Flagellum, antennular

Fig. 7.2 Schematic representations of chemosensory pathways in the brain, (a) Lateral antennular neuropil (LAN) pathway. dCRNs and MRNs from sensilla on the lateral (LF) and medial (MF) antennular flagellum project somatotopically into both lobes of the LAN and couple directly to antennular motoneurons (MN), (b) Olfactory pathway. ORNs project nontopographically into the olfactory lobe (OL) which is organized into glomeruli. Information is processed by various types of multiglomerular local intemeurons (LN) and output is provided by multiglomerular projections neurons (PN) ascending to the lateral protocerebrum in the eyestalk ganglia...

Fig. 7.8 Dendritic arborizations and electrical responses to odors of similar classes of multiglomerular local intemeurons in the deutocerebrum of P. argus (a, c) and P. clarkii (b, d). Note that in both crustaceans the dendrites invest both the OL and LAN, and both respond not only to odorants but also to the onset of hydrodynamic flow past the antennular flagellum, (a, c) from Schmidt and Ache 1996b (b) from Mellon and Alones 1995 (d) from Mellon and Humphrey 2007...

Mellon D, Humphrey JAC (2007) Directional asymmetry in responses of local intemeurons in the crayfish deutocerebrum to hydrodynamic stimulation of the lateral antennular flagellum. J Exp Biol 210 2961-2968... 

Receptors for semiochemicals of lobsters and many other decapod crustaceans are typically restricted to a very limited set of sensors. These are olfactory sensory neurons contained in specialized setae called aesthetascs, localized in the lateral flagellum of the first antenna or antennule (Fig. 12.2). Ablation experiments show the necessity of aesthetascs for the response of lobsters to different types of semiochemicals (Johnson and Atema 2005 Homer et al. 2008 Shabani et al. 2008). The chemosensory neurons innervating the aesthetascs project their axons exclusively to the olfactory lobes, and thus are considered olfactory, while the other setae contain both chemo- and mechanoreceptors that project to the lateral and medial antennular neuropils (Schmidt and Ache 1996a, 1996b) (Schmidt and Mellon, Chap. 7). Many studies showed that receptor sites for semiochemicals are located in the first antenna without showing them to be in aesthetascs (e.g., Raethke et al. 2004 Skog 2009). Detectors of semiochemicals of crayfish have been... 

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