Morphological changes associated with chronic cerebellar stimulation in the human

1979 ◽  
Vol 51 (4) ◽  
pp. 510-520 ◽  
Author(s):  
Lee T. Robertson ◽  
Robert S. Dow ◽  
Irving S. Cooper ◽  
Laurence F. Levy
Keyword(s):  
Brain Stem ◽  
Cerebellar Cortex ◽  
Dentate Nucleus ◽  
Neuronal Damage ◽  
Morphological Changes ◽  
Electrode Array ◽  
Cortical Surface ◽  
Electrode Arrays ◽  
Caudal Portion ◽  
Cerebellar Stimulation

✓ The histopathology associated with chronic cerebellar stimulation is described for three human cerebellum and brain-stem specimens obtained at autopsy. The specimens were from three severely epileptic patients who received cerebellar stimulation at 10 Hz for 6½ to 15 months. The electrode arrays were completely encapsulated with loose connective tissue that included a proliferation of capillaries, an infiltration of lymphocytes, and an occasional macrophage. The capsule of one of the specimens was tightly adherent to the underlying cerebellar cortex, which may have been caused by some trauma during the surgical placement of the electrodes. Severe injury of the cerebellar cortex was generally confined to between 1 and 2 mm directly beneath the electrode array, and included thinning of the molecular layer, and loss of most Purkinje cells, interneurons, and associated fibers. Abnormal Purkinje cell dendritic patterns and loss of climbing fibers were evident 3 to 4 mm from the cortical surface. At a depth of 5 to 6 mm, there was no distinction from the nonstimulated areas. However, in all specimens the most severe changes, including a complete loss of the neuropil, were evident at the caudal border of the electrode array underlying the connecting wires. A calculation of the amount of severe and very severe neuronal damage for two specimens revealed that 1.2% and 3.1% of the total cortical surface was injured by this neuroprosthesis. Neuropathological changes were also evident in the dentate nucleus and the brain stem. Areas of the dentate nucleus that were close to regions of very severe cortical damage showed marked degenerative changes. Retrograde degeneration was evident primarily within the caudal portion of the medial accessory olivary nucleus.

scholarly journals The Importance of Intraoperative Plain Radiographs during Cochlear Implant Surgery in Patients with Normal Anatomy

2021 ◽  
Vol 11 (9) ◽  
pp. 4144
Author(s):  
Ohad Cohen ◽  
Jean-Yves Sichel ◽  
Chanan Shaul ◽  
Itay Chen ◽  
J. Thomas Roland ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Cost Effective ◽  
X Rays ◽  
Normal Anatomy ◽  
Electrode Arrays ◽  
Plain Radiographs ◽  
Hearing Function ◽  
Tertiary Center ◽  
Cochlear Implant Surgery

Although malpositioning of the cochlear implant (CI) electrode array is rare in patients with normal anatomy, when occurring it may result in reduced hearing outcome. In addition to intraoperative electrophysiologic tests, imaging is an important modality to assess correct electrode array placement. The purpose of this report was to assess the incidence and describe cases in which intraoperative plain radiographs detected a malpositioned array. Intraoperative anti-Stenver’s view plain X-rays are conducted routinely in all CI surgeries in our tertiary center before awakening the patient and breaking the sterile field. Data of patients undergoing 399 CI surgeries were retrospectively analyzed. A total of 355 had normal inner ear and temporal bone anatomy. Patients with intra or extracochlear malpositioned electrode arrays demonstrated in the intraoperative X-ray were described. There were four cases of electrode array malposition out of 355 implantations with normal anatomy (1.1%): two tip fold-overs, one extracochlear placement and one partial insertion. All electrodes were reinserted immediately; repeated radiographs were normal and the patients achieved good hearing function. Intraoperative plain anti-Stenver’s view X-rays are valuable to confirm electrode array location, allowing correction before the conclusion of surgery. These radiographs are cheaper, faster, and emit much less radiation than other imaging options, making them a viable cost-effective tool in patients with normal anatomy.

scholarly journals Activation of the cerebellar cortex and the dentate nucleus in a prism adaptation fMRI study

2013 ◽  
Vol 35 (4) ◽  
pp. 1574-1586 ◽  
Author(s):  
Michael Küper ◽  
Meret J.S. Wünnemann ◽  
Markus Thürling ◽  
Roxana M. Stefanescu ◽  
Stefan Maderwald ◽  
...  
Keyword(s):  
Cerebellar Cortex ◽  
Dentate Nucleus ◽  
Prism Adaptation ◽  
Fmri Study

Precise Alignment of Micromachined Electrode Arrays With V1 Functional Maps

2007 ◽  
Vol 97 (5) ◽  
pp. 3781-3789 ◽  
Author(s):  
Ian Nauhaus ◽  
Dario L. Ringach
Keyword(s):  
Receptive Field ◽  
Electrode Array ◽  
Theoretical Models ◽  
Orientation Tuning ◽  
Feedback Signal ◽  
Electrode Arrays ◽  
Tuning Curves ◽  
Alignment Procedure ◽  
Receptive Field Properties ◽  
Orientation Maps

Recent theoretical models of primary visual cortex predict a relationship between receptive field properties and the location of the neuron within the orientation maps. Testing these predictions requires the development of new methods that allow the recording of single units at various locations across the orientation map. Here we present a novel technique for the precise alignment of functional maps and array recordings. Our strategy consists of first measuring the orientation maps in V1 using intrinsic optical imaging. A micromachined electrode array is subsequently implanted in the same patch of cortex for electrophysiological recordings, including the measurement of orientation tuning curves. The location of the array within the map is obtained by finding the position that maximizes the agreement between the preferred orientations measured electrically and optically. Experimental results of the alignment procedure from two implementations in monkey V1 are presented. The estimated accuracy of the procedure is evaluated using computer simulations. The methodology should prove useful in studying how signals from the local neighborhood of a neuron, thought to provide a dominant feedback signal, shape the receptive field properties in V1.

scholarly journals Design and development of a multichannel potentiometer for monitoring an electrode array and its application in flow analysis

2002 ◽  
Vol 24 (4) ◽  
pp. 105-110 ◽  
Author(s):  
Jarbas J. R. Rohwedder ◽  
Celio Pasquini ◽  
Ivo M. Raimundo, Jr. ◽  
M. Conceiçao ◽  
B. S. M. Montenegro ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Flow Analysis ◽  
Reference Electrode ◽  
Electrode Array ◽  
Ion Selective Electrodes ◽  
Electrode Arrays ◽  
Figures Of Merit ◽  
Flow Through ◽  
The Individual ◽  
Intense Signal

A versatile potentiometer that works with electrode arrays in flow injection and/or monosegmented flow systems is described. The potentiometer is controlled by a microcomputer that allows individual, sequential multiplexed or random accesses to eight electrodes while employing only one reference electrode. The instrument was demonstrated by monitoring an array of seven flow-through ion-selective electrodes for Ag+and for three electrodes for Cl-, Ca2+and K+. The figures of merit of the individual and multiplexed (summed) readings of the electrode array were compared. The absolute standard deviation of the measurements made by summing the potential of two or more electrodes was maintained constant, thus improving the precision of the measurements. This result shows that an attempt to combine the signals of the electrodes to produce a more intense signal in the Hadamard strategy is feasible and accompanied by a proportional improvement in the precision of individual measurements. The preliminary tests suggest that the system can allow for 270 determinations per hour, with a linear range from1.0×10−2to1.0×10−4mol l-1for the three di¡erent analytes. Detection limits were estimated as3.1×10−5,3.0×10−6and1.0×10−5mol l-1for Cl-, Ca2+and K+, respectively.

scholarly journals Mathematical Model of Neuronal Morphology: Prenatal Development of the Human Dentate Nucleus

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Katarina Rajković ◽  
Goran Bačić ◽  
Dušan Ristanović ◽  
Nebojša T. Milošević
Keyword(s):  
Mathematical Model ◽  
Dentate Nucleus ◽  
Morphological Changes ◽  
Prenatal Development ◽  
Morphometric Parameters ◽  
Neuronal Morphology ◽  
Dendritic Arbor ◽  
Complex Development ◽  
Sound Foundation ◽  
The Mathematical Model

The aim of the study was to quantify the morphological changes of the human dentate nucleus during prenatal development using mathematical models that take into account main morphometric parameters. The camera lucida drawings of Golgi impregnated neurons taken from human fetuses of gestational ages ranging from 14 to 41 weeks were analyzed. Four morphometric parameters, the size of the neuron, the dendritic complexity, maximum dendritic density, and the position of maximum density, were obtained using the modified Scholl method and fractal analysis. Their increase during the entire prenatal development can be adequately fitted with a simple exponential. The three parameters describing the evolution of branching complexity of the dendritic arbor positively correlated with the increase of the size of neurons, but with different rate constants, showing that the complex development of the dendritic arbor is complete during the prenatal period. The findings of the present study are in accordance with previous crude qualitative data on prenatal development of the human dentate nucleus, but provide much greater amount of fine details. The mathematical model developed here provides a sound foundation enabling further studies on natal development or analyzing neurological disorders during prenatal development.

scholarly journals CRSP, numerical results for an electrical resistivity array to detect underground cavities

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Amin Amini ◽  
Hamidreza Ramazi
Keyword(s):  
Electrical Resistivity ◽  
Geophysical Methods ◽  
Electrode Array ◽  
Electrode Configuration ◽  
Electrode Arrays ◽  
Wide Range ◽  
Underground Cavities ◽  
Conventional Electrode

AbstractThis paper is devoted to the application of the Combined Resistivity Sounding and Profiling electrode configuration (CRSP) to detect underground cavities. Electrical resistivity surveying is among the most favorite geophysical methods due to its nondestructive and economical properties in a wide range of geosciences. Several types of the electrode arrays are applied to detect different certain objectives. In one hand, the electrode array plays an important role in determination of output resolution and depth of investigations in all resistivity surveys. On the other hand, they have their own merits and demerits in terms of depth of investigations, signal strength, and sensitivity to resistivity variations. In this article several synthetic models, simulating different conditions of cavity occurrence, were used to examine the responses of some conventional electrode arrays and also CRSP array. The results showed that CRSP electrode configuration can detect the desired objectives with a higher resolution rather than some other types of arrays. Also a field case study was discussed in which electrical resistivity approach was conducted in Abshenasan expressway (Tehran, Iran) U-turn bridge site for detecting potential cavities and/or filling loose materials. The results led to detect an aqueduct tunnel passing beneath the study area.

scholarly journals A metabolic perspective on CSF-mediated neurodegeneration in multiple sclerosis

Brain ◽  
2019 ◽  
Vol 142 (9) ◽  
pp. 2756-2774 ◽  
Author(s):  
Maureen Wentling ◽  
Carlos Lopez-Gomez ◽  
Hye-Jin Park ◽  
Mario Amatruda ◽  
Achilles Ntranos ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Neuronal Damage ◽  
Morphological Changes ◽  
Progressive Multiple Sclerosis ◽  
Functional Screening ◽  
Disease Course ◽  
Post Translational Modification ◽  
Neurodegenerative Process ◽  
Relapsing Remitting ◽  
Multiple Sclerosis Patients

Abstract Multiple sclerosis is an autoimmune demyelinating disorder of the CNS, characterized by inflammatory lesions and an underlying neurodegenerative process, which is more prominent in patients with progressive disease course. It has been proposed that mitochondrial dysfunction underlies neuronal damage, the precise mechanism by which this occurs remains uncertain. To investigate potential mechanisms of neurodegeneration, we conducted a functional screening of mitochondria in neurons exposed to the CSF of multiple sclerosis patients with a relapsing remitting (n = 15) or a progressive (secondary, n = 15 or primary, n = 14) disease course. Live-imaging of CSF-treated neurons, using a fluorescent mitochondrial tracer, identified mitochondrial elongation as a unique effect induced by the CSF from progressive patients. These morphological changes were associated with decreased activity of mitochondrial complexes I, III and IV and correlated with axonal damage. The effect of CSF treatment on the morphology of mitochondria was characterized by phosphorylation of serine 637 on the dynamin-related protein DRP1, a post-translational modification responsible for unopposed mitochondrial fusion in response to low glucose conditions. The effect of neuronal treatment with CSF from progressive patients was heat stable, thereby prompting us to conduct an unbiased exploratory lipidomic study that identified specific ceramide species as differentially abundant in the CSF of progressive patients compared to relapsing remitting multiple sclerosis. Treatment of neurons with medium supplemented with ceramides, induced a time-dependent increase of the transcripts levels of specific glucose and lactate transporters, which functionally resulted in progressively increased glucose uptake from the medium. Thus ceramide levels in the CSF of patients with progressive multiple sclerosis not only impaired mitochondrial respiration but also decreased the bioavailability of glucose by increasing its uptake. Importantly the neurotoxic effect of CSF treatment could be rescued by exogenous supplementation with glucose or lactate, presumably to compensate the inefficient fuel utilization. Together these data suggest a condition of ‘virtual hypoglycosis’ induced by the CSF of progressive patients in cultured neurons and suggest a critical temporal window of intervention for the rescue of the metabolic impairment of neuronal bioenergetics underlying neurodegeneration in multiple sclerosis patients.

Electrode design and insertional depth-dependent intra-cochlear pressure changes: a model experiment

2017 ◽  
Vol 132 (3) ◽  
pp. 224-229 ◽  
Author(s):  
P Mittmann ◽  
A Ernst ◽  
I Todt
Keyword(s):  
Cochlear Implant ◽  
Fluid Pressure ◽  
Electrode Array ◽  
Lateral Wall ◽  
Peak Frequency ◽  
Peak Amplitude ◽  
Residual Hearing ◽  
Electrode Arrays ◽  
Pressure Peak ◽  
Pressure Changes

AbstractBackground:Preservation of residual hearing is one of the major goals in modern cochlear implant surgery. Intra-cochlear fluid pressure changes influence residual hearing, and should be kept low before, during and after cochlear implant insertion.Methods:Experiments were performed in an artificial cochlear model. A pressure sensor was inserted in the apical part. Five insertions were performed on two electrode arrays. Each insertion was divided into three parts, and statistically evaluated in terms of pressure peak frequency and pressure peak amplitude.Results:The peak frequency over each third part of the electrode increased in both electrode arrays. A slight increase was seen in peak amplitude in the lateral wall electrode array, but not in the midscalar electrode array. Significant differences were found in the first third of both electrode arrays.Conclusion:The midscalar and lateral wall electrode arrays have different intra-cochlear fluid pressure changes associated with intra-cochlear placement, electrode characteristics and insertion.

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