It is found recently that providing strong light to patients with bipolar disorder for 30 minutes a day can significantly alleviate their symptoms, and that patients with bipolar disorder might appear to have lower contrast sensitivity. We want to develop a method to test the hypothesis that light therapy might significantly change the contrast sensitivity of the patients, which in turn might lead to their ¡§brightened outlook¡¨. The general goal of this project is to assess the effectiveness of commercially available portable EEG recording devices for measuring contrast sensitivity and its change in the brain as a result of light therapy, and to develop a computer video game (with or without EEG) that would allow patients to measure their contrast sensitivity at home. Methods to be used: We will develop a JAVA or C# program or using Matlab program (using Psychtoolbox) to display stimuli to perform contrast sensitivity test, equivalent to Pelli-Robson test used in clinical setting. In this test, we will present 2D contrast grating stimuli in different orientation and contrast level to the human subjects, and record both the behavioral response of the subject, and the subject¡¦s responses. The behavioral response is either the subject¡¦s perceptual report of the orientation of the grating, or whether two simultaneously presented gratings are the same or different. The testing program should be easily deployed and learned to use by patients at home. The EEG responses will be recorded using three portable devices: Emotiv headset, Neurosky¡¦s mindset, and B-alert X24. We will analyze the acquired EEG signals using signal processing and classification techniques to extract neural signatures related to contrast sensitivity. We will compare the quality and the effectiveness of the neural signals measured using the three different devices. Anticipated results: The expected outcome of this project is the development of a set of software tools for stimulus presentation and human response measurement that can be used in studies for discovering predictive biomarkers in neural signals on the effectiveness of light therapy. These tools include:
1. A computer `video game¡¦ for performing contrast sensitivity test that can be used in the lab as well as in the home of patients. This program should be able to display dynamic stimulus (simple movies), recording behavioral responses and EEG responses.
2. A set of Matlab routines for processing neural signals to extract neural signatures that are correlated with stimulus contrast level. With this set of tools, we should be able to plot a contrast sensitivity curve based on the subject¡¦s behavioral report, or based on the subject¡¦s EEG signals, and evaluate their correspondence. We can use this set of tools for evaluating the effect of light therapy on the subject¡¦s contrast sensitivity as well as on the subject¡¦s neural signals.