Recent advances in genetic and imaging techniques have established the zebrafish as an excellent model to study behaviour. Their short development time, compact size and ease of imaging deep within the brain have allowed the neural circuits that control behaviour to be mapped. Increasingly sophisticated optogenetic tools and virtual world setups allow larval fish to be manipulated and monitored in real time 1, 2••, 3, 4 and 5]. Adult zebrafish are also emerging as a powerful model for behaviours including aggression, anxiety, learning, memory and shoaling 6, 7, 8•• and 9•] (Table 1). In this review we will highlight recent studies in which zebrafish have contributed to our understanding

of behavioural genetics. Zebrafish larvae start to hunt

prey such as paramecia from around 5-days post fertilisation. Prey capture is achieved through a series of stereotyped manoeuvres which are Selleck RG7204 triggered when prey enters the field of view. The first movement is eye convergence followed by a calibrated series of J-turns — flexions of the caudal tail that orientate the fish towards its target. The sequence is completed by a capture swim [4]. Hunting behaviour can be measured by placing larvae in a virtual environment where films BGB324 manufacturer are used to trigger tail and eye responses [4]. Small moving objects such as paramecia are detected by the optic tectum which responds visuotopically to moving (but not static) stimuli [10], as has been demonstrated using the genetically encoded calcium indicator

GCaMP7a [11•]. GCaMP is a modified version of GFP that increases in brightness upon entry of Ca2+ into the cell [12]. The genetic basis of GCaMP7a enables it to be restricted to specific populations of cells. The optic tectum projects to a pair of neurons in the lateral part of the nucleus of the medial longitudinal fasciculus (MLF) called MeLr and MeLc [13]. Laser ablation of the MeLr or MeLc reduces the ability of larvae to capture prey suggesting this behaviour is largely driven by MLF activation [13]. The combination of fixed-loop virtual environments and genetically based calcium indicators permits the investigation of how objects in the visual field are processed at all levels of the central Cell Penetrating Peptide nervous system. This setup could now be used to screen for novel mutants that show aberrant hunting behaviour. Lateralisation, asymmetries of body viscera, brain areas and behaviour is a widespread property of many vertebrates including fish. In the brain, lateralisation has the potential to specialise neural circuit function which may give rise to new behavioural phenotypes [14]. In zebrafish the left and right habenulae (Hb) of the epithalamus exhibit prominent asymmetries that are established by left-sided expression of Nodal pathway genes during development [15]. The Hb receives inputs from the olfactory bulb and retina and projects to the periaqueductal grey matter via the interpeduncular nucleus (IPN) [14].