title: A low-cost, computer-interfaced drawing pad for FMRI studies of dysgraphia and dyslexia.
abstract: We have developed a pen and writing tablet for use by subjects during fMRI scanning. The pen consists of two jacketed, multi-mode optical fibers routed to the tip of a hollowed-out ball-point pen. The pen has been further modified by addition of a plastic plate to maintain a perpendicular pen-tablet orientation. The tablet is simply a non-metallic frame holding a paper print of continuously varying color gradients. The optical fibers are routed out of the MRI bore to a light-tight box in an adjacent control room. Within the box, light from a high intensity LED is coupled into one of the fibers, while the other fiber abuts a color sensor. Light from the LED exits the pen tip, illuminating a small spot on the tablet, and the resulting reflected light is routed to the color sensor. Given a lookup table of position for each color on the tablet, the coordinates of the pen on the tablet may be displayed and digitized in real-time. While simple and inexpensive, the system achieves sufficient resolution to grade writing tasks testing dysgraphic and dyslexic phenomena.
authors.affiliation: Instrument Development Lab, Center on Human Development and Disability, University of Washington, Seattle, WA 98195, USA. freitz@uw.edu
authors.forename: Frederick
authors.initials: F
authors.lastname: Reitz
authors.forename: Todd
authors.initials: T
authors.lastname: Richards
authors.forename: Kelvin
authors.initials: K
authors.lastname: Wu
authors.forename: Peter
authors.initials: P
authors.lastname: Boord
authors.forename: Mary
authors.initials: M
authors.lastname: Askren
authors.forename: Thomas
authors.initials: T
authors.lastname: Lewis
authors.forename: Virginia
authors.initials: V
authors.lastname: Berninger
mesh_terms: D000381:Agraphia / Q000175:diagnosis* / Q000503:physiopathology*; D003116:Color; D003365:Costs and Cost Analysis; D004410:Dyslexia / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000191:economics* / Q000295:instrumentation*; D009038:Motion; D013997:Time Factors; D014584:User-Computer Interface