Kohatsu et al. (2011) showed that perfuming of females with cis-vaccenyl acetate (mimicking http://www.selleckchem.com/products/PF-2341066.html nonvirginity) reduces their ability both to physiologically stimulate P1 neurons and to provoke courtship behavior. This correlation

is suggestive that the P1 cluster integrates olfactory and gustatory sensory cues when weighing up the decision to court or not ( Figure 1). von Philipsborn et al. (2011) focused their attention on circuit elements downstream of P1 neurons. Through their original thermogenetic screen, they identified four additional classes of FruM neurons whose activation was sufficient to trigger wing extension or vibration. One of these, named pIP10, was male-specific and both necessary and sufficient to reproduce a faithful rendition of male pulse song, similar to the properties of P1 neurons. However, unlike

P1, pIP10 neurons innervate both higher brain centers (including the lateral protocerebrum) and the VNC, thus representing a putative descending (or “command”) neuron that transmits signals from the brain to initiate song (Figure 1). Other types of descending neurons are likely to exist, for example, those that select sine versus pulse song, or control song termination. One of these may be P2b neurons, which Kohatsu et al. (2011) identified in their screen as being sufficient, DAPT molecular weight although only partially necessary, to induce wing vibration. The other three FruM neuron classes characterized by von Philipsborn et al. (2011), dPR1, vPR6, and vMS11, were distinct from P1 and pIP10 in two significant ways: first, activation of these neurons did not lead to faithful recapitulation of pulse song. For example, vMS11 activation induced wing extension but no singing,

while vPR6 activation led to pulse song with a novel temporal structure. Second, all three types are contained within the VNC. These neural classes therefore represent candidate components or direct regulators of the song generator, and may correspond to some of the neurons previously shown to be sufficient to induce singing in decapitated males Bay 11-7085 and females (Clyne and Miesenböck, 2008). Indeed, while dPR1 is male-specific, vPR6 and vMS11 are present in both sexes, albeit exhibiting sexually dimorphic arborizations within the wing neuropil. Furthermore, the impact of vPR6 on pulse song patterning suggests these neurons are a “mutable” part of the song generator that might account for the diversity in courtship serenades critical for species recognition (Murthy, 2010). While physiological evidence for functional connections between P1, pIP10, and the thoracic FruM neurons awaits, von Philipsborn et al. (2011) assess overlap between axonal and dendritic arbors of these neural classes to predict potential synaptic contacts.