In my attempts to establish operant learning in isolated leech ganglia I'm now at preparation number 6. In my last post, I promised to show some screenshots of the software I'm using, WinEDR. Here's a screenshot of the preparation generating swimming patterns after a stimulation of ganglion 18 (click for fullsize image):



And here is one showing crawling patterns in response to the same stimulation in the same preparation:



The first channel is the recording from the DP nerve of ganglion 10 and the second channel is the recording of the anterior ganglion (2 or 3), which I stimulate contingently during training. The window spans 40s of recording, in case that isn't quite clear from the screenshots. This little program works really well and I enjoy doing my experiments with it a lot. Very easy, fast and it does what it needs to do.

This preparation started out to only generate crawling behavior in all ten pre-test trials. Not unexpectedly, during training, the animal started to generate swimming patterns, when crawling patterns were paired with stimulation of the anterior (2/3) ganglion, and I got a 4-6 swim/crawl ratio. Similar to the last two preps, it reverted to its pre-test behavior in the final test (s/c ratio of 1-9), showing that the anterior stimulation can bias decision-making towards swimming, but only transiently. The next two preps will have to be control preps: in the first, I'll omit the anterior stimulation completely, to see what the unstimulated development of the patterns looks like. In the second, the stimulation will be 'yoked' to one of the previous preps, such that the anterior stimulations are not related to any of the animals decisions. This way I'll be able to find out if the anterior stimulation has to be contingent to bias the network towards swimming.
After these two preps, I'll have to think about what the next steps will be. Hopefully, I'll get some insight from these experiments. Maybe I should increase the intensity of the anterior stimulation to make it really aversive?

Sticking with the Open Science mantra, I've now also plugged all the data from the first 6 preps into a Google Spreadsheet for the two persons following this blog, or anyone else with good ideas.

Over the coming weekend I'll be attending the annual GAIN (German Academic International Network) meeting in Boston and won't be able to do any experiments. I'll try to blog from there, but as usual, there is no way to foresee the availability of WiFi and the time I'll have.