Visual pathways in the brain of the jumping spider Marpissa muscosa

Abstract

Some animals have evolved task differentiation among their eyes. A particular example is spiders, where most species have eight eyes, of which two (the principal eyes) are used for object discrimination, whereas the other three pairs (secondary eyes) detect movement. In the ctenid spider Cupiennius salei, these two eye types correspond to two visual pathways in the brain. Each eye is associated with its own first-and second-order visual neuropil.The second-order neuropils of the principal eyes are connected to the arcuate body, whereas the second-order neuropils of the secondary eyes are linked to the mushroom body. We explored the principal-and secondary eye visual pathways of the jumping spider Marpissa muscosa, in which size and visual fields of the two eye types are considerably different. We found that the connectivity of the principal eye pathway is the same as in C. salei, while there are differences in the secondary eye pathways. In M. muscosa, all secondary eyes are connected to their own first-order visual neuropils. The first-order visual neuropils of the anterior lateral and posterior lateral eyes are connected with a secondorder visual neuropil each and an additional shared one (L2). In the posterior median eyes, the axons of their first-order visual neuropils project directly to the arcuate body, suggesting that the posterior median eyes do not detect movement. The L2 might function as an upstream integration center enabling faster movement decisions.

First records and three new species of the family Symphytognathidae (Arachnida, Araneae) from Thailand, and the circumscription of the genus Crassignatha Wunderlich, 1995

“…Nevertheless, ours are, to the best of our knowledge, the smallest palps that have been processed using this method. This was challenging in itself since we wanted to preserve the samples without critical point drying, a method commonly used in micro-CT scanning ( Sentenská et al 2017 ; Keklikoglou et al 2019 ; Steinhoff et al 2017 , 2020 ). The tiny size of the palps, less than 0.2 mm wide, did not allow to properly fix the dissected organ and keep it from moving during the scanning process.…”

Perception of biological motion by jumping spiders

“…However, salticids do not turn toward all moving targets in the visual field, suggesting a selective attention-like process and/or that secondary eyes can inform target differentiation, such as the detection/discrimination of biological motion cues, rather than simply acting solely as motion detectors [27]. This idea is also supported by the fact that, neuroanatomically, the 2 sets of eyes (primary and secondary) possess completely separate early visual processing pathways [28], suggesting that there may be specialized computational tasks for which each network is responsible.…”

Attention and distraction in the modular visual system of a jumping spider

“…In jumping spiders, visual information from the principal and secondary eyes is first processed separately, and then these streams of information are combined in the protocerebrum (Strausfeld, 2012). We hypothesize that the close integration between the principal and secondary eyes, demonstrated here and in Jakob et al (2018), is permitted by their direct connection in the protocerebrum via large neural tracks that allows rapid communication (Long, 2021;Steinhoff et al, 2020).…”