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Stop Animal
Exploitation NOW!
S. A. E. N.
"Exposing the truth to wipe
out animal experimentation"

Government Grants Promoting Cruelty to Animals
Johns Hopkins University, Baltimore, MD
LLOYD B. MINOR - Primate Testing - 2006
Grant Number: 5R01DC002390-12
Project Title: Physiology of Vestibular Compensation
PI Information: PROFESSOR LLOYD B. MINOR,
[email protected]
Abstract: DESCRIPTION (provided by applicant):
Disruption of vestibular signals from one labyrinth results in
asymmetries in the angular vestibuloocular reflex (VOR) evoked by
high-frequency, high-acceleration head movements. Studies during the
previous funding period have elucidated linear and nonlinear components
of the angular VOR in the squirrel monkey, demonstrated selective
adaptation of these components with magnifying or minimizing spectacles,
compared the horizontal angular VOR in squirrel monkeys and macaques in
response to rapid rotations, defined the response properties of
vestibular-nerve afferents to rapid head rotations, and analyzed changes
in the angular VOR, afferents, and hair cells following unilateral
ototoxic vestibular injury with gentamicin. The proposed research builds
upon previous accomplishments through studies that are organized into
three specific aims. The experiments are performed in chinchillas and in
macaques. Studies in Aim I will define the responses of vestibular-nerve
afferents to steps of acceleration and study the contributions of
irregularly discharging afferents to the horizontal VOR evoked by these
rapid head rotations. Bilateral, anodal galvanic currents delivered to
each labyrinth will be used to substantially attenuate or silence
irregular afferents during rapid head rotations. The experiments that
are conducted in macaques will involve analysis of the normal VOR as
well as following spectacle-induced adaptation. Aim II will investigate
the contribution to VOR compensation of preserved resting rate in
afferents on the side of a unilateral vestibular lesion and of afferents
from the contralesional (intact) labyrinth. The unilateral lesion that
preserves resting rate but abolishes or markedly attenuates responses to
motion involves intratympanic injection of gentamicin. Aim III will
examine neural correlates of compensatory changes in the horizontal VOR
in macaques after unilateral labyrinthectomy. These experiments will
determine if the discharge properties of vestibular-nerve afferents on
the contralateral side change following unilateral labyrinthectomy. The
dynamics of vestibular nuclei neurons that mediate the VOR will be
studied following unilateral labyrinthectomy. The role of proprioceptive
inputs and anticipatory mechanisms in modifying the responses of these
central neurons will be determined by comparing neuronal responses
during actively and passively generated head-on-body and whole-body
rotations.
Thesaurus Terms:
afferent nerve, head movement, neurophysiology, vestibular nerve,
vestibuloocular reflex
labyrinth, neural conduction, proprioception /kinesthesia, tympanum,
vestibular nuclei
Macaca, chinchilla, gentamicin, labyrinthectomy
Institution: JOHNS HOPKINS UNIVERSITY
W400 Wyman Park Building
BALTIMORE, MD 212182680
Fiscal Year: 2006
Department: OTOLARYNGOLOGY/HEAD AND NECK SURGERY
Project Start: 01-SEP-1995
Project End: 31-AUG-2010
ICD: NATIONAL INSTITUTE ON DEAFNESS AND OTHER COMMUNICATION
DISORDERS
IRG: ZRG1
The Journal of Neuroscience, 2002, 22:RC226:1-7
Semicircular Canal Afferents Similarly Encode Active
and Passive Head-On-Body Rotations: Implications for the Role of
Vestibular Efference
Kathleen E. Cullen1 and Lloyd B. Minor2
1 Aerospace Medical Research Unit,
Department of Physiology, McGill University, Montreal, Quebec, Canada
H3G 1Y6, and 2 Department of
Otolaryngology Head and Neck Surgery, Department of Biomedical
Engineering, and Department of Neuroscience, The Johns Hopkins
University, Baltimore, Maryland 21093
Two monkeys (a Macaca mulatta and a Macaca fasicularis) were prepared
for chronic extracellular recording. The procedures recently described (Sylvestre
and Cullen, 1999 ) were used for the surgical preparation of monkeys. A
stainless steel recording chamber was positioned stereotaxically on the
skull to record from the vestibular nerve at the point at which it
emerged from the internal auditory meatus. We approached the vestibular
nerve through the floccular complex, which was identified by its eye
movement-related activity (Lisberger and Pavelko, 1986 ). Entry to the
nerve was preceded by a silence, indicating that the electrode had left
the cerebellum, and after exiting the nerve we were able to determine
(as infrequently as possible) the location of the base of the skull by
the abrupt appearance of 60 Hz noise. Before the recording experiments,
the location of the nerve was confirmed in both monkeys as follows:
first, a guide tube was advanced through an X-Y stage (Narishige, Tokyo,
Japan), which was attached to the monkey's recording chamber, to a depth
estimated to be 1.5 mm above the nerve. Second, the proximity of the
guide tube to the internal auditory meatus was then verified by
anesthetizing the monkeys and making x-ray images of their heads in the
horizontal, sagittal, and frontal planes. In one animal, the location of
the microelectrode within the vestibular nerve was later histologically
confirmed. All experimental protocols complied with the guidelines of
the Canadian Council on Animal Care and National Institutes of Health
and were approved by the Animal Care Committee of McGill University and
by the Animal Care and Use Committee of the Johns Hopkins University
School of Medicine.
During the experiments, the monkey was seated in a primate chair. For
six afferents, horizontal and vertical gaze and head movements were
recorded using the magnetic search coil technique (Fuchs and Robinson,
1966 ). For the remaining afferents, horizontal, vertical, and torsional
head movements were measured using two orthogonally placed coils that
were secured to the animal's head implant. For vertical and horizontal
canal units, we analyzed only those head movements for which the
amplitude of the torsional component was <15% of the vertical or
horizontal component, respectively. The extracellular recording
techniques that were used have been recently described (Hullar and
Minor, 1999 ; Sylvestre and Cullen, 1999 ). Monkeys generated voluntary
eye-head movements to track a food target, which was alternatively
presented on either side of an opaque screen facing the monkey (gaze
shifts; Guitton et al., 1984 ), or which was slowly moved in front of
the monkey to elicit eye-head pursuit. To investigate each the response
of each afferent during passive head rotations, the experimenter
manually rotated the animal's head on its neck to induce head-on-body
movements with trajectories comparable to those generated during
voluntary gaze shifts and pursuit (peak head velocity = ±100-400 °/sec
and predominate frequency 0.5-1.5 Hz). Behavioral paradigms, target,
head motion, and the storage of data were controlled by a UNIX-based
real-time data acquisition program, and all data were recorded on a DAT
tape for later playback and analysis. Off-line, gaze, and head position
signals were low-pass filtered at 250 Hz (8 pole Bessel filter) and
sampled at 1000 Hz. These signals were digitally filtered at 125 Hz and
differentiated to produce velocity signals.
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Please email: LLOYD B. MINOR,
[email protected] to protest the inhumane use of animals in this
experiment. We would also love to know about your efforts with this
cause:
[email protected]
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Rats, mice, birds, amphibians and other animals have
been excluded from coverage by the Animal Welfare Act. Therefore research
facility reports do not include these animals. As a result of this
situation, a blank report, or one with few animals listed, does not mean
that a facility has not performed experiments on non-reportable animals. A
blank form does mean that the facility in question has not used covered
animals (primates, dogs, cats, rabbits, guinea pigs, hamsters, pigs,
sheep, goats, etc.). Rats and mice alone are believed to comprise over 90%
of the animals used in experimentation. Therefore the majority of animals
used at research facilities are not even counted.
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