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At least 1,351 records · Page 75Linked to original sources
PubMed1992

Habenula and thalamus cell transplants mediate different specific patterns of innervation in the interpeduncular nucleus.

Innervation of specific peptidergic and cholinergic compartments of the interpeduncular nucleus (IPN) was investigated using embryonic cell suspension transplants immunoreactive for substance P (SP) and ChAT. In both neonatal and adult host rats, the IPN was first denervated of its normal SP and cholinergic input from the medial habenula by bilateral lesions of the fasciculi retroflexi (FR). In adult hosts, transplants of embryonic habenular cells placed near the denervated IPN mediated a return of the normal pattern of SP staining restricted to habenula-target subnuclei, plus an increase in staining intensity of SP cells intrinsic to the IPN. There was no recovery of ChAT staining. A similar pattern of SP staining resulted following habenular transplants into neonatal hosts, but in addition there was a partial recovery of normal ChAT staining in cholinergic subnuclei and anomalous ChAT staining in normally peptidergic subnuclei. Control transplants of embryonic thalamus cells placed into adult hosts produced a surprising pattern of ChAT staining in the IPN identical to that seen with habenula transplants placed into neonatal hosts; the adult IPN was thus able to support reinnervation mediated by an aberrant cholinergic source while being refractory to its normal habenular cholinergic afferents. This pattern of results implies regulation by the IPN of habenular SP and cholinergic innervation, and some interaction between the maturing normal cholinergic afferents and their targets that is missing when these afferent sources are abnormal.

Animals↗
PubMedDate not supplied

[The microsurgical treatment of arteriovenous malformations of the thalamus].

The article analyzes the clinical data of 48 patients with arteriovenous malformations of the thalamus, who were examined at the Burdenko Institute of Neurosurgery, AMS USSR, from 1970 to 1989. The experience in surgical treatment is based on 25 cases. The authors describe in detail the indications for surgical treatment, adequate surgical approaches, and the method for removal of the malformations. Neuropsychological and electrophysiological methods of examination of patients in dynamics were applied to evaluate the results of surgery.

Cerebral Angiography↗
PubMed1991

Nerve cell loss in the thalamus in Alzheimer's disease and Parkinson's disease.

Serial sections through the thalamus from the fixed right cerebral hemispheres of 15 cases (5 Parkinson's disease, 5 Alzheimer's disease (AD) and 5 controls) were used to obtain quantitative estimates of neuronal loss, neurofibrillary tangle formation and Lewy body inclusions within individual thalamic nuclei. Severe neuronal loss and tangle formation were evident in the anterodorsal nucleus from the AD cases. Nerve cell damage was also present in the centromedian nucleus but was not associated with tangle formation and occurred in all but 2 of the brains examined. It is likely that the anterodorsal neurons are damaged locally by the Alzheimer's disease process whereas the changes in the centromedian nucleus may be related to ageing.

Aged↗
PubMed1990

The development of the diencephalon of the rainbow trout (Salmo gairdneri Richardson). Thalamus and hypothalamus.

This article describes a study of the development of the thalamus and hypothalamus of the rainbow trout from the embryo to the juvenile fish. The areas from which the various nuclei derived are reported together with the order of their appearance, the earliest being the nucleus geniculatus lateralis, the nucleus pretectalis, the nucleus of the torus lateralis hypothalami, the nucleus preglomerulosus and the nucleus diffusus of the lateral lobes, all of were beginning to be distinguishable in 9 mm embryos. The lateral lobes of the hypothalamus developed mainly after hatching, and medial regions generally developed later than lateral areas, though certain periventricular structures appeared very soon. Cell proliferation persisted in 35 mm juveniles, especially in the walls of the lateral and posterior recesses.

Animals↗
PubMed1978

Relations between the pulvinar-lateralis posterior complex of the thalamus and the hippocampus in wakefulness and sleep in cats.

Paucisynaptic connections between n. lateralis posterior (LP) and dorsal hippocampus (Hip) have been demonstrated in acute experiments. In the free moving cats, with chronic implanted electrodes on the neocortex, in LP, pulvinar (Pul), VA and VL nuclei of the thalamus and in the dorsal hippocampus (Hip), the theta waves recorded in LP, Pul and Hip were not of the same frequency and origin. In wakefulness and in slow-wave sleep, the theta waves were of 3.5-4 c/s and occurred exclusively or predominantly in Pul-LP, while in paradoxical sleep they were of 5-6 c/s, occurred' in Hip and invaded the Pul-LP. These two types of theta waves represent two distinct modalities of their organization and reflect the involvement of different mechanisms in the different phases of sleep.

Animals↗
PubMed1990

[Experimental study on the difference of ischemic threshold between cerebral cortex and thalamus with middle latency auditory evoked potentials].

Middle latency auditory evoked potentials (ML-AEPs) have not yet been established as a device of assessing neurological events because their origins have not been definitely identified. In this study, we assessed the neurological usefulness of MLA-EPs through experimental approach using canine models of acute ischemia localized within the cerebral cortex or thalamus. Two types of localized cerebral ischemia were produced in mongrel dogs by clipping of major cerebral arteries and inducing of hypotension; they were, unilateral cortical ischemia involving the right primary auditory area (group A) and unilateral thalamic ischemia involving the right medial geniculate body (group B). Using these two ischemia models, auditory evoked potentials (AEPs) were intracranially and extracranially recorded in addition to the measurement of local cerebral blood flow (1-CBF). Prior to the induction of ischemia, it was confirmed that positive waves with a latency of 20 ms (P20) were evoked in the bilateral primary auditory areas by sound stimulation (90 dB 5 Hz click) given to the ear contralateral to the planned ischemic side in both groups. The right P20 disappeared when the 1-CBF in the right primary auditory area decreased below the ischemic flow threshold of synaptic transmission failure, approximately 18 ml/100 g/min, in group A, and when the 1-CBF in the right medial geniculate body decreased below the threshold, 10 ml/100 g/min, in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Unilateral cavernous angioma of the thalamus disclosed by transitional disorders in the upward gaze].

We describe a case of a cavernous angioma of the right thalamus, identified by MRI, showing transient vertical diplopia in the upward gaze, present only in protracted recumbency. We consider possible pathogenetic mechanisms in an attempt to explain this peculiar disturbances. In addition we emphasize that MRI is the most sensitive procedure for detection of the cavernous angioma.

Adult↗
PubMed1990

[A comparison of the functional vulnerability of the cerebral cortex and thalamus to acute ischemia].

Using cerebral cortical and thalamic ischemia models produced in mongrel dogs, the reversibility of short-latency somatosensory-evoked potentials (SSEPs) and the effects of ischemic brain edema on reversibility were compared. The mean systemic blood pressure (MSBP) of animals was reduced by exsanguination until cortical SSEPs disappeared, and was held constant at that level. The MSBP was recovered by autogenous blood transfusion at 30 minutes (subgroup A), 60 minutes (subgroup B) and 90 minutes (subgroup C) after SSEP disappearance in the cortical ischemia group; and at 15 minutes (subgroup D) and 30 minutes (subgroup E) after SSEP disappearance in the thalamic ischemia group. Local cerebral blood flows (lCBF) were measured and SSEPs were monitored serially up to 2 hours after blood transfusion. At the end of measurement, the leakage of Evans blue was evaluated and brain tissue water content was measured. Cortical SSEPs disappeared when lCBF in the right cerebral cortex, measured by hydrogen clearance method decreased to 18.4 +/- 5.4 ml/100 g/min (mean +/- SD) and neuronal transmission failure in thalamus occurred when thalamic blood flow decreased to 10.0 +/- 3.3 ml/100 g/min. After blood transfusion. SSEP reappeared in all 12 animals in subgroup A, but did not appear in 2 of 9 animals in subgroup B and in all of 7 animals in subgroup C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Distribution of the enkephalin neuron system in the rat thalamus; an immunohistochemical analysis].

Met-and Leu-enkephalin immunoreactive structures in the rat thalamus were investigated by indirect immunofluorescent method. Both structures showed similar distributions. Distribution: A large number of enkephalin-like immunoreactive (ENKI) terminals were observed in the antero-ventral nucleus (AV), the region between the parataenial nucleus, the antero-medial thalamic nucleus and ventral part of the ventral nucleus. ENKI cells were seen in the medial thalamic nucleus and ventral nucleus of the lateral geniculate body. Furthermore, ENKI cells are seen at the pars parvicellular of the posterior commissure and the lateral posterior thalamic nucleus detected only following pretreatment with colchicine. Fiber connection: The origin of ENKI terminals in the AV was examined by means of experimental manipulations. Injections of HRP (horseradish peroxidase) into the AV resulted in labeling of the MM (medial mammillary nucleus pars medialis) and MMC (medial mammillary nucleus pars centralis) but not the PM (premammillary nucleus). Destruction of the MM, where a number of ENKI neurons were seen, resulted in a disappearance of ENKI terminals in the ipsilateral AV. These findings suggest that MM is a major source of ENKI terminals in the AV.

Animals↗
PubMed1988

[Ultrastructural changes in the thalamus in chronic morphine intoxication and abstinence].

Electron microscopy was utilised to study the course of ultrastructure changes in Wistar rats' dorsomedial thalamus under the effect of chronic morphine intoxication (LD50 and increasing doses) and abstinence. Medial hypothalamic neurons proved highly vulnerable during dependence formation. Neurons, large dendrites and glia displayed various degrees of destruction increasing with the intoxication time. Synapses destruction paralleled the intoxication severity. In abstinence, the nerve tissue destructive processes were ousted by reparative ones. Small axon terminals emerged and large granular vesicles became hyperplastic under the adverse effect of morphinization and the morphine dependence formation.

Animals↗
PubMed1987

[Local blood flow in the optic thalamus and frontal lobe in conscious and anesthetized dogs].

Control values of local blood flow in the thalamus of alert dogs were 68.7 +/- 1.6 ml/100g/min and in their frontal cortex 84.8 +/- 2.9 ml/100 g/min. As a result of the hexenal anesthesia, the local blood flow decreased by 3 to 12 per cent of control values. The mild effect suggests that the anesthesia maintained with the 70% N2O is an acceptable procedure for studying the cerebral circulation.

Anesthesia↗
PubMed1986

Neuronal cilia in the embryonic thalamus and striatum of Gallotia galloti (Reptilia, Lacertidae).

Cilia are a common characteristic of the embryonic neurons of the thalamus and striated centers of Gallotia galloti from E.35. The ciliogenesis process occurs around the stages E.33 and E.34. The ciliary morphology shows no substantial variations between the different stages and the ciliary structure in the embryonic period is 8 + 1. On the other hand, the adult cilia has a 9 + 2 arrangement of microtubules. We do not rule out the possibility of other axonemes.

Animals↗
PubMed1986

Tooth pulp evoked potential in the thalamus of freely moving rats.

Eleven hooded rats with bipolar stimulating electrodes in the left upper incisor and recording electrodes in the ventral posteromedial (VPM), ventral dorsomedial (VDM) and paracentral (NPC) nuclei of the contralateral thalamus and the somatosensory cortex (SC) were investigated in different states of spontaneous behaviour. The early complex of the thalamic averaged tooth pulp evoked potentials (TPEP) consisted of two negative-positive waves, a small (N2, P4) and a larger one (N6, P14). Later components appeared with different peak times and amplitudes depending on the localization of the recording electrode. The single components of the thalamic TPEP decreased differently during behavioural activation between 20 and 80% with maximal expression during intensive grooming.

Animals↗
PubMed1986

[Role of the thalamus in subcortical aphasias].

27 cases of patients who presented language disorders of aphasic nature consecutive to a strictly subcortical lesion of vascular origin are reported. From a topographic point of view, the population is divided into 3 groups: thalamic lesions (15 cases), striatal lesions (9 cases), isolated lesions of the white matter (3 cases). The results of the neurolinguistic analysis of the aphasia show a great symptomatological variety. Nevertheless, in spite of this apparent diversity, certain semiologic elements appear to be common to all of the observed linguistic profiles, no matter where the lesion is: hypophonia, non fluent speech, verbal paraphasias, normal repetition, comprehension generally good. A discussion is proposed as to the specific part which certain structures, notably the thalamus, might play in the origin of these various disturbances.

Aphasia↗
PubMed1986

The somatosensory thalamus of the raccoon: properties of single neurons responsive to light mechanical stimulation of the forepaw.

These studies were undertaken to characterize the discharge properties of single neurons of the raccoon thalamic ventrobasal complex (VB) that respond to light mechanical stimulation of the glabrous surfaces of the forepaw. Microelectrodes were used to record the extracellular activity of 146 cells in anesthetized raccoons, and all neurons were histologically verified as falling within or along the boundaries of VB. Sixty-one neurons were tested for activation by electrical stimulaton of primarily somatosensory cortex. Of these, 88% were antidromically activated, 5% were synaptically activated, and the remaining 7% were unresponsive. Out of the total sample of 146 neurons, 136 had peripheral receptive fields (RFs) that were restricted to glabrous skin and revealed properties of modality and place-specificity predictable through knowledge of properties of primary mechanoreceptive afferents. Rapidly adapting (RA) neurons accounted for 77% of this modality-place-specific sample, while 19% were slowly adapting (SA), and 4% revealed properties indicative of input from Pacinian afferents (Pc). Absolute displacement thresholds were comparable for RA and SA neurons (range = 6-415 micron). Palmar RF areas (range = 3.3-328 mm2) were significantly larger than digital RF areas (range = 0.5-98.2 mm2). As defined by exponents (b) of power functions relating instantaneous discharge frequency to displacement ramp velocity, SA neurons formed a single, homogeneous group (range of values of b = 0.633-0.720). However, RA neurons fell into three distinct groups: those showing relatively steep functions (b = 0.559-0.938), those showing relatively flat functions (b = 0.146-0.334), and those showing discontinuous, or step, functions. A small number of neurons (7% of total sample) revealed "complex" properties, not predictable from knowledge of properties of primary afferents. These included five neurons whose RFs encompassed both glabrous and hairy skin, and several linear orientation, or "tactile edge," detectors. The present results, in conjunction with those of earlier studies of the raccoon dorsal column-medial lemniscal system, lead to the conclusion that different types of information transformation are emphasized at different levels of the system. Intramodality convergences (increases in RF area) occur primarily within the cuneothalamic relay, while changes in the coding of quantitative information are primarily a function of VB neurons. The appearance of linear orientation detectors--a type of tactile "feature detector"--indicates that the synthesis of information regarding complex spatial properties of stimuli has its beginnings within the somatosensory thalamus.

Animals↗
PubMed1979

Connections of the posterior thalamus with the amygdaloid body of the rat.

The thalamo-amygdaloid connections arising in the posterior thalamus were studied in the brains of rats by the Nauta-Gygax and Fink-Heimer methods. They begin mainly in the neurons of the supero-medial area of the posterior segment of the pulvinar and in the peripeduncular nucleus. The amygdalopetal fibers of this pathway pass through the zona incerta, cerebral peduncle, and the lateral hypothalamus. They end in the lateral nucleus and in the lateral part of the central nucleus of the amygdaloid body.

Amygdala↗
PubMed1979

Study of two cases of aphasia by infarction of the left thalamus, without cortical lesion.

Two patients suffering from a left thalamus infarct were studied over a long period. The precise location of the lesion has been demonstrated by the C.T. scan. In spite of the absence of any cortical lesion, both presented with aphasia and other neuropsychological disorders (left-right confusion, dyscalculia and possible finger agnosia). Their speech disorders although different, had several features in common. The observations were compared with the other cases reported in the literature.

Aged↗