@article {69594, title = {Activity of nested neural circuits drives different courtship songs in Drosophila.}, journal = {Nat Neurosci}, year = {2024}, month = {2024 Aug 28}, abstract = {

Motor systems implement diverse motor programs to pattern behavioral sequences, yet how different motor actions are controlled on a moment-by-moment basis remains unclear. Here, we investigated the neural circuit mechanisms underlying the control of distinct courtship songs in Drosophila. Courting males rapidly alternate between two types of song: pulse and sine. By recording calcium signals in the ventral nerve cord in singing flies, we found that one neural population is active during both songs, whereas an expanded neural population, which includes neurons from the first population, is active during pulse song. Brain recordings showed that this nested activation pattern is present in two descending pathways required for singing. Connectomic analysis reveals that these two descending pathways provide structured input to ventral nerve cord neurons in a manner consistent with their activation patterns. These results suggest that nested premotor circuit activity, directed by distinct descending signals, enables rapid switching between motor actions.

}, issn = {1546-1726}, doi = {10.1038/s41593-024-01738-9}, url = {https://doi.org/10.1038/s41593-024-01738-9}, author = {Shiozaki, Hiroshi M and Wang, Kaiyu and Lillvis, Joshua L and Xu, Min and Dickson, Barry J and Stern, David L} } @article {67966, title = {The Consistency of Gastropod Identified Neurons Distinguishes Intra-Individual Plasticity From Inter-Individual Variability in Neural Circuits.}, journal = {Frontiers in Behavioral Neuroscience}, volume = {16}, year = {2022}, month = {2022 Mar 03}, pages = {855235}, abstract = {

Gastropod mollusks are known for their large, individually identifiable neurons, which are amenable to long-term intracellular recordings that can be repeated from animal to animal. The constancy of individual neurons can help distinguish state-dependent or temporal variation within an individual from actual variability between individual animals. Investigations into the circuitry underlying rhythmic swimming movements of the gastropod species, and have uncovered intra- and inter-individual variability in synaptic connectivity and serotonergic neuromodulation. has a reliably evoked escape swim behavior that is produced by a central pattern generator (CPG) composed of a small number of identifiable neurons. There is apparent individual variability in some of the connections between neurons that is inconsequential for the production of the swim behavior under normal conditions, but determines whether that individual can swim following a neural lesion. Serotonergic neuromodulation of synaptic strength intrinsic to the CPG creates neural circuit plasticity within an individual and contributes to reorganization of the network during recovery from injury and during learning. In , variability over time in the modulatory actions of serotonin and in expression of serotonin receptor genes in an identified neuron directly reflects variation in swimming behavior. Tracking behavior and electrophysiology over hours to days was necessary to identify the functional consequences of these intra-individual, time-dependent variations. This work demonstrates the importance of unambiguous neuron identification, properly assessing the animal and network states, and tracking behavior and physiology over time to distinguish plasticity within the same animal at different times from variability across individual animals.

}, issn = {1662-5153}, doi = {10.3389/fnbeh.2022.855235}, author = {Tamvacakis, Arianna N and Lillvis, Joshua L and Sakurai, Akira and Katz, Paul S} } @article {64841, title = {Neural evolution of context-dependent fly song.}, journal = {Current Biology : CB}, volume = {29}, year = {2019}, month = {2019 Mar 08}, pages = {1089-99}, abstract = {

It is unclear where in the nervous system evolutionary changes tend to occur. To localize the source of neural evolution that has generated divergent behaviors, we developed a new approach to label and functionally manipulate homologous neurons across Drosophila species. We examined homologous descending neurons that drive courtship song in two species that sing divergent song types and localized relevant evolutionary changes in circuit function downstream of the intrinsic physiology of these descending neurons. This evolutionary change causes different species to produce divergent motor patterns in similar social contexts. Artificial stimulation of these descending neurons drives multiple song types, suggesting that multifunctional properties of song circuits may facilitate rapid evolution of song types.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2019.02.019}, author = {Ding, Yun and Lillvis, Joshua L and Cande, Jessica and Berman, Gordon J and Arthur, Benjamin J and Long, Xi and Xu, Min and Dickson, Barry J and Stern, David L} } @article {56201, title = {Threshold-based ordering of sequential actions during Drosophila courtship.}, journal = {Current Biology : CB}, volume = {29}, year = {2019}, month = {2019 Jan 07}, pages = {426-34}, abstract = {

Goal-directed animal behaviors are typically composed of sequences of motor actions whose order and timing are critical for a successful outcome. Although numerous theoretical models for sequential action generation have been proposed, few have been supported by the identification of control neurons sufficient to elicit a sequence. Here, we identify a pair of descending neurons that coordinate a stereotyped sequence of engagement actions during Drosophila melanogaster male courtship behavior. These actions are initiated sequentially but persist cumulatively, a feature not explained by existing models of sequential behaviors. We find evidence consistent with a ramp-to-threshold mechanism, in which increasing neuronal activity elicits each action independently at successively higher activity thresholds.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2018.12.019}, author = {McKellar, Claire E and Lillvis, Joshua L and Bath, Daniel E and Fitzgerald, James E and Cannon, John G and Simpson, Julie H and Dickson, Barry J} } @article {45038, title = {Reconciling the deep homology of neuromodulation with the evolution of behavior.}, journal = {Current Opinion in Neurobiology}, volume = {29C}, year = {2014}, month = {2014 May 27}, pages = {39-47}, abstract = {

The evolution of behavior seems inconsistent with the deep homology of neuromodulatory signaling. G protein coupled receptors (GPCRs) evolved slowly from a common ancestor through a process involving gene duplication, neofunctionalization, and loss. Neuropeptides co-evolved with their receptors and exhibit many conserved functions. Furthermore, brain areas are highly conserved with suggestions of deep anatomical homology between arthropods and vertebrates. Yet, behavior evolved more rapidly; even members of the same genus or species can differ in heritable behavior. The solution to the paradox involves changes in the compartmentalization, or subfunctionalization, of neuromodulation; neurons shift their expression of GPCRs and the content of monoamines and neuropeptides. Furthermore, parallel evolution of neuromodulatory signaling systems suggests a route for repeated evolution of similar behaviors.

}, issn = {1873-6882}, doi = {10.1016/j.conb.2014.05.002}, author = {Katz, Paul S and Lillvis, Joshua L} }