Consensus Paper: Experimental Neurostimulation of the Cerebellum.

The cerebellum is best known for its role in controlling motor behaviors. However, recent work supports the view that it also influences non-motor behaviors. The contribution of the cerebellum towards different brain functions is underscored by its involvement in a diverse and increasing number of neurological and neuropsychiatric conditions including ataxia, dystonia, essential tremor, Parkinson's disease (PD), epilepsy, stroke, multiple sclerosis, autism spectrum disorders, dyslexia, attention deficit hyperactivity disorder (ADHD), and schizophrenia.

The role of the cerebellum in reconstructing social action sequences: a pilot study.

Recent research has revealed that the cerebellum plays a critical role in social reasoning and in particular in understanding false beliefs and making trait attributions. One hypothesis is that the cerebellum is responsible for the understanding of sequences of motions and actions, which may be a prerequisite for social understanding. To investigate the role of action sequencing in mentalizing, we tested patients with generalized cerebellar degenerative lesions on tests of social understanding and compared their performance with matched healthy volunteers.

A Postural Tremor Highly Responsive to Transcranial Cerebello-Cerebral DCS in ARCA3.

Background And Objectives: Cerebellar ataxias are disabling disorders that impact the quality of life of patients. In many cases, an effective treatment is missing. Despite the increasing knowledge on the pathogenesis of cerebellar disorders including genetic aspects, there is currently a gap in the therapeutical management of cerebellar deficits.

The in vivo reduction of afferent facilitation induced by low frequency electrical stimulation of the motor cortex is antagonized by cathodal direct current stimulation of the cerebellum.

Background: Low-frequency electrical stimulation to the motor cortex (LFSMC) depresses the excitability of motor circuits by long-term depression (LTD)-like effects. The interactions between LFSMC and cathodal direct current stimulation (cDCS) over the cerebellum are unknown.

Methods: We assessed the corticomotor responses and the afferent facilitation of corticomotor responses during a conditioning paradigm in anaesthetized rats.

Marked reduction of cerebellar deficits in upper limbs following transcranial cerebello-cerebral DC stimulation: tremor reduction and re-programming of the timing of antagonist commands.

Cerebellar ataxias represent a very heterogeneous group of disabling disorders for which we lack effective symptomatic therapies in most cases. There is currently an intense interest in the use of non-invasive transcranial DC stimulation (tDCS) to modulate the activity of the cerebellum in ataxic disorders. We performed a detailed laboratory assessment of the effects of transcranial cerebello-cerebral DC stimulation (tCCDCS, including a sham procedure) on upper limb tremor and dysmetria in 2 patients presenting a dominant spinocerebellar ataxia (SCA) type 2, one of the most common SCAs encountered during practice.

Trains of epidural DC stimulation of the cerebellum tune corticomotor excitability.

We assessed the effects of anodal/cathodal direct current stimulation (DCS) applied epidurally over the cerebellum. We studied the excitability of both the motor cortex and the anterior horn of the spinal cord in adult rats under continuous anesthesia. We also investigated the effects on the spatial representation of a couple of agonist/antagonist muscles on primary motor cortex.

The contributions of the cerebellum in sensorimotor control: what are the prevailing opinions which will guide forthcoming studies?

Although considerable progress has been made in developing models of cerebellar function in sensorimotor control, the exact nature of the basic operations performed by the cerebellum remain elusive. Several major theories have emerged these last decades. According to the hypothesis of Marr and Albus, the climbing fiber input carries an error signal weakening the strength of a subset of parallel fibers/Purkinje neurons synapses in the cerebellar cortex.

Consensus paper: roles of the cerebellum in motor control--the diversity of ideas on cerebellar involvement in movement.

Considerable progress has been made in developing models of cerebellar function in sensorimotor control, as well as in identifying key problems that are the focus of current investigation. In this consensus paper, we discuss the literature on the role of the cerebellar circuitry in motor control, bringing together a range of different viewpoints. The following topics are covered: oculomotor control, classical conditioning (evidence in animals and in humans), cerebellar control of motor speech, control of grip forces, control of voluntary limb movements, timing, sensorimotor synchronization, control of corticomotor excitability, control of movement-related sensory data acquisition, cerebro-cerebellar interaction in visuokinesthetic perception of hand movement, functional neuroimaging studies, and magnetoencephalographic mapping of cortico-cerebellar dynamics.

Trains of transcranial direct current stimulation antagonize motor cortex hypoexcitability induced by acute hemicerebellectomy.

Object: The cerebellum is a key modulator of motor cortex activity, allowing both the maintenance and fine-tuning of motor cortex discharges. One elemental defect associated with acute cerebellar lesions is decreased excitability of the contralateral motor cortex, which is assumed to participate in deficits in skilled movements and considered a major defect in motor cortex properties. In the present study, the authors assessed the effect of trains of anodal transcranial direct current stimulation (tDCS), which elicits polarity-dependent shifts in resting membrane potentials.

Effects of trains of high-frequency stimulation of the premotor/supplementary motor area on conditioned corticomotor responses in hemicerebellectomized rats.

We studied the effects of low- and high-frequency premotor electrical stimulations on conditioned corticomotor responses, intra-cortical facilitation (ICF) and spinal excitability in hemicerebellectomized rats (left side). Trains of stimulation were applied in prefrontal region rFr2 (the equivalent of the premotor/supplementary motor area in primates) at a rate of 1 Hz (low-frequency stimulation LFS) or 20 Hz (high-frequency stimulation HFS). Test stimuli on the motor cortex were preceded by a conditioning stimulus in contralateral sciatic nerve (two inter-stimulus intervals ISIs were studied: 5 ms or 45 ms).

Reinstating the ability of the motor cortex to modulate cutaneomuscular reflexes in hemicerebellectomized rats.

The pathways passing through the cerebellum calibrate cutaneomuscular responses. Indeed, the enhancement of cutaneomuscular responses associated with subthreshold high-frequency trains of stimulation applied on motor cortex following a period of peripheral repetitive stimulation (PRS) is prevented by hemicerebellectomy. We analysed the effects of low-frequency repetitive stimulation of motor cortex (LFRSM1) on interhemispheric inhibition (IHI) and on the modulation of cutaneomuscular reflexes in rats with left hemicerebellar ablation.

A novel approach for treating cerebellar ataxias.

The terminology of cerebellar ataxias encompasses a variety of sporadic and inherited debilitating diseases. Patients exhibit disabling deficits such as dysmetria, kinetic tremor and ataxia of stance/gait. We are currently lacking effective treatments in degenerative cerebellar ataxias.

Selective image-guided venous sinus exposure for direct embolization of dural arteriovenous fistula: technical case report.

Background: Transcranial approaches for transsinusal endovascular therapy of DAVF have been sporadically reported by large craniectomies. Large craniectomies carry nevertheless a risk of postembolization extradural hematoma, reduced by delaying the endovascular procedure. We report a 1-session technique of SIGC for percutaneous transvenous DAVF embolization.

Hemicerebellectomy impairs the modulation of cutaneomuscular reflexes by the motor cortex following repetitive somatosensory stimulation.

We examined the cutaneomuscular reflex of the plantaris muscle of rats in response to cutaneous stimulation in isolation and in conjunction with subthreshold high-frequency trains of stimuli applied on the motor cortex, prior to and following repetitive peripheral stimulation. The cutaneomuscular reflex was also investigated under the same paradigm following hemicerebellectomy. The enhancement of cutaneomuscular responses associated with subthreshold high-frequency trains of stimulation following repetitive peripheral stimulation was prevented by hemicerebellectomy.

[Metastasis of a lumbosacral ependymoma with very long disease-free survival: a case report and review of the literature].

Ependymoma is rare glial tumour of the central nervous system and is considered to be low-grade. The lumbosacral location of spinal ependymoma is the most common. Prognosis of ependymomas is dependent on tumour location, histological subtype and differentiation, extent of the tumour and of the completeness of the surgical resection.

Integrated positron emission tomography and magnetic resonance imaging-guided resection of brain tumors: a report of 103 consecutive procedures.

Object: The aim of this study was to evaluate the integration of positron emission tomography (PET) scanning data into the image-guided resection of brain tumors.

Methods: Positron emission tomography scans obtained using fluorine-18 fluorodeoxyglucose (FDG) and L-[methyl-11C]methionine (MET) were combined with magnetic resonance (MR) images in the navigational planning of 103 resections of brain tumors (63 low-grade gliomas [LGGs] and 40 high-grade gliomas [HGGs]). These procedures were performed in 91 patients (57 males and 34 females) in whom tumor boundaries could not be accurately identified on MR images for navigation-based resection.

Modulation of excitability as an early change leading to structural adaptation in the motor cortex.

The excitability of the motor cortex is a function of single cell excitability, synaptic strength, and the balance between excitatory cells and inhibitory cells. Sustained periods of sensory stimulation enhance the excitability in the motor cortex. This adaptation, which represents an early change in cortical network function effective in motor learning and recovery from a motor deficit, is followed by longer-lasting changes, such as modifications in cortical somatotopy, and by structural plasticity.

Modulation of motor cortex excitability by sustained peripheral stimulation: the interaction between the motor cortex and the cerebellum.

The excitability of cortical neurons in the motor cortex is determined by their membrane potential and by the level of intracortical inhibition. The excitability of the motor cortex as a whole is a function of single cell excitability, synaptic strength, and the balance between excitatory cells and inhibitory cells. It is now established that a sustained period of somatosensory stimulation increases the excitability of motor cortex areas controlling muscles in those body parts that received the stimulation prior to excitability testing.

Hemicerebellectomy blocks the enhancement of cortical motor output associated with repetitive somatosensory stimulation in the rat.

Repetitive peripheral stimulation is associated with an enhancement of the intensity of corticomotor responses. We analysed the effects of hemicerebellectomy on the modulation of cortical motor output associated with repetitive electrical stimulation of the sciatic nerve in the rat. Hemicerebellectomy blocked the enhancement of the corticomotor response.

The cerebellum modulates rodent cortical motor output after repetitive somatosensory stimulation.

Objective: To analyze the possible role of the cerebellum in the modulation of cortical motor output associated with repetitive electrical stimulation of the sciatic nerve in the rat.

Methods: A sustained somatosensory stimulation induces an increase in the intensity of the response of the rodent motor cortex. Wistar rats were anesthetized for surgical preparation using a continuous infusion of chloral hydrate.

Interaction between repetitive stimulation of the sciatic nerve and functional ablation of cerebellar nucleus interpositus in the rat.

It is established that cerebellar nuclei exert a significant effect on the excitability of spinal neurons. However, their output is heterogeneous. Conditioning trains of dentate nucleus stimuli are known to modify the post-synaptic potentials evoked in motoneurons by stimulation of group Ia and Ib afferents in appropriate peripheral nerves.