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Published January 6, 2012 | Published
Journal Article Open

An Optically Stabilized Fast-Switching Light Emitting Diode as a Light Source for Functional Neuroimaging


Neuroscience research increasingly relies on optical methods for evoking neuronal activity as well as for measuring it, making bright and stable light sources critical building blocks of modern experimental setups. This paper presents a method to control the brightness of a high-power light emitting diode (LED) light source to an unprecedented level of stability. By continuously monitoring the actual light output of the LED with a photodiode and feeding the result back to the LED's driver by way of a proportional-integral controller, drift was reduced to as little as 0.007% per hour over a 12-h period, and short-term fluctuations to 0.005% root-mean-square over 10 seconds. The LED can be switched on and off completely within 100 µs, a feature that is crucial when visual stimuli and light for optical recording need to be interleaved to obtain artifact-free recordings. The utility of the system is demonstrated by recording visual responses in the central nervous system of the medicinal leech Hirudo verbana using voltage-sensitive dyes.

Additional Information

© 2012 Daniel A. Wagenaar. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Received September 5, 2011; Accepted December 6, 2011; Published January 6, 2012. Editor: Björn Brembs, Freie Universitaet Berlin, Germany. Funding: This work was supported by a Senior Research Fellowship from the Broad Foundations. The author holds a Career Award at the Scientic Interface from the Burroughs Wellcome Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. John Nagarah, Sotiris Masmanidis, William B. Kristan, and Andrew Steele provided valuable comments. Author Contributions: Conceived and designed the experiments: DAW. Performed the experiments: DAW. Analyzed the data: DAW. Contributed reagents/materials/ analysis tools: DAW. Wrote the paper: DAW.

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