Biology subjects

Rogulja, D.

Publications and source records attributed to Rogulja, D..

3 recordsLinked to original sources

bioRxiv2020

Daily rewiring of a neural circuit generates a predictive model of environmental light

Ongoing sensations are compared to internal, experience-based, reference models; mismatch between reality and expectation can signal opportunity or danger, and can shape behavior. The nature of internal reference models is largely unknown. We describe a model that enables moment-to-moment luminance evaluation in flies. Abrupt shifts to lighting conditions inconsistent with the subjective time-of-day trigger locomotion, whereas shifts to appropriate conditions induce quiescence. The time-of-day prediction is generated by a slowly shifting activity balance between opposing neuronal populations, LNvs and DN1as. The two populations undergo structural changes in axon length that accord with, and are required for, conveying time-of-day information. Each day, in each population, the circadian clock directs cellular remodeling such that the maximum axonal length in one population coincides with the minimum in the other; preventing remodeling prevents transitioning between opposing internal states. We propose that a dynamic predictive model resides in the shifting connectivities of the LNv- DN1a circuit.

neuroscience↗

bioRxiv2020

A gut-secreted peptide controls arousability through modulation of dopaminergic neurons in the brain

Since sensory information is always present in the environment, animals need to internally regulate their responsiveness to fit the context. During sleep, the threshold for sensory arousal is increased so that only stimuli of sufficient magnitude can cross it. The mechanisms that make arousability flexible are largely mysterious, but they must integrate sensory information with information about physiology. We discovered a gut-to-brain signaling pathway that uses information about ingested nutrients to control arousability from sleep, without affecting sleep duration. Protein ingestion causes endocrine cells in the Drosophila gut to increase production of CCHa1, a peptide that decreases sensory responsiveness. CCHa1 is received by a small group of brain dopaminergic neurons whose activity gates behavioral responsiveness to mechanical stimulation. These dopaminergic neurons innervate the mushroom body, a brain structure involved in determining sleep duration. This work describes how the gut tunes arousability according to nutrient availability, allowing deeper sleep when dietary proteins are abundant. It also suggests that behavioral flexibility is increased through independent tuning of sleep depth and duration.

neuroscience↗

bioRxiv2019

Hormonal control of motivational circuitry orchestrates the transition to sexuality in Drosophila

Newborns and hatchlings of many species perform incredibly sophisticated behaviors, but all vertebrates and many invertebrates selectively abstain from sexual activity at the beginning of life. Hormonal changes have long been associated with adolescence, but it is not clear how these circulating factors create a new motivation and drive its associated behaviors. We show that the transition to sexuality in male Drosophila is controlled by juvenile hormone, which spikes at eclosion and declines over days as the propensity for courtship gradually increases. Juvenile hormone directly inhibits the activity of at least three courtship-motivating circuit elements, ensuring the complete suppression of sexual motivation and behavior. Blocking or overriding these inhibitory mechanisms evokes immediate and robust sexual behavior from very young and otherwise asexual males. These results provide a first example of hormonal changes gating the transition to sexuality by activating latent, but largely developed and functional, motivational circuitry.

neuroscience↗