Three-dimensional reconstruction of an orb weaver brain. Image credit: Artiushin et al.
Spiders display fascinating behaviors, perhaps none more famous than web weaving. Yet little is known about the neural processes underlying this skill. A necessary step toward unravelling this enigma is the development of a three-dimensional brain atlas of a web-building spider.
To date, spider brain anatomy has been studied primarily in species that do not build webs. Moreover, most previous work involved thin tissue sections stained to highlight specific structures. These sliced views can often be discontinuous, making it difficult to relate information across different stains and brain regions.
To overcome these limitations, Artiushin, Corver and Gordus employed an antibody-based staining method that preserves intact brains for confocal microscopy. This approach enabled the creation of a detailed, three-dimensional anatomical map. The researchers further used a computational approach to align multiple scans into a single reference volume, allowing comparative overlays of different neuron classes. This strategy made it possible to identify areas known from other spiders, as well as new features that had not been previously documented.
Using this atlas, Artiushin et al. described new details of established brain regions – including neural circuits containing major neurotransmitters and neuromodulators. They also identified previously unknown brain structures, such as a region they termed the tonsillar neuropil, as well as a potential protocerebral bridge.
This work represents the first standardized brain atlas for any spider species. While earlier studies have imaged individual neuronal populations across disparate species and brain regions, this atlas provides the most comprehensive view to date within a single species. The newly identified brain regions offer promising candidates for future functional studies and may play roles in the intricate process of web building. More broadly, these findings advance our understanding of spider neuroanatomy and will be of interest to comparative and evolutionary studies of brain structure across animals.
A brain atlas provides a foundation for functional studies that link neuronal activity to behavior. Web building in spiders is a complex, innate form of animal construction that unfolds over multiple hours in distinct stages, making it a compelling model system for investigating the neural basis of extended, sequential behaviors.
