Somehow, I didn't really manage to adjust the posterior stimulation properly in this 9th preparation in my attempts to establish operant learning in isolated leech ganglia, it generated a swim/crawl ratio of 9-1. Don't know what went wrong. Either way, I proceeded to yoke the animal to prep #5, which meant stimulating it anteriorly some 20 times by hand during the next ten trials.

In a very eerie way, the training period, especially in the beginning, really paralleled the sequence of patterns and stimulations of the preparation this one was yoked to, somewhat synchronized due to the 3 minute inter-trial-interval. By the end of the training phase, though, the current prep. behaved quite differently from the preparation it was yoked to, ending up in an identical swim-crawl ratio to the pre-test of 9-1.

Further corroborating the trend in the control data so far, the prep biased its decisions towards crawling at the end of the experiment. The final swimming/crawling ratio was 0-9 (one trial went without response).

Tomorrow will be either another control without anterior stimulation or a regular experimental preparation with contingent anterior stimulation, haven't decided, yet.