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SUMMARY:BMI Distinguished Seminar // Yvette Fisher: Flexibility of visual 
 input to the Drosophila head direction network
DTSTART:20260624T121500
DTEND:20260624T131500
DTSTAMP:20260404T063303Z
UID:4250b4189e58a3959e8e267ebe513d76477e3e2dd31aba5768c8947e
CATEGORIES:Conferences - Seminars
DESCRIPTION:Yvette Fisher\, UC Berkeley\nMany plasticity rules rely on ad
 justing the strength of synapses between pairs of cells based on their coi
 ncident activity. We uncovered a new mechanism for coincidence detection i
 n the Drosophila head direction network. To maintain an accurate sense of 
 direction\, head direction neurons that signal orientation during navigati
 on must learn to anchor to relevant external sensory cues in novel environ
 ments. Yet the synaptic mechanism for this form of unsupervised learning i
 s unknown in any organism. In Drosophila\, GABAergic visual inputs converg
 e onto head direction neurons\, and these inhibitory synapses change stren
 gth with experience to learn the relationship between visual landmarks and
  head direction. However\, how coincident pre- and postsynaptic activity i
 s 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 termin
 als of visual inputs. This octopamine pathway is required for anchoring th
 e 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 mechani
 sms at excitatory synapses\; our work defines a novel mechanism for coinci
 dence detection at an inhibitory synapse\, in which postsynaptic activity 
 is relayed via a neuromodulatory neuron onto presynaptic terminals.\n 
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717 https://epfl.zoom.u
 s/j/64813563657
STATUS:CONFIRMED
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