Wide-field feedback neurons dynamically tune early visual processing

Summary

Date: 
April 23, 2014 - 1:00pm
Location: 
NW 243
About the Speaker
Name: 
John Tuthill (Wilson Lab)

An important strategy for efficient neural coding is to match the range of cellular responses to the distribution of relevant input signals. However, the structure and relevance of sensory signals depend on behavioral state. In this talk, I will describe how flight behavior modifies neural activity at the earliest stages of fly vision. This state-dependent modulation of visual processing occurs through a novel class of wide-field neurons that provide feedback to the most peripheral layer of the Drosophila visual system, the lamina. Using in vivo patch-clamp electrophysiology, I found that lamina wide-field neurons respond to low-frequency luminance fluctuations. Recordings in flying flies revealed that the gain and frequency tuning of wide-field neurons changes during flight, and that these effects are mimicked by the neuromodulator octopamine. Genetically silencing wide-field neurons increased behavioral responses to slow motion stimuli.  Together, these findings identify a cell-type that is gated by behavior to enhance neural coding by subtracting low-frequency signals from the inputs to motion-detection circuits.