As the three people reading this blog know, I'm currently trying hard to somehow establish operant learning in isolated leech ganglia. This is preparation number eleven after some initial trying-out and getting used to this great model system. You'd think that after so many preps I'd be an expert and I could do these experiments in my sleep. Well, I thought so too. Especially after only two tries at adjusting the stimulation of ganglion 18 I got the prep to generate both swimming and crawling motor patterns. I was very pleased with myself to have gotten to know the system so well in just a few weeks.

However, as usual, pride goes before a fall. After the usual 20min rest period after I adjust the anterir an dposterior stimulations, I start the experiment and, in contrast to just 20 minutes ago, the preparation responds only with swimming to the posterior stimulations, all ten times! So much for my abilities to adjust the stimulations to get the preparation to switch between swimming and crawling. I'm going to have to put a lot more effort in this tomorrow!

The ten training trials went rather as expected, I got a swimming/crawling ratio of 8-2. The nice thing was that I needed exactly 8 anterior stimulations which stopped each pattern immediately and the swimming did not come back until the next trial.

Confirming the previous experiments, this prep hardly showed a bias towards crawling at the end of the experiment, as the final s/c ratio was still 9-1.

Tomorrow, I'll have to be very thorough and get the prep to generate a bunch of crawls which I will then 'punish' with anterior stimulation.