Looking deep into the eyes of insects

Like most animals, insects rely on eyesight for orientation. In order for them to get the best possible picture of their surroundings, input from photoreceptors in the eye must be processed afterwards by the brain. It is as if the input travels through a multi-layer filter, constantly being filtered, categorized and ultimately being forwarded along in reduced form to the next area of the brain. In the case of insects, this task initially falls to the lamina – the brain's first visual processing centre directly connected to the eye. At the University of Konstanz, neuroethologists Anna Stöckl and Ronja Bigge have now made an important contribution to the understanding of this signal processing.

Not all insect eyes are the same
The study focused on the motion vision of insects in different light conditions and how the animals adapt to them. "There is a great body of research on the insect eye and how the brain processes visual information, especially in the case of fruit flies. A lot of data and findings are available on this topic", Stöckl says. "Yet in some aspects of the perception and processing of visual stimuli, fruit flies have evolved fundamentally differently from most other insect species." For this reason, the researchers set their sights on studying hummingbird hawkmoths. Since the diurnal species' neuronal processing in early visual parts of the brain has a similar structure and function to most other insect species, the results are more widely applicable to other insects.

To investigate how insect brains process visual stimuli, the researchers first studied the lamina – the most peripheral processing centre for visual information. Using electron microscopy, they were able to identify all the different types of lamina neuron cells and then map how they are connected to each other. This enabled the team to reclassify these cells – an important step for better understanding their respective tasks in the visual system.

Integrating or inhibiting signals to increase efficiency
"Since insect brains are so small, the neuronal system must operate extremely efficiently. Visual stimuli are pre-filtered in the outer areas of the brain on several different levels so that only a fraction of the original information has to be processed when it arrives at its destination", Bigge explains. One of these filtering steps takes place in the lamina cells. In dim light, visual signals can be enhanced by integrating them. However, this takes place at the expense of resolution and results in a more blurred image.

In bright light, by contrast, the individual visual signals are inhibited (and not integrated), which results in greater image clarity. "As a result, the image has a better resolution, even as the signal becomes somewhat weaker. This allows the brain to operate as efficiently as possible in response to current light conditions and to maintain a balance between signal strength and image resolution", Stöckl says.

Different tasks for different layers
Over the course of their study, the researchers also investigated exactly how lamina cells process visual input. Ultra-fine electrodes allowed the team to measure the electrical signals of individual nerve cells as they responded to different light stimuli. "We already knew that, in principle, cells are able to take on several tasks. Now, we have observed how individual cells are able to take on different tasks and switch between them", Bigge explains. The team's results indicate that the same cell fulfils different tasks in different layers of the lamina: "For the first time, we see that the lamina is split into functional layers: in one layer, a cell collects signals, while, in another, the same cell inhibits neighbouring cells.

The findings demonstrate a mechanism for the processing of visual information that had not previously been known in this area of the brain. Further studies now aim to investigate how spatial processing differs between diurnal moths, like the hummingbird hawkmoth, and nocturnal moths. "Since they live with completely different light conditions, we assume that they must also process information in significantly different ways. We are excited to uncover what evolution has in store for us", Stöckl concludes.

Key facts:

• Original publication: Ronja Bigge, Kentaro Arikawa, Anna Stöckl (2026): The functional morphology of hawkmoth lamina monopolar cells reveals mechanisms of spatial processing in insect motion vision, Current Biology. DOI: 10.1016/j.cub.2025.12.004
• Anna Stöckl is a junior professor of neurobiology and behaviour as well as the leader of an Emmy Noether research group at the University of Konstanz.
• Ronja Bigge is a postdoctoral researcher in the field of neurobiology at the University of Konstanz and is currently receiving funding through the Hector Fellow Academy.

Note to editors:

Images are available for download at:

Hummingbird hawkmoth: LINK
Caption: The hummingbird hawkmoth is a diurnal species of moth.
Copyright: Elisabeth Böker/University of Konstanz

Cell structures: LINK
Caption: Microscope image of two cell bundles running through the lamina – a key control centre for the initial processing of visual information in the insect brain
Copyright: University of Konstanz

Cross section: LINK
Caption: Using images from electron microscopes (left), the researchers identified different cell types (marked in different colours) and then reconstructed them three-dimensionally (right).
Copyright: University of Konstanz