Cross-Modal Interaction and Integration Through Stimulus-Specific Adaptation in the Thalamic Reticular Nucleus of Rats / 神经科学通报·英文版

Stimulus-specific adaptation (SSA), defined as a decrease in responses to a common stimulus that only partially generalizes to other rare stimuli, is a widespread phenomenon in the brain that is believed to be related to novelty detection. Although cross-modal sensory processing is also a widespread phenomenon, the interaction between the two phenomena is not well understood. In this study, the thalamic reticular nucleus (TRN), which is regarded as a hub of the attentional system that contains multi-modal neurons, was investigated. The results showed that SSA existed in an interactive oddball stimulation, which mimics stimulation changes from one modality to another. In the bimodal integration, SSA to bimodal stimulation was stronger than to visual stimulation alone but similar to auditory stimulation alone, which indicated a limited integrative effect. Collectively, the present results provide evidence for independent cross-modal processing in bimodal TRN neurons.

Three-Dimensional Heterogeneity of Cerebellar Interposed Nucleus-Recipient Zones in the Thalamic Nuclei / 神经科学通报·英文版

The cerebellum is conceptualized as a processor of complex movements and is also endowed with roles in cognitive and emotional behaviors. Although the axons of deep cerebellar nuclei are known to project to primary thalamic nuclei, macroscopic investigation of the characteristics of these projections, such as the spatial distribution of recipient zones, is lacking. Here, we studied the output of the cerebellar interposed nucleus (IpN) to the ventrolateral (VL) and centrolateral (CL) thalamic nuclei using electrophysiological recording in vivo and trans-synaptic viral tracing. We found that IpN stimulation induced mono-synaptic evoked potentials (EPs) in the VL but not the CL region. Furthermore, both the EPs induced by the IpN and the innervation of IpN projections displayed substantial heterogeneity across the VL region in three-dimensional space. These findings indicate that the recipient zones of IpN inputs vary between and within thalamic nuclei and may differentially control thalamo-cortical networks.

Altered Local Field Potential Relationship Between the Parafascicular Thalamic Nucleus and Dorsal Striatum in Hemiparkinsonian Rats / 神经科学通报·英文版

The thalamostriatal pathway is implicated in Parkinson's disease (PD); however, PD-related changes in the relationship between oscillatory activity in the centromedian-parafascicular complex (CM/Pf, or the Pf in rodents) and the dorsal striatum (DS) remain unclear. Therefore, we simultaneously recorded local field potentials (LFPs) in both the Pf and DS of hemiparkinsonian and control rats during epochs of rest or treadmill walking. The dopamine-lesioned rats showed increased LFP power in the beta band (12 Hz-35 Hz) in the Pf and DS during both epochs, but decreased LFP power in the delta (0.5 Hz-3 Hz) band in the Pf during rest epochs and in the DS during both epochs, compared to control rats. In addition, exaggerated low gamma (35 Hz-70 Hz) oscillations after dopamine loss were restricted to the Pf regardless of the behavioral state. Furthermore, enhanced synchronization of LFP oscillations was found between the Pf and DS after the dopamine lesion. Significant increases occurred in the mean coherence in both theta (3 Hz-7 Hz) and beta bands, and a significant increase was also noted in the phase coherence in the beta band between the Pf and DS during rest epochs. During the treadmill walking epochs, significant increases were found in both the alpha (7 Hz-12 Hz) and beta bands for two coherence measures. Collectively, dramatic changes in the relative LFP power and coherence in the thalamostriatal pathway may underlie the dysfunction of the basal ganglia-thalamocortical network circuits in PD, contributing to some of the motor and non-motor symptoms of the disease.

Bradicardia extrema por infarto talámico paramediano bilateral / Extreme bradycardia due to bilateral paramedian thalamic infarction

RESUMEN Alteraciones autonómicas agudas por infartos cerebrales se han descrito con frecuencia comprometiendo la región insular, dentro de las anormalidades se han documentado alteraciones de severidad variable del ritmo cardíaco, incluyendo la bradicardia extrema sintomática; en la literatura solo hay un reporte de caso de bradi-cardia extrema asociado a un infarto talámico paramediano bilateral, a continuación, describimos un segundo caso de un infarto talámico con la misma presentación.

SUMMARY Acute autonomic disturbances due to cerebral in farcts has been describe frequently with association of the insular cortex, within the describe abnormalities had been document a variety of cardiac disturbances including extreme symptomatic bradycardia; In the literature just exist a case report of extreme bradycardia associate with a bilateral paramedian thalamic infarct, in the following article, we describe a second case of this infarct with the same presentation.

Effects of electroacupuncture combined with polysaccharide of gastrodia elate blume on expression of nestin and stem cell factor in thalamic ventroposterolateral nucleus in rats with focal cerebral ischemia / 中国针灸

<p><b>OBJECTIVE</b>To explore the nerve regeneration mechanism of electroacupuncture (EA) combined with polysaccharide of gastrodia elate blume (PGB) for secondary thalamic damage of focal cerebral ischemia.</p><p><b>METHODS</b>Forty Sprague-Dawley adult rats were randomly divided into a normal control group, a model group, an EA group, a PGB group and an EA + PGB group, 8 rats in each group. The rat model of right middle cerebral artery occlusion was prepared by suture-occluded method. Two weeks after model establishment, rats in the normal control group and model group received no treatment; rats in the EA group were treated with EA at "Baihui" (GV 20) and left "Zusanli" (ST 36), 30 min per treatment, once a day for 14 successive days; rats in the PGB group were treated with intragastric administration of PGB (100 mg/kg) , once a day for 14 days; rats in the EA + PGB group were treated with EA and PGB treatment, once a day for totally 14 days. The expressions of nestin and stem cell factor (SCF) in thalamic ventroposterolateral nucleus (VPL) were detected by immunohistochemical method.</p><p><b>RESULTS</b>There were positive cells of nestin in ischemia VPL in the model group, and the number of SCF positive cells was increased compared with that in the normal control group (P<0.05). The number of positive cells of nestin and SCF in ischemia VPL in the EA group, PGB group and the EA + PGB group was increased compared with that in the model group (all P<0.05), and the average gray value of immune positive product was all reduced (all P<0.05). The number of positive cells of nestin and SCF in the EA + PGB group was higher than that in the EA group or the PGB group (all P<0.05).</p><p><b>CONCLUSION</b>EA combined with PGB can significantly increase the SCF expression in ischemia VPL and promote the proliferation of neural stem cells, which is likely to be one of the nerve regeneration mechanism of acupuncture and medication tor secondary thalamic damage of local cerebral isctemia.</p>

Arteria de Percheron: presentación de caso / Artery of Percheron: case report

La isquemia bitalámica es un evento poco común que generalmente se debe a una variante anatómica de las arterias paramedianas, la arteria de Percheron, que en casos de oclusión puede llevar a infartos bitalámicos y mesencefálicos. Presentamos el caso de un paciente de 74 años traído a nuestro servicio de urgencias luego de ser encontrado inconsciente, sin apertura ocular, sin respuesta verbal a la estimulación física, con pupilas isocóricas normorreactivas y sin otras alteraciones al hacer el examen físico. En los estudios de imágenes diagnósticas se encontró un infarto agudo bitalámico, con afectación de los núcleos ventromediales (los cuales no realzan con el gadolinio), y múltiples variantes anatómicas del polígono de Willis. Esto sugiere que la variante de Percheron es la causade esta lesión. Se discuten los hallazgos clínicos y de imágenes diagnósticas.

Thalamic nuclear abnormalities as a contributory factor in sudden cardiac deaths among patients with schizophrenia

Patients with schizophrenia have a two- to three-fold increased risk of premature death as compared to patients without this disease. It has been established that patients with schizophrenia are at a high risk of developing cardiovascular disease. Moreover, an important issue that has not yet been explored is a possible existence of a "cerebral" focus that could trigger sudden cardiac death in patients with schizophrenia. Along these lines, several structural and functional alterations in the thalamic complex are evident in patients with schizophrenia and have been correlated with the symptoms manifested by these patients. With regard to abnormalities on the cellular and molecular level, previous studies have shown that schizophrenic patients have fewer neuronal projections from the thalamus to the prefrontal cortex as well as a reduced number of neurons, a reduced volume of either the entire thalamus or its subnuclei, and abnormal glutamate signaling. According to the glutamate hypothesis of schizophrenia, hypofunctional corticostriatal and striatothalamic projections are directly involved in the pathophysiology of the disease. Animal and post-mortem studies have provided a large amount of evidence that links the sudden unexpected death in epilepsy (SUDEP) that occurs in patients with schizophrenia and epilepsy to thalamic changes. Based on the results of these prior studies, it is clear that further research regarding the relationship between the thalamus and sudden cardiac death is of vital importance.

Understanding of Structure and Function of Vestibular Cortex / 대한평형의학회지

The vestibular end-organs generate very sophisticated gravity sensory information about head movement by sensing head acceleration in three-dimensional space. Vestibular information is crucial for higher brain functions such as cognition of spatial orientation, spatial memory, and perception of self-motion. The term "vestibular cortex" represents cortical area where vestibular information is processed, converged with other sensory inputs to maintain cortical functions. The vestibular cortex gives rise to commend signals that control the vestibulosomatic reflex through the modulation of vestibular nuclear activity in the brainstem. The vestibular cortex includes such different cortical regions as the premotor region of the frontal cortex, parietal areas, temporal areas, and a central core region called parietoinsular vestibular cortex. This paper summarizes systemically animal and clinical research data concerned with the vestibular cortex in order to understand anatomy and functions of the vestibular cortex and to provide a basic literature for further study.

Inhibitory effect of anterior cingulate cortex on spontaneous activity of thalamic ventrobasal nucleus neurons / 生理学报

The purpose of this study was to investigate the influence of electrical stimulation of anterior cingulate cortex (ACC) on spontaneous activity of neurons in thalamic ventrobasal nucleus (VB). Experiments were performed on 12 male Sprague-Dawley rats weighing 250-310 g (4-5 months old). According to Paxinos and Watson's coordinate atlas of the rat, the frontal and parietal cortical areas were exposed by craniotomy, the recording electrodes were then inserted into the VB (P 2.4-4.1 mm, R 2.0-3.5 mm, H 5.2-6.8 mm) and the stimulating electrodes into the ACC (A 1.1-3.0 mm, R 0.0-1.0 mm, H 1.5-2.4 mm). Single-unit activities were recorded extracellularly in the VB by glass micropipettes (impedance 3-8 MOmega) filled with 0.5 mol/L sodium acetate solution containing saturated Fast Green. To study the effects of ACC activation on the spontaneous activities of VB cells, single electrical pulse (0.2 ms duration) was delivered to the ACC by a concentric bipolar stainless steel electrode (0.32 mm outer diameter). An effective ACC stimulation was determined for each VB neuron by gradually increasing the current intensity from 0.1 mA until either a significant change in the spontaneous activity of the VB neuron was observed, or the current intensity reached 0.4 mA. The results showed that ACC stimulation significantly suppressed the spontaneous activities in 12 out of 53 VB neurons (22.6%). (1) After the stimulation was delivered to ACC, the spontaneous activities of different VB neurons were totally suppressed for different time span. (2) There was obvious dose-effect relevance between ACC stimulation intensity and their inhibitory effect. The duration of complete inhibition was prolonged with the increases in the intensity and number of stimulation impulses in ACC. (3) The stimulation in the ACC depressed the spontaneous activities of VB neurons in different forms and this inhibition exhibited an accumulative effect. All these results indicate that the stimulation of ACC exerts an inhibitory influence on the spontaneous activities of VB neurons.

Properties of tactile responses of neurons in rat thalamic ventroposterolateral nucleus / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To determine whether the convergences of tactile information also occur at thalamic ventroposterolateral nucleus in rats, we investigated the properties of tactile responses of the thalamic ventroposterolateral nucleus in rats.</p><p><b>METHODS</b>Unit responses were recorded extracellularly from thalamic ventroposterolateral nucleus in anesthetized rats.</p><p><b>RESULTS</b>Among 156 neurons examined, 140 neurons (89.7%) had the single, continual and small receptive fields, and 16 neurons (10.3%) had two discrete receptive fields. Some neurons?exhibited different responses to the same intensity stimulation which delivered to different points in their receptive fields. In addition, 4.5% neurons (n = 7) responded only to locomotive stimulation but?not to a punctiform tactile stimulation.</p><p><b>CONCLUSION</b>The majority of neurons in ventroposterolateral nucleus of rats have the spatial, temporal and submodal characteristics of cutaneous receptors, while the minority of neurons exhibit the responses of interaction of different peripheral receptors. Therefore, it is concluded that there are convergences of tactile information at the ventroposterolateral nucleus of rats.</p>

Effect of stimulation and lesion of the thalamic nucleus submedius on formalin-evoked nociceptive behavior in rats / 生理学报

The aim of the present study was to examine whether the thalamic nucleus submedius (Sm) was involved in the modulation of persistent nociception. Using an automated movement detection system to measure nociceptive behavior (agitation) induced by subcutaneous injection of formalin into the hind paw pad, the effects of electrical stimulation or electrolytic lesion of the Sm on the agitation response were examined in conscious rats. Unilateral stimulation (100 μA, 5 min) of the Sm ipsilateral or contralateral to the formalin-injected paw produced a significant inhibition of agitation response in the second phase, while stimulation of thalamic structures more than 0.5 mm away from the Sm had no effect on agitation response. Bilaterally electrolytic lesion of the Sm did not significantly influence the number of agitation events induced by formalin injection in the first phase or the second phase. These results suggest that the Sm is not only involved in the modulation of phase nociception, as reported previously, but also of persistent nociception. The present study provides novel evidence for the participation of the Sm in descending modulation of pain.

Neo-Timm staining in the thalamus of chronically epileptic rats

The thalamus is an important modulator of seizures and is severely affected in cholinergic models of epilepsy. In the present study, chronically epileptic rats had their brains processed for neo-Timm and acetylcholinesterase two months after the induction of status epilepticus with pilocarpine. Both controls and pilocarpine-treated animals presented neo-Timm staining in the anterodorsal nucleus, laterodorsal nucleus, reticular nucleus, most intralaminar nuclei, nucleus reuniens, and rhomboid nucleus of the thalamus, as well as in the zona incerta. The intensity of neo-Timm staining was similar in control and pilocarpine-treated rats, except for the nucleus reuniens and the rhomboid nucleus, which had a lower intensity of staining in the epileptic group. In animal models of temporal lobe epilepsy, zinc seems to modulate glutamate release and to decrease seizure activity. In this context, a reduction of neo-Timm-stained terminals in the midline thalamus could ultimately result in an increased excitatory activity, not only within its related nuclei, but also in anatomical structures that receive their efferent connections. This might contribute to the pathological substrate observed in chronic pilocarpine-treated epileptic animals.

The Effect and the Mechanism of Action of High Frequency Electrical Stimulation of Subthalamic Nucleus on Status Epilepticus Induced by Lithium-Pilocarpine of Rat / 대한간질학회지

OBJECTIVES: Deep brain stimulation (DBS) of subthalamic nuclei (STN) is one of the current modalities of refractory epilepsy, but its exact mechanism and route of action have not been elucidated yet. We investigated the effect of STN stimulation on the development and propagation of seizures in the rats with lithium-pilocarpine induced status epilepticus in its functional anatomy. METHODS: Both pilocarpine injection and high frequency stimulation on STN (HFSSTN) were provided to rats (STN group, n=12), but pilocarpine injection with no stimulation was done on the sham group (n=8). The latency to first discrete ictal discharges and the latency to status epilepticus (SE) were analyzed and the electrical stimulation lasted for 30, 60, 90, 120 minutes after its first discrete spikes. After stimulation, the rats were immediately decapitated for immunohistochemistry and histologic examination. RESULTS: Both the latency to first discrete ictal discharges and the latency to the onset of SE were delayed in the STN group than in the sham group. The latency to the first SE was also more delayed in the STN group (42.7+/-7.9 min) than in the sham group (p<0.05). Remarkably, there was marked Fos immunoreactivity (FIR) on the reticular thalamic nuclei in the STN group, but not in the sham group. CONCLUSIONS: Increased FIR in the reticular thalamic nuclei during HFSSTN suggested that the facilitation of the inhibitory thalamic output prevented generalized motor seizure behavior. We assume that HFSSTN has a pivotal role in the suppression or progression to SE, but cannot prevent seizure onset.

Differential effects of opioid receptors in nucleus submedius and anterior pretectal nucleus in mediating electroacupuncture analgesia in the rat / 生理学报

Previous studies have indicated that the thalamic nucleus submedius (Sm) and the anterior pretectal nucleus (APtN) are involved in the descending modulation of nociception. The aim of the present study was to examine whether the opioid receptors in the Sm and APtN mediated the electroacupuncture (EA)-produced analgesia. The latency of tail flick (TF) reflex induced by radiant heat was used as an index of nociceptive response. The effects of microinjection of opioid receptor antagonist naloxone (1.0 microg, 0.5 ml) into Sm or APtN on the inhibition of the TF reflex induced by EA of "Zusanli" point (St. 36) with high- (5.0 mA) and low- (0.5 mA) intensity were examined in the lightly anesthetized rats. Sm microinjection of naloxone blocked the high- but not low-intensity EA-induced inhibition of the TF reflex. In contrast, naloxone applied to APtN blocked the low- but not high-intensity EA-induced inhibition. When naloxone applied to other brain regions adjacent to Sm or APtN, the EA-induced inhibition was not influenced under either high- or low-intensity condition. These results suggest that opioid receptors in Sm are involved in mediating the analgesia by high-intensity EA for exciting small (A-delta and C group) afferent fibers, while opioid receptors in APtN are involved in mediating the analgesia induced by low-intensity EA for only exciting large (A-beta) afferent fibers.

Abnormal Cerebral Glucose Metabolism in Patients with Narcolepsy

BACKGROUND: The purpose of this study was to investigate the differences of cerebral glucose metabolism between narcoleptic patients and normal controls. METHODS: We enrolled 24 patients with narcolepsy who underwent night polysomnography and multiple sleep latency tests to confirm the narcolepsy. 18F-fluorodeoxy glucose positron emission tomography scan was performed in all narcoleptic patients and 24 normal age-sex matched controls. To compare the cerebral glucose metabolism between the two groups, statistical parametric mapping (SPM99) was used. RESULTS: Patients with narcolepsy showed significant decreases of cerebral glucose metabolism in the bilateral rectal and subcallosal gyri, right superior frontal gyrus, right medial frontal gyrus, bilateral precuneus, right inferior parietal lobule, and left supramarginal gyrus of the parietal lobe at the uncorrected P<0.001. The bilateral posterior hypothalami and mediodorsal thalamic nuclei showed glucose hypometabolism at the level of corrected P<0.05 with small volume correction. CONCLUSIONS: This study showed cerebral glucose hypometabolism of hypothalamus-thalamus-orbitofrontal pathways in narcoleptic brains. The distribution of abnormal glucose metabolism is concordant to the cerebral pathways of the hypocretin system.

Effect of atropine on the inhibition of melatonin to the unit discharges evoked in the posterior group of thalamic nuclei in cats / 药学学报

<p><b>AIM</b>To study the effect of atropine, muscarinic cholinergic antagonist, on the central analgesic action of melatonin (MT) and to explore the mechanism of MT analgesia.</p><p><b>METHODS</b>As an indicator of visceral pain, the unit discharges of the neurons in the posterior group of thalamic nuclei (PO) were caused by stimulating the great splanchnic nerve (GSN) of the cat. The cranial stereotaxic and extracellular glass microelectrode record technique were used. The drugs were given through the intra-cranial-ventricle (icv).</p><p><b>RESULTS</b>0.1% MT (10 micrograms.kg-1, icv) was shown to inhibit the unit discharge of the neurons in PO of the cat, whether the long latency or the short latency, which was evoked by stimulating GSN. The inhibition of 0.1% MT (10 micrograms.kg-1, icv) on the short latency discharge of neurons in PO was antagonized by 0.1% atropine (20 micrograms, icv). However, 0.1% atropine (20 micrograms, icv) did not show antagonistic effect on the inhibition of 0.1% morphine (5 micrograms, icv) at the same latency.</p><p><b>CONCLUSION</b>MT exhibited central analgesic action with mechanism different from morphine. It was suggested that the cholinergic system may be involved in analgesic process of MT.</p>

organization of non - dopaminergic nigral projection to the thalamic nucleus of the rat

Nigrotnalamocortical tract is one of the important outputs of the basal ganglia, but its role in motor disturbances is still vauge, because there is little informations on its connection structure. Some electrophysiological and pharmacological studies report that non-dopaminergic outputs originate from reticular part of substatia nigra to thalamus. In this study the topographical and organization connection of substantia nigra pars reticulata [SNR] with thalamic MD nucleus was investigated using HRP tracer. 25 male rats received injection of 33 percent HRP into the ipsilateral MD nucleus of thalamus stereotaxically. 48 hours later the animals were perfused transcardially, and the brain tissue was fixed. 40 micrometer sections were prepared from diencephalon and midbrain. Following enzymatic reactions of TMB, the sections were stained by neutral red. The light microscopic study showed that there is a high concentration of neurons which project to the MD nucleus from the rostro-lateral part and middle parts of pars reticulata [SNR] and the number of labeled cells decrease in the caudal parts. Other labeled neurons are located at the border of SNC, SNR and VTA, especially close to the passage of III cranial nerve. In general, the size of neurons was mostly medium; and they were multipolar in shape. Any labeled cells were observed in the SNR controlateral to injection site. Our findings show that the SNR connection to the MD arise mainly from lateral and dorsomedial part of SNR. It seems that these connections may influence the limbic system in orientating behaviour

Influence of Antedorsal Thalamic nuclei on the hypophyseal-adrenal axis and cardiac beta receptors in tars submitted to vatriable chronic stress

The limbic structures play an important role in the control of the neuroendocrine and sympathical adrenal function in basal and stress conditions. This work was undertaken to evaluate plasma ACTH, adrenocortical activity, cardiac adrenoceptors density and affnity response to variable chronic stress (VCS) in anterodorsal thalamic nuclei (ADTN) lesioned rats. Thirty days after lesion, shamlesioned stressed animals increased plasma ACTH and corticosterone as compared to sham-lesioned unstressed animals (p<0.05); lesioned rats increased ACTH levels after VCS (p<0.05) as compared unstressed-lesioned rats. Whereas in sham-lesion plasma corticosterone (C) increased after stress. in lesioned animals (C) remained unchanged as compared to unstressed-lesioned animals. In the stressed groups, adrenal C contents were below those found in unstressed rats. Beta-receptors affinity, in all the experimental groups, was similar, but VCS sham-lesioned animals underwent a significant increase in cardiac D-adrenergic receptors density when compared with basal and lesioned groups (P<0.001). Our findings would demonstrate that the increment in cardiac Beta adrenoceptors density appears as a consequence of the increase in ACTH, plasma corticosterone and sympathetic response provoked by stress situations. ADTN lesion attenuated this hipophisoadrenal system response to chronic stress as well as the above mentioned cardiac beta adrenoceptors density increment.

Dolor talámico su mecanismo y tratamiento / Thalamic pain mechanism and therapy

Basados en datos anatómicos y clínicos creemos que el dolor talámico es producido por una lesión selectiva del núcleo ventrocaudal parvocelular (Vcpc) del tálamo. Por el contrario, la recuperación funcional de éste núcleo así como de las fibras A-delta y A-beta a nivel del núcleo ventral posterior (VP), puede aliviar o curar este tipo de dolor central.