Grant Number: 5R01EY001778-30
Project Title: Visual System Organization and Development
PI Information: PROFESSOR VIVIEN A. CASAGRANDE,
[email protected]
Abstract: DESCRIPTION (provided by applicant):
In our working model of visual information processing, we hypothesize
that there are three segregated parallel pathways [magnocellular (M),
parvocellular (P), and koniocelIular (K)] from the lateral genicuIate
nucleus (LGN) to primary visual cortex (V1), forming both dedicated and
multi-functional systems and networks. Within this scheme, separate
output layers and compartments of V1 have distinct modes for utilizing
signals from all three input pathways and generating output signals that
contribute to the dynamics and functional maps of extrastriate areas. In
light of this model, the major effort of our project is to understand
how parallel LGN pathways in primates contributes to the properties of
V1 and its extrastriate targets. This proposal focuses on all three LGN
relays and how their inputs affect V1 and higher visual centers, but
places added emphasis on the K pathway considering the fact that it has
been, until recently, largely ignored. Our specific aims are designed to
test hypotheses generated by our working model. In Aim I, we will
determine the number of physiologically distinct K channels and the
classes of retinal ganglion ceils that project to K LGN layers. In Aim
II, we will determine the relationship between LGN relay cells and the
dynamics and functional maps found within V1. In Aim III, we will apply
the same techniques utilized in Aim II to determine how LGN relays
contribute to the dynamics and functional maps found within extrastriate
areas V2, V3, and DM/V3a. The results of our proposed studies will
contribute important new information to our understanding of the
fundamentals of how the brain processes visual information and of brain
architecture in general.
Thesaurus Terms:
developmental neurobiology, lateral geniculate body, neural information
processing, visual cortex, visual pathway brain electrical activity, eye
movement, neuronal transport, retinal ganglion, visual deprivation,
visual perception Aotus, Callithricidae, Macaca, Prosimii, brain imaging
/visualization /scanning, electron microscopy, electrophysiology,
experimental brain lesion, histology, single cell analysis
Institution: VANDERBILT UNIVERSITY
Medical Center, NASHVILLE, TN 372036869
Fiscal Year: 2006
Department: CELL AND DEVELOPMENTAL BIOLOGY
Project Start: 01-FEB-1978
Project End: 31-MAR-2008
ICD: NATIONAL EYE INSTITUTE
IRG: VISB
J Neurophysiol 95: 3401-3413, 2006. First published March 1, 2006
Low-Threshold Ca2+-Associated Bursts Are Rare Events
in the LGN of the Awake Behaving Monkey
Octavio Ruiz1,*, David Royal2,*,
Gyula S�ry4, Xin Chen1,
Jeffrey D. Schall2,3 and Vivien A.
Casagrande1,2,3
1Department of Cell and Developmental
Biology, 2Institutes of Cognitive,
Integrative and Molecular Neuroscience and 3Department
of Psychology, Vanderbilt University, Nashville, Tennessee; and
4Department of Physiology, University of
Szeged, Szeged, Hungary
Submitted 4 January 2006; accepted in final form 22 February 2006
Subjects and LGN localization
Three male bonnet macaque monkeys (Macaca radiata, 6.0�8.0 kg) were used
in this study. Because the methods for locating the LGN are described in
detail elsewhere (Royal et al. 2006 ), only a short summary is presented
here. We used magnetic resonance imaging (MRI) maps to position a
recording chamber over the LGN. All the procedures, care and training of
the monkeys conformed to the guidelines of the National Institutes of
Health Guide for the Care and Use of Laboratory Animals and the
guidelines of the Vanderbilt University Animal Care and Use Committee
under an approved protocol.
Surgery
Attachment of the recording chamber, the head post, and eye coil were
performed under sterile conditions under general anesthesia (either
ketamine and xylazine or 1.5�3% isofluorane in O2 as described in detail
in Royal et al. (2006 ). Briefly, this involved securing head posts and
wells with titanium screws and dental cement, and implanting an eye coil
under the conjunctiva of the right eye (Judge et al. 1980 ).
Recording
Monkeys were seated in a primate chair in front of a computer monitor,
within a frame generating a magnetic field received by the eye-coil. The
head of the monkey was fixed by means of a head post attachment to the
chair. Single-unit recordings were made with Parylene-coated tungsten
microelectrodes (1�3 M ; FHC). The cellular activity was amplified and
band-pass filtered, and spikes were discriminated with an
amplitude-and-time window discriminator (BAK Instruments, Mount Airy,
MD). A PC-based system running Tempo (Reflective Computing, St. Louis,
MO) was used to control experiments, present stimuli, and store analog
eye-position data and digital spike-timing data. Eye-position and
neuronal activity were sampled at 250 Hz and 1 kHz, respectively. |