Forebrain asymmetry in zebrafish

Despite our apparent perfect bilateral symmetric body plan, we all show small but conspicuous left-right asymmetries that are thought to be evolutionarily advantageous. Brain lateralisation, for instance, leads to an increase in cognitive performance. Zebrafish are particularly useful models to study how left-right brain asymmetries arise during embryonic development and how the resultant asymmetric neuronal circuitry ultimately impacts on function and behaviour. This image shows a dorsal view of the forebrain of a 4 days post-fertilization zebrafish larvae labelled for Synaptic Vesicle Protein 2 (SV2). SV2 proteins are membrane glycoproteins that mediate synaptic transmission by regulating cytoplasmic calcium levels in nerve terminals during repetitive stimulation. Therefore, they can be used to identify synaptic boutons (pre-synaptic terminals) and help us visualise the synaptic networks in the brain. Wild-type specimens display noticeable asymmetries of their synaptic network. Width of image is 275 micrometres.