Drosophila melanogaster grooming possesses syntax with distinct rules at different temporal scales
Fig 8
Grooming bout duration contributes to syntax at the scale of individual transitions.
A: Probabilities from the maximum likelihood transition matrix (top) differ significantly from null hypothesis transition matrices (bottom) to varying degrees, indicating that both grooming action order and bout duration contribute to grooming syntax. Shown on the top left is the network visualization of anterior motif transitions, with edge withs proportional to transition probabilities. Notice that transitions between actions belonging to the same duration category possess relatively high probabilities and appear nearly symmetric, suggesting a coupling mechanism between anterior motif actions. BIC values (right of matrices) provide validation that the maximum likelihood model captures statistically significant features of the data. The maximum likelihood transition matrix has a lower BIC value than the null hypotheses used for comparison, indicating that both bout order and duration contribute to sequence syntax. B: The residual values, or the difference between the maximum likelihood matrix and the null model matrices, illustrate that specific transitions differ from what the null hypotheses would predict. The duration permuted null model matrix exhibits block structure but fails to capture the temporal relationship between bouts, as illustrated by the red values in several “long-to-long” transitions, for example. The order permuted null model differs even more severely, indicating that, while duration dependence plays a role in sequence structure, action order is still the primary determinant.