Editorial: models of invertebrate neurons in culture

Abstract

In an attempt to better model the human nervous system, experimental preparations in current neuroscience have become increasingly complex: Advances in recording and imaging techniques as well as in analysis methods, enable the study of the mammalian nervous systems at a greater resolution than ever previously possible (e.g. Baker 2010; Stevenson and Kording 2011), and allows investigation of intricate phenomena in higher vertebrate models. At the same time, however, with the renaissance of the notion of conserved principles in neurobiology (e.g. Ache and Young 2005; Marder and Bucher 2007; Hobert et al. 2010; see Greenspan 2005 and references within), there has been a revival of interest in invertebrate models in neuroscience. There are striking similarities between species in regard to basic neural features, from the nature of relevant proteins, to cellular processes, to the organization of neuronal networks and pathways, through neural computation and dynamic processes leading to behavior (e.g. Godenschwege et al. 2006; Yanay et al. 2008; Humeau et al. 2011; and see Lichtneckert and Reichert 2005; Arendt et al. 2008; Brand and Livesey 2011; for reviews). These common features span a phylogenetically broad array of animals, vertebrate and invertebrate alike, implying both common ancestors and optimal-homologue solutions to similar problems (Clarac and Pearlstein 2007; Humeau et al. 2011; Chittka and Skorupski 2011 and references within). Similarly to the above, a second duality characterizes current research; Together with important breakthroughs in the ability to conduct in vivo studies (e.g. Tsytsarev et al. 2006; Cardin et al. 2010), there is continued interest in the unique advantages offered by in vitro models. The fundamental questions of how a collection of single entities (i.e. neurons and glia), organize to form a complex functional unit—the neural network, and how these building blocks connect and interact to form further elaborate neuronal structures are extremely tractable in two-dimensional in vitro preparations of primary neuronal cultures (e.g. Bulloch and Syed 1992; Jimbo et al. 2000; Shefi et al. 2002; Darya et al. 2009; and see Beadle 2006 for review of insect neural cultures). The in vitro system is simple (relative to any in vivo network), and allows control over as many of its variables as possible. Most importantly, two-dimensional cultures enable a close look at the dynamics of neural growth and network organization (Fig. 1) by offering easy access for non-invasive optical observations. These processes can also be manipulated by various methods, such as genetic treatments (Bai et al. 2009; Tessier and Broadie 2011), pharmacological interventions (Perk and Mercer 2006; Heck et al. 2009), and the use of patterned growth surfaces (Liu et al. 2000; Anava et al. 2009), all of which can affect the neural network development and activity. The experimental results, or the rules discovered in these model systems, can then be translated to theoretical predictions and simple model assumptions, in order for them to be tested and applied to more complex systems. This special issue of the Journal of Molecular Histology combines and builds upon the different trends mentioned above by focusing on in vitro preparations of invertebrate neurons. Neurons of various invertebrates in primary culture have served as the preparation of choice in numerous studies, focusing on nervous system development, form-function interactions, neural pharmacology and many more (e.g. Acklin and Nichlls 1990; Hayashi and Hildebrand 1990; Howes et al. 1991; Kirchhof and Bicker 1992; Lapied et al. A. Ayali (&) Department of Zoology, Tel-Aviv University, 69978 Tel-Aviv, Israel e-mail: ayali@tauex.tau.ac.il