BEHAVIOURAL PLASTICITY AND NEURAL CORRELATES IN ADULT CUTTLEFISH V. AGIN a,* , R. CHICHERY a , M.P. CHICHERY a , L. DICKEL a , A.S. DARMAILLACQ b , C. BELLANGER a a L.P.C.C., EA 3211, Université de Caen Basse-Normandie, 14032 Caen cedex, France a C.R.E.C., Rue Charcot, 14530 Luc-sur-Mer, France b InterUniversity Institute of Eilat, P.O. Box 469, Eilat 88 103, Israël * Corresponding author: veronique.agin@unicaen.fr CEPHALOPODS SEPIA OFFICINALIS PREDATORY BEHAVIOUR LEARNING MEMORY NEURAL NETWORKS NEUROTRANSMITTERS ABSTRACT. – Cephalopods display a wide repertoire of complex behaviours, due to their large and complex nervous system, allowing comparative studies that are essential for an investigation of general and/or species-specific properties in neural systems. This review focuses on cellular and molecular events that underlie the plasticity of predatory behaviour in adult cuttlefish. Three main aspects are de- scribed: 1) the localisation of memory traces following learning, 2) the dependency of de novo brain protein synthesis on memory formation, 3) the involvement of neuromodulators / neurotransmitters in predatory behaviour as well as in learning and memory processes. Data presented here improve our understanding of the verti- cal lobe complex networks that undergo plastic changes during predatory behav- iour, and establish Sepia officinalis as a valuable model for a variety of neurobiological analyses of learning and memory. INTRODUCTION From an evolutionary and comparative stand- point, understanding the neural bases of behav- ioural plasticity across a wide range of taxa is of large interest, and for analysis of this kind, coleoid cephalopods (cuttlefish, squid, octopuses) are ideal models. These molluscs have been extensively studied over the last decades for their remarkable behavioural abilities, and particularly for their learning capabilities, which can rival those of many vertebrates (for review, see Hanlon & Mes- senger 1996). For example, cephalopods have been shown to perform complex tasks such as spatial learning (Alves et al . 2006, Boal et al . 2000, Karson et al . 2003, Mather 1991), and observa- tional learning (Boal 1996, Fiorito & Scotto 1992). Their well-developed central nervous system (CNS) provides a useful model for studies involv- ing the neural networks of behavioural plasticity. It is considered to be by far the most highly evolved of all the molluscs, and has been the subject of ex- tensive anatomical and histological research (Mes- senger 1979, Young 1974, 1976, 1977, 1979) as well as electrophysiological recordings (Chrachri & Williamson 2004, Höchner et al . 2003, William- son & Budelmann 1991). Behavioural experiments have investigated brain functions in cephalopods (Boycott 1961, Chichery & Chanelet 1976, Chichery & Chichery 1987, Fiorito & Chichery 1995, Messenger 1973, Novicki et al . 1992, Sanders & Young 1940), but cellular and molecular analyses of behavioural plasticity remain scarce. Our studies have been based primarily on the neurobiological aspects of plasticity in the preda- tory behaviour of cuttlefish, Sepia officinalis (Agin et al . 2001, 2003, Bellanger et al. 2003, Chichery & Chichery 1991, 1992, 1994, Dickel et al . 1997, 2001, Halm et al . 2002, 2003). This review covers the most recent findings in this area. Predatory behaviour The cuttlefish, Sepia officinalis, is an active predator capable of capturing large and very mo- bile living prey: shrimp, fishes and crabs. Attack is typically composed of the following sequence of events: (1) prey detection starting with colour changes over the entire body, and ocular saccadic movement, (2) orientation of the head towards the prey, (3) pursuit behaviour, (4) frontal positioning with respect to the prey accompanied by ocular convergence, (5) prey seizure proper, (6) more or less extensive manipulation of the prey, and (7) in- gestion (Chichery & Chichery 1987, 1988, 1991, Messenger 1968). Two well described strategies are employed in prey seizure: ejection of the two prehensile tentacles (tentacle strategy, Fig. 1), or jumping on the prey and seizing it with the arms (jumping strategy, Fig. 1; Duval et al . 1984, Mes- senger 1968). Small crabs, fishes and shrimp are preferentially seized by tentacle ejection, while large crabs are captured by using the jumping strat- egy. We showed that the choice of attack strategy is VIE ET MILIEU – LIFE & ENVIRONMENT, 2006, 56 (2) : 81-87 The cuttle Sepia officinalis (N. Koueta, J.P. Andrade, S. v. Boletzky, eds)