Threshold-Based Ordering of Sequential Actions during Drosophila Courtship

Abstract

Graphical AbstractHighlights d A descending neuron, aSP22, controls multiple actions in Drosophila male courtship d aSP22 activation triggers these actions in the same sequence as found in courtship d The courtship actions are sequenced by a ramp-to-threshold mechanism d Distinct action thresholds are best explained by spike count, not spike frequency SUMMARY Goal-directed animal behaviors are typically composed of sequences of motor actions whose order and timing are critical for a successful outcome. Although numerous theoretical models for sequential action generation have been proposed, few have been supported by the identification of control neurons sufficient to elicit a sequence.Here, we identify a pair of descending neurons that coordinate a stereotyped sequence of engagement actions during Drosophila melanogaster male courtship behavior. These actions are initiated sequentially but persist cumulatively, a feature not explained by existing models of sequential behaviors. We find evidence consistent with a ramp-to-threshold mechanism, in which increasing neuronal activity elicits each action independently at successively higher activity thresholds.

Unsupervised identification of the internal states that shape natural behavior

“…This represents an increase of 70% for all song and 110% for song transitions over a GLM. While we have here accounted for much of the variability in song patterning, we speculate that the remaining variability is due to either some noise in our segmentation of song [3] or the fact that we do not measure some male behaviors that are known to be part of the courtship interaction, including tapping of the female via the forelegs and proboscis extension [49, 72]. The use of new methods that estimate the full pose of each fly [52] combined with acoustic recordings should address this possibility.…”

Alcohol Increases Aggression in Flies

“…We find that a pharmacologically relevant blood alcohol concentration (BAC) promotes male aggression. Furthermore, this alcohol dosage impairs male courtship-a goal-directed behavior (4). In addition, there exists a secondary mechanism through which alcohol induces aggression.…”

Behavioral Evolution of Drosophila: Unraveling the Circuit Basis

“…This study also identified P1 and a pair of descending neurons named pIP10, likely a member of P2b, as neurons that can initiate male courtship singing ( Figure 1B). Other studies identified the dsx-positive pC2l cluster [35] and the fru-positive aSP22 descending neurons [36] as neurons activating licking and attempted copulation, two later-phase components of mating behavior, in addition to following pursuits and singing.…”