Hierarchical diversification of neurons regulating motivated behaviors

Brain regions that regulate motivated behaviors, including the vertebrate hypothalamus and arthropod cerebrum, house bespoke neural circuits dedicated to perceptual and internal regulation of many behavioral states ^1,2 . These circuits are built to purpose from complex sets of cell types whose patterning has been challenging to elucidate. Here, we developed methods in Drosophila melanogaster to embed well-studied neurons that regulate mating in the transcriptional contexts of the neuronal lineages that generate them ^3–5 . By comparing transcription within and between lineages, we identified a large set of transcription factors expressed in complex combinations that delineate cerebral hemilineages – classes of postmitotic neurons born from the same stem cell and sharing Notch status ^6,7 . Hemilineages comprise the major anatomic classes in the cerebrum ^8–10 and these transcription factors are required to generate their gross features. We show that subtypes of the same hemilineage can provide a common computational module to circuits regulating different drives, and identify an orthogonal set of transcription factors that stratify hemilineage subtypes of differing birth order. Our findings suggest that distinct sets of transcription factors operate in a hierarchical system to build, diversify, and sexually differentiate lineally-related neurons that compose motivated behaviors circuits. By linking developmental patterning to separable transcriptional axes that produce gross versus fine aspects of information flow, we provide a logical framework for cerebral control of diverse drives.