Positive controls in joystick optogenetics

on Tuesday, March 31st, 2020 7:40 | by

I’ve started rescreening Christian’s most consistent dopaminergic lines with the positive controls at the joystick machine, to see if everything works. These flies express the optogenetic channel Chrimson in Gr28bd and TrpA1 heat sensitive neurons, so they should use the joystick to switch the light off.

I tested three rounds of three flies each and I got the impression that it worked while I was looking at the flies. The data didn’t look that great, however:

Experimental time course of positive control flies. PIs (Y-axis) should be mostly negative.

Setting up the experiments, I noticed that the middle setup didn’t really focus the light on the head of the fly very well. This shows in the raw performance index data:

The two middle flies (row #2 and #8) have positive preferences, but never avoid the light, while nearly all other flies do avoid the light to various extents, even if they start out with a positive preference. So I deleted these two flies to see how the data would look then:

As above, only this time with the training periods averaged at the end (“Means”).

I decided that this should be good enough. I improved the middle setup to focus the light better on the fly’s head. Hopefully it will improve the PIs of the flies placed there now.