find that, in the rabbit central nervous system, the thalamus, followed by frontal cortex and caudate nucleus, shows the highest content of kappa-opiate binding sites.

Animals↗
PubMed1983

Ascending projections to the medial geniculate body of the cat: evidence for multiple, parallel auditory pathways through thalamus.

The sources of ascending input to the medial geniculate body (MGB) of the cat were studied using the retrograde transport of horseradish peroxidase (HRP). HRP injections were made iontophoretically through micropipettes which were also used to record physiological properties at the injection sites. This technique produced small injections which appeared to be restricted to single subnuclei. The tectothalamic projection of the auditory system was found to consist of at least four distinct and separate pathways. The ventral division of the MGB receives a topographical projection from the central nucleus of the inferior colliculus (ICC) which preserves tonotopicity and provides short latency, sharply frequency-tuned responses. The medial part of the ICC projects to the deep dorsal nucleus, which contains only units tuned to high frequencies. The major inputs to the caudodorsal nucleus (DC) stem from nucleus sagulum and the pericentral nucleus of the inferior colliculus (ICP). Units in DC and the ventrolateral nucleus, which also receive input from ICP, have very broad tuning properties and late, habituating responses. Injections of HRP into the medial division (MGM) produced labeled cells scattered throughout the external nucleus of the inferior colliculus and the ventral part of ICC. This widespread input is reflected in the wide range of auditory responses found in MGM. Auditory responses in the suprageniculate nucleus were poorly defined and many units did not respond to tonal stimuli; following HRP injections no filled cells were found in the inferior colliculus, but labeled cells were found in the deeper layers of the superior colliculus and in the interstitial nucleus of the brachium of the inferior colliculus. Together with recent findings on the auditory thalamocortical projection, these results provide evidence for multiple parallel auditory pathways through the thalamus.

Afferent Pathways↗
PubMed1978

[Experimental cerebral infarction. Part 1: Production of thalamus infarction model in dogs (author's transl)].

Difficulties in producing temporary cerebral ischemia in experimental animals have delayed the study on the prevention and treatment of cerebral infarction. Although occlusion of the middle cerebral artery in dog proved to be fruitless, we eventually succeeded in producing focal cerebral infarction by temporary occlusions of brain arteries. Infarction confined to the anterior portion of the thalamus was obtained by simultaneous occlusion of four arteries for 60 or 120 minutes: internal carotid, anterior cerebral, middle cerebral and posterior communicating arteries. This experimental model in dogs is unique, since a marked infarction can be seen in high frequency, and the dogs can be managed for sufficient periods after temporary clipping. Consequently, it is possible to investigate cerebral infarction not only from the pathophysiological viewpoint, but also for its prevention and treatment.

Animals↗
PubMed1984

[A case of moyamoya disease associated with a peripheral artery aneurysm of the thalamus].

The authors report a case of moyamoya disease associated with a peripheral artery aneurysm in the thalamus of a 54-year-old woman. Plain CT scans revealed the right thalamic hemorrhage with ventricular penetration. Cerebral angiography demonstrated the characteristic appearance of moyamoya disease with a peripheral artery aneurysm in the territory of the right medial posterior choroidal artery. This aneurysm ruptured three times during 8 days since onset and the thalamic hemorrhage became larger on each occasion. Although the clinical symptoms and signs and plain CT scans disclosed thalamic hemorrhage, it was difficult to explain the cause of the hemorrhage. The authors emphasize that cerebral angiography and enhanced CT scans are quite necessary to clarify the genesis of cerebrovascular disease.

Aneurysm↗
PubMedDate not supplied

[Mikroiontophoretic analysis of the interrelation between spike activity and chemical sensitivity of neurons of the medial thalamus to acetylcholine and noradrenaline in alert rats].

An interconnection between spontaneous impulse activity of medial thalamus (MT) neurones and their chemical sensitivity to acetylcholine (ACh) and noradrenaline (NA) was revealed in rats by means of microelectrode recording and microionophoresis in conditions of free behaviour and during immobilization stress. The neurones with the most rare reactions (inhibitory to ACh and excitatory to NA) had higher frequency and variance of discharges in comparison to the cells with most typical responses (excitatory to ACh and inhibitory to NA). The number of cases with changed sensitivity of single units in these conditions directly correlated with the firing rate and variance of the unit discharges. Qualitative changes in cells' sensitivity to ACh and NA elicited in rats both "spontaneously" in conditions of immobilization stress and under the action of electrocutaneous stimulation were not always tightly connected with the observed phasic changes of their discharges.

Acetylcholine↗
PubMed1983

[Reflexogenic changes in the spontaneous and evoked activity of the parafascicular neurons in the rat thalamus during electroacupuncture stimulation].

Acute experiments on cats were made to study the electroacupuncture (EAP) effect on neuronal impulse activity in the parafascicular complex (PFC) of the thalamus in response to solitary peripheral nociceptive and non-nociceptive stimuli. EAP stimulation affects the pattern of spontaneous and evoked activity of PFC neurons and forms their new functional status. It is suggested that the analgetic effect is brought about by the changes in neuronal activity in subcortical structures of the brain including the thalamic nuclei which transmit the ascending nociceptive input.

Acupuncture Therapy↗
PubMed1983

[Experimental anatomic study of the topography of the retinofugal projections in Discoglossus pictus (Amphibia, Anura). I. The thalamus: re-examination of the contralateral retinotopy and the origin of the uncrossed optic fibers].

The topography of retinofugal projections on the thalamus of an Anuran Amphibia was studied by Fink-Heimer technique. After small lesions in retina, degeneration was found in all contralateral neuropils and in one or several ipsilateral neuropils according to retinal location: A lesion in temporal retina is followed by large axonal degeneration in neuropil of Bellonci; a dorsal lesion invaded whole geniculate neuropil while within it, contralateral ventral and nasal projections are scarce. Ipsilaterally, excepted for the nasal retina, all territories project to anterior neuropils; but, only temporal fibres ended in ipsilateral pretectal neuropil. The incinate neuropil receives bilateral projections from the whole retina. This study shows that, rather than a strict segregation, an overlap of quadratic projections into the same neuropil and a divisional repartition of these projections between the two anterior neuropils seem to be the rule.

Animals↗
PubMed1978

[Experimental cerebral infarction.--Part 3: The protective effect of mannitol in thalamus infarction in dogs (author's transl)].

One day during an aneurysm surgery under the preoperative administration of mannitol, the feeding artery was accidentally occluded temporarily. Since then, investigation on whether or not mannitol can prevent infarctions in ischemic brain tissues have been carried out utilizing the thalamus infarction model in dogs. Twenty dogs were divided into equal groups, the control and the mannitol group. Temporary clipping for sixty minutes was adopted as a standard for both groups. The only difference between the groups was the administration of 2 g/kg of mannitol before the arterial occlusions. In the control, six of ten dogs showed infarctions verified as histological changes on the seventh post-ischemic day. In the mannitol group only one of ten showed infarction. Each of the difference is statistically significant (P less than 0.03).

Animals↗
PubMed1982

[Role of the dorso-medical thalamus in the development of the adrenocortical response to acute stress in the pigeon].

Stress application elicited successive attenuating peaks of plasma corticosterone level occurring 14, 35, 60 and 90 min. later. Late peaks were suppressed after bilateral electrolytic lesions were placed in the nuclei dorsomedialis anterior thalami, resulting in a single peak (the first one) of corticosteronemia after stress application. It is suggested that reverberating adrenocortical response to stress depends upon interrelationships between the adrenocorticotropic hypothalamus and the anterior medio-dorsal thalamus.

Adrenal Cortex↗
PubMed1982

[Structure and evaluation of the paramedian side of thalamus].

The adhaesio interthalamica in humans as apposed to animals is formed only by the nucleus reuniens which is of very variable size and which is conspicuously small if there is no adhaesio interthalamica. It is larger than in animals and is probably of special importance for humans. Its fliber connections have not been elucidadat and its effects on other parts of the brain cannot be determined with certainty. As the adhaesio interthalamica may be enlarged under certain condition-and is frequently preserved in sensecence, so it is probably of special significance for humans. Similar findings have been obtained for the adacent paramedian part of the thalamus the cells of which are irregularly distributed.

Adult↗
PubMed1994

Medial lemniscal and spinal projections to the macaque thalamus: an electron microscopic study of differing GABAergic circuitry serving thalamic somatosensory mechanisms.

The synaptic relationships formed by medial lemniscal (ML) or spinothalamic tract (STT) axon terminals with neurons of the somatosensory ventroposterolateral thalamic nucleus of the macaque monkey have been examined quantitatively by electron microscopy. ML and STT axons were labeled by the anterograde axon transport of WGA-HRP following injection of the tracer into the contralateral dorsal column nuclei, or the dorsal horn of the spinal cord, respectively. Thalamic tissue was histochemically reacted for the presence of HRP. Serial thin sections were stained with a gold-labeled antibody to GABA, to determine which neuronal elements exhibited GABA immunoreactivity (GABA-ir). Serially sectioned thalamic structures were recorded in electron micrographs and reconstructed in three dimensions by computer. Individual ML axon terminals form multiple synaptic contacts with segments of the proximal dendritic trees of thalamocortical relay neurons and also synapse upon the dendritic appendages of GABA-ir interneurons (local circuit neurons). These GABA-ir dendritic appendages contain synaptic vesicles and are presynaptic (presynaptic dendrites) to the same segments of relay neuron dendrites that receive ML contacts. When analyzed in serial sections and reconstructed by computer, the ML terminals form triadic relationships (ML, GABA appendage, and relay neuron dendrite) or more complex glomerular arrangements involving multiple appendages, all of which then contact the relay neuron dendritic segment. In contrast, multiple STT terminals make synaptic contacts along segments of projection neuron dendrites and are usually the only type of profile to contact that segment of dendrite. More than 85% of the spinal afferents form simple axodendritic synapses with relay cells and do not contact GABA-ir appendages. The thalamic synaptic relationships of ML terminals are fundamentally different from those formed by the STT. Because STT neurons predominatly transmit information about noxious stimuli, the simple axodendritic circuitry of the majority of these spinal afferents suggests that the transmission of noxious information is probably not subject to GABAergic modulation by thalamic interneurons, in contrast to the GABAergic processing of non-noxious information carried by the ML afferents. The differences in the GABAergic circuits of the thalamus that mediate ML and STT afferent information are believed to underlie differential somatosensory processing in the forebrain. We suggest that changes in thalamic GABAergic dendritic appendages and GABA receptors following CNS injury may play a role in the genesis of some central pain states.

Afferent Pathways↗
PubMed1995

[Bilateral paramedian thalamus infarction syndrome. Differential diagnosis in vigilance and cognition disorders].

In a 63-year-old woman admitted to the emergency ward because of coma of unknown origin, clinical examination, analysis of blood and cerebrospinal fluid, electroencephalography, and computed tomography of the brain were unrevealing. On the fourth hospital day the coma was followed by an apathetic state and amnesic syndrome, suggesting bilateral thalamic infarction. Magnetic resonance imaging of the brain demonstrated bilateral thalamic infarction of the paramedian territories. The role of the thalamus for functions of vigilance and cognition is emphasized.

Cerebral Infarction↗
PubMedDate not supplied

Angiolipoma of thalamus presenting with abrupt onset suggestive of cerebrovascular disease.

A 25-year-old man had angiolipoma of the left thalamus producing sudden severe headache, coma, right hemiparalysis, and aphasia as usually observed in cerebrovascular disease. The patient remained right hemiparalytic and aphasic after removal of the thalamic lesion. A vascular lesion was also detected angiographically in the left lateral ventricular choroid plexus but was not excised. Only 3 intracranial angiolipomas including the current instance were on record. However, it was only in our patient that the lesion suddenly presented with intracerebral hemorrhage. The pathogenesis of the angiolipoma was suggested to be associated with maldifferentiation of mesenchyme and/or its derivatives toward the vascular and adipose tissue within the same mass, resulting in the formation of the angiolipoma.

Adult↗
PubMed1995

Elevated levels of nerve growth factor in the thalamus and spinal cord of rats affected by experimental allergic encephalomyelitis.

In a previous study it was shown that the levels of NGF in the cerebrospinal fluid of patients affected by multiple sclerosis (MS) increase during the acute phase of the disease and decrease in the remission phase. In the present study, using an animal model of MS, we investigate whether any changes in NGF levels occur in brains of rats affected by Experimental Allergic Encephalomyelitis (EAE). The results show an enhanced level of NGF in the thalamus and spinal cord and a numerical increase of mast cells (MCs) expressing mRNA-NGF localized in these two regions. These observations suggest that NGF is involved in EAE and that MCs contribute to the local increase of NGF.

Animals↗
PubMed1995

Anticipatory head direction signals in anterior thalamus: evidence for a thalamocortical circuit that integrates angular head motion to compute head direction.

Several regions in the rat brain contain neurons known as head-direction cells, which fire only when the rat's head is facing in a specific direction. Head-direction cells are influenced only by the direction of the head with respect to the static environmental surroundings, and not by the position of the head relative to the body. Each head-direction cell has its own preferred direction of firing, so that together, the population of cells provides a continuous signal of momentary directional heading. Here, head-direction cells were recorded from the post-subicular cortex (PSC) and anterodorsal nucleus (ADN) of the thalamus of freely moving rats. Cell activity was analyzed in relation to both momentary head direction, and the angular velocity of head turns. Head-direction cells in PSC maintained the same directional firing preference, regardless of the angular head velocity. By contrast, head-direction cells in ADN systematically shifted their directional firing preference, as a function of angular head velocity. The ADN cells always shifted their directional tuning peak to the left during clockwise head turns, and to the right during counterclockwise head turns. These results suggest that ADN neurons anticipate the future direction of the head, whereas PSC neurons encode the present direction of the head. Based on these findings, we hypothesize that neurons in PSC and ADN are reciprocally connected to form a thalamocortical circuit, which computes the directional position of the rat's head by integrating the angular motion of the head over time.

Animals↗
PubMed1976

[Topography of the optic thalamus, caudate and lenticular nuclei of the human brain in frontal section (an anatomical-statistical study applied to stereotaxis)].

Topographic coordinates of the thalamus, caudate and lentiform nuclei of the human brain in relation to the medial-sagittal plane and inferior-medial part of the corpus callosum were studied in 70 preparations. The parameters under study are characterized by mean values of the variants and square deviations. Detailed tables of these values are given which may be employed in stereotaxical calculations for all coordinates, for men and women separately, for the right and left hemispheres, brachy- and mesencephaly. Statistically reliable differences of coordinates found for 3 of 13 parameters studied were not regular. The necessity to identify the above subgroups in topometrical investigations of the human brain is under doubt.

Adult↗
PubMedDate not supplied

[Longitudinal density of the vascular network of the human thalamus].

The longitudinal density of the vascular net in twenty human thalamuses was measured. In all cases the lumen of the arterial branches of the posterior communicating artery and the posterior cerebral artery were measured, and in six cases the lumen of the branches of the anterior choroidal artery. The average longitudinal density of the examined arterial branches in the thalamic vascular net was 5.550 +/- 0.170 mm2. The morphologic analysis of the frontal thalamic section revealed highly anisotropic thalamic blood vessels.

Blood Vessels↗