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 181 records · Page 10Linked to original sources
PubMed1981

Projections of the cerebellar and dorsal column nuclei upon the thalamus of the rhesus monkey.

Projections from the cerebellar and dorsal column nuclei to the midbrain and thalamus of the rhesus monkey were traced with anterograde autoradiographic techniques, or, in a few cases, with the Fink-Heimer method. The cerebellar nuclei give rise to a massive projection to the contralateral midbrain and thalamus via the ascending limb of the superior cerebellar peduncle. Cerebellar efferent fibers terminate contralaterally in both divisions of the red nucleus, and bilaterally in the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the oculomotor nucleus, and the central gray. All the deep cerebellar nuclei project upon a broad area of the contralateral ventral thalamus as well as certain intralaminar nuclei. Corresponding ipsilateral thalamic terminations are sparse. The topographic organization of cerebellothalamic fibers does not correspond to individual cerebellar nuclei or to cytoarchitectonic divisions of the ventral thalamic nuclei. Rather there are longitudinally oriented strips of terminal labeling which extend through all divisions of the ventral lateral nucleus, i.e., the VLps, the VLc, the VLo, as well as nucleus X, the oral division of the ventral posterolateral nucleus (VPLo), the central lateral nucleus (CL), and the most caudal region of the ventral anterior nucleus (VA). The topography of the cerebellothalamic fibers is arranged in a mediolateral pattern with fibers originating from anterior zones of the dentate and interpositus ending most laterally and those from posterior dentate and interpositus terminating most medially. The fastigial contribution is relatively sparse. The longitudinal strips of terminal labeling in the ventral thalamic nuclei are made up of still smaller terminal units consisting of disk-like aggregates of silver grains separated from one another by grain-free spaces. The dorsal column nuclei terminate primarily in the contralateral caudal division of the VPL (VPLc) and never extend rostrally into VPLo. These results demonstrate a segregation of cerebellar and dorsal columnar inputs to motor and sensory regions of the thalamus, respectively. Since these regions are separate and discrete in their cortical associations as well (Kalil, '76), it seems unlikely that fast afferent pathways relaying to motor cortex (Lemon and Porter, '76) could arise from the dorsal column nuclei.

Afferent Pathways↗
PubMed1987

Choline acetyltransferase immunoreactivity in the rat thalamus.

The distribution of choline acetyltransferase immunoreactivity in the rat thalamus was investigated by using a specific monoclonal antibody and was compared with the pattern of acetylcholinesterase staining. The only choline acetyltransferase-immunoreactive cell bodies in the thalamus were in the medial habenula. A wide range of densities of immunoreactive fibers and varicosities was found. The highest densities of stained varicosities were in the anteroventral, reticular, lateral mediodorsal, and intralaminar nuclei. At the other extreme, the anterodorsal, ventroposteromedial, and paraventricular nuclei were almost devoid of immunoreactive varicosities. A light density of fibers was observed in several medial nuclei, including parataenial, reuniens, and gelatinosus. Most other nuclei contained moderately dense regions of varicose fibers that were often heterogeneous or patchy. The pattern of choline acetyltransferase immunoreactivity in the thalamus was in general similar to that of acetylcholinesterase. A marked discrepancy, however, was found in the anterodorsal nucleus, which was intensely stained for acetylcholinesterase but contained no apparent choline acetyltransferase immunoreactivity. Numerous physiologic studies have demonstrated striking effects of acetylcholine on thalamic activity. The present study provides a description of choline acetyltransferase-immunoreactive structures in the thalamic nuclei, providing a first step toward elucidating the anatomical basis for the physiologic and functional importance of cholinergic transmission in the thalamus.

Acetylcholinesterase↗
PubMed1988

Distribution of cells projecting to thalamus vs. those projecting to cerebellum in subdivisions of the dorsal column nuclei in raccoons.

To learn the distribution of cells projecting to the thalamus, as opposed to the cerebellum, in the mechanosensory nuclei of the dorsal medulla of raccoons, we analyzed the retrograde transport of horseradish peroxidase from the ventrobasal complex of the thalamus and from the cerebellum. We found six nuclear regions projecting heavily to the thalamus with very small projections to the cerebellum: Bischoff's, central cuneate, central gracile, rostral cuneate, rostral gracile nuclei, and cell group z. Two regions showed heavy projections to the cerebellum with no projections to the thalamus: the lateral portion of the external cuneate nucleus and the compact portion of cell group x. Four regions showed more equivalent projections to both target regions: basal cuneate, medial portion of the external cuneate nucleus, medial tongue extension of the external cuneate nucleus, and reticular portion of cell group x. Three more ventral regions were labeled: lateral cervical nucleus from thalamic injections but not from cerebellar injections; central cervical nucleus from cerebellar injections, which crossed the midline, but not from thalamic injections; and lateral reticular nucleus from both target regions. In most medullary regions, most cells project to one target and very few project to the other; we suggest that the cells projecting to the minor target convey samples of the information going to the major target.

Animals↗
PubMed1988

Topologic and connectional analysis of the dorsal thalamus of Triturus alpestris (amphibia, urodela, salamandridae).

A morphological and connectional analysis was performed on the dorsal thalamus of the alpine newt, Triturus alpestris. We have used a graphic reconstruction technique for the evaluation of the connectional (HRP) data. On the basis of these reconstructions, we propose a subdivision of the salamandrid dorsal thalamus into subhabenular, anteroventral, and posterodorsal zones. Each of these zones is defined by its telencephalic projections ("ascending thalamofugal systems"). The posterodorsal zone projects to the striatum, the anteroventral zone to the pallium. The subhabenular zone projects to the subpallial telencephalon and to the tegmentum. This zonal subdivision allows a more detailed comparison of the salamandrid dorsal thalamic features with ranid dorsal thalamic structures. We compare our dorsal thalamic zones to the ones proposed by Herrick (J. Comp. Neurol. 62:239-261, '35, The Brain of the Tiger Salamander. Chicago: The University of Chicago Press, '48). Furthermore, using the same reconstructive technique, we undertook an analysis of the spatial relations of various inputs to the salamandrid dorsal thalamus ("thalamopetal systems"). Besides the well-known retinal inputs, we identified the tectum and the tegmentum as sources of inputs to the thalamus. We provide evidence that there is no extensive multi- or unimodal overlap of these thalamopetal systems.

Afferent Pathways↗
PubMed1988

Fetal homotypic transplant in the excitotoxically neuron-depleted thalamus: light microscopy.

One month after an in situ injection of kainic acid into the ventrobasal thalamic complex (VB), the lesioned area is totally depleted of neurons. The present study has been undertaken to determine the cytoarchitecture and connectivity of the nucleus constructed by fetal thalamic neurons implanted into the excitotoxically lesioned area. Adult rats received an injection of kainic acid inducing a total neuronal depletion of the right lateral thalamus (including both the nucleus reticularis thalami and the lateral portion of the ventrobasal complex). One month later, homotypic neurons were taken from the dorsal thalamic primordium of rat embryos (gestational age 15-16 days), dissociated, and injected into the lesioned area as a cell suspension. After 2-4-month survival, the cytoarchitecture of the neonucleus formed by the grafted neurons within the previously neuron-depleted area was analyzed. Additionally, connectivity was analyzed in seven rats in which dorsal column nuclei and/or cortical projections to the area were labeled anterogradely with either 3H-leucine or wheat-germ agglutinin conjugated to HRP, and the animals were perfused and processed following various histological procedures (Nissl staining, autoradiographic processing, and histochemistry for visualization of peroxidase). Fetal neurons grew, differentiated, and progressively occupied the previously neuron-depleted area of the adult host CNS. They organized themselves into a neonucleus with particular cytoarchitectural features including 1) the existence of two concentric zones--a central zone containing neurons and glial cells and a marginal zone only filled with a band of glial cells, 2) an increase in cellular density compared to the intact thalamus, 3) the grouping of neurons in spherical clusters, and 4) apparent polymorphism of neuronal somata. Lemniscal and corticothalamic afferents originating from the host were observed in the neonucleus when the fetal neurons had been implanted correctly into the lesioned area but not when they had been misplaced into either normal thalamic tissue or the internal capsule. The afferents labeled from either the dorsal column nuclei or the somatosensory cortex were, however, less dense in the neonucleus than in the normal thalamus. These results are discussed with regard to the normal cytoarchitecture and connectivity of the ventrobasal complex of the rat thalamus.

Animals↗
PubMed1992

Organization of parabrachial nucleus efferents to the thalamus and amygdala in the golden hamster.

While gustation in the hamster has been extensively studied at the behavioral and physiological level, very little is known about the central anatomy of the taste system. The purpose of this study was to trace the connections of the parabrachial nucleus (PBN) in the golden Syrian hamster (Mesocricetus auratus) using wheat germ agglutinin-conjugated horseradish peroxidase. The PBN is the site of the second central synapse for the ascending gustatory system and receives taste afferents from the nucleus of the solitary tract. Following large injections into the PBN, anterogradely transported label was seen in the lateral hypothalamus, dorsal thalamus, bed nucleus of the stria terminalis, and amygdala. The anatomy of the two primary targets, the ventral posteromedial thalamus and central nucleus of the amygdala, is described based on Nissl-stained material, and acetylcholinesterase and NADH dehydrogenase histochemistry. Injections into these two regions revealed different patterns of efferents within the PBN. Following injections into the thalamus, retrogradely labelled cell bodies were distributed throughout the PBN subdivisions bilaterally, but concentrated in the central medial (CM) and external lateral (EL) subdivisions. Following injections into the amygdala, retrogradely labelled cell bodies were primarily in the ipsilateral PBN EL, while anterogradely transported label was distributed throughout much of the ipsilateral PBN. The majority of CM efferents projecting to the thalamus were elongate cells, whereas the majority of CM efferents to the amygdala were round-oval cells. These results indicate that the ascending central gustatory system changes from a serial pathway (nucleus of the solitary tract-PBN) to a parallel organization consisting of two major projections, the parabrachio-thalamo-cortical and parabrachio-amygdaloid pathways.

Acetylcholinesterase↗
PubMed1994

Projections from the lateral and interposed cerebellar nuclei to the thalamus of the rat: a light and electron microscopic study using single and double anterograde labelling.

The lateral and interposed cerebellar nuclei may have different functions in the control of movement. Efferent fibres from both nuclei project predominantly to areas of the thalamus, which in turn project to the motor cortex. In this study, single and double anterograde-tracing techniques have been used to examine and compare the pathways from the lateral and interposed nuclei to the thalamus in the rat by using both light and electron microscopy to look for evidence of organisational or structural features that may underlie the proposed functional differences between these nuclei. Terminals from the lateral nucleus were found to be located most medially in the thalamus, predominantly in the ventral lateral nucleus and the rostral pole of the posterior nuclear group. Terminals from the posterior interposed nucleus were located slightly rostral and lateral to those from the lateral nucleus, mainly around the border between the ventral lateral nucleus and the ventral posterior medial nucleus. Terminals from the anterior interposed nucleus were located slightly rostral and lateral to those from the posterior interposed nucleus, predominantly in the rostral pole of the ventral posterior lateral nucleus. Terminals from the lateral and interposed nuclei were also found in double anterograde-tracing experiments to be nonoverlapping in the regions between these main areas of termination. The structure of terminals from the lateral and interposed nuclei, however, as well as their synaptic relationship with thalamic neurones, were found to be similar. The terminals are large and form synapses with proximal dendrites of thalamic neurones. They contained round vesicles and formed multiple synaptic contacts with dendritic shafts, as well as dendritic spines. The findings indicate that information from the lateral and interposed nuclei is processed in separate regions of the thalamus but that the mode of synaptic transfer to thalamic neurones is likely to be similar for the two projections.

Animals↗
PubMed2006

MRI study of thalamus volumes in juvenile patients with bipolar disorder.

In vivo imaging studies suggest functional abnormalities of the thalamus in adult patients with bipolar disorder, but the presence of anatomical abnormalities is controversial. Our objective in this study was to compare the thalamus volumes of children and adolescents with bipolar disorder versus healthy controls to determine whether any morphological abnormalities exist early in illness course. We studied 16 patients with bipolar disorder according to DSM-IV criteria (mean age+/-SD=15.5+/-3.4 years) and 21 healthy control subjects (mean age+/-SD=16.9+/-3.8 years). Blinded examiners measured thalamic gray matter volumes with a semiautomated technique. Analysis of covariance, with age, gender, and intracranial brain volume as covariates, revealed no significant differences in left and right thalamic volumes between patients with bipolar disorder and healthy controls. Our findings indicate there are no significant differences in thalamus size between children and adolescents with bipolar disorder and healthy comparison subjects, in contrast to available findings for schizophrenia and first-break psychosis. Any differences in thalamus size that may exist between patients with bipolar disorder and healthy controls must amount to small effect sizes.

Adolescent↗
PubMed1997

Modification of gonadotropin releasing hormone (GnRH) mRNA expression in the retinal-recipient Thalamus.

Although the environmental cues that trigger reproductive behaviors are known for many species, the mechanisms through which these signals influence the neurochemistry of the brain to produce behavior have been elusive. In this study, we describe a retinally modulated system of gonadotropin releasing hormone (GnRH) producing neurons in the thalamus of the plainfin midshipman fish, Porichthys notatus. Previously, we cloned and sequenced the cDNA for prepro-GnRH in midshipman. Here, using in situ hybridization, we localized prepro-GnRH mRNA to the ventrolateral nucleus of the thalamus, three divisions of the preoptic area, the ganglion of the terminal nerve, and the olfactory bulb. Since the thalamus, terminal nerve ganglion, and preoptic area have been associated with visual functions, we investigated the retinal connections in midshipman. In particular, biocytin tract tracing delineated a reciprocal connection between the ventrolateral nucleus of the thalamus and the retina. Retinofugal projections are exclusively contralateral. Experimental manipulation of this retinalthalamic loop through complete optic nerve transection shows that GnRH mRNA expression in the contralateral ventrolateral nucleus may be influenced by the retina. We hypothesize that a reciprocal retinothalamic GnRH circuit is important in modulating the expression of seasonal reproductive behaviors.

Animals↗
PubMed2002

Regional changes in human cerebral blood flow during dipyridamole stress: neural activation in the thalamus and prefrontal cortex.

Intravenous dipyridamole increases the concentration of circulating adenosine and produces coronary vasodilation. However, it decreases global cerebral blood flow (CBF) due to hyperventilation side effect of adenosine. In the present study, changes in regional CBF during dipyridamole stress were identified in detail. In 11 healthy men (51-71 years of age), CBF was measured by positron emission tomography with oxygen-15-labeled water at rest (baseline) and during dipyridamole stress. All images were normalized to global CBF and transformed to standard brain anatomy. A t map between baseline and dipyridamole stress conditions was then created on a pixel-by-pixel basis. CBF was globally decreased during dipyridamole stress. However, a significant relative increase in CBF was observed bilaterally in the thalamus and prefrontal cortex, indicating neural activation in these regions. Adenosine plays an important role in the production of anginal pain by stimulation of A(1) adenosine receptors. Neural activation in the thalamus and prefrontal cortex during angina pectoris has been reported. Although no subject felt chest pain during dipyridamole stress, neural activation in the thalamus and prefrontal cortex indicates that stimulation of A(1) adenosine receptors during dipyridamole stress may produce input from the heart to the thalamus through the vagal fiber.

Blood Pressure↗
PubMed1992

Widely distributed GABA-mediated afferent inhibition processes within the ventrobasal thalamus of rat and their possible relevance to pathological pain states and somatotopic plasticity.

We have recently described extensive inhibitory interactions between inputs to the ventroposterolateral (VPL) (Roberts and Wells 1990, 1991) and ventroposteromedial (VPM) (Salt 1989) portions of the ventrobasal nucleus of the thalamus (VB). We wished to determine whether (i) the inhibition observed in the VPL was operating at the thalamic level, (ii) was dependent on GABA receptors, (iii) was demonstrable on neurons of the ventro-posteromedial nucleus of the thalamus (VPM) and (iv) was operant on test responses evoked by natural stimuli. Conditioning stimulation of sciatic nerve afferents caused inhibition of air jet evoked test responses of single VB neurons in urethane-anaesthetized rats. Both VPM and VPL neurons were subject to inhibition by conditioning stimulation of hindlimb afferents, indicating the wide-spread nature of the inhibitory process. This inhibition was reduced by the iontophoretic application of SR95531, a GABAA receptor antagonist. We conclude that there is a widely distributed inhibitory system operating in the somatic thalamus which involves both the medial and lateral portions of the nucleus and is, at least in part, mediated by GABAA receptors. The possible involvement of inhibitory processes and intrinsic membrane properties of thalamic neurones in the somatotopic plasticity of the sensory thalamus following deafferentation and in deafferentation pain is discussed.

Animals↗
PubMed1990

Movement induced modulation of afferent transmission to single neurons in the ventroposterior thalamus and somatosensory cortex in rat.

Single neurons were simultaneously recorded in the forepaw areas of the primary somatosensory (SI) cortex and ventroposterolateral (VPL) thalamus of awake rats during rest and running behaviors. Movement dependent changes in somatic sensory transmission were tested by generating post-stimulus histograms of these neurons' responses to stimulation through electrodes chronically implanted under the skin of the forepaw, while the animal ran on a timed treadmill. As viewed in post-paw-stimulus histograms, the evoked unit responses (EURs) could be differentiated into short (4.5 +/- 0.1-10.9 +/- 0.2 ms) and longer (12.9 +/- 0.4-31.3 +/- 0.9 ms) latency components ("SEURs" and "LEURs", respectively). The magnitudes of firing during these responses were measured and normalized as percent increases over background firing. By comparison with resting behavior, treadmill movement suppressed both SEURs and LEURs in the thalamus, as well as the cortex. The SEURs, however, were much more strongly suppressed in the SI cortex (-48.3 +/- 2.7%) than in the VPL thalamus (-28.1 +/- 6.7%). By contrast, similar magnitudes of suppression of LEURs were found in the SI (-25.8 +/- 8.6%) and VPL (-26.5 +/- 11.1%). These results suggest that the suppression of LEURs observed in the SI cortex may result from modulatory actions on subcortical circuits. Major suppression of SEURs, on the other hand, may occur intracortically, with a minor component occurring subcortically. Thus, VPL thalamus and SI cortex in the rat appear to be differentially subject to movement related modulation of sensory transmission.

Animals↗
PubMed2002

MRI of secondary changes in the thalamus following a cerebral infarct.

We investigated acute secondary degeneration in the thalamus following a cerebral infarct in 21 patients with an infarct in the territory of the middle cerebral artery, using serial MRI at various time after the stroke. Secondary degeneration in the ventral nuclei of the thalamus was seen as regions of slightly low signal on proton-density and/or T2-weighted images, mostly obtained a few weeks after the onset. An area of slightly high signal was observed in the dorsomedial nucleus of the thalamus on T2-weighted images about 6 weeks after the onset. Damage to the superior and anterior thalamic radiation caused degeneration in the ventral and dorsomedial nucleus, respectively. Thus, the time of detection and the abnormalities seen on MRI in secondary degeneration vary depending upon which area of the thalamus is involved. The mechanism underlying the degeneration is therefore also likely to differ in these areas.

Aged↗
PubMed2004

Novel vistas of calcium-mediated signalling in the thalamus.

Traditionally, the role of calcium ions (Ca(2+)) in thalamic neurons has been viewed as that of electrical charge carriers. Recent experimental findings in thalamic cells have only begun to unravel a highly complex Ca(2+) signalling network that exploits extra- and intracellular Ca(2+) sources. In thalamocortical relay neurons, interactions between T-type Ca(2+) channel activation, Ca(2+)-dependent regulation of adenylyl cyclase activity and the hyperpolarization-activated cation current ( I(h)) regulate oscillatory burst firing during periods of sleep and generalized epilepsy, while a functional triad between Ca(2+) influx through high-voltage-activated (most likely L-type) Ca(2+) channels, Ca(2+)-induced Ca(2+) release via ryanodine receptors (RyRs) and a repolarizing mechanism (possibly via K(+) channels of the BK(Ca) type) supports tonic spike firing as required during wakefulness. The mechanisms seem to be located mostly at dendritic and somatic sites, respectively. One functional compartment involving local GABAergic interneurons in certain thalamic relay nuclei is the glomerulus, in which the dendritic release of GABA is regulated by Ca(2+) influx via canonical transient receptor potential channels (TRPC), thereby presumably enabling transmitters of extrathalamic input systems that are coupled to phospholipase C (PLC)-activating receptors to control feed-forward inhibition in the thalamus. Functional interplay between T-type Ca(2+) channels in dendrites and the A-type K(+) current controls burst firing, contributing to the range of oscillatory activity observed in these interneurons. GABAergic neurons in the reticular thalamic (RT) nucleus recruit a specific set of Ca(2+)-dependent mechanisms for the generation of rhythmic burst firing, of which a particular T-type Ca(2+) channel in the dendritic membrane, the Ca(2+)-dependent activation of non-specific cation channels ( I(CAN)) and of K(+) channels (SK(Ca) type) are key players. Glial Ca(2+) signalling in the thalamus appears to be a basic mechanism of the dynamic and integrated exchange of information between glial cells and neurons. The conclusion from these observations is that a localized calcium signalling network exists in all neuronal and probably also glial cell types in the thalamus and that this network is dedicated to the precise regulation of the functional mode of the thalamus during various behavioural states.

Animals↗
PubMed2006

Neurochemical changes in brain induced by chronic morphine treatment: NMR studies in thalamus and somatosensory cortex of rats.

To investigate the effects of chronic morphine treatment and its cessation on thalamus and the somatosensory cortex, an ex vivo high resolution (500 MHz) (1)H nuclear magnetic resonance spectroscopy (NMRS), in the present study, was applied to detect multiple alterations of neurochemicals and/or neurometabolites in the rats. Ten days of chronic morphine administration was observed to markedly increase the total amount of lactate (Lac), myo-inositol (my-Ins) (each P < 0.01) and aspartate (Asp) (P < 0.05), and significantly decrease that of glutamate (Glu) and glutamine (Gln) in the rats thalamus (each P < 0.05). In the somatosensory cortex, chronic morphine was shown to increase the level of Lac and my-Ins, and decrease that of Glu (each P < 0.05). Interestingly, the ratio of Glu/GABA was found to decrease in these two brain areas after chronic morphine treatment, and among the detectable neurochemicals in those two cerebral areas, only taurine (Tau) showed to result in a significant increment in thalamus during the process of morphine discontinuation (P < 0.05). Moreover, the alterations of multiple neurochemicals due to chronic morphine exhibited a tendency of recovery to the normal level over the course of morphine withdrawal. The results suggested that, in thalamus and the somatosensory cortex, chronic morphine administration and its cessation could induce multiple neurochemical changes, which may involve in the brain energy metabolism, activity and transition of neurotransmitters.

Animals↗
PubMed1988

Distribution and binding parameters of GABA and benzodiazepine receptors in the cat motor thalamus and adjacent nuclear groups.

Quantitative receptor binding autoradiography technique was utilized to study GABA and benzodiazepine receptors in the cat motor thalamus (ventral anterior, ventral medial and ventral lateral nuclei) and adjacent thalamic subdivisions. Binding parameters (Bmax and Kd) and distribution pattern of the binding sites for 3 tritiated ligands [3H]muscimol ([3H]MUS), [3H]flunitrazepam ([3H]FLU) and [3H]baclofen ([3H]BAC) were analyzed and compared using measurements from discrete and anatomically well-defined thalamic regions. There was little correlation in the regional distribution of the 3 binding sites. The concentration of [3H]BAC binding sites in thalamic nuclei of interest was very low, practically at the limit of resolution of the quantitative autoradiographic technique; whereas appreciable quantities of [3H]MUS and [3H]FLU binding sites were present in the motor and adjacent limbic nuclei of the thalamus. There was more difference between the nuclei in regard to the number of high affinity GABA receptors than benzodiazepine receptors. Moreover, the ratio of Bmax[3H]MUS/Bmax[3H]FLU varied from 2.2 to 4.4 in different thalamic regions suggesting the presence of a diverse population of GABAA and benzodiazepine receptors. The distribution pattern of the 3 binding sites was compared to the topography of GABAergic afferents of the basal ganglia origin and the frequency of GABAergic synapses formed by thalamic local circuit neurons (LCN) in the motor thalamus that were established earlier. It was concluded that in the cat motor thalamus: (1) none of the ligands studied appear to reveal the receptors associated with nigro- or pallidothalamic synapses; (2) [3H]MUS binding sites may be associated with the dendrodendritic contacts formed by LCN; and (3) the [3H]FLU binding sites are physically unrelated to [3H]MUS binding sites. The concentration of [3H]FLU and [3H]MUS binding sites in the midline nuclei and of [3H]MUS binding sites in the limbic nuclei was remarkably high. It was concluded that in addition to previously suggested limbic structures, the midline nuclei with their very high content of benzodiazepine receptors may be considered as a neuroanatomical substrate of certain forms of anxiety.

Animals↗
PubMed1989

Tongue-muscle-controlling motoneurons in the Japanese toad: neural inputs from the thalamus.

The anuran tongue is an effector organ specialized for snapping up prey during visually guided prey-catching behavior. As a step toward elucidating the control mechanisms of the tongue movement and overall organization of visually guided behavior, properties of neural inputs from the thalamus (of which electrical stimulation elicited a behavior very similar to the visually guided predator-avoidance behavior under freely behaving conditions) were investigated in paralyzed Japanese toads. Tongue-muscle-controlling motoneurons (tongue-protractor motoneurons (PMNs) and tongue-retractor motoneurons (RMNs)) were identified antidromically, and synaptic inputs in response to electrical stimuli applied to various points in the thalamus (mainly the posterocentral thalamic nucleus) were examined. Hyperpolarizing potentials were evoked in both PMNs and RMNs in response to single electrical stimuli applied to the thalamus contralateral or ipsilateral to the recording side. Since these potentials reversed to depolarizing ones after injecting Cl- ions into the cell interior, these hyperpolarizing potentials were concluded to be the usual fast type of inhibitory postsynaptic potentials (IPSPs). On the other hand, depolarizing potentials which were superimposed on the underlying IPSPs were evoked when repetitive electrical stimuli were applied to the thalamus. The amplitude of these depolarizing potentials was decreased when depolarizing currents were injected intracellularly, while it was increased when hyperpolarizing currents were injected, indicating that these depolarizing potentials are excitatory postsynaptic potentials (EPSPs).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

The anatomical evidence of recurrent axonal collaterals of the thalamus projecting neurons of the rostral pole of the trigeminal sensory nuclear complex in the rat.

Thalamus projecting neurons and their recurrent axonal collaterals were observed in the dorsomedial part of the trigeminal principal sensory nucleus (Vpdm) and the caudolateral part of supratrigeminal nucleus (Vsup CL) after injection of horseradish peroxidase (HRP) into the contralateral ventrobasal complex of the thalamus (VBm) by using the HRP retrogradely tracing-Golgi-like staining method. About 7% (8/120) parent axons of the labeled cells gave rise to recurrent axon collaterals. However, no retrogradely labeled cells were observed in the VBm after injection of HRP into the Vpdm and Vsup CL. In an electron microscopic study, the terminals of recurrent axon collaterals made synapses with the dendrites of the thalamus projecting neurons or non-labeled neurons in the neuropil of the Vpdm and Vsup CL. It is suggested that the recurrent axon collaterals might play a role of negative feedback in transmission of the proprioceptive message from the jaw-closing muscle spindles to the thalamus.

Animals↗