A low cost color visual stimulator for fMRI

Bill Rogers, Yen Yu I. Shih, Bryan de la Garza, Joseph M. Harrison, John Roby, Timothy Q. Duong

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


This low cost visual stimulator was developed for use in small animal imaging. The stimulator uses a single tri-color LED for each eye and can output red, green, or blue light or any combination of the three. When all three LED colors are illuminated at the same time achromatic light is the output. The stimulator is almost entirely implemented in software with only minimal electronics. The LEDs are controlled via the parallel port of a desktop computer. Flicker frequency, wavelength, intensity and waveform shape are under software control. The LEDs are coupled to fiber optic cables which run into the MRI scanner room leaving the LEDs and the power source in the control room. Calibration with a radiometer shows the light output to be very linear from zero to full intensity. The stimulator was used in fMRI visual stimulation studies performed on Sprague Dawley rats with an 11.7. Tesla magnet. As the stimulator is software driven, modifications to accommodate other protocols and extensions for new functionality can be readily incorporated. With this in mind, the visual stimulator circuit diagram and software including source code are available upon request.

Original languageEnglish (US)
Pages (from-to)379-382
Number of pages4
JournalJournal of Neuroscience Methods
Issue number2
StatePublished - Mar 15 2012
Externally publishedYes


  • Biomedical measurements
  • Magnetic resonance imaging
  • Visual stimulation

ASJC Scopus subject areas

  • Neuroscience(all)


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