Biology subjects

Seelig, J. D.

Publications and source records attributed to Seelig, J. D..

5 recordsLinked to original sources

bioRxiv2025

Goal learning, memory, and drift in the Drosophila head direction system

Heading information is represented in head direction systems across species, including Drosophila. However, how navigation decisions are made and how goal memories are represented, particularly during rest, is little understood. Here, using a navigation learning assay for flies walking in virtual reality, we describe neural dynamics for direction selection and memory. Neurons in the fan-shaped body, a navigation and memory related structure, continually drift when the animal is at rest, shifted by 180{degrees} compared to walking directions. Optogenetic activation during rest biases subsequent walking direction. Learning leads to changes in drift during rest, revealing a memory of goal direction. Downstream neurons correct the 180{degrees} shift, therefore reactivating walking directions during rest. The connectome reveals a compact circuit architecture for reactivation, as validated using computational modeling. Thus, drift drives behavior, reactivates walking directions during rest, and is shaped by memory, suggesting similarities for memory consolidation in navigation circuits across species.

neuroscience↗

bioRxiv2022

Dynamics of a sleep homeostat observed in glia during behavior

Sleep is critical for homeostatic processes in the brain, including metabolism and waste removal. Here, we identify brain-wide, locally acting sleep homeostats for the short, naturally occurring sleep bouts of Drosophila in the two major classes of glia that arborize inside the brain, astrocytes and ensheathing glia. We show that glia surround respiratory tracheal tubes, that the metabolic gas carbon dioxide, changes in pH, or behavioral activity, all induce long lasting calcium responses, and that astrocytes and glia show circadian calcium modulations. Glia describe sleep homeostasis in behaving flies more faithfully than previously identified sleep circuits in the central complex, but a subset of neurons in the fan-shaped body is important for feeding homeostasis. Local optogenetic activation of astrocytes or ensheathing glia is sufficient to induce sleep. Together, glia calcium levels can be modeled as homeostatic controllers of metabolic activity, thus establishing a link between metabolism and sleep.

neuroscience↗

bioRxiv2021

Axial motion estimation and correction for simultaneous multi-plane two-photon calcium imaging

Two-photon imaging in behaving animals is typically accompanied by brain motion. For functional imaging experiments, for example with genetically encoded calcium indicators, such brain motion induces changes in fluorescence intensity. These motion related intensity changes or motion artifacts cannot easily be separated from neural activity induced signals. While lateral motion within the focal plane can be corrected by computationally aligning images, axial motion, out of the focal plane, cannot easily be corrected. Here, we develop an algorithm for axial motion correction for non-ratiometric calcium indicators taking advantage of simultaneous multi-plane imaging. Using at least two simultaneously recorded focal planes, the algorithm separates motion related and neural activity induced changes in fluorescence intensity. The developed motion correction approach allows axial motion estimation and correction at high frame rates for isolated structures in the imaging volume in vivo, such as sparse expression patterns in the fruit fly brain.

neuroscience↗

bioRxiv2021

Automated long-term two-photon imaging in head-fixed walking Drosophila

The brain of Drosophila shows dynamics at multiple timescales, from the millisecond range of fast voltage or calcium transients to functional and structural changes occurring over multiple days. To relate such dynamics to behavior requires monitoring neural circuits across these multiple timescales in behaving animals. Here, we develop a technique for automated long-term two-photon imaging in fruit flies, during wakefulness and sleep, navigating in virtual reality over up to seven days. The method is enabled by laser surgery, a microrobotic arm for controlling forceps for dissection assistance, an automated feeding robot, as well as volumetric, simultaneous multiplane imaging. The approach is validated in the flys head direction system. Imaging in behaving flies over multiple timescales will be useful for understanding circadian activity, learning and long-term memory, or sleep.

neuroscience↗

bioRxiv2020

Integration of sleep drive and navigation in Drosophila

During sleep, the brain undergoes dynamic and structural changes. In Drosophila, such changes have been observed in the central complex, a brain area important for sleep control and navigation. The connectivity of the central complex raises the question about how navigation, and specifically the head direction system, can operate in the face of sleep related plasticity. To address this question, we develop a model that integrates sleep homeostasis and head direction. We show that by introducing plasticity, the head direction system can function in a stable way by balancing plasticity in connected circuits that encode sleep pressure. With increasing sleep pressure, the head direction system nevertheless becomes unstable and a sleep phase with a different plasticity mechanism is introduced to reset network connectivity. The proposed integration of sleep homeostasis and head direction circuits captures features of their neural dynamics observed in flies and mice.

neuroscience↗