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

Area of Science:

• Neuroscience
• Animal Behavior
• Sensory Processing

Background:

• Widefield optic flow generated by self-movement is processed by insect optic lobe neurons.
• Optic flow-sensitive descending neurons are key for sensorimotor transformations controlling movement.
• Understanding their spatio-temporal response properties is vital for deciphering sensorimotor control.

Purpose of the Study:

• To quantify the impulse response properties of optic flow-sensitive descending neurons in hoverflies.
• To investigate the role of these neurons in processing roll motion for stabilizing reflexes.
• To explore how different visual stimuli affect the neurons' response characteristics.

Main Methods:

• Utilized m-sequences, a white noise technique, to efficiently measure neural impulse responses.
• Focused on quantifying the roll impulse responses of descending neurons in male Eristalis tenax hoverflies.
• Investigated the effect of constant velocity roll or lift stimuli on the impulse response shape.

Main Results:

• Roll impulse responses were rapid, peaking between 16.5-18.0 ms, comparable to lobula plate tangential cells.
• Response amplitude scaled with stimulus impulse size.
• The addition of excitatory stimuli (roll or lift) accelerated and strengthened the response, while also reducing the return-to-baseline time.

Conclusions:

• Descending neurons in hoverflies exhibit fast and adaptable responses to roll optic flow.
• These neurons are well-suited for rapid sensorimotor transformations underlying stabilizing reflexes.
• Stimulus context significantly modulates neural responses, highlighting the dynamic nature of sensory processing.