Neural organization of afferent pathways from the stomatopod compound eye

Hanne H. Thoen, Nicholas J. Strausfeld, Justin Marshall

Crustaceans and insects share many similarities of brain organisation suggesting that their common ancestor possessed some components of those shared features. Stomatopods (mantis shrimps) are basal eumalacostracan crustaceans famous for their elaborate visual system, the most complex of which possesses 12 types of colour photoreceptors and the ability to detect both linearly and circularly polarised light. Here, using a palette of histological methods we describe neurons and their neuropils most immediately associated with the stomatopod retina. We first provide a general overview of the major neuropil structures in the eyestalk, medial protocerebrum, with respect to the optical pathway originating from the 6 rows of specialised ommatidia in the stomatopod eye, termed the midband. We then focus on the structure and neuronal types of the lamina, the first optic neuropil in the stomatopod visual system. Using Golgi-impregnations to resolve single neurons we identify cells in different parts of the lamina corresponding to the three different regions of the stomatopod eye (midband and the upper and lower eye halves). While the optic cartridges relating to the spectral and polarization sensitive midband ommatidia show some specializations not found in the lamina serving the upper and lower eye halves, the general morphology of the midband lamina reflects cell types elsewhere in the lamina and cell types described for other species of Eumalacostraca. This article is protected by copyright. All rights reserved.