Associative learning in zebrafish

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Although past research has explored the mechanisms of learning & memory, a lot remains to be discovered. I argue that the zebrafish will significantly accelerate the progress of this research. Zebrafish is a small freshwater fish. It is prolific, cheap to breed and keep in large numbers in the laboratory. It has several features typical of vertebrates and even similar to mammals, e.g., its genes are similar to human genes. Therefore, if one discovers a gene involved in learning & memory in zebrafish, it is likely that one will find the human gene homologous to it. Discovery of such genes may be faster with zebrafish because of the simplicity of this species. Indeed, large scale mutagenesis screens have been employed and led to the identification of genes affecting a range of biological processes from embryo development to cocaine addiction. However, such screens may only be performed if appropriate screening methods are available. Unfortunately, such methods are lacking for learning & memory in zebrafish. The goal of the proposal is to fill this gap. We will study whether zebrafish are capable of simple and complex forms of learning and memory typical of more advanced vertebrates, e.g. mammals. We will study non-spatial and spatial associative learning and other forms of complex learning where relationships of multiple cues must be acquired. For example, we will analyze how zebrafish learn that a visual cue predicts the appearance of a group of zebrafish (a reward), or of a dangerous predator (a punishment), or where in their test environment these stimuli will appear, or what other cues may influence when and where these stimuli appear. Also, we will investigate how long zebrafish may remember certain stimuli, and we will dissociate different memory processes and study short term, medium term and long term memory of this fish. We will develop software applications to allow computer controlled presentation of cues and automated quantification of behavioural responses. This way many learning tests can be run in parallel and thus a large number of fish can be tested. In the future, this will allow us and others to screen a large number of mutations and identify those that are involved in specific learning and memory processes.