Weighting of Celestial and Terrestrial Cues in the Monarch Butterfly Central Complex
Nguyen TAT, Beetz MJ, Merlin C and others. Frontiers in neural circuits, June 2022.
Read the paper Free to read · doi:10.3389/fncir.2022.862279
What this paper is about
A migrating monarch does not see one compass cue at a time. It sees the sun, polarized light and the ground together, and has to weigh them against each other.
Earlier work tested each cue separately. This study recorded from the central complex while presenting several at once, to find out which wins when they disagree.
Summarised here from the abstract below. Not the authors’ words.
Abstract
Monarch butterflies rely on external cues for orientation during their annual long-distance migration from Northern US and Canada to Central Mexico. These external cues can be celestial cues, such as the sun or polarized light, which are processed in a brain region termed the central complex (CX). Previous research typically focused on how individual simulated celestial cues are encoded in the butterfly's CX. However, in nature, the butterflies perceive several celestial cues at the same time and need to integrate them to effectively use the compound of all cues for orientation. In addition, a recent behavioral study revealed that monarch butterflies can rely on terrestrial cues, such as the panoramic skyline, for orientation and use them in combination with the sun to maintain a directed flight course. How the CX encodes a combination of celestial and terrestrial cues and how they are weighted in the butterfly's CX is still unknown. Here, we examined how input neurons of the CX, termed TL neurons, combine celestial and terrestrial information. While recording intracellularly from the neurons, we presented a sun stimulus and polarized light to the butterflies as well as a simulated sun and a panoramic scene simultaneously. Our results show that celestial cues are integrated linearly in these cells, while the combination of the sun and a panoramic skyline did not always follow a linear integration of action potential rates. Interestingly, while the sun and polarized light were invariantly weighted between individual neurons, the sun stimulus and panoramic skyline were dynamically weighted when both stimuli were simultaneously presented. Taken together, this dynamic weighting between celestial and terrestrial cues may allow the butterflies to flexibly set their cue preference during navigation.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
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year = {2026},
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