Color Calibration of a CRT Monitor For Use in Fly Behavior Experiments

1. Color Calibration of a CRT Monitor For Use in Fly Behavior Experiments By Kristin Granlund and Mariel Velez

2. Psychophysics Electrophysiology How does a neural circuit compute visual information? • Benefits: • Humans! • Can create models of visual processing • Can study visual perception directly • Limitations: • Cannot study neurons directly • Benefits: • Can study activity of neurons directly • Limitations: • Lots--**Hard to manipulate the circuit**Cannot easily determine which/how neurons contribute to visual perception

3. Why Drosophila? • Unlike psychophysics----Can determine which neurons contribute to visual perception • Unlike neurophysiology-Can silence these neurons and ask how they contribute to visual perception How can we do all of these things with flies?

4. Proof of principle

5. Fly Visual Behavior • It turns out flies behave to visual stimuli Demonstration

6. Experimental Setup So we have all the equipment we need: 1)flies whose individual neurons can be imaged and silenced 2)Flies that behave in response to visual stimuli in a precise and reproducible way

7. Electrophysiology Psychophysics -Has found neurons in the monkey visual system that respond to color stimuli • provided many mathematical models that describe how we compute color information ? We still do not understand the relationship between the color percepts characterized in psychophysics and the neurons that compute them (ex-color constancy) Color Vision

8. Adapted from Wernet et al., Cell 115, 2003 Adapted from Salcedo et al., JofNeuroscience19(24), 1999 Can flies see color?

9. Need to Calibrate • To run color vision stimuli we need to calibrate the monitor • Gamma • Phosphor Independent • Calibration matrix

10. Data: Gamma Curves γred = 2.35 γgreen= 2.36 γblue= 2.53

11. Data: Gamma Verification

12. Data: Phosphor Independence Relative Error

13. Calibration Matrix • To control the relative absorption rates of fly photoreceptors, we will create a matrix to convert monitor RGB values into fly LMS values: • B = Cone Absorption Matrix (fat matrix) • M = SPDs of Monitor Phosphors at max intensity (skinny matrix) • H = B * M = Calibration Matrix • Cone sensitivities = H * (rgbmonitor)

14. Other Calibrations • Spatial independence • Consistent over time • Consistent over experiments

15. Problems Pitfalls • The PR650 code was not designed for Matlab 7.0 • Data collection is tedious • Experimental setup not finished • Physical rig under construction • Fly spectral sensitivity data not available (yet) • Can’t characterize UV spectrum

16. Thanks To…. • Peter Catrysse • Xiaowei Ding • Bob Dougherty • Brian Wandell • Tom Clandinin

17. The magic of Drosophila