Grant Number: 5R01EY010562-11
Project Title: Hierarchical Processing in the Motion System
PI Information: KENNETH H. BRITTEN,
Phone: (530) 754-5080 Fax: (530) 757-8827
Abstract: DESCRIPTION (provided by applicant):
The basic "building
blocks" of visual perception are starting to become reasonably well
understood, and we can make a fairly good account of how simple
discriminations are done.
What we understand much less is how the visual
system solves more realistic, everyday challenges. Visually guided
navigation is a particularly good "model system" for studying real-world
visual processes in the laboratory. The perception of self-motion from
the pattern of motion on the retina has been studied extensively, though
we still know very little about where in the brain the critical
processing steps occur, and how the complex pattern of motion is
converted into effective movement.
The present proposal seeks to answer
these open questions. First, we will seek direct evidence for the
involvement of multiple cortical areas in the perception of self-motion,
by using multiple, simultaneous recording techniques while our
experimental animals are performing a discrimination of self-motion
Secondly, we will seek to ask if the parietal cortical area
(the ventral intraparietal area or VIP) is both necessary for
self-motion perception and is actually used. We will do this by
perturbing the pattern of activity in VIP in the context of the
self-motion task, both by reversible inactivation as well as by
These complementary methods should greatly extend
our understanding of how the parietal cortex participates in self-motion
perception. However, to really extend our knowledge of self-motion
perception, we need to extend the inquiry into a more active context.
Human-factors studies have revealed that guidance of self-motion
("steering") is a very active process, with the direction of gaze being
a critical component. However, next to nothing is known about the
central nervous system mechanisms used in this active task.
propose to establish, characterize and exploit an animal model of active
locomotion to study the involvement of brain structures in this task. We
will train our subject to direct their "virtual" trajectories by
joystick, and characterize how their normal behavior is influenced by
cues including target direction, gaze direction, gaze velocity, and
visual motion information.
We will then record activity in multiple
cortical areas while animals are engaged in this task, and explore the
signals in visual and parietal cortex to better understand brain
mechanisms of visually guided navigation. This information, in the long
term, might be useful in helping the disabled to navigate, and in the
development of visual prosthetics for the blind.
motion perception, neural information processing, neuropsychology,
parietal lobe /cortex, visual cortex, visual perception
chordate locomotion, computational neuroscience, cue, eye movement,
Macaca mulatta, behavior test, behavioral /social science research tag,
single cell analysis
Institution: UNIVERSITY OF CALIFORNIA DAVIS
OFFICE OF RESEARCH - SPONSORED PROGRAMS
DAVIS, CA 95618
Fiscal Year: 2006
Department: CENTER FOR NEUROSCIENCE
Project Start: 01-APR-1994
Project End: 31-DEC-2009
ICD: NATIONAL EYE INSTITUTE
J Neurophysiol 88: 3469-3476, 2002; doi:10.1152/jn.00276.2002
J Neurophysiol (December 1, 2002);10.1152/jn.00276.2002
Submitted on 2 April 2002
Accepted on 13 August 2002
Motion Adaptation in Area MT
Richard J. A. Van Wezel and Kenneth H. Britten
University of California, Davis Center for Neuroscience and Section of
Neurobiology, Physiology, and Behavior, Davis, California 95616
Preparation and recordings
We recorded single MT cells in three adult female rhesus monkeys (Macaca
mulatta). Before recording, each monkey had been trained to fixate a
stationary red spot of 0.23° diam in the presence of visual stimuli. The
animal's fluid intake was restricted, and behavioral control was
achieved using operant conditioning techniques. The animal received a
fluid reward (a drop of water or juice) for keeping its eyes within a
window (1-2.5° width) surrounding the fixation point for the duration of
All surgical and experimental methods followed previously
described procedures (Britten et al. 1992 ), conformed to the National
Institutes of Health Guide for the Care and Use of Laboratory Animals,
and were approved by the UC Davis Animal Care and Use Committee.
deep surgical anesthesia, each animal was implanted with a scleral
search coil (Judge et al. 1980 ) and was equipped with a stainless steel
head restraint post and recording cylinder (Crist Instrument, Damascus,
MD) located over the occipital cortex. The monkeys were given at least 2
weeks to recover from surgery before recording.
A plastic grid secured inside the cylinder provided a coordinate system
of guide tube support holes at 1-mm intervals (Crist et al. 1988 ).
Guide tubes were inserted transdurally through these holes, with local
anesthetic if necessary. Parylene-insulated tungsten microelectrodes (MicroProbe,
Potomac, MD) were inserted through these guide tubes, and neural signals
from these electrodes were amplified, filtered, and displayed by
Spikes were isolated using a time-amplitude window
discriminator (Bak Electronics, Germantown, MD) and converted to voltage
pulses that were fed to the computer controlling the experiment. Data
acquisition and experimental control were managed by the software
package REX (Hays et al. 1982 ). Neurons were determined to be located
in MT by physiological criteria: receptive field size, directionally
selective responses, columnar organization for preferred directions, and
appropriate retinotopic organization (Albright et al. 1984 ; Maunsell
and Van Essen 1983b ; Zeki 1974 ).
In two monkeys, we verified histologically that the recording region corresponded to the heavily
myelinated zone on the posterior bank of the superior temporal sulcus
(STS). This landmark is a very reliable indicator of the location of MT
(Desimone and Ungerleider 1986 ; Maunsell and Van Essen 1983a ). This
verification is not yet available for the third monkey because it is
currently involved in other experiments.
Once a single unit was isolated, the receptive field was mapped using
hand-controlled stimuli, typically moving bars of light. We only
included in our analysis cells that were fully directionally selective,
by which we mean that there is no overlap in the response distributions
for the preferred and null directions at the highest coherence tested
(Britten et al. 1992 ).
This criterion need not imply a DSI [the
standard index of directionality, calculated as (pref null)/(pref +
null)] near 1.0, nor that the cells be silent in their null direction.
Thirteen of 87 cells did not meet this criterion.
We imposed this
criterion only for consistency with previous work, but inspection of the
excluded cells' data showed that the adaptation effects were very
similar as that from the retained cells (data not shown).