By Irene Varela
February’s neuron of the month is a type of sexually dimorphic neuron known as an aSP-g.
In females, aSP-g neurons extend their dendrites (bright green) throughout the lateral horn (yellow), a higher olfactory centre for innate behaviour, whereas in males they do not. This morphological difference explains how the sex pheromone cis-vaccenyl acetate (cVA) elicits different mating-related behaviours in males and females. The axons (bright red) drive the output of pheromone information to higher processing regions on both sides of the brain; the superior intermediate protocerebrum (SIP, pink) and the superior lateral protocerebrum (SLP, purple), via output synapses (red spheres). Input synapses are also represented (cyan spheres).
Sex-specific behaviours arise from anatomical and molecular differences in neuronal populations, such as these aSP-g neurons. Pheromones in insects and sex steroid hormones in mammals represent an important input into the neurons that control these behaviours. We are reconstructing aSP-g neurons, as well as other neurons involved in cVA processing, within a whole female fly brain to achieve a better understanding of how sex is represented in the brain and how pheromonal information is transformed into sexually dimorphic behaviours.