Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THALAMUS”

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 1,045 records · Page 58Linked to original sources
PubMed1984

Thermoafferent signal processing in rats: an electrophysiological analysis of midbrain influences on thermoresponsive neurons in the ventrobasal thalamus.

The influence of electrical midbrain stimulation on thalamic cells which respond to scrotal skin warming with steep increases in firing rate was studied in anaesthetized rats. Square-wave stimuli of 200 microseconds duration and 30-250 microA intensity at 15 Hz were applied in trains lasting about 1 min. At low scrotal temperatures stimulation of the nucleus raphe dorsalis, the adjacent central grey or the median raphe nucleus was nearly always followed by a rise in thalamic activity. Inhibition occurred only in 4 of 75 experiments. Often midbrain stimulation caused neuronal responses similar to those following scrotal warming. Single stimulation experiments and the combination of electrical stimulation and electrolytic lesions indicated local interactions between excitatory and inhibitory neuronal networks in midbrain. Poststimulus latencies revealed polysynaptic midbrain/thalamic connections. Direct projections with no more than a few synaptic interruptions were seen in about 10% of the experiments. It is concluded that medial midbrain neurons influence the transmission of peripheral thermal information to the specific thalamus and contribute to the typical switching form of thalamic responses to scrotal warming.

Afferent Pathways↗
PubMed1993

Infantile panthalamic infarct with a striking sonographic finding: the "bright thalamus".

A "bright thalamus" is not uncommonly observed in cranial sonograms of asphyxiated neonates, but not those of older infants. Three infants, aged 9-14 months, developed acute onset of seizures and disturbance of consciousness after a minor prodromal illness. Bilateral thalamic infarcts were demonstrated by ultrasonography and CT. One patient expired from causes not directly related to the infarcts; the other two survived with severe neurological sequelae.

Cerebral Infarction↗
PubMed1987

Correlation between auditory evoked responses in the thalamus and species-specific call characteristics. I. Rana catesbeiana (Anura: Ranidae).

This evoked potential study of the bullfrog's auditory thalamic area (an auditory responsive region in the posterior dorsal thalamus) shows that complex processing, distinct from that reported in lower auditory regions, occurs in this center. An acoustic stimulus consisting of two tones, one which stimulates either the low-frequency or the mid-frequency sensitive population of auditory nerve fibers from the amphibian papilla and the other the high-frequency sensitive population of fibers from the basilar papilla, evoked a maximal response. The amplitude of the response to the simultaneous stimulation of the two auditory organs was, in some locations, much larger than the linear sum of the responses to the individual tones presented separately. Bimodal spectral stimuli that had relatively long rise-times (greater than or equal to 100 ms) evoked much larger responses than similar sounds with short rise-times. The optimal rise-times were close to those occurring in the bullfrog's mating call. The response was dependent on the waveform periodicity and harmonic content, with a fundamental frequency of 200 Hz producing a larger response than those with fundamentals of 50, 100 or 300 Hz. Six of the natural calls in the bullfrog's vocal repertoire were tested and the mating call and warning call were found to evoke the best responses. Each of these calls stimulate the two auditory organs simultaneously. The evoked response had a long refractory period which could not be altered by lesioning the efferent telencephalic pathways. The type of spectral and temporal information extracted by the auditory thalamic area suggests that this center is involved in processing complex sounds and likely plays an important role in the bullfrog's detection of some of its vocal signals.

Acoustic Stimulation↗
PubMed1980

Intracytoplasmic neuronal inclusions in the human thalamus. Light-microscopic, histochemical, and ultrastructural observations.

Intracytoplasmic eosinophilic inclusions were found by light microscopy in the thalamic neurons of 35 consecutive normal adult brains and in a case of myotonic dystrophy, but not in six newborn children, including one with myotonic dystrophy. Histochemical tests suggested a protein composition. Ultrastructurally, the inclusions were composed of stacks of parallel alternating dark and light rectilinear profiles not surrounded by a limiting membrane. Such inclusions are a virtually constant finding in the adult human thalamus and probably represent sites of neuronal protein storage.

Adult↗
PubMed1978

[Amyotrophic lateral sclerosis with degeneration of thalamus and substantia nigra (author's transl)].

A 40-year-old man suffering from amyotrophic lateral sclerosis with symmetrical degeneration of the thalamus and the substantia nigra is reported. The distribution pattern of the thalamic degeneration in the present case was characteristic in that the Nucleus centralis was the severest affected of the thalamic nuclei. As far as we know, there is no such case of amyotrophic lateral sclerosis in the literature. Nosologically, this case may represent a form of combined heredosystemic degeneration.

Adult↗
PubMedDate not supplied

A neuropharmacological analysis of compensatory-restorative processes in organic deficit of the parafascicular complex of the thalamus.

It has been demonstrated in freely behaving cats, on the basis of a model of the biological precursors of concrete and abstract thinking, that, in the presence of a neurosurgical lesion of various divisions of the parafascicular complex of the thalamus, the restoration of disturbed functions by neuropharmacological agents through an effect on dopamine-, choline-, and GABAergic systems is possible. There is specialization in the neurochemical pathways of the lateral and medial regions of the complex, which opens the possibility of the topical correction of psychopathology of the thalamic level.

Animals↗
PubMed1991

Effects of neonatal bilateral eye enucleation on postnatal development of the monoamines in posterior thalamus of the rat.

Levels of dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (serotonin, 5-HT) and their metabolites, and the activities of tyrosine hydroxylase (TH), tryptophan hydroxylase (TPH) and monoamine oxidase A and B (MAO-A and MAO-B) have been determined in the rat posterior thalamus after enucleation during postnatal development. DA and 5-HT turnover rate have been measured as 3,4-dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) accumulation rates after central decarboxylase inhibition by 3-hydroxybenzylhydrazine (NSD-1015). The major changes were an increase in noradrenergic and serotoninergic metabolism in enucleated animals compared with control animals. A decrease of the MAO-A to MAO-B ratio during postnatal development was found.

5-Hydroxytryptophan↗
PubMed1981

Response properties of visual units in the anterior dorsolateral thalamus of the chick (Gallus domesticus).

Receptive fields of neurons in the anterior dorsolateral thalamus (DLA) of the chick were plotted and their response properties analyzed. The average size was 18 degrees X 13 degrees but there were some wide-field units. DLA cells were classified as detectors of 1. general movement (uniform-field), 22%; 2. general movement (centre-periphery), 22%; 3. moving dark objects, 29%; 4. direction, 8%; and 5. illumination, 19%.

Animals↗
PubMed1994

The echogenic thalamus in hypoxic ischaemic encephalopathy.

This paper reports 16 term infants in whom an echogenic thalamus was identified on cranial ultrasonography. Fourteen of the patients suffered severe birth asphyxia. The prognostic significance of this finding and the underlying pathogenesis is assessed.

Asphyxia Neonatorum↗
PubMed1989

Excitatory effect of histamine on EEGs of the cortex and thalamus in rats.

When low frequency electrical stimulations were repeatedly applied to the rat midbrain reticular formation, the EEG spectral power recorded at the cortex and thalamus increased markedly, especially in the low frequency bands (0-6 Hz). The intraventricular administration of histamine (Hi) inhibited this increase. Hi-induced inhibition was antagonized by simultaneous injection of an equimolar dose of either pyrilamine or diphenhydramine, but not by that of cimetidine. In accordance with this, 2-methylHi decreased the power in the slow wave region, while 4-methylHi was not effective. It was assumed that the EEG arousal effect of Hi is exerted via H1 receptors but not related to H2 receptors. Adverse effects of H1 blockers on the brain, such as drowsiness, may be produced as a consequence of this inhibitory action.

Animals↗
PubMedDate not supplied

Neurophysiological investigations of the features of the state and physiological activity of some structures of the striopallidum and thalamus in various forms of parkinsonism.

The results of many years of investigations of the features of the functional state and physiological activity of some structures of the striopallidum (Cd, GP, Put) and thalamus (VP, VL, CM) as links in the brain systems of the organization of mental and motor activity in patients with various forms of parkinsonism are presented in generalized form. The possibilities for the use of various types of ultraslow physiological processes to study the brain mechanisms of the activational and emotional states, with more precise definition of the role of structures of the striopallidal complex in the formation of systems supporting these types of mental activity in parkinsonism, are reviewed.

Globus Pallidus↗
PubMedDate not supplied

Disorders of higher mental function due to single infarctions in the thalamus and in the area of the thalamofrontal tracts.

Nine patients (five female and four male, mean age 58 years) with small infarcts in the thalamus (TH) or in the region of the thalamofrontal tracts and producing acute mental disturbances which in the acute phase of insult consisted of dementia in seven cases and mild cognitive disturbances in two cases. The complex of mental changes was similar to that seen in "frontal syndrome" and was characterized largely by lack of spontaneity, adynamia, disorientation, loss of attention and memory, slowing of all mental processes, and lack of criticality and adequacy. Accompanying focal neurological symptoms were mild in seven patients and moderate or pronounced in two. In five patients, the severity of mental disturbances decreased with time. Computer tomography demonstrated small infarcts in the anterior or medial parts of the TH in seven patients and in the posteromedial parts of the anterior limb of the internal capsule, i.e., the thalamofrontal tracts, in two cases. In five cases, infarcts were located in the dominant hemisphere, with lesions in the non-dominant hemisphere in three and in both hemispheres in one. The positions of all foci corresponded to structures traversed by pathways connecting the TH and the lower part of the reticular formation to the frontal lobes. It is suggested that disconnection of these pathways leads to cognitive lesions or dementia because of functional inactivation of the frontal cortex.

Adult↗
PubMed1996

Comparative effects of the GABA uptake inhibitors, tiagabine and NNC-711, on extracellular GABA levels in the rat ventrolateral thalamus.

The primary mechanism by which the action of synaptically released GABA is thought to be terminated is by re-uptake into neurones and glial cells, and the pharmacological inhibition of this uptake may be beneficial in conditions where decreased GABAergic transmission has been implicated, such as epilepsy. We have compared the effects of two of these uptake inhibitors, tiagabine and NNC-711, on extracellular GABA levels in the thalamus of the rat, after both systemic and local administration. Both compounds produced dose-dependent increases in GABA concentration irrespective of the route of administration, but the concentrations required to produce increased extracellular GABA levels were considerably higher than those known to be effective for anticonvulsant purposes. These data suggest that, initially at least, alternative GABA transporters, not susceptible to inhibition by the compounds used, may still be able to remove synaptically released GABA from the extracellular space.

Analysis of Variance↗
PubMed2005

Projections from the entorhinal cortex, perirhinal cortex, presubiculum, and parasubiculum to the medial thalamus in macaque monkeys: identifying different pathways using disconnection techniques.

The projections from the perirhinal cortex, entorhinal cortex, parasubiculum, and presubiculum to the thalamus were examined using both anterograde and retrograde tracers. Attention focused on the routes taken by these projections, which were delineated by combining surgical tract section with the placement of a tracer. Projections to the anterior thalamic nuclei almost exclusively used the fornix. These relatively light projections, which arose from all areas of the entorhinal cortex, from the presubiculum, parasubiculum, and area 35 of the perirhinal cortex, terminated mainly in the anterior ventral nucleus. In contrast, the projections to the lateral dorsal nucleus from the entorhinal cortex, presubiculum and parasubiculum were denser than those to the anterior thalamic nuclei. The projections to the lateral dorsal nucleus used two routes. While nearly all of the projections from the subicular complex used the fornix, many of the entorhinal cortex projections passed caudally in the temporopulvinar bundle to reach the lateral dorsal nucleus. The perirhinal cortex, as well as the entorhinal cortex, also projects to nucleus medialis dorsalis. These projections exclusively used the external capsule and thence the inferior thalamic peduncle. Other temporal-thalamic projections included those to the medial pulvinar, via the temporopulvinar bundle, from the perirhinal and entorhinal cortices, and those to the paraventricular nucleus from the entorhinal cortex. By identifying these routes, it is possible to appreciate how different lesions might disconnect temporal-diencephalic pathways and so contribute to memory disorders.

Amidines↗
PubMed1998

Microstimulation of movements from cerebellar-receiving, but not pallidal-receiving areas of the macaque thalamus under ketamine anaesthesia.

The motor thalamic areas receiving input from the globus pallidus (VA) and the cerebellar nuclei (VL) appear to have different roles in the generation and guidance of movements. In order to further test these differences, we used electrical stimulation to map the ventro-anterior and ventro-lateral nuclei of the thalamus in three ketamine anaesthetised monkeys. Movements were readily evoked from VL at currents of down to 10 microA. The movements were typically multijoint, and stimulation could evoke arm and trunk or arm and facial movement at the same current threshold. Evoked arm movements often involved multiple joints, with or without finger movements. Facial movements included the lips, tongue, jaw, eyebrows and, occasionally, the eyes. The thalamic map was topographic, but complex with at least two separate regions related to arm movement. Very few sites within the VA could stimulate movement, even at high currents. We therefore suggest that the cerebellar projections to motor regions of the cortex, which pass through the VL thalamic nuclei, have a different relationship and are closer to movement execution than the projections from basal ganglia via the ventro-anterior nucleus.

Anesthetics, Dissociative↗
PubMed1999

Relationships between thalamostriatal neurons and pedunculopontine projections to the thalamus: a neuroanatomical tract-tracing study in the rat.

The present study aimed to investigate whether the pedunculopontine projection to the thalamus overlaps with identified thalamostriatal neurons. These projections were studied using a dual tract-tracing procedure combining anterogradely transported biotinylated dextran amine (pedunculopontine projections) and retrogradely transported Fluoro-Gold (thalamostriatal projections). Overlapping thalamic territories between thalamostriatal neurons and the axon terminals arising from the pedunculopontine tegmental nucleus were observed in the midline (paraventricular) and in the intralaminar (centrolateral, central medial, paracentral and parafascicular) thalamic nuclei. Other thalamic nuclei, such as the ethmoid, intermediodorsal, mediodorsal, paratenial, posteromedian, ventromedian, ventrolateral and rhomboid thalamic nuclei, displayed a lesser degree of overlap. These observations suggest the existence of presumptive contacts between thalamostriatal neurons and axons emerging from the pedunculopontine tegmental nucleus, therefore supporting the possible existence of feedback circuits in the rat basal ganglia in which the tegmento-thalamic projection would play a major role.

Animals↗
PubMed1996

Progressive supranuclear palsy with asymmetric lesions in the thalamus and cerebellum, with special reference to the unilateral predominance of many torpedoes.

This report concerns a notable case of progressive supranuclear palsy exhibiting asymmetric dentate nucleus and thalamic degeneration with numerous torpedoes. The neuronal loss in the ventral lateral nucleus of the thalamus was predominant on the right side, while in the cerebellum, a quantitative study revealed the contralateral predominance of the neuronal loss in the dentate nuclei and torpedo formation, with preserved Purkinje cells. The abnormal tau-protein-related profiles in the two nuclei did not show any laterality in their distribution, indicating that the dentatothalamic tract may have been affected in a non-specific way in this case. In addition, the fact that the prominent sites of torpedo formation and loss of dentate nucleus neurons are identical supports the hypothesis that the torpedoes may be formed in association with neuronal loss in the dentate nucleus because of a plausible metabolic change in Purkinje cells through synaptic detachment of their axon terminals.

Aged↗