The neural basis of threat-sensitive behaviour in fish

Fear, or threat-sensitive behaviour, is an emotionally guided response allowing animals to minimize exposure to potential danger. Stress is a set of physiological/behavioural responses to such exposure. Among other functions, stress responses prompt learning, and as a result, similar circumstances are later recognised and avoided (feared). In parallel with higher vertebrates, fish show a strong and consistent individual variation in behaviour exhibiting two primary types of personalities: proactive and reactive response patterns. The aim of this thesis is to study the neural basis of threat-sensitive behaviour in teleost fish, by focusing on brain monoaminergic activity and individual differences in threat-sensitive behaviour. Results indicate that fish with contrasting stress coping styles show clear differences in behavioural output when exposed to a fearful situation, with reactive individuals displaying a more fearful behaviour. Proactive individuals appear to respond less to changes in the environment; suggesting that their behaviour is to a larger degree guided by previously learned routines rather than environmental cues. When exposed to fear and/or stress-inducing stimuli, experimental fish showed regionally discrete changes in limbic monoamine neurotransmission, supporting the view that homologues to the mammalian hippocampus and amygdala control individual differences in behaviour and stimulus perception even in non-mammalian vertebrates