Filter characteristics of low‐frequency cochlear nerve fibers as determined by synchrony response patterns to two‐component signals

1983 ◽  
Vol 74 (S1) ◽  
pp. S7-S7
Author(s):  
Steven Greenberg ◽  
C. Daniel Geisler ◽  
L. Deng
Keyword(s):  
Low Frequency ◽  
Nerve Fibers ◽  
Cochlear Nerve ◽  
Response Patterns ◽  
Two Component

scholarly journals Synaptic events and discharge patterns of cochlear nucleus cells. II. Frequency-modulated tones

1976 ◽  
Vol 39 (1) ◽  
pp. 179-194 ◽  
Author(s):  
R. Britt ◽  
A. Starr
Keyword(s):  
Cochlear Nucleus ◽  
Tone Burst ◽  
Nerve Fibers ◽  
Cochlear Nerve ◽  
Response Patterns ◽  
Eighth Nerve ◽  
Rate Dependent ◽  
Fm Signals ◽  
Symmetry Factor ◽  
Modulation Rate

Responses of 99 cochlear nucleus cells and 24 cochlear nerve fibers were studied with FM signals; 14 cochlear nerve fibers and 57 cochlear nucleus cells were studied at four rates of modulation and several signal intensities. Classification of FM response patterns as symmetrical, asymmetrical, or unidirectional was based on the calculation of a symmetry factor (S), which compared the number of discharges evoked by the ascending and by the descending phases of the FM sweep. Certain FM response patterns could not adequately be described by the symmetry factor along and variables of modulation rate and signal intensity had significant influence. A correspondence was found between the four response classes evoked by a steady-frequency tone burst (primarylike, buildup, onset, and pause) and the FM response pattern. Cochlear nerve fibers showed symmetrical response patterns to FM stimulation. Primarylike units were similar to eighth nerve fibers and generally showed symmetrical FM responses. Occasional eighth nerve fibers and primarylike cells developed asymmetry at the fastest rate of modulation (50 sps). Buildup units showed a variety of response patterns to FM signals. Onset units generally showed asymmetrical response patterns with the greater response occurring to the ascending than to the descending phase of the FM sweep. Pause units showed a characteristic inhibition of activity at 5 sps (rate-dependent inhibition). Of the 57 cochlear nuclear cells studied in response to FM signals, 16 were symmetrical, another 16 were symmetrical except at the fastest modulation rate, 12 were asymmetrical, 3 were unidirectional, and 10 showed complex responses to certain signal rates or intensities. It is clear the the cat cochlear with its complex cytoarchitecture is involved in the recoding of acoustic information. Some units in cochlear nucleus demonstrate differential responses to the direction and to the rate of frequency movement. Other cochlear nucleus cells respond as eighth nerve fibers and may serve as simple "relays" in transmitting information from the cochlea to higher auditory centers.

The response of the cochlear nerve fibers to ultrasonic sounds in rats

1985 ◽  
Vol 1 ◽  
pp. S2
Author(s):  
Zheng Chang-Mu ◽  
Susumu Ito ◽  
Junsei Horikawa ◽  
Keiichi Murata
Keyword(s):  
Nerve Fibers ◽  
Cochlear Nerve

Tinnitus: some thoughts about its origin

1984 ◽  
Vol 98 (S9) ◽  
pp. 31-37 ◽  
Author(s):  
J. J. Eggermont
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Basilar Membrane ◽  
Stimulus Frequency ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Ear Ossicles ◽  
Stimulus Transduction ◽  
Low Levels ◽  
Inner Ear Fluids

An auditory sensation follows generally as the result of the sequence stimulus, transduction, coding, transformation and sensation. This is then optionally followed by perception and a reaction. The stimulus is usually airborne sound causing movements of the tympanic membrane, the middle ear ossicles, the inner ear fluids and the basilar membrane. The movements of the basilar membrane are dependent on stimulus frequency: high frequency tones excite only the basal part of the cochlea, regardless of the stimulus intensity; low frequency tones at low levels only excite the so-called place specific region at the apical end but at high levels (above 60–70 dB SPL) cause appreciable movement of the entire basilar membrane. Basilar membrane tuning is as sharp as that of inner hair cells or auditory nerve fibers (Sellick et al., 1982) at least in the basal turn of animals that have a cochlea in physiologically impeccable condition.

Histologic Findings in Two Very Small Intracanalicular Solitary Schwannomas of the Eighth Nerve

1986 ◽  
Vol 95 (5) ◽  
pp. 460-465 ◽  
Author(s):  
J. Gail Neely ◽  
Jack Hough
Keyword(s):  
Nerve Fiber ◽  
Longitudinal Direction ◽  
Nerve Fibers ◽  
Vestibular Nerve ◽  
Cochlear Nerve ◽  
The Other ◽  
En Bloc ◽  
Hearing Conservation ◽  
Eighth Nerve ◽  
Conservation Surgery

Two very small intracanalicular tumors, resected en bloc with the complete eighth nerve, were serially sectioned in order to study the relationship between the tumors and the nerves of origin. Both cases met the size criteria for hearing conservation surgery; however, the patient with the smaller tumor and the better hearing had no recognizable cochlear nerve fibers passing the tumor. The cochlear nerve in the patient with poorer hearing was completely free of tumor. The tumor with the infiltrated cochlear nerve seemed to originate from the inferior vestibular nerve. The other tumor seemed to arise from the superior vestibular nerve. Proximally, the tumors occupied a more central location in the involved nerves, but they abruptly became eccentric and exophytic as they proceeded laterally. Nerve fibers remaining about the tumors were displaced to the periphery. These nerve fiber aggregates became quite thin and attenuated, frequently separating into smaller aggregates which, ultimately, were incorporated into the tumors. As fibers came closer to the tumors, they tended to change from their longitudinal direction toward a more circumferential orientation about the surface of the tumors. The tumor-nerve fiber interfaces were quite variable throughout the course of the tumor, ranging from large aggregates of nerve fibers distinctly separate from the tumors to aggregates separate but tightly applied to the tumors without a tissue plane between, to aggregates partially incorporated within the periphery of the tumors, to aggregates completely incorporated into the periphery of the tumors. Frequently several types of interfaces were seen in the same section. These findings showed that in one case the cochlear nerve could have been surgically separated from the acoustic tumor; in the other specimen, it could not have been separated. It was impossible to predict between the two. In these two very small tumors, the gross specimen observation correlated reasonably well with the histology, thus suggesting that intraoperative observation may be a predictor in hearing conservation surgery; however, previous studies in slightly larger tumors make this an extremely guarded concept.

Sign in / Sign up

Export Citation Format

Share Document