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Neurology Mar 1964
Topics: Cell Biology; Cochlear Nerve; Cytodiagnosis; Electrons; Microscopy; Microscopy, Electron; Neurilemmoma; Neuroma, Acoustic; Vestibulocochlear Nerve
PubMed: 14129045
DOI: 10.1212/wnl.14.3.171 -
Journal of Neurology, Neurosurgery, and... Nov 1950
Topics: Cochlear Nerve; Humans; Neoplasms; Neuroma; Neuroma, Acoustic; Vestibulocochlear Nerve
PubMed: 14795241
DOI: 10.1136/jnnp.13.4.272 -
The Journal of Cell Biology Feb 1962Nerve cell bodies in the spiral and vestibular ganglia of the adult rat are surrounded by thin (about ten lamellae) myelin sheaths which differ in several respects from...
Nerve cell bodies in the spiral and vestibular ganglia of the adult rat are surrounded by thin (about ten lamellae) myelin sheaths which differ in several respects from typical axonal myelin. In some instances lamellae surrounding perikarya appear as typical major dense lines, and in others as thin Schwann cell sheets in which cytoplasm persists. Discontinuities and irregularities appear in the structure of perikaryal myelin. Lamellae may terminate anywhere within the sheaths; they may bifurcate; they may reverse their direction; or they may merge with each other. The number of lamellae varies from one part of a sheath to another. In addition, the myelin of a single perikaryal sheath may receive contributions from more than one Schwann cell, which overlap and interleave with each other. The ganglion cells are of two types: those which are densely packed with the usual cytoplasmic organelles but have few neurofilaments (granular neurons), and those which exhibit large areas containing few organelles but have a high concentration of neurofilaments (filamented neurons). The latter cell type is ensheathed by myelin which is generally more compact that that surrounding the former. The formation and the physiologic significance of perikaryal myelin are discussed.
Topics: Animals; Axons; Cochlear Nerve; Cytoplasm; Ganglia; Microscopy, Electron; Myelin Sheath; Neurons; Rats; Schwann Cells; Vestibular Nerve
PubMed: 14493992
DOI: 10.1083/jcb.12.2.329 -
The Laryngoscope Oct 2010One limitation with cochlear implants is the difficulty stimulating spatially discrete spiral ganglion cell groups because of electrode interactions. Multipolar...
OBJECTIVES/HYPOTHESIS
One limitation with cochlear implants is the difficulty stimulating spatially discrete spiral ganglion cell groups because of electrode interactions. Multipolar electrodes have improved on this some, but also at the cost of much higher device power consumption. Recently, it has been shown that spatially selective stimulation of the auditory nerve is possible with a mid-infrared laser aimed at the spiral ganglion via the round window. However, these neurons must be driven at adequate rates for optical radiation to be useful in cochlear implants. We herein use single-fiber recordings to characterize the responses of auditory neurons to optical radiation.
STUDY DESIGN
In vivo study using normal-hearing adult gerbils.
METHODS
Two diode lasers were used for stimulation of the auditory nerve. They operated between 1.844 μm and 1.873 μm, with pulse durations of 35 μs to 1,000 μs, and at repetition rates up to 1,000 pulses per second (pps). The laser outputs were coupled to a 200-μm-diameter optical fiber placed against the round window membrane and oriented toward the spiral ganglion. The auditory nerve was exposed through a craniotomy, and recordings were taken from single fibers during acoustic and laser stimulation.
RESULTS
Action potentials occurred 2.5 ms to 4.0 ms after the laser pulse. The latency jitter was up to 3 ms. Maximum rates of discharge averaged 97 ± 52.5 action potentials per second. The neurons did not strictly respond to the laser at stimulation rates over 100 pps.
CONCLUSIONS
Auditory neurons can be stimulated by a laser beam passing through the round window membrane and driven at rates sufficient for useful auditory information. Optical stimulation and electrical stimulation have different characteristics; which could be selectively exploited in future cochlear implants.
Topics: Acoustic Stimulation; Action Potentials; Animals; Cochlear Implants; Cochlear Nerve; Gerbillinae; Lasers, Semiconductor; Nerve Fibers
PubMed: 20830761
DOI: 10.1002/lary.21102 -
Prensa Medica Argentina Feb 1949
Topics: Cochlear Nerve; Deglutition; Deglutition Disorders
PubMed: 18124319
DOI: No ID Found -
Brain Research Sep 1979
Comparative Study
Topics: Acoustic Stimulation; Animals; Cats; Cochlear Nerve; Habituation, Psychophysiologic; Organ Specificity; Time Factors; Vestibulocochlear Nerve
PubMed: 487109
DOI: 10.1016/0006-8993(79)90253-1 -
Voprosy Neirokhirurgii 1962
Topics: Cochlear Nerve; Female; Humans; Neurilemmoma; Pregnancy; Pregnancy Complications; Vestibulocochlear Nerve
PubMed: 14458483
DOI: No ID Found -
A.M.A. Archives of Surgery Mar 1951
Topics: Cochlear Nerve; Facial Paralysis; Humans; Neoplasms; Neurosurgical Procedures; Vestibulocochlear Nerve
PubMed: 14799049
DOI: 10.1001/archsurg.1951.01250030385007 -
Acta Oto-laryngologica Nov 1993To facilitate identification and preservation of the auditory nerve during cerebello-pontine angle surgery, bipolar recording of cochlear nerve compound action...
To facilitate identification and preservation of the auditory nerve during cerebello-pontine angle surgery, bipolar recording of cochlear nerve compound action potentials (CNAPs) was performed. Two silver wires insulated with teflon up to the exposed ends were utilized as electrodes. They were twisted together, the distance between the two tips being 1 mm or less. Rarefaction polarity clicks (31/s) ranging from the psychoacoustical threshold to 120 dB pe SPL were used as stimuli. The investigation was performed in three groups of patients. The first group consisted of 9 patients submitted to vestibular neurectomy and 4 patients operated on by microvascular decompression of the eighth nerve. The second group comprised 8 patients with acoustic tumors smaller than 2 mm and serviceable hearing. Postoperative audiometric results in the subjects in the second group were compared with those obtained in well-matched homogeneous controls consisting of patients with acoustic neuroma operated on without the aid of CNAP recording. Bipolar recording from the eighth nerve was extremely selective, a good response being obtained only when positioning the electrode on the cochlear portion of the eighth nerve. During removal of the acoustic neuroma, repeated bipolar probing of the tumor and eighth nerve facilitated the task of distinguishing the cochlear nerve from other nervous structures and from the tumor, and contributed to preserving hearing in most patients.
Topics: Action Potentials; Adult; Aged; Cerebellopontine Angle; Cochlear Nerve; Evoked Potentials, Auditory, Brain Stem; Female; Humans; Male; Middle Aged; Monitoring, Intraoperative; Neuroma, Acoustic; ROC Curve; Vestibular Nerve
PubMed: 8291433
DOI: 10.3109/00016489309135895 -
New York State Journal of Medicine Nov 1947
Topics: Cochlear Nerve; Neoplasms; Vestibulocochlear Nerve
PubMed: 18896237
DOI: No ID Found