Auditory Activity is Diverse and Widespread Throughout the Central Brain ofDrosophila

Abstract

Sensory pathways are typically studied by starting at receptor neurons and following postsynaptic neurons into the brain. However, this leads to a bias in analysis of sensory activity towards the earliest layers of sensory processing or to brain regions containing the majority of postsynaptic neurons. Here, we present new methods for unbiased volumetric neural imaging with precise across-brain registration, to characterize auditory activity throughout the entire central brain of Drosophila, and to make comparisons across trials, individuals, and sexes. We discover that auditory activity is widespread across nearly all central brain regions and in neurons known to carry responses to other modalities. These auditory representations are diverse in their temporal profiles, but the majority of activity, regardless of brain region, is focused on aspects of the conspecific courtship song. We find that auditory responses are stereotyped across trials and animals in early mechanosensory regions, becoming more variable at higher layers of the putative pathway. This study highlights the power of using an unbiased, brain-wide approach for mapping the functional organization of sensory activity.

The Neural Basis for a Persistent Internal State inDrosophilaFemales

“…5 and 6). We used pan-neuronal imaging with registration to map responses that continue following pC1 optogenetic activation (previously this technique had only been used to map sensory activity (Pacheco et al, 2019) and spontaneous activity (Mann et al, 2017)). We found that activation of pC1-Alpha neurons drives robust persistent neural activity throughout the posterior dorsal regions of the central brain (known to contain the processes of sexually dimorphic neurons (Cachero et al, 2010;Kimura et al, 2015)), lasting for minutes following activation.…”

“…5A). To compare activity across flies and to map activity onto a reference atlas, we used a recently developed pipeline for two-photon volumetric calcium imaging, motion correction, registration, and region of interest (ROI) segmentation (Pacheco et al, 2019), and scanned the entirety (in the z dimension) of a dorsal portion of a single brain hemisphere in each fly ( Fig. 5A).…”

“…Making use of anatomical segmentation of an in vivo brain atlas to which all ROIs were registered (Pacheco et al, 2019), we evaluated the distribution of pC1-elicited activity by brain neuropil (Ito et al, 2014). Persistent activity was clustered in the posterior-dorsal portion of the brain spanning the Superior Medial, Lateral and Intermediate Protocerebrum (SMP, SLP, SIP), the Anterior Optic Tubercle (AOTU), and the Inferior and Superior Clamp (ICL and SCL; see (Rideout et al, 2010;.…”

“…(E) Maps of transient and persistent activity types. ROIs from response types 1-4 per animal were registered to an in vivo intersex atlas (Pacheco et al, 2019) to generate probability density maps across animals per brain voxel (each voxel is 0.75x0.75x1 µm 3 ).…”

Complete connectomic reconstruction of olfactory projection neurons in the fly brain

“…The perception of wind is crucial for animal navigation, particularly for flying animals and for anemotaxis. The LH receives projections from a third-order mechanosensory region of the brain known as the wedge [5,15,[66][67][68] (Figure S6A). Activating a line labelling WED-PN1 (R37E08) can generate increased wing-flick motion and differential wingangling [69] ( Figure S6C).…”