Fiber Microdissection Technique for Demonstrating the Deep Cerebellar Nuclei and Cerebellar Peduncles

2020 ◽  
Author(s):  
Nupur Pruthi ◽  
Paulo A S Kadri ◽  
Uğur Türe
Keyword(s):  
Cerebellar Nuclei ◽  
Operating Microscope ◽  
Deep Cerebellar Nuclei ◽  
Inferior Surface ◽  
Topographical Organization ◽  
Superior Surface ◽  
Cerebellar Peduncles ◽  
The Brain ◽  
Complex Parts ◽  
Formalin Fixed

Abstract BACKGROUND The cerebellum is one of the most primitive and complex parts of the human brain. The fiber microdissection technique can be extremely useful for neurosurgeons to understand the topographical organization of the cerebellum's important contents, such as the deep cerebellar nuclei and the cerebellar peduncles, and their relationship with the brain stem. OBJECTIVE To dissect the deep cerebellar nuclei and the cerebellar peduncles using the fiber microdissection technique. METHODS Under the operating microscope, 5 previously frozen, formalin-fixed human cerebellums and brain stems were dissected from the superior surface, and 5 were dissected from the inferior surface. Each stage of the process is described. The primary dissection tools were handmade, thin, wooden spatulas with tips of various sizes, toothpicks, and a fine regulated suction. RESULTS In 15 simplified dissection steps (6 for the superior surface and 9 for the inferior surface), the deep cerebellar nuclei (dentate, interpositus, and fastigial) and the cerebellar peduncles (inferior, middle, and superior) are delineated. Their anatomical relationships with each other and other neighboring structures are demonstrated. CONCLUSION The anatomy of the deep cerebellar nuclei and the cerebellar peduncles are clearly defined and understood through the use of the fiber microdissection technique. These stepwise dissections will guide the neurosurgeon in acquiring a topographical understanding of these complex and deep structures of the cerebellum. This knowledge, along with radiological information, can help in planning the most appropriate surgical strategy for various lesions of the cerebellum.

Morphological and Electrophysiological Properties of GABAergic and Non-GABAergic Cells in the Deep Cerebellar Nuclei

2007 ◽  
Vol 97 (1) ◽  
pp. 901-911 ◽  
Author(s):  
Marylka Uusisaari ◽  
Kunihiko Obata ◽  
Thomas Knöpfel
Keyword(s):  
Fluorescent Protein ◽  
Cerebellar Nuclei ◽  
Spike Rate ◽  
Deep Cerebellar Nuclei ◽  
Homogeneous Population ◽  
Electrophysiological Properties ◽  
Glutamatergic Neurons ◽  
Green Fluorescent ◽  
The Brain ◽  
High Firing

The deep cerebellar nuclei (DCN) integrate inputs from the brain stem, the inferior olive, and the spinal cord with Purkinje cell output from cerebellar cortex and provide the major output of the cerebellum. Despite their crucial function in motor control and learning, the various populations of neurons in the DCN are poorly defined and characterized. Importantly, differences in electrophysiological properties between glutamatergic and GABAergic cells of the DCN have been largely elusive. Here, we used glutamate decarboxylase (GAD) 67-green fluorescent protein (GFP) knock-in mice to unambiguously identify GABAergic (GAD-positive) and non-GABAergic (GAD-negative, most likely glutamatergic) neurons of the DCN. Morphological analysis of DCN neurons patch-clamped with biocytin-containing electrodes revealed a significant overlap in the distributions of the soma sizes of GAD-positive and GAD-negative cells. Compared with GAD-negative DCN neurons, GAD-positive DCN neurons fire broader action potentials, display stronger frequency accommodation, and do not reach as high firing frequencies during depolarizing current injections. Furthermore, GAD-positive cells display slower spontaneous firing rates and have a more shallow frequency-to-current relationship than the GAD-negative cells but exhibit a longer-lasting rebound depolarization and associated spiking after a transient hyperpolarization. In contrast to the rather homogeneous population of GAD-positive cells, the GAD-negative cells were found to consist of two distinct populations as defined by cell size and electrophysiological features. We conclude that GABAergic DCN neurons are specialized to convey phasic spike rate information, whereas tonic spike rate is more faithfully relayed by the large non-GABAergic cells.

scholarly journals Mapping of long-term cognitive and motor deficits in pediatric cerebellar brain tumor survivors into a cerebellar white matter atlas

2021 ◽  
Author(s):  
Frederik Grosse ◽  
Stefan Mark Rueckriegel ◽  
Ulrich-Wilhelm Thomale ◽  
Pablo Hernáiz Driever
Keyword(s):  
Brain Tumor ◽  
Executive Function ◽  
Cognitive Function ◽  
White Matter ◽  
Cerebellar Nuclei ◽  
Motor Deficits ◽  
Deep Cerebellar Nuclei ◽  
Cerebellar White Matter ◽  
Lesion Symptom Mapping

Abstract Purpose Diaschisis of cerebrocerebellar loops contributes to cognitive and motor deficits in pediatric cerebellar brain tumor survivors. We used a cerebellar white matter atlas and hypothesized that lesion symptom mapping may reveal the critical lesions of cerebellar tracts. Methods We examined 31 long-term survivors of pediatric posterior fossa tumors (13 pilocytic astrocytoma, 18 medulloblastoma). Patients underwent neuronal imaging, examination for ataxia, fine motor and cognitive function, planning abilities, and executive function. Individual consolidated cerebellar lesions were drawn manually onto patients’ individual MRI and normalized into Montreal Neurologic Institute (MNI) space for further analysis with voxel-based lesion symptom mapping. Results Lesion symptom mapping linked deficits of motor function to the superior cerebellar peduncle (SCP), deep cerebellar nuclei (interposed nucleus (IN), fastigial nucleus (FN), ventromedial dentate nucleus (DN)), and inferior vermis (VIIIa, VIIIb, IX, X). Statistical maps of deficits of intelligence and executive function mapped with minor variations to the same cerebellar structures. Conclusion We identified lesions to the SCP next to deep cerebellar nuclei as critical for limiting both motor and cognitive function in pediatric cerebellar tumor survivors. Future strategies safeguarding motor and cognitive function will have to identify patients preoperatively at risk for damage to these critical structures and adapt multimodal therapeutic options accordingly.

Streptococcus pluranimalium meningoencephalitis in a horse

2021 ◽  
pp. 104063872110234
Author(s):  
Dah-Jiun Fu ◽  
Akhilesh Ramachandran ◽  
Craig Miller
Keyword(s):  
Ribosomal Rna ◽  
Cross Sections ◽  
Nucleotide Sequencing ◽  
Formalin Fixed Paraffin ◽  
Quarter Horse ◽  
Formalin Fixed Paraffin Embedded ◽  
History Of ◽  
The Brain ◽  
Gram Positive Cocci ◽  
Formalin Fixed

A 3-y-old, female Quarter Horse with a history of acute neurologic signs was found dead and was submitted for postmortem examination. Areas of petechial and ecchymotic hemorrhage were present on cross-sections of the cerebrum, cerebellum, and brainstem. Histologic examination of the brain revealed severe, purulent meningoencephalitis and vasculitis with a myriad of intralesional gram-positive cocci. Streptococcus pluranimalium was identified from formalin-fixed, paraffin-embedded tissue obtained from sites with active lesions by PCR and nucleotide sequencing of bacterial 16S ribosomal RNA. S. pluranimalium should be considered as a cause of meningoencephalitis in a horse.

scholarly journals A model of on/off transitions in neurons of the deep cerebellar nuclei: deciphering the underlying ionic mechanisms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hugues Berry ◽  
Stéphane Genet
Keyword(s):  
Cerebellar Nuclei ◽  
Biophysical Model ◽  
High Threshold ◽  
Deep Cerebellar Nuclei ◽  
Functional Link ◽  
Electrophysiological Properties ◽  
Voltage Dependent ◽  
Ionic Mechanisms ◽  
The Central Nervous System ◽  
Overall Functioning

AbstractThe neurons of the deep cerebellar nuclei (DCNn) represent the main functional link between the cerebellar cortex and the rest of the central nervous system. Therefore, understanding the electrophysiological properties of DCNn is of fundamental importance to understand the overall functioning of the cerebellum. Experimental data suggest that DCNn can reversibly switch between two states: the firing of spikes (F state) and a stable depolarized state (SD state). We introduce a new biophysical model of the DCNn membrane electro-responsiveness to investigate how the interplay between the documented conductances identified in DCNn give rise to these states. In the model, the F state emerges as an isola of limit cycles, i.e. a closed loop of periodic solutions disconnected from the branch of SD fixed points. This bifurcation structure endows the model with the ability to reproduce the $\text{F}\to \text{SD}$ F → SD transition triggered by hyperpolarizing current pulses. The model also reproduces the $\text{F}\to \text{SD}$ F → SD transition induced by blocking Ca currents and ascribes this transition to the blocking of the high-threshold Ca current. The model suggests that intracellular current injections can trigger fully reversible $\text{F}\leftrightarrow \text{SD}$ F ↔ SD transitions. Investigation of low-dimension reduced models suggests that the voltage-dependent Na current is prominent for these dynamical features. Finally, simulations of the model suggest that physiological synaptic inputs may trigger $\text{F}\leftrightarrow \text{SD}$ F ↔ SD transitions. These transitions could explain the puzzling observation of positively correlated activities of connected Purkinje cells and DCNn despite the former inhibit the latter.

Experimental intracerebral and subarachnoid/intraventricular haemorrhages: MR detectability at 0.5 T and 1.5 T

2002 ◽  
Vol 43 (5) ◽  
pp. 464-473
Author(s):  
M. Alemany Ripoll ◽  
R. Raininko
Keyword(s):  
Cerebrospinal Fluid ◽  
Mr Imaging ◽  
Spin Echo ◽  
Autologous Blood ◽  
Pulse Sequences ◽  
Proton Density ◽  
Gradient Echo ◽  
The Brain ◽  
Formalin Fixed

Purpose: To compare the detectability of small experimental intracranial haemorrhages on MR imaging at 0.5 T and 1.5 T, from hyperacute to subacute stages. Material and Methods: 1 ml of autologous blood was injected into the brain of 15 rabbits to create intraparenchymal haematomas. Since the blood partially escaped into the cerebrospinal fluid (CSF) spaces, detectability of subarachnoid and intraventricular blood was also evaluated. MR imaging at 0.5 T and at 1.5 T was repeated up to 14 days, including T1-, proton density- and T2-weighted (w) spin-echo (SE), FLAIR and T2*-w gradient echo (GE) pulse sequences. The last MR investigation was compared to the formalin-fixed brain sections in 7 animals. Results: The intraparenchymal haematomas were best revealed with T2*-w GE sequences, with 100% of sensitivity at 1.5 T and 90–95% at 0.5 T. Blood in the CSF spaces was significantly ( p < 0.05) better detected at 1.5 T with T2*-w GE sequences and detected best during the first 2 days. The next most sensitive sequence for intracranial blood was FLAIR. SE sequences were rather insensitive. Conclusion: 1.5 T equipment is superior to 0.5 T in the detection of intracranial haemorrhages from acute to subacute stages. T2*-w GE sequences account for this result but other sequences are also needed for a complete examination.

scholarly journals Cerebellar Theta-Burst Stimulation Impairs Memory Consolidation in Eyeblink Classical Conditioning

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jessica Monaco ◽  
Lorenzo Rocchi ◽  
Francesca Ginatempo ◽  
Egidio D'Angelo ◽  
John C. Rothwell
Keyword(s):  
Classical Conditioning ◽  
Cerebellar Nuclei ◽  
Cerebellar Hemisphere ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Deep Cerebellar Nuclei ◽  
Significant Impairment ◽  
Conditioned Responses ◽  
The Right ◽  
Theta Burst

Associative learning of sensorimotor contingences, as it occurs in eyeblink classical conditioning (EBCC), is known to involve the cerebellum, but its mechanism remains controversial. EBCC involves a sequence of learning processes which are thought to occur in the cerebellar cortex and deep cerebellar nuclei. Recently, the extinction phase of EBCC has been shown to be modulated after one week by cerebellar continuous theta-burst stimulation (cTBS). Here, we asked whether cerebellar cTBS could affect retention and reacquisition of conditioned responses (CRs) tested immediately after conditioning. We also investigated a possible lateralized cerebellar control of EBCC by applying cTBS on both the right and left cerebellar hemispheres. Both right and left cerebellar cTBSs induced a statistically significant impairment in retention and new acquisition of conditioned responses (CRs), the disruption effect being marginally more effective when the left cerebellar hemisphere was stimulated. These data support a model in which cTBS impairs retention and reacquisition of CR in the cerebellum, possibly by interfering with the transfer of memory to the deep cerebellar nuclei.

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