Many plasticity rules rely on adjusting the strength of synapses between pairs of cells based on their coincident activity. We uncovered a new mechanism for coincidence detection in the Drosophila head direction network. To maintain an accurate sense of direction, head direction neurons that signal orientation during navigation must learn to anchor to relevant external sensory cues in novel environments. Yet the synaptic mechanism for this form of unsupervised learning is unknown in any organism. In Drosophila, GABAergic visual inputs converge onto head direction neurons, and these inhibitory synapses change strength with experience to learn the relationship between visual landmarks and head direction. However, how coincident pre- and postsynaptic activity is detected across this inhibitory synapse is not understood. We discovered that neurons which release the monoamine octopamine close a feedback loop that conveys postsynaptic head direction activity onto presynaptic terminals of visual inputs. This octopamine pathway is required for anchoring the head direction network to visual cues. Furthermore, pairing structured activation of octopamine neurons with a visual cue is sufficient to drive rapid plasticity, even without postsynaptic head direction cell activity. Previous work has extensively characterized coincidence detection mechanisms at excitatory synapses; our work defines a novel mechanism for coincidence detection at an inhibitory synapse, in which postsynaptic activity is relayed via a neuromodulatory neuron onto presynaptic terminals.
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The MARVEL Junior Seminar series is continuing in hybrid mode, in order to maintain in-person contacts and allow off-campus attendees to follow the seminars remotely! The MARVEL Junior Seminars aim to intensify interactions between the MARVEL Junior scientists belonging to different research groups. The seminar consists of two 25-minute presentations, followed by time for discussion.
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\r\nZacharie Waysenson
\r\nLaboratoire de Physique de l’École Normale Supérieure, Sorbonne Université
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\r\nMaria Andolfatto
\r\nLaboratory for Materials Simulations, PSI
Thesis Director: Prof. B. T. A. Lecampion,
\r\nMechanics doctoral program
\r\nThesis Nr. 11652
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\r\nTo take part in the public defense, please contact directly the speaker
Thesis Director: Prof. J. Luterbacher,
\r\nChemistry and Chemical Engineering doctoral program
\r\nThesis Nr. 11207
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\r\nTo take part in the public defense, please contact directly the speaker
Thesis Directors: Prof. A. Buffa, Dr E. Sande
\r\nMathematics doctoral program
\r\nThesis Nr. 11727
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\r\nTo take part in the public defense, please contact directly the speaker
14:15–15:00 (Swiss Time)
\r\nDr. Xavier Hernandez-Alias (Max Planck Institute of Biochemistry; in person)
\r\nMulti-scale analysis of mRNA translation adaptation to nutrient shifts reveals novel regulatory elements
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\r\n15:00–15:45 (Swiss Time)
\r\nProf. Silvi Rouskin (Harvard Medical School; online)
\r\nSequence is all you need – Large Language Models Decode the Structural Grammar of IRESes
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\r\nFree coffee & cakes for in-person participants from 14:00 at the AI Lounge
\r\nAI Center, ELE 117, EPFL
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\r\nRegister (in person): https://forms.office.com/e/KbdLYQ52fj
\r\nJoin online: https://epfl.zoom.us/j/61493685341
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