No abstract available.
Cerebellar Nuclei* ; Myoclonus*

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.
Axons ; Cerebellar Nuclei ; Cerebellum ; Thalamic Nuclei

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

Cerebellum is known as a center for sensory/motor coordination and memory storage in motor learning. The vestibular nuclei have extensive afferent and efferent connections with posterior cerebellum which can be referred to as vestibulocerebellum. While secondary vestibular afferents are distributed bilaterally in the vestibulocerebellum, primary afferents may directly project to ipsilateral vestibulocerebellum. The Purkinje cells which are the only output neurons from the cerebellar cortex receive vestibular information via parallel and climbing fibers. That information is integrated and encoded in the Purkinje cells and then conveyed into the vestibular nucleus or deep cerebellar nucleus, which permits adaptive guidance of vestibular function by the vestibulocerebellum.
Cerebellar Cortex ; Cerebellar Nuclei ; Cerebellum ; Electrophysiology ; Learning ; Membranes ; Memory ; Neurons ; Patch-Clamp Techniques ; Purkinje Cells ; Vestibular Nuclei

Transient mutism resolving to cerebellar speech after posterior fossa surgery is a well recognized phenomenon, particularly in pediatric patients. The anatomic basis for this postoperative functional change is unclear, but may reside in the dominant superior cerebellar hemisphere or the medial deep cerebellar nuclei. We report a case of a 9-year-old boy who presented for surgical resection of a medulloblastoma. Preoperatively, his complaint consisted of headache, nausea, vomiting and cerebellar ataxia. He had normal speech. At one day after operation, suddenly he was unable to speech, however, communication through a variety of verbal cues, including sign language was possible. His mutism lasted 12 days and cerebellar dysarthria was slowly resolved.
Cerebellar Ataxia ; Cerebellar Nuclei ; Child* ; Cues ; Dysarthria ; Headache ; Humans ; Male ; Medulloblastoma* ; Mutism* ; Nausea ; Sign Language ; Vomiting

What is memory? How does the brain process the sensory information and modify an organism's behavior? Many neuroscientists have focused on the activity- and experience-dependent modifications of synaptic functions in order to solve these fundamental questions in neuroscience. Recently, the plasticity of intrinsic excitability (called intrinsic plasticity) has emerged as an important element for information processing and storage in the brain. As the cerebellar Purkinje cells are the sole output neurons in the cerebellar cortex and the information is conveyed from a neuron to its relay neurons by forms of action potential firing, the modulation of the intrinsic firing activity may play a critical role in the cerebellar learning. Many voltage-gated and/or Ca²⁺-activated ion channels are involved in shaping the spiking output as well as integrating synaptic inputs to finely tune the cerebellar output. Recent studies suggested that the modulation of the intrinsic excitability and its plasticity in the cerebellar Purkinje cells might function as an integrator for information processing and memory formation. Moreover, the intrinsic plasticity might also determine the strength of connectivity to the sub-cortical areas such as deep cerebellar nuclei and vestibular nuclei to trigger the consolidation of the cerebellar-dependent memory by transferring the information.
Action Potentials ; Automatic Data Processing ; Brain ; Cerebellar Cortex ; Cerebellar Nuclei ; Cerebellum ; Fires ; Ion Channels ; Learning* ; Memory ; Neuronal Plasticity ; Neurons ; Neurosciences ; Plastics* ; Purkinje Cells* ; Vestibular Nuclei

Through the use of stereotactic neurosurgical operation, some authors have employed chronic electrical stimulation of the dentate nucleus spasticity and each trial on spastic patients has show marked clinical improvement. We investigated the electrophysiological changes of cats after stereotactic electrical stimulation of the dentate nucleus to elucidate the possibility of clinical application and to evaluate the clinical results. The M-wave is an initial response and the F-wave is a late response in the electromyography of a muscle, which is stimulated by its original controlling nerve itself. There is evidence that the size of the F-wave is dependent on motor neuron excitability and its amplitude is increased significantly at spastic condition. If such a relationship exists, procedures which are carried out to relieve spasticity might be exerted to change the F-wave size and thus it might be possible to use the F-wave as an objective monitor during electrical stimulation of the dentate nucleus. We investigated this possibility in experiments on 10cats weighing between 2.7 Kg and 4.4 Kg. We studied the changes of M and F waves, recorded in EMG, after stereotactic stimulation to cerebellar dentate nucleus in cats. The results were as follows : 1) The change of mean value of M-wave amplitude was not significant(control group, 3591+/-1029 microV : stimulation group, 3424+/-927 microV, P>0.05). 2) The mean value of F-wave amplitude was significantly reduced about 56.7% after the dentate stimulation(control group, 443.2+/-119 microV : stimulation group, 251.3+/-99.4 microV, P<0.05). 3) The F/M ratio also significantly reduced, about 56.8% after the dentate stimulation(control group, 12.5+/-1.9%, stimulation group, 7.1+/-1.2%, P<0.05). Our experimental results demonstrated that the dentate stimulation markedly decreased the size of F-wave amplitude and F/M ration in the experimental cats and we concluded that these electrophysiological changes can be applied as a parameter of clinical evaluation of electrical dentate stimulation for the spasticity.
Animals ; Cats* ; Cerebellar Nuclei* ; Cerebellum ; Electric Stimulation ; Electromyography ; Humans ; Motor Neurons ; Muscle Spasticity ; Muscle, Skeletal*

Wernicke's encephalopathy (WE) is an acute neuropsychiatric syndrome resulting from thiamine deficiency. Traditionally, diagnosis of WE rests on a clinical symptom triad consisting of ocular signs, altered consciousness, and ataxia. However, the complete triad is only present in a fraction of cases, which means that WE tends to be under-diagnosed, especially in nonalcoholic patients. Brain MRI of WE patients usually shows symmetrical signal intensity alterations in the thalami, mammillary bodies, and periaqueductal area, because of cytotoxic edema in the same region. These typical findings are useful diagnostic leads in WE patients with atypical symptoms. However, atypical findings can occasionally be seen in the vermis of cerebellum and cerebellar nuclei. Notably, alterations of signal intensity in the cerebellar dentate nuclei, which is a typical finding of metronidazole-induced encephalopathy (MIE), need to be distinguished according to medication history and response to thiamine.
Ataxia ; Brain ; Cerebellar Nuclei ; Cerebellum ; Consciousness ; Edema ; Humans ; Mamillary Bodies ; Metronidazole ; Thiamine ; Thiamine Deficiency ; Wernicke Encephalopathy

PURPOSE: Palatal myoclonus(PM) is an involuntary cyclic movement of the soft palate and is known to be caused by the hypertrophic degeneration of the inferior oilvary nucleus of the medulla, secondary to the dentato-rubro-tegmental tract lesions. Our purpose is to describe the brain magnetic resonance(MR) imaging findings in palatal myoclonus. MATERIALS AND METHODS: We retrospectively analyzed the locations and causes of primary lesions in the dentato-rubro-tegmental tract and correlated them with changes in MR signal intensity and size of the inferior olive on T2-weighted MR images in 10 patients with palatal myoclonus. RESULTS: All cases showed hyperintensity in one or both inferior olive and six cases showed accompaning enlargement. The locations of the primary lesions were dorsal aspect of pons(central tegmental tract) in eight patients and the dentate nucleus in one, and no lesion was found in the dentato-rubro-tegmental tract in one. Among eight patients who had lesions in the ports, the ipsilateral inferior olivary nuclei showed changes in five and bilateral olive were involved in three. In the case with a lesion in the dentate nucleus, the contralateral inferior olivary nucleus was involved. The causes of primary lesions were hemorrhage in eight cases and traumatic brain stem injury in one. CONCLUSION: MR specifically showed enlargement and hyperintensity of the inferior olivary nucleus on T2-weighted images and matching lesions in the ports or the dentate nucleus in patients with palatal myoclonus.
Brain ; Brain Stem ; Cerebellar Nuclei ; Hemorrhage ; Humans ; Myoclonus ; Olea ; Olivary Nucleus ; Palate, Soft ; Retrospective Studies

We investigated the location of neurons related to lateral rectus muscle in the cerebellum of rats. Horseradish peroxidase (HRP) and Pseudorabies virus (PRV) were injected into right lateral rectus muscle of rats. After 84~90 hours, cardiac perfusion was performed with 4% paraformaldehyde in HRP injection group and 4% paraformaldehyde-lysine-periodate in PRV injection group. Tetramethylbenzidine (TMB) neurohistochemical stain in HRP injection group and immuno-histochemical stain in PRV injection group were performed after frozen section. HRP-reactive neuronal cells were observed in ipsilateral abducens nucleus. PRV-immunoreactive neuronal cells were observed ipsilaterally in abducens nucleus, flocculus, paraflocculus, ansiform lobule, declive, dentate nucleus, infracerebellar nucleus and y nucleus and also bilaterally in nodulus, lobulus centralis, lingula, uvula vermis and fastigial nucleus. These findings show the existence of neuronal projection from the abducens nucleus to the cerebellum. This projection could be part of nerve circuits through which the cerebellum modulates visuomotor activities.
Animals ; Cerebellar Nuclei ; Cerebellum* ; Frozen Sections ; Herpesvirus 1, Suid* ; Horseradish Peroxidase ; Neurons* ; Perfusion ; Pseudorabies* ; Rats* ; Uvula