How visual space maps in the optic neuropils of a crab

Abstract

The Decapoda is the largest order of crustaceans, some 10,000 species having been described to date. The order includes shrimps, lobsters, crayfishes, and crabs. Most of these are highly visual animals that display complex visually guided behaviors and, consequently, large areas of their nervous systems are dedicated to visual processing. However, our knowledge of the organization and functioning of the visual nervous system of these animals is still limited. Beneath the retina lie three serially arranged optic neuropils connected by two chiasmata. Here, we apply dye tracers in different areas of the retina or the optic neuropils to investigate the organization of visual space maps in the optic neuropils of the brachyuran crab Chasmagnathus granulatus. Our results reveal the way in which the visual space is represented in the three main optic neuropils of a decapod. We show that the crabs' optic chiasmata are oriented perpendicular to each other, an arrangement that seems to be unique among malacostracans. Crabs use retinal position in azimuth and elevation to categorize visual stimuli; for instance, stimuli moving above or below the horizon are interpreted as predators or conspecifics, respectively. The retinotopic maps revealed in the present study create the possibility of relating particular regions of the optic neuropils with distinct behavioral responses elicited by stimuli occurring in different regions of the visual field.

Unidirectional Optomotor Responses and Eye Dominance in Two Species of Crabs

“…To achieve this, animals were firmly held in an adjustable clamp, and their eyestalks were immobilized to the carapace using cyanoacrylate (loctite super glue). Care was taken to fix their eyes at their normal seeing position: N. granulata , 50° from the horizontal line (De Astrada et al., 2011); U. uruguayensis , 80° from the horizontal line (see Figures 1A–C). After eye fixation, animals were kept isolated in glass containers and they were tested between 6 and 8 days after eye immobilization.…”

“…The semiterrestrial grapsid crab Neohelice granulata proved to be a good model system for neuroscience research. In particular, in the last years, we have produced abundant information about how the optic neuropils are composed and organized in Neohelice (Sztarker et al., 2005, 2009; Medan et al., 2007, 2015; Berón de Astrada et al, 2009; De Astrada et al., 2011; Bengochea and Berón de Astrada, 2014; Sztarker and Tomsic, 2014; Bengochea et al., 2018; Scarano et al., 2018). We have gained knowledge about how visual information (of single objects) coming from the two eyes is processed, and we learnt that information from the two eyes is first combined at the level of the lobula (Sztarker and Tomsic, 2004; Scarano et al., 2018).…”

Comparative analyses of olfactory systems in terrestrial crabs (Brachyura): evidence for aerial olfaction?

“…If present, the lobula plate adheres the lobula. The architecture of these visual neuropils which often are referred to as optic neuropils is best known in crayfish and lobsters (review Harzsch, Sandeman & Chaigneau, 2012 ) but was also analyzed in a number of marine and amphibious brachyurans including Chasmagnathus granulatus , Hemigrapsus oregonensis ( Sztarker, Strausfeld & Tomsic, 2005 ; Sztarker et al, 2009 ; Berón de Astrada, Medan & Tomsic, 2011 ; Berón de Astrada et al, 2013 ), and Carcinus maenas ( Elofsson & Hagberg, 1986 ; Krieger et al, 2012 ). Although the visual neuropils are not the focus of the present study, successful eyestalk preparations from C .…”

Peer Review #1 of "Comparative analyses of olfactory systems in terrestrial crabs (Brachyura): evidence for aerial olfaction? (v0.1)"

“…If present, the lobula plate adheres the lobula. The architecture of these visual neuropils which often are referred to as optic neuropils is best known in crayfish and lobsters (review Harzsch et al 2012) but was also analyzed in a number of marine and amphibious brachyurans including Chasmagnathus granulatus, Hemigrapsus oregonensis (Sztarker, Strausfeld & Tomsic, 2005;Sztarker et al, 2009; Berón de Astrada, Medan & Tomsic, 2011;Berón de Astrada et al, 2013), and Carcinus maenas (Elofsson & Hagberg, 1986;Krieger et al, 2012). Although the visual neuropils are not the focus of the present study, successful eyestalk preparations from C. armatum (Fig.…”