? The objective of this proposal is to investigate the coupling between brain activation and cerebral perfusion. The details behind this neurovascular coupling are yet unclear, but form the basis for several widely used imaging modalities such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and optical imaging of intrinsic signals (OIS). To help clarify the properties of this relationship, this proposal outlines two specific goals: (l) to characterize the spatial and temporal evolution of hemoglobin oxygenation changes within and between vascular and parenchymal compartments; and (2) to determine how well these perfusion signals are coupled to underlying neuronal activity. ? ? OIS is well-suited for the proposed studies because if offers high spatial and temporal resolution, as well as the opportunity for simultaneous electrophysiological recording. A technique for extracting hemoglobin (Hb) concentration changes from the OIS images in two spatial dimensions is presented and, in combination with field potential recording, used to study spatial and temporal aspects of neurovascular coupling in rodent somatosensory cortex. The results of these experiments will influence the design and interpretation of perfusion-based brain imaging techniques, especially fMRI. Identifying aspects of the fMRI signal that more closely reflect underlying neuronal activity will improve the technique's ability to localize brain activity. This development would significantly increase its utility for pre-operative surgical planning, for example. Determining whether coupling breaks down in certain instances will also identify possible limitations to these techniques. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Individual Predoctoral NRSA for M.D./Ph.D. Fellowships (ADAMHA) (F30)
Project #
5F30MH067432-02
Application #
6663686
Study Section
Special Emphasis Panel (ZRG1-F01 (20))
Program Officer
Desmond, Nancy L
Project Start
2002-09-30
Project End
2004-09-29
Budget Start
2003-09-30
Budget End
2004-09-29
Support Year
2
Fiscal Year
2003
Total Cost
$28,229
Indirect Cost
Name
University of California Los Angeles
Department
Neurology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Sheth, Sameer A; Prakash, Neal; Guiou, Michael et al. (2009) Validation and visualization of two-dimensional optical spectroscopic imaging of cerebral hemodynamics. Neuroimage 47 Suppl 2:T36-43
Sheth, Sameer A; Nemoto, Masahito; Guiou, Michael W et al. (2005) Spatiotemporal evolution of functional hemodynamic changes and their relationship to neuronal activity. J Cereb Blood Flow Metab 25:830-41
Sheth, Sameer A; Nemoto, Masahito; Guiou, Michael et al. (2004) Linear and nonlinear relationships between neuronal activity, oxygen metabolism, and hemodynamic responses. Neuron 42:347-55
Sheth, Sameer A; Nemoto, Masahito; Guiou, Michael et al. (2004) Columnar specificity of microvascular oxygenation and volume responses: implications for functional brain mapping. J Neurosci 24:634-41
Nemoto, Masahito; Sheth, Sameer; Guiou, Michael et al. (2004) Functional signal- and paradigm-dependent linear relationships between synaptic activity and hemodynamic responses in rat somatosensory cortex. J Neurosci 24:3850-61