@article {70220, title = {Time or distance encoding by hippocampal neurons via heterogeneous ramping rates.}, journal = {Nat Commun}, volume = {16}, year = {2025}, month = {2025 Dec 17}, pages = {11083}, abstract = {

To navigate their environments effectively, animals frequently track time elapsed or distance traveled while seeking food and avoiding threats. The hippocampus is implicated in this process, but the neural mechanisms remain unclear. Using virtual reality tasks that require mice to integrate time or distance to collect a reward, we identified two previously unknown functional subpopulations of CA1 pyramidal neurons. Both subpopulations encode time or distance via distinct ramping dynamics. The first subpopulation exhibits a rapid, synchronous rise in activity upon movement-initiated integration. Subsequently, individual neurons ramp down at heterogeneous rates, creating progressively diverging firing rates that encode elapsed time or distance. Closed-loop optogenetic inactivation of somatostatin-positive (SST) interneurons counterintuitively reduced the ramping activity, leading mice to prematurely attempt reward collection, suggesting impaired time/distance estimation. Conversely, the second CA1 subpopulation shows opposite dynamics - an initial rapid suppression followed by a gradual ramp-up. Inactivating parvalbumin-positive (PV) interneurons diminished this initial suppression, resulting in transient attempts to collect reward near integration onset. These findings reveal parallel hippocampal circuits that initiate and maintain time or distance encoding, controlled by PV and SST interneurons, respectively, and provide insights into the neural computations supporting goal-directed navigation.

}, keywords = {Action Potentials, Animals, CA1 Region, Hippocampal, Hippocampus, Interneurons, Male, Mice, Mice, Inbred C57BL, Neurons, Optogenetics, Parvalbumins, Pyramidal Cells, Reward, Somatostatin, Virtual Reality}, issn = {2041-1723}, doi = {10.1038/s41467-025-67038-3}, url = {https://doi.org/10.1038/s41467-025-67038-3}, author = {Heldman, Raphael and Pang, Dongyan and Zhao, Xiaoliang and Mensh, Brett and Wang, Yingxue} } @article {49002, title = {Persistent activity in a recurrent circuit underlies courtship memory in Drosophila.}, journal = {eLife}, volume = {7}, year = {2018}, month = {2018 Jan 11}, abstract = {

Recurrent connections are thought to be a common feature of the neural circuits that encode memories, but how memories are laid down in such circuits is not fully understood. Here we present evidence that courtship memory in Drosophila relies on the recurrent circuit between mushroom body gamma (MBg), M6 output, and aSP13 dopaminergic neurons. We demonstrate persistent neuronal activity of aSP13 neurons and show that it transiently potentiates synaptic transmission from MBγ\>M6 neurons. M6 neurons in turn provide input to aSP13 neurons, prolonging potentiation of MBγ\>M6 synapses over time periods that match short-term memory. These data support a model in which persistent aSP13 activity within a recurrent circuit lays the foundation for a short-term memory.

}, issn = {2050-084X}, doi = {10.7554/eLife.31425}, author = {Zhao, Xiaoliang and Lenek, Daniela and Dag, Ugur and Dickson, Barry and Keleman, Krystyna} } @article {6859, title = {The Drosophila female aphrodisiac pheromone activates ppk23(+) sensory neurons to elicit male courtship behavior.}, journal = {Cell Reports}, volume = {1}, year = {2012}, month = {2012 Jun 28}, pages = {599-607}, abstract = {

Females of many animal species emit chemical signals that attract and arouse males for mating. For example, the major aphrodisiac pheromone of Drosophila melanogaster females, 7,11-heptacosadiene (7,11-HD), is a potent inducer of male-specific courtship and copulatory behaviors. Here, we demonstrate that a set of gustatory sensory neurons on the male foreleg, defined by expression of the ppk23 marker, respond to 7,11-HD. Activity of these neurons is required for males to robustly court females or to court males perfumed with 7,11-HD. Artificial activation of these ppk23(+) neurons stimulates male-male courtship even without 7,11-HD perfuming. These data identify the ppk23(+) sensory neurons as the primary targets for female sex pheromones in Drosophila.

}, keywords = {Alkadienes, Animal, Animals, Aphrodisiacs, Courtship, Drosophila melanogaster, Drosophila Proteins, Female, Ion Channels, Male, Pheromones, Sensilla, Sensory Receptor Cells, Sexual Behavior, Taste}, issn = {2211-1247}, doi = {10.1016/j.celrep.2012.05.007}, author = {Toda, Hirofumi and Zhao, Xiaoliang and Dickson, Barry J} }