Tim’s paper is out at Elife

Ending 2020 on a high note, Tim and Andrew’s paper just came out today at Elife. Tim performed a painstaking electrophysiological survey of central complex columnar neurons using three different stimuli known to drive orientation behaviors: a vertical stripe, airflow (wind), and an attractive odor. He found that PFN* neurons that target the ventral-most players of the fan-shaped body strongly encode wind direction— so precisely that during his pilot experiments he was able to troubleshoot a 1° offset in his stimulus by looking at the neurons’ responses. While most central complex neurons to date have been shown to represent sensory stimuli as a “map,” PFNs instead represent wind as two “basis vectors”, originating 45° to the right and left of the fly’s midline. Andrew showed that this is likely because PFNs in one hemisphere all receive input from a single neuron called LNa, that encodes wind direction and provides input to PFNs in the nodulus. When Tim silenced ventral PFNs in his flight simulator, he found that flies could no longer orient “down-wind” as they normally do. But these flies could orient just fine when the wind stopped, and they showed a normal range of turns. He concluded that ventral PFNs perform a specific role linking the sensation of wind direction to a corrective turn that allows the fly to maintain a fixed orientation to the wind.

Stay tuned for Andrew and Aaron’s work showing how odor modulates this circuit…

*PFNs are named for the three areas they innervate: proto-cerebral bridge—fan-shaped body—noduli.