Neurons sensitive to non-celestial polarized light in the brain of the desert locust

Abstract

Owing to alignment of rhodopsin in microvillar photoreceptors, insects are sensitive to the oscillation plane of polarized light. This property is used by many species to navigate with respect to the polarization pattern of light from the blue sky. In addition, the polarization angle of light reflected from shiny surfaces such as bodies of water, animal skin, leaves, or other objects can enhance contrast and visibility. Whereas photoreceptors and central mechanisms involved in celestial polarization vision have been investigated in great detail, little is known about peripheral and central mechanisms of sensing the polarization angle of light reflected from objects and surfaces. Desert locusts, like other insects, use a polarization-dependent sky compass for navigation but are also sensitive to polarization angles from horizontal directions. In order to further analyze the processing of polarized light reflected from objects or water surfaces, we tested the sensitivity of brain interneurons to the angle of polarized blue light presented from ventral direction in locusts that had their dorsal eye regions painted black. Neurons encountered interconnect the optic lobes, invade the central body, or send descending axons to the ventral nerve cord but are not part of the polarization vision pathway involved in sky-compass coding.

Peculiar influence of linearly polarized spectrum illumination patterns on the sensitivity characteristics of locust response to polarized light

“…Meanwhile, other studies have shown that locusts visual response sensitivity is related to the total sensitivity of the locust visual system to light information, the photo-induced vision state change, and the difference in the photo-induced function effect of the heterogeneous light attributes. The perceptual specificity of locusts polarization-sensitive (POL) neurons to the polarization vector and the sensitive recognition of spectral intensity by compound vision cause the driving and controlling effects of different spectrum vector light movement responses to varying [19][20][21][22] . Thus, the vector sensitivity response mode difference of the chord function periodic variation of locusts polartactic response originated from the visual sensitivity difference induced by linearly polarized hetero-spectral light intensity and from the specific tuning characteristics of locusts polarization vision to a linearly polarized vector under hetero-spectral light intensity; in contrast, the tuning response period of the chord function reflected the degree of fast and slow modulation of locusts polarization vision to the linearly polarized vector light mode.…”

A perspective on neuroethology: what the past teaches us about the future of neuroethology

“…The third most represented insect group were locusts and crickets (≈ 6%). Crickets are often used to address questions on acoustic communication (Huber et al 1984;Pires and Hoy 1992;Ronacher 2019;Römer 2021), while locusts are often investigated in the context of orientation behavior (Beetz et al 2016c;Beck et al 2023;Homberg et al 2023) or locomotion (Dürr et al 2018;Dürr and Mesanovic 2023). Because of their relatively large size, descending neurons are highly accessible with electrodes enabling an investigation of flight control and looming induced escape behavior in locusts (Rowell 1989;Santer et al 2006;Duch and Büschges 2022).…”

The influence of stimulus history on directional coding in the monarch butterfly brain

“…Consequently, many central complex neurons are sensitive to both the sun position and linearly polarized light (Heinze and Reppert 2011 ; el Jundi et al 2014 ; Pegel et al 2018 , 2019 ; Hardcastle et al 2021 ; Nguyen et al 2022 ; Takahashi et al 2022 ). Directional coding of central complex neurons has traditionally been tested with a polarizer or a virtual sun being rotated at constant angular velocities around the insect’s head (Vitzthum et al 2002 ; Heinze and Homberg 2007 ; Heinze and Reppert 2011 ; el Jundi et al 2015 ; Zittrell et al 2020 ; Nguyen et al 2021 , 2022 ; Beck et al 2023 ). However, considering that insects often change their velocity and direction during flight, these stimulus dynamics are highly artificial.…”