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PubMed1975

[Ultrastructural characteristics of axon terminals of the posterior lateral nucleus of the thalamus in the cat].

Two kinds of axon terminals: fine M-terminals with the diameter up to 2 mkm and large K-terminals with the diameter up to 6 mkm were found in electron microscopic study of the posterior lateral nucleus of the cat's thalamus. M-terminals comprising 88% of the total amount of the axon terminations under analysis are characterized by a great amount of densely packed light round synaptic vesicles and solitary mitochondria. These terminals form asymmetrical type of contacts in which the post-synaptic network is distinguished with a high degree of osmiophilia. The K-terminals contain a few rarely distributed round light synaptic vesicles and many mitochondria which are disposed in the central part of the termination. These terminals form a symmetrical type of synaptic contacts with poorly pronounced active zones in these formations. In axo-axonal contacts between the described kinds of terminals the K-terminals always serve as a presynapse. After extirpation of the sincipital cortex M-terminals underwent degeneration.

Animals↗
PubMedDate not supplied

Proton magnetic resonance spectroscopy of the thalamus in patients with chronic neuropathic pain after spinal cord injury.

BACKGROUND AND PURPOSE: Spinal cord injury (SCI) results in a number of consequences; one of the most difficult to manage is chronic neuropathic pain. Thus, defining the potential neural and biochemical changes associated with chronic pain after SCI is important because this may lead to development of new treatment strategies. Prior studies have looked at the thalamus, because it is a major sensory relay station. The purpose of our study was to define alterations in metabolites due to injury-induced functional changes in thalamic nuclei by using single-voxel stimulated echo acquisition mode MR spectroscopy. METHODS: Twenty-six men were recruited: 16 patients with SCI and paraplegia (seven with pain, nine without pain) and 10 healthy control subjects. Pain was evaluated in an interview, which included the collection of information concerning the location, quality, and intensity of pain, carefully identifing the dysesthetic neuropathic pain often seen in SCI. Localized single-voxel (8-cm(3) volume) proton spectra were acquired from the left and right thalami. RESULTS: The concentration of N-acetyl (NA) was negatively correlated with pain intensity (r = -0.678), and the t test showed that NA was significantly different between patients with pain and patients without pain (P =.006). Myo-inositol was positively correlated with pain intensity (r = 0.520); difference between patients with pain and those without pain was almost significant (P =.06). CONCLUSION: The observed differences in metabolites in SCI patients with and pain and in those without pain suggest anatomic, functional, and biochemical changes in the thalamic region.

Adult↗
PubMedDate not supplied

[An analysis of the interaction of the parietal and visual regions of the cortex with the posterior lateral nucleus of the thalamus].

Cooling and ablation of the parietal associative (P) and primary visual projection (VI) areas in nembutalized cats revealed facilitating and inhibitory descending influences of the above areas on the postero-lateral nucleus (LP) of the ipsilateral thalamus where visual signals generate an early specific and a late unspecific components of heterogenous evoked responses. Unidirectional influences activating the early component and fully controlling the appearance and course of the late component are more manifest in P which is a part of the same associative brain system as LP; they are less manifest in VI which belongs to the projection system. At later cooling stages the centrifugal influences of P and VI are sometimes of opposite signs; this effect is connected with reciprocal relations between projection and association systems and processes or selfcontrol within the association system. The corticofugal effects also participate in the common activity of P and VI taking place to a certain degree at the level of the LP which activates these cortical structures.

Animals↗
PubMed2002

[Deep brain stimulation of thalamus for tremor control].

PURPOSE: We present our results in 4 patients with tremor, in whom electrodes (uni and bilateral) for Deep Brain Stimulation (DBS) were implanted in the ventral intermediate nucleus (VIM) of the thalamus. METHOD: Four patients with disabling tremor, with drug-resistant spite of optimum therapeutic trials with poor response were referred to do surgery. Two patients had bilateral essential tremor. These patients were implanted with electrodes for DBS 3387 (Medtronic). Two patients had unilateral parkinsonian tremor and they received unilateral implantation of model 3387 DBS. RESULTS: All four patients showed relieve of the tremor symptoms with significant tremor control seen at the scores. There were no definite adverse events after the electrodes implants for DBS; adverse events were transient and promptly reversed after the adjustment of the parameters. CONCLUSIONS: The results the authors found in this study indicate that VIM-stimulation is effective for tremor control either parkinsonian or essential tremor. The results correlate with the data in the literature.

Electric Stimulation Therapy↗
PubMed1976

[Reactions of neurons in the primary and secondary somatosensory zones of the cortex to stimulation of the ventral posterior nucleus of the thalamus].

Neuronal responses in the first and second somatosensory cortex (SI and SII) to stimulation of the ventroposterior nucleus of the thalamus (VP) were studied in experiments on cats immobilized with d-tubocurarine. 12.0% responding neurons in SI and 9.5% in SII were activated antidromically by VP stimulation. In the majority of antidromic responses the latencies did not exceed 1.0 ms. The minimal latency of orthodromic spikes was 1.5 ms in SI and 1.7 ms in SII. In SI the number of neurons whose orthodromic spike latencies did not exceed 3.0 ms was larger than neurons activated with latencies of 3.1-4.5 ms. In SII an inverse quantitative relationship between those two neuronal groups was observed. In SII a significantly larger number of neurons was excited with latencies of EPSPs ranged between 1.1-9.0 ms in SI and between 1.4-6.6 ms in SII and the latencies of IPSPs between 1.5-6.8 ms in SI and 2.2-9.4 ms in SII. The importance of different pathways for excitatory and inhibitory VP influences to neurons of SI and SII is discussed.

Animals↗
PubMed2003

Qualitative and quantitative analysis of the postnatal development of the ventroposterolateral nucleus of the thalamus in rat and rabbit.

The morphometric analysis of changes occurring in the rat and rabbit ventroposterolateral (VPL) nucleus of the thalamus during the postnatal development was performed using unbiased stereological methods. The materials used in the study included 30 Wistar rats and 32 New Zealand rabbits aged from P0 to P180 (P-postnatal day), which were divided into six and eight age groups, respectively. The following stereological parameters of VPL nucleus on the cresyl violet stained sections were determined: volume of the nucleus, numerical density and total number of neurons. The total number of neurons indicated that the development of VPL nucleus in both species ended within the third week of postnatal life. The volume of VPL nucleus increased gradually (by about 2.2 and 5 times in rats and rabbits, respectively) in comparison with the volume of the cerebral hemisphere during the development from P0 to adulthood. The numerical density of VPL neurons decreased rapidly at the beginning of postnatal life and stabilized by the end of the third week. In both species, the gradual increase in the volume of VPL nucleus and the simultaneous decrease in the neuronal density in the first week of postnatal life were mainly caused by changes in the neuropil volume. The total number of cells did not change remarkably during the first postnatal week. However, it decreased significantly during the second week. This decrease was probably due to the naturally occuring cell death. These results show that the most prominent qualitative and quantitative changes in VPL nucleus and its neurons occur during the first two weeks of postnatal life of rats and rabbits. Also, because the thalamocortical relay neurons completely acquire their physiological features, this the most critical period of time for their morphological maturation.

Animals↗
PubMedDate not supplied

[Role of the ventromedial nucleus of the rats thalamus in food-procuring movements].

The characteristics of ballistic food-procuring movements were studied in albino rats. After electrolytic destruction of ventromedial nucleus of thalamus (VM) of contralaterally preferred extremity the number of attempts and frequency of movements were determined to increase with a decrease of their duration. The restoration of parametres of movements took place during a week. A phase structure of movements also undergoes some modifications: in the case of invariance of initial ballistic components, conditioned by strict links of programme one-side switching off of VM tells on the following components, subject to correction. Re-teaching, requiring the modification of motor programme caused considerable difficulties in rats with switched off VM. The obtained results illustrate the significance of rats' VM in the formation and realization of motor programmes.

Animals↗
PubMed2003

Rhabdoid tumor of the thalamus.

Rhabdoid tumors of the central nervous system are uncommon tumors. About 188 cases have been reported in the literature so far. In this report, we describe a case of a rhabdoid tumor of the thalamus in a 35-year-old male patient. Light microscopic and immunohistochemical features are discussed and the relevant literature reviewed.

Adult↗
PubMed2006

[Neuronal activities in the ventrolateral thalamus and basal ganglia in relation to Parkinson's disease].

OBJECTIVE: To investigate the neuronal activities in the ventrolateral thalamus (VL), internal globus pallidus (GPi), and subthalamic nucleus (STN) in relation to parkinsonian symptoms. METHODS: Twenty-seven patients with Parkinson's disease, 17 males and 10 females, aged 59 +/- 8, received stereotactic surgical treatment on the VL (n = 10), GPi (n = 10), or STN (n = 7) respectively. Microelectrode recording in the three nuclei and electromyography (EMG) on the limbs contralateral to the surgical side were performed intraoperatively. All patients were evaluated with the unified Parkinson's disease rating scale (UPDRS) in "off" medication state pre-and post-operatively. Single unit analysis and cross-correlation analysis were carried out to explore the relationship among the neuronal activities and limb EMG. One-way ANOVA was performed to study the numbers of neuron in these 3 nuclei in different discharge patterns and the improvement of the 3 main symptoms of Parkinson's disease. RESULTS: Three hundred and sixty-one neurons were obtained from 27 microrecording trajectories (146 for VL, 139 for GPi, and 76 for STN). Three patterns of neuronal activities were identified: tremor-related activities ("tremor cells", n = 159); tonic neuronal activities (n = 134), and irregular neuronal activities (n = 68). The rhythm of the tremor-related activities was correlated with the frequency of limb tremor in VL (r(2) = 0.8, P < 0.01), GPi (r(2) = 0.7, P < 0.01), and STN (r(2) = 0.5, P < 0.01). The average number of cells in each tract of VL, GPi, and STN were 9.0, 4.9, and 3.0 for tremor-related activities (ANOVA, P < 0.05); 4.2, 6.2 and 4.3 for tonic neuronal activities (ANOVA, P > 0.05) and 1.4, 2.8 and 3.7 for irregular neuronal activities (ANOVA, P < 0.05). The UPDRS revealed that VL had the highest effect on tremor improvement (91.7%) as compared to GPi (84.8%) and STN (62.7%), whereas STN and GPi had significant effects on bradykinesia improvement (70.8% and 62.3% respectively) as compared to VL (36.9%). However there was no significant difference in the improvement of rigidity among VL, GPi, and STN (56.2%, 71.3%, and 68.8% respectively, all P > 0.05). CONCLUSION: Different patterns of neuronal activities in VL, GPi and STN are likely to associate with parkinsonian symptoms. The results are important not only for the target selection, but also for understanding of neurophysiological basis underlying Parkinson's disease.

Adult↗
PubMed1990

[Effects of radix Salviae Miltiorrhizae on visceral pain discharges in the posterior nucleus of the thalamus in cats].

Extracellular microelectrode method and stereotaxic technique of brain were used to investigate the effects of Radix Salviae Miltiorrhizae on the discharges of visceral pain in the posterior nucleus of thalamus(po)in cats. Experiments showed that Radix Salvia Miltiorrhizae inhibited the discharges of visceral pain in po, Radix Salviae Miltiorrhizae acts directly on the peripheral nerve trunk and cannot block its exciting conduction. This suggests that the analgesic effect of Radix Salviae Miltiorrhizae is exerted via central nervous system.

Analgesics↗
PubMed1990

[Relationship between the precruciate cortex and the ventral lateral posterior nucleus of the thalamus in acupuncture analgesia].

The present study was designed to investigate the relationship between the precruciate cortex (PreCtx) and the ventral lateral posterior nucleus (VPL) of the thalamus in the mechanisms of acupuncture analgesia. Neuronal responses in the nucleus VPL to electrical noxious stimulation of the superficial peroneal nerve were extracellularly recorded. Lidocaine was topically applied at PreCtx. Twenty minutes after the application electroacupuncture (EA) was employed at "Zusanli" and "Huantiao" points for 5 minutes. The nociceptive responses were recorded immediately after cessation of EA and consecutively recorded at the interval of 2 minutes. Similar procedures were made in the control group, in which 0.9% Nacl was topically applied at PreCtx. It was found that topical application of lidocaine at PreCtx did not influence the nociceptive responses of VPL neurons. Following topical application of lidocaine at PreCtx, the nociceptive responses were obviously inhibited 0', 4', 6', 10', and 12' after cessation of EA. In the saline control group the remarkable inhibitory effect of EA was observed 0'-8' after ceasing EA, The results showed that the inhibitory effect of EA in the test group was weaker than that in the control group. However, the difference was not statistically significant. It is suggested that PreCtx participates in the corticofugal modulation of EA effects in the nucleus VPL only to small extent.

Acupuncture Analgesia↗
PubMed1990

[Effect of injection of thyrotropin-releasing hormone into nucleus accumbens on the pain discharges in nucleus parafascicularis of rat thalamus].

Glass microelectaod recording method was used to investigate the effect of thyrotropin-releasing hormone (TRH) into nucleus accumbens, nucleus amygdaloid or nucleus caudate-putamen on unit discharges of pain-excitation neurons (PEN) in nucleus parafascicularis of thalamus in rats. The results showed that: (1) TRH injected into the nucleus accumbens results in a significant inhibition of pain discharges of PEN in nucleus parafascicularis. But injection of TRH into nucleus amygdaloid, nucleus caudate-putamen had no significant effect. (2) Pretreatment with auropine abolished the inhibitory effect of TRH. (3) Pretreatment with haloperidol also abolished the inhibitory effect of TRH. (4) Pretreatment with naloxone, propranolol or phentolamine did not affect the inhibitory effect of TRH. The results mentioned above suggested that nucleus accumbens could be a special area in response to TRH and the effect of TRH seems to be involved in both cholinergic M-receptor and dopamine receptor.

Amygdala↗
PubMed1990

Correlation and revised nomenclature of ventral nuclei in the thalamus of human and monkey.

The application of histochemical and immunocytochemical methods to the human thalamus, when allied with traditional staining methods, permits a clearer definition of the borders between many nuclei. The findings of electrophysiological and anatomical tracing studies in monkeys can then be correlated with the human material and a nomenclature that is applicable to both monkeys and humans introduced. The ventral nuclei can be divided into four channels relaying pallidal, substantia nigral, cerebellar, and lemniscal information separately to the cerebral cortex. The lemniscal relay is further divided into a proprioceptive component and a cutaneous component, corresponding to Hassler's V.c.e.a. and V.c.e.p nuclei, respectively, and now called VPLa and VPLp.

Animals↗
PubMed1990

Influence of morphine microinjected into head of caudate nucleus on electric activities of nociceptive neurons in parafascicular nucleus of rat thalamus.

Morphine (8 micrograms/microliter) was injected into the head of the caudate nucleus (CN). The pain-discharges of the pain-excitation neurons (PEN) in the parafascicular nucleus (Pf) were inhibited, ie, decreasing in frequency of pain-discharges and lengthening in latent period of pain-discharges. The inhibitory effect of the pain-inhibition neurons (PIN) in the Pf induced by noxious peripheral stimulation were relieved, ie, increasing the firing rate and shortening the inhibitory duration. The opiate receptor antagonist naloxone (0.75 mg/kg, ip) blocked the above effects of morphine. These results suggest that the intracaudate opioid peptide system play an important role in the modulation of pain information in the Pf of thalamus.

Animals↗
PubMed1990

[The neuronal reactions of the reticular nucleus of the human thalamus to verbal and sensory stimuli of differing signal strengths].

Responses of 340 single units of the n. Rt of the human thalamus to significant and insignificant verbal and sensory stimuli during the performance of voluntary motor acts recorded by microelectrodes were investigated in dyskinetic patients in the course of 46 stereotaxic operations. Two types of polymodal units with irregular continuous (A-type, "triggered verbal command" units, 183 neurons, 56% reacting) and burst rhythmic (2-5 per s.) discharges (B-type, 139 neurons, 59% reacting) have revealed reactivity to a verbal command with a specialized multicomponent pattern at functionally different stages of purposive motor acts. The analysis of principal components has shown that the extracted components of responses correlated with the functional significance of verbal or sensory signals, especially with voluntary acts of the verbal message triggering, but not with physical, somatotopic or semantic parameters of stimulation. It was suggested that the transient time-connectivity of A and B neurons at the trigger stages of purposive tasks reflected the coexistence in the Rt of two functionally different cellular subsystems participating in the transmission of significant signals during speech-provoked voluntary acts.

Acoustic Stimulation↗
PubMed1990

[The influences of morphine microinjected into preoptic area on electric activities of pain response neurons in parafascicular nucleus of thalamus in rat].

We have observed the influences of opioid-like substances in preoptic area (POA) on the electric activities of pain response neurons in parafascicular nucleus of thalamus (Pf). The results were as follows: 1. Morphine 10 micrograms/microliters or 1 micrograms/microliters microinjected into POA could remarkably inhibit the pain discharges of most (20/26, 19/23 respectively) pain excitatory neurons (PEN) in Pf. The frequency of evoked discharges was decreased nd the duration was shortened. After injecting 10 micrograms/microliters morphine, three neurons showed inhibitory responses to noxious stimuli. 2. Morphine of the two doses could shorten the complete inhibitory period of pain inhibitory neurons (PIN, 23/33). These results suggest that the opioid-like substances in POA might have an inhibitory effects on pain response neurons in Pf.

Animals↗
PubMed1990

Brainstem afferents to the intralaminar nuclei of the cat thalamus studied by the horseradish peroxidase method.

Brainstem afferents to the intralaminar thalamic nuclei of the cat have been studied by retrograde axonal transport of horseradish peroxidase (HRP) or wheat germ agglutinin conjugated to HRP (WGA-HRP). Injections of HRP or WGA-HRP into the lateral central and paracentral nuclei led to labeling of cells in various diencephalic structures of the injected side. Some cells were labeled in the intralaminar and medial pulvinar nuclei. A large number of labeled cells were detected in the thalamic reticular and ventral lateral geniculate nuclei. The zona incerta and field of Forel contained a few labeled cells. Occasional labeled cells were seen in the dorsomedial, ventromedial, posterior and lateral hypothalamic nuclei. Labeling of cells in the more caudal brainstem structures was found bilaterally, mostly with ipsilateral predominance. Some labeled cells were detected in the pretectal nuclei, the periaductal gray and the pars reticulata of the substantia nigra as well. The nuclei of Darkschewitsch and Cajal contained occasional labeled cells. Numerous cells were labeled in the superior colliculus, mainly in layers 3 and 4. A number of labeled cells were distributed in almost the entire extent of the brainstem reticular formation. It should be mentioned that the gigantocellular reticular nucleus contained labeled cells bilaterally with contralateral predominance. Very few labeled cells were encountered in the ipsilateral dorsal tegmental and parabrachial nuclei. A few cells were labeled in the vestibular nuclei and nucleus prepositus hypoglossi bilaterally. Some labeled cells were detected mainly contralaterally in three cerebellar nuclei; the fastigial, the interposed and the dentate. Injections of WGA-HRP into the medial central nucleus showed a different pattern of labeling. It is noteworthy that no labeled cells were found in the dorsal thalamus, the hypothalamus (except for the lateral mamillary nucleus), the superior colliculus or the cerebellar nuclei.

Animals↗
PubMed1989

[The influence of GABA injected into cerebral ventricle on electrical activities of pain-excitation neurons and pain-inhibition neurons in nucleus parafascicularis of the thalamus of rats].

The influence of intraventricular injection of GABA on electrical activities of PEN and PIN in nucleus parafascicularis of the thalamus of rats was studied. The results showed that GABA could significantly inhibit the electrical discharges of PEN and increase the electrical discharges of PIN. So it was believed that intraventricularly injected GABA could antagonize or partly antagonize the excitatory action of noxious stimuli and might thus produce analgesia.

Animals↗