This study aims to explore the auditory response characteristics of the thalamic reticular nucleus (TRN) in awake mice during auditory information processing, so as to deepen the understanding of TRN and explore its role in the auditory system. By in vivo electrophysiological single cell attached recording of TRN neurons in 18 SPF C57BL/6J mice, we observed the responses of 314 recorded neurons to two kinds of auditory stimuli, noise and tone, applied to mice. The results showed that TRN received projections from layer six of the primary auditory cortex (A1). Among 314 TRN neurons, 56.05% responded silently, 21.02% responded only to noise and 22.93% responded to both noise and tone. The neurons with noise response can be divided into three patterns according to their response time: onset, sustain and long-lasting, accounting for 73.19%, 14.49% and 12.32%, respectively. The response threshold of the sustain pattern neurons was lower than those of the other two types. Under noise stimulation, compared with A1 layer six, TRN neurons showed unstable auditory response (P < 0.001), higher spontaneous firing rate (P < 0.001), and longer response latency (P < 0.001). Under tone stimulation, TRN's response continuity was poor, and the frequency tuning was greatly different from that of A1 layer six (P < 0.001), but their sensitivity to tone was similar (P > 0.05), and TRN's tone response threshold was much higher than that of A1 layer six (P < 0.001). The above results demonstrate that TRN mainly undertakes the task of information transmission in the auditory system. The noise response of TRN is more extensive than the tone response. Generally, TRN prefers high-intensity acoustic stimulation.
Rats ; Mice ; Animals ; Wakefulness ; Auditory Pathways/physiology* ; Rats, Wistar ; Mice, Inbred C57BL ; Thalamus/physiology*

The deep cerebellar nuclei (DCN) integrate various inputs to the cerebellum and form the final cerebellar outputs critical for associative sensorimotor learning. However, the functional relevance of distinct neuronal subpopulations within the DCN remains poorly understood. Here, we examined a subpopulation of mouse DCN neurons whose axons specifically project to the ventromedial (Vm) thalamus (DCN^Vm neurons), and found that these neurons represent a specific subset of DCN units whose activity varies with trace eyeblink conditioning (tEBC), a classical associative sensorimotor learning task. Upon conditioning, the activity of DCN^Vm neurons signaled the performance of conditioned eyeblink responses (CRs). Optogenetic activation and inhibition of the DCN^Vm neurons in well-trained mice amplified and diminished the CRs, respectively. Chemogenetic manipulation of the DCN^Vm neurons had no effects on non-associative motor coordination. Furthermore, optogenetic activation of the DCN^Vm neurons caused rapid elevated firing activity in the cingulate cortex, a brain area critical for bridging the time gap between sensory stimuli and motor execution during tEBC. Together, our data highlights DCN^Vm neurons' function and delineates their kinematic parameters that modulate the strength of associative sensorimotor responses.
Animals ; Blinking ; Cerebellar Nuclei/physiology* ; Cerebellum ; Mice ; Neurons/physiology* ; Thalamus

Crossmodal information processing in sensory cortices has been reported in sparsely distributed neurons under normal conditions and can undergo experience- or activity-induced plasticity. Given the potential role in brain function as indicated by previous reports, crossmodal connectivity in the sensory cortex needs to be further explored. Using perforated whole-cell recording in anesthetized adult rats, we found that almost all neurons recorded in the primary somatosensory, auditory, and visual cortices exhibited significant membrane-potential responses to crossmodal stimulation, as recorded when brain activity states were pharmacologically down-regulated in light anesthesia. These crossmodal cortical responses were excitatory and subthreshold, and further seemed to be relayed primarily by the sensory thalamus, but not the sensory cortex, of the stimulated modality. Our experiments indicate a sensory cortical presence of widespread excitatory crossmodal inputs, which might play roles in brain functions involving crossmodal information processing or plasticity.
Animals ; Auditory Cortex/physiology* ; Neuronal Plasticity/physiology* ; Neurons ; Rats ; Thalamus ; Visual Cortex/physiology*

To investigate the effects of neuronal histamine on spatial memory acquisition impairment in rats with pentylenetetrazole-kindling epilepsy, and to explore its mechanisms.A subconvulsive dose of pentylenetetrazole (35 mg/kg) was intraperitoneally injected in rats every 48 h to induce chemical kindling until fully kindled. Morris water maze was used to measure the spatial memory acquisition of the rats one week after fully pentylenetetrazole-kindled, and the histamine contents in different brain areas were measured spectrofluorometrically. Different dosages of hitidine (the precursor of histamine), pyrilamine (H1 receptor antagonist), and zolantidine (H2 receptor antagonist) were intraperitoneally injected, and their effects on spatial memory acquisition of the rats were observed.Compared with control group, escape latencies were significantly prolonged on Morris water maze training day 2 and day 3 in pentylenetetrazole-kindling epilepsy rats (all<0.05); and the histamine contents in hippocampus, thalamus and hypothalamus were decreased significantly (all<0.05). Escape latencies were markedly shortened on day 3 by intraperitoneally injected with histidine 500 mg/kg, and on day 2 and day 3 by intraperitoneally injected with histidine 1000 mg/kg in pentylenetetrazole-kindling epilepsy rats (all<0.05). The protection of histidine was reversed by zolantidine (10 and 20 mg/kg), but not by pyrilamine.Neuronal histamine can improve the spatial memory acquisition impairment in rats with pentylenetetrazole-kindling epilepsy, and the activation of H2 receptors is possibly involved in the protective effects of histamine.
Animals ; Benzothiazoles ; pharmacology ; Brain Chemistry ; drug effects ; Epilepsy ; chemically induced ; complications ; Hippocampus ; chemistry ; Histamine H1 Antagonists ; pharmacology ; Histamine H2 Antagonists ; pharmacology ; Histidine ; pharmacology ; Hypothalamus ; chemistry ; Kindling, Neurologic ; physiology ; Memory Disorders ; drug therapy ; etiology ; Pentylenetetrazole ; Phenoxypropanolamines ; pharmacology ; Piperidines ; pharmacology ; Pyrilamine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Histamine H2 ; drug effects ; physiology ; Spatial Memory ; drug effects ; Spectrometry, Fluorescence ; Thalamus ; chemistry

OBJECTIVE: To examine the changes of metabolites in the bilateral thalamus of patients with secondarily generalized tonic-clonic seizure (SGTCS) and to explore the mechanism of SGTCS. METHODS: Thirty patients with SGTCS (epilepsy group) and 30 matched healthy controls (control group) were examined by 1H-magnetic resonance spectroscopy (1H-MRS). The levels of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine phosphocreatine (Cr-PCr), and myo-inositol (mI) of the bilateral thalamus were measured in both the epilepsy group and the control group. The ratios of NAA/Cr-PCr, NAA/(Cr-PCr+Cho), Cho/Cr-PCr and mI/Cr-PCr were compared and analyzed in the 2 groups. RESULTS: The ratios of NAA/Cr-PCr, and NAA/(Cr-PCr+Cho)(1.7074 ± 0.2214; 0.9333 ± 0.2173) in the left thalamus in the epilepsy group were significantly lower than those in the control group(1.8834 ±0.2093; 1.1243 ±0.2447)(P<0.05). The ratios of NAA/Cr-PCr, and NAA/(Cr- PCr+Cho) (1.7472 ±0.2439; 0.9165 ±0.2462) in the right thalamus in the epilepsy group were also significantly lower than those in the control group(1.8925 ± 0.2004; 1.0941 ± 0.2372)(P<0.05). There were no significant differences in the ratios of NAA/Cr-PCr, NAA/(Cr-PCr+Cho), Cho/Cr- PCr, and mI/Cr-PCr between the bilateral thalamis in the epilepsy group (P>0.05). CONCLUSION There is neuronal dysfunction in the bilateral thalamus in the epilepsy group. Abnormal changes of the bilateral thalamus are involved in the mechanism of SGTCS.
Adolescent ; Adult ; Aspartic Acid ; analogs & derivatives ; analysis ; Brain Chemistry ; Case-Control Studies ; Choline ; analysis ; Energy Metabolism ; physiology ; Epilepsy, Generalized ; metabolism ; physiopathology ; Epilepsy, Tonic-Clonic ; metabolism ; physiopathology ; Female ; Humans ; Magnetic Resonance Spectroscopy ; methods ; Male ; Middle Aged ; Thalamus ; metabolism ; physiopathology ; Young Adult

Synaptic plasticity of barrel cortex is one of the most widely studied topics in neuroscience in recent years. The primary somatosensory cortex of the rodent has a good topology character,which provides an ideal experimental model for plasticity study. This system displays very strong experience-dependent plasticity both during development and in adulthood. The changes of sensory cortex's neural circuit can induce experience-dependent plasticity. In the synaptic level,thalamocortical synapse is considered to be the main location of plasticity. In the circuit level,both synapses from layer 4 to layer 2/3 and those within layer 2/3 are also the necessary parts of achieving synaptic plasticity in primary somatosensory cortex. The GABAergic inhibitory circuit may be involved in this plasticity of S1, but the exact mechanism remains unknown.
Animals ; Neural Pathways ; physiology ; Neuronal Plasticity ; Somatosensory Cortex ; physiology ; Synapses ; physiology ; Thalamus ; physiology ; Vibrissae ; physiology

The aim of this study was to evaluate the effect of early motor balance and coordination training on functional recovery and brain plasticity in an ischemic rat stroke model, compared with simple locomotor exercise. Adult male Sprague-Dawley rats with cortical infarcts were trained under one of four conditions: nontrained control, treadmill training, motor training on the Rota-rod, or both Rota-rod and treadmill training. All types of training were performed from post-operation day 1 to 14. Neurological and behavioral performance was evaluated by Menzies' scale, the prehensile test, and the limb placement test, at post-operation day 1, 7, and 14. Both Rota-rod and treadmill training increased the expression of synaptophysin in subcortical regions of the ischemic hemisphere including the hippocampus, dentate gyrus, and thalamus, but did not affect levels of brain-derived neurotrophic factor or tyrosin kinase receptor B. The Rota-rod training also improved Menzies' scale and limb placement test scores, whereas the simple treadmill training did neither. The control group showed significant change only in Menzies' scale score. This study suggests that early motor balance and coordination training may induce plastic changes in subcortical regions of the ischemic hemisphere after stroke accompanied with the recovery of sensorimotor performance.
Animals ; Brain Ischemia/metabolism/physiopathology ; Brain-Derived Neurotrophic Factor/metabolism ; Dentate Gyrus/metabolism ; Disease Models, Animal ; Hippocampus/metabolism ; Immunohistochemistry ; Male ; Motor Activity ; Neuronal Plasticity/physiology ; Physical Conditioning, Animal ; Physical Therapy Modalities ; Rats ; Rats, Sprague-Dawley ; Receptor, trkB/metabolism ; Stroke/*metabolism/physiopathology ; Synaptophysin/*metabolism ; Thalamus/metabolism ; Time Factors

Acute pain is a warning protective sensation for any impending harm. However, chronic pain syndromes are often resistant diseases that may consume large amount of health care costs. It has been suggested by recent studies that pain perception may be formed in central neural networks via large-scale coding processes, which involves sensory, affective, and cognitive dimensions. Many central areas are involved in these processes, including structures from the spinal cord, the brain stem, the limbic system, to the cortices. Thus, chronic painful diseases may be the result of some abnormal coding within this network. A thorough investigation of coding mechanism of pain within the central neuromatrix will bring us great insight into the mechanisms responsible for the development of chronic pain, hence leading to novel therapeutic interventions for pain management.
Animals ; Cerebral Cortex ; physiology ; Humans ; Nociception ; physiology ; Pain ; physiopathology ; Thalamus ; physiology

OBJECTIVE: To detect the activation pattern of the thalamus in human by the functional magnetic resonance imaging (fMRI) with the electrical stimulation of different intensities, and to explore the mechanism of this area in pain modulation. METHODS: Ten healthy right-handed volunteers were given different electrical stimulations of 1-, 2-, and 3- times pain threshold respectively. The whole-brain was scanned simultaneously by GE 1.5T magnetic resonance imaging system. The data were postprocessed by analysis of functional neuroimages (AFNI) to establish the regional activity maps of the thalamus. RESULTS: Patterns of functional activity showed a positive linear relationship between the activation signals and stimulation intensity in bilateral thalamus, whereas the BOLD signal of bilateral medial thalamus demonstrated that the curve was similar to the exponential function. Meanwhile, the activation in the contralateral lateral thalamus (cThl), but not the contralateral medial thalamus (cThm), was prominent compared with the corresponding ipsilateral subregions, and only the lateral thalamus displayed a contralateral biased representation while the medial thalamus lacked this property. CONCLUSION Thalamus is one of the vital components in the pain modulation network, which can present spatial segregation activations with unique characteristics of stimulation intensity-response in each subregion. All the results are helpful to understand the crucial role of thalamus in processing the pain information.
Adult ; Electric Stimulation ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Pain ; physiopathology ; Pain Threshold ; Thalamus ; physiology

Acupuncture analgesia is involved in various functions of the whole nervous system. The spinal cord is the first station for processing and translating the acupuncture analgesia; the brain stem is the relay station for systematization, differentiation and analysis, excitation, synthesis of acupuncture analgesic message, playing an important role in acupuncture analgesia; the thalamus functions complicated analysis and comprehensive regulation on various messeges with many kinds of neurohumoral factors involved and it is a coordinate center for strengthening and controlling acupuncture analgesia; the limbic system and its nuclear groups with many neurotransmitters involved, play coordinate action on acupuncture analgesia; the cerebral cortex is the high center and functions not only excitation and inhibition processes, but also is a center for complicated regulation and command, strengthening acupuncture analgesia and inhibiting the excess, so as to exerts interaction of dynamic balance.
Acupuncture Analgesia ; Brain Stem ; physiology ; Cerebral Cortex ; physiology ; Humans ; Limbic System ; physiology ; Pain ; physiopathology ; Spinal Cord ; physiology ; Thalamus ; physiology