Abstract
Light emitting diodes (LEDs) are increasingly being used as light sources in a myriad of vision research paradigms. Here we present a visual stimulator based on LEDs and an open-source Arduino microcontroller prototyping platform (Teikari et al. 2012). The system is implemented as an “Arduino shield” that can be hot-plugged on top of the commercially available 32-bit Arduino Due board. The system integrates high-current LED drivers with an additional light sensor board for a real-time closed feedback loop. The chosen LED drivers provide a dynamic range of over 4 log units for LED intensity. The shield board is designed using EagleCAD and the design files are provided for users for possible custom modification and manufacturing.
The software interface is developed using Python programming language which, as opposed to commercial platforms such as Matlab and LabView, is available for free. Furthermore, choosing Python allowed us to integrate the proposed hardware system to the increasingly popular open-source software package PsychoPy (Peirce 2007). PsychoPy handles the presentation of stimuli and collection of data for a wide range of neuroscience, psychology and psychophysics experiments. The authors have used the system for example in heterochromatic flicker photometry and QUEST adaptive psychometric method for estimating discrimination thresholds.
References:
Peirce JW. PsychoPy--Psychophysics software in Python. J Neurosci Methods.2007; 162: 8–13.
Teikari P, Najjar RP, Malkki H, Knoblauch K, Dumortier D, Gronfier C, Cooper HM. An inexpensive Arduino-based LED stimulator system for vision research. J Neurosci Methods.2012; 211:227–236.