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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
The University of Chicago, Chicago, IL
ROBERT A. MCCREA - Primate Testing - 2006
Grant Number: 5R01EY008041-16
Project Title: Physiology of Oculomotor Premotor Pathways
PI Information: PROFESSOR ROBERT A. MCCREA,
[email protected]
Abstract: DESCRIPTION (provided by applicant):
The aim of the proposed studies is to study the firing behavior of
afferent inputs to the vestibular nuclei that are influential in
modifying signal processing in vestibulo-ocular reflex (VOR) pathways
during smooth tracking head movements and during near viewing. The
initial studies will focus on the contribution of cerebello-vestibular
pathways to these functions. Other possible sources of vestibular
nucleus afferent inputs that modify signal processing in VOR pathways as
a function of behavioral context will be considered if the cerebello-vestibular
pathways do not appear to be sufficient to suppress the VOR during
active head movements or for modifying signal processing in VOR pathways
during near viewing. The first specific aim is to determine the source
and characteristics of the head movement efference copy inputs to the
vestibular nuclei that cancel or attenuate vestibular signals on
secondary VOR neurons during gaze pursuit. Monkeys will be trained to
pursue targets moving in the horizontal plane using smooth movements of
the eye, head and/or body. Unit responses during active and passive
movements will be compared. Regions of the cerebellum and brainstem that
contain cells that are differentially sensitive to active head movements
will be investigated further using electrical stimulation and chemical
inactivation techniques. Anatomical studies will be carried out using
retrograde tracers in combination with localized marking of recording
sites to determine whether regions containing active head movement cells
also project to the vestibular nuclei. The second specific aim is to
determine the contribution of the cerebellar flocculus to viewing
distance related changes in the angular and linear VOR during passive
and active head movements. Monkeys will be trained to fixate or pursue
visual targets presented on an earth stationary display mounted on a
motorized track so that its distance can be varied from 10-150 cm.
Vestibular stimuli will consist of passive whole body angular rotation
or linear translation in head-restrained monkeys. Single unit recordings
will be obtained from flocculus Purkinje cells and secondary VOR
neurons. Unit responses to passive and active whole body motion at
different viewing distances and target eccentricities will be recorded.
The contribution of the flocculus to viewing distance related changes in
the VOR will be assessed by examining the viewing distance related
changes in the responses of Purkinje cells and VOR pathway neurons.
Vestibular nucleus neurons that receive inputs from the cerebellar
flocculus will be identified by electrical stimulation of the flocculus.
Particular attention will be paid to determine whether different
Purkinje cells are differentially sensitive to the movements of one or
both eyes or to heave or thrust translation. The neurophysiological
observations will be evaluated in the context of the observed effects of
unilateral or bilateral inactivation of the cerebellar flocculus on the
angular and linear VOR. The results should increase our understanding of
the central mechanisms that allow clear vision of objects in a 3D
environment during passive and active head movements.
Thesaurus Terms:
head movement, neural information processing, neurophysiology,
vestibular pathway, vestibuloocular reflex, visual pathway, visual
tracking
brain electrical activity, cerebellar Purkinje cell, neuroanatomy,
neuron, smooth pursuit eye movement, visual field, visual fixation
Saimiri, microelectrode, single cell analysis
Institution: UNIVERSITY OF CHICAGO
5801 S ELLIS AVE
CHICAGO, IL 60637
Fiscal Year: 2006
Department: NEUROBIOLOGY, PHARMACOLOGY AND PHYSIOLOGY (NPP)
Project Start: 01-APR-1989
Project End: 30-NOV-2007
ICD: NATIONAL EYE INSTITUTE
IRG: VISB
J Neurophysiol 92: 797-807, 2004. First published April 7, 2004
Context Contingent Signal Processing in the Cerebellar
Flocculus and Ventral Paraflocculus During Gaze Saccades
T. Belton and R. A. McCrea
Department of Neurobiology, Pharmacology, and Physiology, University of
Chicago, Illinois 60637
Submitted 4 March 2004; accepted in final form 30 March 2004
The methods used for recording and analyzing eye movements and
single-unit activity in squirrel monkeys during combined eye-head
saccades have been described previously (Belton and McCrea 2000a ,2000b
; McCrea and Gdowski 2003 ). All practices complied with National
Institutes of Health principles of laboratory animal care (National
Institutes of Health Publication No. 86-23).
Surgical preparation
Two adult squirrel monkeys were prepared for recording both single-unit
activity and eye movements. A woven coil of fine, Teflon-coated wire (Cooner)
was sutured to the sclera of one eye for recording eye movements using
the magnetic search coil technique. A Plexiglas well was fitted onto the
parietal bone for the placement of microelectrodes, and a metal
reference pin was affixed to the skull adjacent to the probe insertion
site.
Experimental recording conditions
Animals were seated in a Plexiglas primate chair atop a vestibular
turntable (Inland 832). A harness that was fitted over the shoulders and
in front of the trunk inhibited arm-raising and trunk-twist movements. A
rod was attached to a keyed metal stud affixed to the occipital bone.
The rod was coaxial with the rotational axis of the turntable and
positioned within 5 mm of the C1�C2 axis. It rotated within a
low-friction ball bearing assembly fixed to the table, which allowed
�45� head movements in the plane of the horizontal semicircular canals.
A universal joint 5 cm above the head allowed pendular head position
adjustments around the universal joint axis. The head could be
reversibly fixed to the turntable by disabling the universal joint and
blocking angular rotation of the vertical axis rod. The monkeys were
trained to fixate and pursue a small visual target (0.5 W HeNe laser,
<0.2� diam) projected onto a cylindrical, surrounding projection screen
90 cm distant from the monkey. The background presented by the screen
was not an effective optokinetic stimulus during constant-velocity
turntable rotations (30�60�/s). Target movement was produced with a pair
of galvanometer-controlled mirrors mounted on the turntable. The animals
were rewarded for fixation of the target using a sweetened milk mixture
according to a variable reinforcement schedule. After training the
monkeys were able to produce on-demand performance for sustained periods
of 5 h, three to four times per week. Eye and head movements were
measured using a magnetic search-coil system mounted on the turntable.
These signals were low-pass filtered (5�10 kHz) and sampled (200�500 Hz)
at 16-bit resolution using a Cambridge Electronics 1401 data-acquisition
system. Eye position was computed off-line as the difference between
gaze and head position. Head- and gaze-velocity signals were created by
digitally differentiating and filtering (low-pass smoothing, 20�50 Hz)
the position signals. |
Please email: ROBERT A. MCCREA,
[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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