Strange results after pooling data

on Thursday, December 19th, 2024 3:55 | by Björn Brembs

Because the effect of yaw torque training on optomotor responses (OMRs) is still very small for now (we work on improving that), I pooled the two groups in which aPKC was knocked out in either motor neuron (MN) b1 or MN b3, as both these two groups and their WTB x aPKC/Cas9 controls seem to learn just fine (torque preference text after 8 minutes of training):

Obviously, we still need to check the Gal4 driver lines are really targeting the right neurons, but assuming they are ok, it seems like neither an aPKC knock-out in b1 alone nor in b3 alone is sufficient to affect operant self-learning. Maybe this is due to b1 and b3 acting as an agonist/antagonist pair and if one of them fails to show plasticity, the other is sufficient on its own? Another explanation could be that the torque preference depicted above is mediated by other neurons than b1 or b3 and that the OMR modulation is gone in these flies. Because the OMR effect is so small, I pooled the two groups, threw out all flies that didn’t have at least an acceptable OMR and halfway accurate OMR parameter estimation and plotted the OMR traces of the remaining 35 flies after training:

So despite these flies learning well, the OMR does not seem modulated as one can see in WT flies. However, there my be a slight effect for the fly punished on right turning torque, perhaps? However, this group also has much larger errors, which I would need to check the reason for. The quantification of the OM symmetry does not show any hint of an effect, though:

Below the total evaluation before and after training. What is weird is that despite there being no effect after training, the correlation between torque preference and OMR asymmetry seems to be there – or is it just the three outliers?

Either way, when I pooled the control flies from this experiment with the same genotype from the last experiment to get to 42 flies, only the group that was punished on left-turning torque showed the modulation:

Accordingly, the quantification shows no difference ion the control group either:

And no significant correlation between the indices either:

All in all rather puzzling results that reinforce my view that the OMR effect is much too small to practically work with. That means one of the next goals must be to get this effect size increased by, perhaps, decreasing the strength of the optomotor stimulus?

Category: operant self-learning, Optomotor response, PKC

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