Search results for "Cerebellar cortex"
showing 10 items of 28 documents
Somatosensory event-related potentials in the rabbit cerebral and cerebellar cortices: a correspondence with mismatch responses in humans.
2001
Somatosensory event-related potentials (ERPs) were recorded from the cerebellar (CerCx), somatosensory (SomCx) and visual (VCx) cortices in rabbits in two stimulus conditions. In the oddball condition, airpuffs to two different locations in the rabbit's muzzle corresponded to infrequently presented deviant stimuli (oddball-deviants) interspersed with frequently presented standard stimuli. In the deviant-alone condition, deviants (alone-deviants) were presented without standards. ERPs to oddball-deviants differed significantly from those to standards in CerCx and SomCx, but not in VCx. Furthermore, some of these differences were not found between ERPs to alone-deviants and those to standards…
Electron microscopic demonstration of intracelluar promethazine accumulation sites by a precipitation technique: application to the cerebellar cortex…
1996
A method is described that allows electron microscopic identification of the phenothiazine neuroleptic promethazine after supravital intracardiac injection of high drug concentrations (greater than or equal to 3 %). The cerebellar cortex of the mouse was used for the investigation. This procedure is based on simultaneous fixation of drug and tissue by immersion in a paraformaldehyde-glutaraldehyde solution with the addition of phosphomolybdic acid. The electron microscopic investigation revealed that the drug could easily be identified as an electron-dense precipitate. Subpopulations of neurons exhibited a higher affinity for the drug than others, but no preference for any nerve cell type …
Computation of inverse functions in a model of cerebellar and reflex pathways allows to control a mobile mechanical segment.
2003
Abstract The command and control of limb movements by the cerebellar and reflex pathways are modeled by means of a circuit whose structure is deduced from functional constraints. One constraint is that fast limb movements must be accurate although they cannot be continuously controlled in closed loop by use of sensory signals. Thus, the pathways which process the motor orders must contain approximate inverse functions of the bio-mechanical functions of the limb and of the muscles. This can be achieved by means of parallel feedback loops, whose pattern turns out to be comparable to the anatomy of the cerebellar pathways. They contain neural networks able to anticipate the motor consequences …
Cerebellar learning of bio-mechanical functions of extra-ocular muscles: modeling by artificial neural networks
2003
A control circuit is proposed to model the command of saccadic eye movements. Its wiring is deduced from a mathematical constraint, i.e. the necessity, for motor orders processing, to compute an approximate inverse function of the bio-mechanical function of the moving plant, here the bio-mechanics of the eye. This wiring is comparable to the anatomy of the cerebellar pathways. A predicting element, necessary for inversion and thus for movement accuracy, is modeled by an artificial neural network whose structure, deduced from physical constraints expressing the mechanics of the eye, is similar to the cell connectivity of the cerebellar cortex. Its functioning is set by supervised reinforceme…
Purkinje cell loss and motor coordination defects in profilin1 mutant mice.
2012
Profilin1 is an actin monomer-binding protein, essential for cytoskeletal dynamics. Based on its broad expression in the brain and the localization at excitatory synapses (hippocampal CA3-CA1 synapse, cerebellar parallel fiber (PF)-Purkinje cell (PC) synapse), an important role for profilin1 in brain development and synapse physiology has been postulated. We recently showed normal physiology of hippocampal CA3-CA1 synapses in the absence of profilin1, but impaired glial cell binding and radial migration of cerebellar granule neurons (CGNs). Consequently, brain-specific inactivation of profilin1 by exploiting conditional mutants and Nestin-mediated cre expression resulted in a cerebellar hyp…
Profilin1 activity in cerebellar granule neurons is required for radial migration in vivo.
2014
Neuron migration defects are an important aspect of human neuropathies. The underlying molecular mechanisms of such migration defects are largely unknown. Actin dynamics has been recognized as an important determinant of neuronal migration, and we recently found that the actin-binding protein profilin1 is relevant for radial migration of cerebellar granule neurons (CGN). As the exploited brain-specific mutants lacked profilin1 in both neurons and glial cells, it remained unknown whether profilin1 activity in CGN is relevant for CGN migration in vivo. To test this, we capitalized on a transgenic mouse line that expresses a tamoxifen-inducible Cre variant in CGN, but no other cerebellar cell …
Effects of tetrahydrocannabinol on glucose uptake in the rat brain
2017
Δ9-Tetrahydrocannabinol (THC) is the psychoactive component of the plant Cannabis sativa and acts as a partial agonist at cannabinoid type 1 and type 2 receptors in the brain. The goal of this study was to assess the effect of THC on the cerebral glucose uptake in the rat brain. 21 male Sprague Dawley rats (12-13 w) were examined and received five different doses of THC ranging from 0.01 to 1 mg/kg. For data acquisition a Focus 120 small animal PET scanner was used and 24.1-28.0 MBq of [18F]-fluoro-2-deoxy-d-glucose were injected. The data were acquired for 70 min and arterial blood samples were collected throughout the scan. THC, THC-OH and THC-COOH were determined at 55 min p.i. Nine volu…
Expression of connexin36 in the adult and developing rat brain.
2000
The distribution of connexin36 (Cx36) in the adult rat brain and retina has been analysed at the protein (immunofluorescence) and mRNA (in situ hybridization) level. Cx36 immunoreactivity, consisting primarily of round or elongated puncta, is highly enriched in specific brain regions (inferior olive and the olfactory bulb), in the retina, in the anterior pituitary and in the pineal gland, in agreement with the high levels of Cx36 mRNA in the same regions. A lower density of immunoreactive puncta can be observed in several brain regions, where only scattered subpopulations of cells express Cx36 mRNA. By combining in situ hybridization for Cx36 mRNA with immunohistochemistry for a general neu…
Changes in intracortical circuits of the human motor cortex following theta burst stimulation of the lateral cerebellum
2008
Objective: The cerebellum takes part in several motor functions through its influence on the motor cortex (M1). Here, we applied the theta burst stimulation (TBS) protocol, a novel form of repetitive Transcranial Magnetic Stimulation (rTMS) over the lateral cerebellum. The aim of this study was to test whether TBS of the lateral cerebellum could be able to modulate the excitability of the contralateral M1 in healthy subjects. Methods: Motor-evoked potentials (MEPs) amplitude, short intracortical inhibition (SICI), long intracortical inhibition (LICI) and short intracortical facilitation (SICF) were tested in the M1 before and after cerebellar continuous TBS (cTBS) or intermittent TBS (iTBS)…
Disruption of the ASTN2 / TRIM32 locus at 9q33.1 is a risk factor in males for Autism Spectrum Disorders, ADHD and other neurodevelopmental phenotypes
2014
Rare copy number variants (CNVs) disrupting ASTN2 or both ASTN2 and TRIM32 have been reported at 9q33.1 by genome-wide studies in a few individuals with neurodevelopmental disorders (NDDs). The vertebrate-specific astrotactins, ASTN2 and its paralog ASTN1, have key roles in glial-guided neuronal migration during brain development. To determine the prevalence of astrotactin mutations and delineate their associated phenotypic spectrum, we screened ASTN2/TRIM32 and ASTN1 (1q25.2) for exonic CNVs in clinical microarray data from 89 985 individuals across 10 sites, including 64 114 NDD subjects. In this clinical dataset, we identified 46 deletions and 12 duplications affecting ASTN2. Deletions o…