Cerebellar cortical activity during stretch of antagonist muscles

1986 ◽  
Vol 64 (9) ◽  
pp. 1202-1213 ◽  
Author(s):  
Daniel Bourbonnais ◽  
Charles Krieger ◽  
Allan M. Smith
Keyword(s):  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Muscle Length ◽  
Thoracic Spinal Cord ◽  
Muscle Stretch ◽  
Thoracic Spinal ◽  
Antagonist Muscles ◽  
Discharge Patterns ◽  
Dynamic Stretch ◽  
Complex Spikes

Single unit activity was recorded from the anterior lobe of the cerebellum during ramp and hold stretches of limb muscles in chloralose anesthetized cats. The activity of 95 "phasic" units showed a transient response during dynamic stretch of at least one muscle usually lasting for less than 350 ms following the stimulus onset. The activity of 59 phasic–tonic units was modified not only during dynamic stretch but also during the 1 s of maintained muscle length. All Purkinje cells, identified by their complex spikes, that responded to muscle stretch demonstrated exclusively phasic changes in discharge. Fourteen of 25 Purkinje cells (56%) responded to stretch of both antagonist muscles and these responses were always similar rather than reciprocal. From the 129 units without complex spikes, 70 demonstrated phasic discharge patterns whereas 59 had tonic responses. Seventy-five (59%) of these unidentified units revealed convergent responses to stretch of both antagonists, compared with 54 which responded to stretch of one muscle only. Of the unidentified units receiving convergent afferents from antagonist muscles, 62 (83%) had similar responses and only 13 (17%) had reciprocal reactions. There appeared to be no evidence that muscle afferents alone can induce reciprocal discharge patterns in Purkinje neurons of the cerebellar cortex. The firing frequency of some phasic–tonic units was correlated with both the velocity and amplitude of muscle stretch. No Purkinje cells were found with activity related to either velocity or amplitude of muscle stretch. One phasic and seven phasic–tonic unidentified units were activated at fixed latencies following trains of electrical stimulation applied to the thoracic spinal cord at frequencies exceeding 200 Hz, implying they were terminal portions of mossy fibers originating from direct spinocerebellar tracts. A few recordings of compound potentials were presumed to arise from the cerebellar glomeruli. The changing form of one of these potentials suggested that the glomerulus might be a site at which somatosensory peripheral information is modified by the cerebellar cortex.

scholarly journals Transcranial direct current stimulation of cerebellum alters spiking precision in cerebellar cortex: A modeling study of cellular responses

2021 ◽  
Vol 17 (12) ◽  
pp. e1009609
Author(s):  
Xu Zhang ◽  
Roeland Hancock ◽  
Sabato Santaniello
Keyword(s):  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Cellular Response ◽  
Cerebellar Neurons ◽  
Direct Current Stimulation ◽  
Repolarization Phase ◽  
Cerebellar Tdcs ◽  
Complex Spikes

Transcranial direct current stimulation (tDCS) of the cerebellum has rapidly raised interest but the effects of tDCS on cerebellar neurons remain unclear. Assessing the cellular response to tDCS is challenging because of the uneven, highly stratified cytoarchitecture of the cerebellum, within which cellular morphologies, physiological properties, and function vary largely across several types of neurons. In this study, we combine MRI-based segmentation of the cerebellum and a finite element model of the tDCS-induced electric field (EF) inside the cerebellum to determine the field imposed on the cerebellar neurons throughout the region. We then pair the EF with multicompartment models of the Purkinje cell (PC), deep cerebellar neuron (DCN), and granule cell (GrC) and quantify the acute response of these neurons under various orientations, physiological conditions, and sequences of presynaptic stimuli. We show that cerebellar tDCS significantly modulates the postsynaptic spiking precision of the PC, which is expressed as a change in the spike count and timing in response to presynaptic stimuli. tDCS has modest effects, instead, on the PC tonic firing at rest and on the postsynaptic activity of DCN and GrC. In Purkinje cells, anodal tDCS shortens the repolarization phase following complex spikes (-14.7 ± 6.5% of baseline value, mean ± S.D.; max: -22.7%) and promotes burstiness with longer bursts compared to resting conditions. Cathodal tDCS, instead, promotes irregular spiking by enhancing somatic excitability and significantly prolongs the repolarization after complex spikes compared to baseline (+37.0 ± 28.9%, mean ± S.D.; max: +84.3%). tDCS-induced changes to the repolarization phase and firing pattern exceed 10% of the baseline values in Purkinje cells covering up to 20% of the cerebellar cortex, with the effects being distributed along the EF direction and concentrated in the area under the electrode over the cerebellum. Altogether, the acute effects of tDCS on cerebellum mainly focus on Purkinje cells and modulate the precision of the response to synaptic stimuli, thus having the largest impact when the cerebellar cortex is active. Since the spatiotemporal precision of the PC spiking is critical to learning and coordination, our results suggest cerebellar tDCS as a viable therapeutic option for disorders involving cerebellar hyperactivity such as ataxia.

The coactivation of antagonist muscles

1981 ◽  
Vol 59 (7) ◽  
pp. 733-747 ◽  
Author(s):  
Allan M. Smith
Keyword(s):  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Precision Grip ◽  
Reciprocal Inhibition ◽  
Inhibitory Neurons ◽  
Voluntary Movements ◽  
Renshaw Cells ◽  
Power Grip ◽  
Antagonist Muscles ◽  
Antagonist Coactivation

Since Sherrington's convincing demonstration of the reciprocal innervation of opposing muscles, it has generally been thought that antagonist muscles are inactive during most voluntary movements. However, more recent evidence suggests that excitation of Renshaw cells may facilitate antagonist coactivation whereas excitation of Ia inhibitory neurons can induce reciprocal inhibition. A body of evidence has accumulated to indicate some of the circumstances which particularly favour the co-contraction of antagonist muscles. Isometric prehension, either in the precision grip or the power grip, can be shown to be one of the most important examples of antagonist coactivation. Studies of the discharge of single Purkinje cells of the intermediate cerebellar cortex in awake monkeys during performance of a maintained grip revealed that the majority of these neurons are deactivated during antagonist co-contraction. In contrast, other, unidentified neurons of the cerebellar cortex were as a group activated during grasping. It is suggested that the Purkinje cells act to inhibit antagonist muscles during reciprocal inhibition but are themselves inhibited during antagonist coactivation. These results support a suggestion made by Tilney and Pike in 1925 that the cerebellum plays an important role in switching between the coactivation and reciprocal inhibition of antagonist muscles.

Cerebellar cortical activity during antagonist cocontraction and reciprocal inhibition of forearm muscles

1984 ◽  
Vol 51 (1) ◽  
pp. 32-49 ◽  
Author(s):  
R. C. Frysinger ◽  
D. Bourbonnais ◽  
J. F. Kalaska ◽  
A. M. Smith
Keyword(s):  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Discharge Frequency ◽  
Wrist Movement ◽  
Movement Velocity ◽  
Wrist Position ◽  
Forearm Muscles ◽  
Antagonist Muscles ◽  
Primary Fissure ◽  
Flexion And Extension

Monkeys were trained to perform a maintained isometric grip of the thumb and forefinger that elicited a simultaneous cocontraction of the antagonist muscles of the forearm. The same monkeys were also trained to flex and extend the wrist against a stop with the fingers extended and to maintain an isometric wrist position for 1.0-1.5 s. During wrist movement, some of the synergist forearm muscles contracted during both flexion and extension. However, during the maintained isometric wrist position, the prime mover and synergist muscles were reciprocally active or silent. In the culmen-simplex region of the cerebellar cortex bordering on the primary fissure, 62% of the Purkinje cells that were identified by the climbing fiber discharge and that changed firing frequency decreased activity during maintained prehension. Almost all of these same Purkinje cells were reciprocally active during isometric wrist flexion and extension, although three neurons had similar discharge patterns during movements in both directions. In contrast, 79% of the unidentified neurons recorded from the same region of the cerebellar cortex increased discharge frequency during prehension. In general, most of these same neurons had reciprocal patterns of discharge during wrist movement even though a few cells were active during the dynamic phase in both directions. Together, the Purkinje cells and the unidentified neurons with bidirectional response patterns were thought to be related to muscles active during both flexion and extension wrist movements. No cells were found that increased discharge with the static isometric wrist torque exerted in both directions. The discharge frequency of some Purkinje and some unidentified neurons could be shown to be related to prehensile force as well as wrist movement velocity and isometric wrist torque. These data suggest that the discharge of about two-thirds of the Purkinje cells related to forearm muscles located along the borders of the primary fissure may depend on whether antagonist muscles are activated reciprocally or coactively. As a consequence, these cells may play a role in the selection or alternation between either of these two modes of muscular contraction. The increased discharge of the remaining one-third of the Purkinje cells excited during antagonist coactivation may provide inhibition of nuclear cells to stabilize the posture at joints other than the wrist and fingers or, alternatively, they may act to reduce nuclear cell discharge in proportion to the intensity of cutaneous stimulation.

Identification and discharge patterns of spinal sympathetic interneurons

1976 ◽  
Vol 231 (3) ◽  
pp. 722-733 ◽  
Author(s):  
GL Gebber ◽  
RB McCall
Keyword(s):  
Cardiac Cycle ◽  
Time Interval ◽  
Cell Column ◽  
Thoracic Spinal Cord ◽  
Antidromic Activation ◽  
Preganglionic Neurons ◽  
Thoracic Spinal ◽  
Cervical Sympathetic ◽  
Discharge Patterns ◽  
Spinal Inhibition

Sympathetic interneurons, in the vicinity of the intermediolateral cell column of the cat thoracic spinal cord, were identified by determining whether the probability of spontaneously occurring unitary discharge was correlated in time with the R wave of the ECG. Fifteen units which could not be antidromically activated by stimulation of the cervical sympathetic nerve exhivited a positive post-R wave relationship. The discharge patterns of these cells were distinctly different from those of antidromically identified preganglionic neurons. The interneurons discharged spontaneously in bursts with short interspike intervals (less than 20 ms). Preganglionic neurons rarely discharged more than once during a cardiac cycle. Single shocks applied to medullary pressor sites evoked a train of spikes in the interneurons. Preganglionic units usually discharged only once to medullary pressor stimulation. Electrial activation of medullospinal inhibitory tracts suppressed the discharges of both interneurons and preganclionic units. This observation indicates that spinal inhibition is exerted at an interneuronal level within sympathoexictatory pathways. No evidence was found for the existence of inhibitory interneurons in the intermediolateral cell column. This study demonstrated that the post-R wave time interval histogram in combination with a test for antidromic activation can be used to differentiate between spinal sympathetic internuerons and preganglionic cells.

scholarly journals A spike-sorting method based on hierarchical clustering to discriminate extracellularly recorded simple spikes and complex spikes from cerebellar Purkinje cells

2021 ◽  
Author(s):  
Takayuki Michikawa ◽  
Keisuke Isobe ◽  
Shigeyoshi Itohara
Keyword(s):  
Purkinje Cell ◽  
Purkinje Cells ◽  
Quantitative Evaluation ◽  
Cerebellar Cortex ◽  
Single Unit ◽  
Spike Sorting ◽  
Sorting Method ◽  
Single Unit Recordings ◽  
Cerebellar Purkinje Cells ◽  
Complex Spikes

Background: In the cerebellar cortex, Purkinje cells are the only output neurons and exhibit two types of discharge. Most Purkinje cell discharges are simple spikes, which are commonly appearing action potentials exhibiting a rich variety of firing patterns with a rate of up to 400 Hz. More infrequent discharges are complex spikes, which consist of a short burst of impulses accompanied by a massive increase in dendritic Ca2+ with a firing rate of around 1 Hz. The discrimination of these spikes in extracellular single-unit recordings is not always straightforward, as their waveforms vary depending on recording conditions and intrinsic fluctuations. New Method: To discriminate complex spikes from simple spikes in the extracellular single-unit data, we developed a semiautomatic spike-sorting method based on divisive hierarchical clustering. Results: Quantitative evaluation using parallel in vivo two-photon Ca2+ imaging of Purkinje cell dendrites indicated that 96.6% of the complex spikes were detected using our spike-sorting method from extracellular single-unit recordings obtained from anesthetized mice. Comparison with Existing Method(s): No reports have conducted a quantitative evaluation of spike-sorting algorithms used for the classification of extracellular spikes recorded from cerebellar Purkinje cells. Conclusions: Our method could be expected to contribute to research in information processing in the cerebellar cortex and the development of a fully automatic spike-sorting algorithm by providing ground-truth data useful for deep learning.

Spontaneous Herniation of the Thoracic Spinal Cord: A Case Report

2001 ◽  
Vol 45 (4) ◽  
pp. 353 ◽  
Author(s):  
Sung Chan Jin ◽  
Seoung Ro Lee ◽  
Dong Woo Park ◽  
Kyung Bin Joo
Keyword(s):  
Spinal Cord ◽  
Case Report ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Spontaneous Herniation

Lipomeningocele associated with diplomyelia in a dog

2018 ◽  
Vol 46 (05) ◽  
pp. 323-329 ◽  
Author(s):  
Nele Ondreka ◽  
Sara Malberg ◽  
Emma Laws ◽  
Martin Schmidt ◽  
Sabine Schulze
Keyword(s):  
Spinal Cord ◽  
Neurological Status ◽  
Split Cord Malformation ◽  
Lumbar Spinal Cord ◽  
Histopathological Diagnosis ◽  
Type I ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Subcutaneous Mass ◽  
Lumbar Spinal

SummaryA 2-year-old male neutered mixed breed dog with a body weight of 30 kg was presented for evaluation of a soft subcutaneous mass on the dorsal midline at the level of the caudal thoracic spine. A further clinical sign was intermittent pain on palpation of the area of the subcutaneous mass. The owner also described a prolonged phase of urination with repeated interruption and re-initiation of voiding. The findings of the neurological examination were consistent with a lesion localization between the 3rd thoracic and 3rd lumbar spinal cord segments. Magnetic resonance imaging revealed a spina bifida with a lipomeningocele and diplomyelia (split cord malformation type I) at the level of thoracic vertebra 11 and 12 and secondary syringomyelia above the aforementioned defects in the caudal thoracic spinal cord. Surgical resection of the lipomeningocele via a hemilaminectomy was performed. After initial deterioration of the neurological status postsurgery with paraplegia and absent deep pain sensation the dog improved within 2 weeks to non-ambulatory paraparesis with voluntary urination. Six weeks postoperatively the dog was ambulatory, according to the owner. Two years after surgery the owner recorded that the dog showed a normal gait, a normal urination and no pain. Histopathological diagnosis of the biopsied material revealed a lipomeningocele which confirmed the radiological diagnosis.

Primary Melanocytoma of the Lower Thoracic Spinal Cord: Case report and review of the literature

2019 ◽  
Vol 8 (1) ◽  
pp. 5
Author(s):  
Dimitrios Panagopoulos
Keyword(s):  
Total Resection ◽  
Thoracic Spinal Cord ◽  
Meningeal Melanocytoma ◽  
Melanocytic Tumors ◽  
Thoracic Spinal ◽  
Thoracolumbar Region ◽  
Rare Benign Tumor ◽  
Mri Scans ◽  
History Of ◽  
The Central Nervous System

Background: Meningeal melanocytoma is a rare benign tumor, most frequently located in the posterior fossa and spinal canal. Our objective is to illustrate a case of this tumor that originated in the thoracolumbar area of the spine and had an uneventful clinical course after total resection. Case description: We present the case of a 59 years old woman who presented with a medical history of ongoing neurological deterioration due to spastic paresis of the lower extremities. MRI of the thoracolumbar region identified a melanocytic melanoma as the underlying cause. Conclusions: Melanocytic tumors of the central nervous system have a typical appearance on MRI scans, varying with the content and distribution of melanin. However, the differential diagnosis between malignant melanoma and melanocytoma still depends on pathological criteria. Spinal meningeal melanocytoma has a benign course, and it is amenable for gross total resection. The outcome is favorable following complete resection.

Sign in / Sign up

Export Citation Format

Share Document