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The impulse response of optic flow sensitive descending neurons to roll m-sequences

Citation

Nordström, Karin; Leibbrandt, Richard; Nicholas, Sarah (2021), The impulse response of optic flow sensitive descending neurons to roll m-sequences, Dryad, Dataset, https://doi.org/10.5061/dryad.pzgmsbcm0

Abstract

When animals move through the world, their own movements generate widefield optic flow across their eyes. In insects, such widefield motion is encoded by optic lobe neurons. These lobula plate tangential cells (LPTCs) synapse with optic flow sensitive descending neurons, which in turn project to areas that control neck, wing and leg movements. As the descending neurons play a role in sensori-motor transformation, it is important to understand their spatio-temporal response properties. Recent work shows that a relatively fast and efficient way to quantify such response properties is to use m-sequences or other white noise techniques. We therefore here used m-sequences to quantify the impulse responses of optic flow sensitive descending neurons in male Eristalis tenax hoverflies. We focused on roll impulse responses as hoverflies perform exquisite head roll stabilizing reflexes, and the descending neurons respond particularly well to roll. We found that the roll impulse responses were fast, peaking after 16.5-18.0 ms. This is similar to the impulse response time-to-peak (18.3 ms) to widefield horizontal motion recorded in hoverfly LPTCs. We found that the roll impulse response amplitude scaled with the size of the stimulus impulse, and that its shape could be affected by the addition of constant velocity roll or lift. For example, the roll impulse response became faster and stronger with the addition of excitatory stimuli, and vice versa. We also found that the roll impulse response had a long return to baseline, which was significantly and substantially reduced by the addition of either roll or lift.

Methods

Extracellular electrophysiology of descending neurons in male Eristalis tenax hoverflies. Spike sorted to get responses from type 2 optic flow sensitive descending neurons, likely homolog of DNOVS2. The impulse responses have been extracted using m-sequences, and scripts provided (see ReadMe file).

Usage Notes

Please read the ReadMe file, which explains the details of the content of the submitted folders. Briefly:

"AnalyzedData" contains the filters and extracted parameters shown in the different figures.

"Code" folder, which contains all code used in the paper and a separate ReadMe file for how to use the code.

"PrimFiles" contains the AnalyzedData in prism files, organized in the way they are displayed in the paper.

"RawData" folder which contains the raw data from each neuron, where each data file has been merged with the parameters from its corresponding trial.

"SuppInfo" contains the prism file for the data shown in the Supp Figure.

Funding

Air Force Office of Scientific Research, Award: FA9550-19-1-0294

Australian Research Council, Award: DP170100008

Air Force Office of Scientific Research, Award: FA9550-15-1-0188

Australian Research Council, Award: DP180100144

Australian Research Council, Award: FT180100289