We propose to design, fabricate and test a series of anthropromorphically designed helmets for optical tomographic functional neuroimaging studies. The helmet design will be based on dimensions derived from an existing database generated by laser scanning cranial anthropometry. Arc-like structures that provide mechanical support to springloaded optical fibers will be fabricated, and will be fitted to an adjustable scaffold having a helmet-type design. These arcs, which will embody optimally contoured geometries corresponding to the three dominant head shapes, will be designed to allow placement on the head of a subject in either a frontal or oblique orientation, thus enabling complete access to the any site on the cranium. They will also act as stand-offs that will permit direct visual inspection of fiber-scalp contact. We will also introduce a flexible low-buoyancy mechanical support arm that will serve to offload the weight of the helmet from the subject's head. We also propose to perform repeatability studies on healthy non-balding and nearly bald volunteers of different races, to determine the variability in optical signal levels at various sites on the head associated with a global blood pressure provocation (quantitative Valsalva maneuver). This information will be used to introduce adjustments to the attachment mechanisms of the fiber-optic support arcs to allow for optimal performance of the helmet design. For a select group of volunteers, we will perform finger-tapping studies to assess the ability of the imaging helmet and associated measuring system to provide for repeatable measures of localized hemodynamic changes in response to neural activation. In a subgroup of these, we will also perform functional MR studies using a similar protocol, to independently validate results from the optical studies. Successful completion of the listed aims, combined with additional refinements under a Phase II effort, will provide the research and clinical investigational community with comprehensively designed (hardware and software) and economical optical neuroimaging system capable of evaluating a broad spectrum of functional states.
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