The long term goal of the proposed experiments is to determine the causes of attention impairment during disease. However, it is first necessary to understand the organization of circuits that may contribute to attention mechanisms in the normal brain. Many studies have implicated the pulvinar nucleus as an area that may regulate visual attention. We propose to study the rodent lateral posterior (LP) nucleus, a region comparable to inferior regions of the primate pulvinar nucleus. We will use a combination of tract tracing, immunocytochemistry, electron microscopy and in vitro electrophysiology to examine the synaptic organization and functional properties of LP neurons. We propose that the rat LP nucleus contains at least 2 subdivisions that are characterized by distinct synaptic inputs, axonal projection patterns, and cellular firing properties. Regular spiking cells in the caudal LP nucleus are predicted to receive tectal input and project to the striatum. The synaptic arrangements of tectothalamic terminals, coupled with the linear firing properties of caudal LP neurons, may serve to accurately transfer signals related to the movement of visual stimuli. This circuitry may underlie the coordination of visually guided movements. Clustered spiking cells in the rostral LP nucleus are predicted to receive input from layer 5 of the visual cortex and in turn project to cortical layer 1. The synaptic arrangements of layer 5 corticothalamic terminals, coupled with the non-linear firing properties of rostral LP neurons, may serve to amplify and synchronize cortical activity, providing a substrate for the selective enhancement of visual signals. A thorough understanding of the firing characteristics of LP neurons and the organization and dynamic properties of their synaptic connections is necessary to begin to formulate reasonable hypotheses regarding the function of the rat LP nucleus, and ultimately the human pulvinar nucleus. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS035377-10A1
Application #
6875962
Study Section
Special Emphasis Panel (ZRG1-IFCN-F (05))
Program Officer
Coulombe, James N
Project Start
1995-09-30
Project End
2008-11-30
Budget Start
2004-12-01
Budget End
2005-11-30
Support Year
10
Fiscal Year
2005
Total Cost
$317,498
Indirect Cost
Name
University of Louisville
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
057588857
City
Louisville
State
KY
Country
United States
Zip Code
40292
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Masterson, Sean P; Li, Jianli; Bickford, Martha E (2009) Synaptic organization of the tectorecipient zone of the rat lateral posterior nucleus. J Comp Neurol 515:647-63
Bickford, Martha E; Wei, Haiyang; Eisenback, Michael A et al. (2008) Synaptic organization of thalamocortical axon collaterals in the perigeniculate nucleus and dorsal lateral geniculate nucleus. J Comp Neurol 508:264-85
Chomsung, Ranida D; Petry, Heywood M; Bickford, Martha E (2008) Ultrastructural examination of diffuse and specific tectopulvinar projections in the tree shrew. J Comp Neurol 510:24-46

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