State dependant modulation of optic flow-processing lobula plate cells in butterflies

Recent studies have revealed that biological systems employ a strategy of canceling predictable components of sensory signals while preserving sensitivity to external changes imposed by the environment. This adaptive approach is crucial for maintaining task-specific sensor responses in areas like posture, locomotion, and gaze control.

Optic flow-processing interneurons, which respond to visual image shifts caused by the relative motion between an organism's eyes and its surroundings, are a prime example of this phenomenon. These cells have been extensively studied in Dipteran and other flying insects, with the Monarch butterfly being a notable subject of investigation.

In the Monarch butterfly, large and highly contrasted wings undergo rapid movements with each wing-beat, potentially obscuring the output signals from optic flow-processing interneurons. Our research focused on these interneurons in the Monarch butterfly and discovered that baseline spiking activity increases when the animals flap their wings. Intriguingly, individual spikes are phase-locked to the wing-beat cycle, even in complete darkness, when no visual motion input is present.

The patterns of recorded activity from these interneurons cannot be fully explained by considering only the response to directional wing motion through their receptive fields. However, our findings suggest that an additional internal signal plays a critical role in suppressing responses to wing-induced visual motion. This suppression is essential for supporting effective vision-based stabilization reflexes in the Monarch butterfly.

These insights underscore the principle that self-generated signals are intentionally suppressed, while sensitivity to external modulation is maintained, allowing for precise sensory processing and control.