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Suppose all the assumptions made in the introduction to this study are correct - namely that different associations are made in operant and classical conditioning and our paradigms represent operant and classical conditioning - then there is only one possibility why the behavioral strategies of the four groups are so strikingly similar: the range of behaviors a fly uses for flight orientation seems to be very limited and rather hard wired; the components of this behavior are tightly interconnected. Therefore, the CR in the classical conditioning paradigm is the same as the response conditioned in the operant paradigm and there is only very little room for acquiring 'new' strategies. An observation mentioned above (3.5) is in favor of this notion: very similarly to the volley of spikes depicted in Fig. 16, some flies produce spike volleys and a shift in the torque baseline when heated under open loop conditions (Fig. 17). In this view, the significant difference in fixation/spike polarity might be a cue as to how the expression of learning is accomplished in the Drosophila flight simulator: modulating spike dynamics and -timing irrespectively of the spikes' direction seems to be a set of very basic and interdependent behaviors that is activated whenever the fly is asked "stay or leave?" while the directional usage of spikes is a more sophisticated behavior that becomes important when the fly is asked "how can I stay?" or "how can I leave?". In the classical conditioning paradigm studied here, the latter questions are never asked, since the patterns are presented stationarily during training. In the standard paradigm, however, the question how to stay away from the heat is of great importance. Nevertheless, the 'knowledge' how to perform that task is only acquired slowly during the experiment - there are no training effects in spike polarity indicating a rather fixed, responsive behavior. Unpublished data from Reinhard Wolf (pers. comm.) lead him to the idea of a two-process theory, too.
The important implication of this hypothesis is that for both groups, in essence, the same has been learned, namely that a certain orientation of the patterns is 'hot' and has to be avoided (i.e. a stimulus-reinforcer association has been formed). In surplus, the flies of the operant group have learned how to avoid the pattern more effectively. This is well in line with the expectations.
Concentrating on the first, more basic process of avoidance, it can be inferred from the behavior of the control groups that our type of conditioning merely switches or confirms the sign of the individual fly's spontaneous preference. In addition to the data on the flies' behavior presented so far, it can be observed that the preference at t1 is carried as a 'socket' throughout the whole experiment (not shown). Then the procedure of subtracting the pre-test values (t1) from the test values (t2) is admittable. After this subtraction, only one of the indices calculated in dependence of the differently treated (hot/cold) sectors showed significant differences between the two test groups: the 'cold' spike polarity indices (Figs. 24 and 29). All the other parameters showed the same modulation. If modulating the direction of spikes is considered a more sophisticated strategy, maybe acquired after learning the 'basic' avoidance task, then the flies apparently employed the same behavioral output irrespectively of their training to perform the basic task of avoiding the pattern orientation associated with the reinforcer: the flies from both groups generate many, large spikes when the previously heated pattern orientation is in the frontal sector of the visual field.
If the lack of significant differences in the basic responses generated by the flies were due to the same associations made during the different training procedures, several questions have to be asked: how classical is the standard paradigm? Is the distinction between operant and classical merely operational? What is learned during conditioning?
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