Figure 11. Proposed circuit underlying female aggressive behaviors.

A diagram of key neuronal pathways centered on pC1d and aIPg type1, type 2 and type 3 neurons is shown. The numbers in arrows represent synapse number. We propose that pC1d facilitates female aggressive behaviors by acting through aIPg type 1 (orange), type 2 (green), and type 3 (purple) neurons. The top four inputs to pC1d and three other neurons of interest are shown. These include neurons implicated in other female behaviors (highlighted with a blue circumference), including oviposition (oviIN, pC1a) and mating (vpoDN), suggesting communication between the circuits underlying these behaviors and aggression. We propose that aIPg neurons integrate diverse upstream signals and then alter brain state in a way that increases the likelihood of engaging in aggressive social interactions. Upstream neuronal populations are color-coded by the proportion of their synapses they make onto the aIPg type 1, aIPg type 2, and aIPg type 3 subtypes. The post-synaptic targets of aIPg type 1, aIPg type 2, and aIPg type 3 neurons are shown color-coded by the relative proportion of their synaptic input they receive from each aIPg type. AOTU neurons that also get input from LC10 neurons (see Figure 10B) are highlighted with a dark green circumference. Inputs to the aIPg neurons were thresholded in proportion to the number of cells in each aIPg type resulting in thresholds of 24, 30, and 12 synapses to type 1, type 2, and type 3, respectively. Downstream outputs receiving more than 50 synapses from aIPg neurons (outputs from all 11 aIPg neurons pooled) are shown, with neurons receiving fewer synapses included when a majority came from aIPg type 3. For cell types that get input from multiple types of aIPg neurons, the relative proportions of inputs from different types are indicated by the color-coding of the circle. Connections with DNs with more than 50 synapses are shown. VES041 neurons have strong reciprocal connections with aIPg type 2 neurons; both the right and left hemisphere VES041 neurons are connected to the right-hemisphere DNa03 (321 total synapses; see Figure 9A) and are shown as solid and dotted arrows, respectively, in this diagram. Connections from AOTU019, SMP148, and AOTU023 from the contralateral hemisphere to DNs are similarly shown as dotted arrows (see Figure 10A).