Exploring adaptations and integration in the zebrafish visual and olfactory systems.

Sensory integration is fundamental to survival. Each of our sensory systems function to perform three essential tasks – firstly, they must detect changes in the surrounding environment. Secondly, they must also understand the meaning behind this change, for example, comprehend whether it possesses a threat to its survival or the possibility that food is nearby. Thirdly, each sensory system must also be able to localise where the change is occurring. Each sensory system can encode different elements of the stimulus with varying speed and accuracy (Angelaki et al., 2009). With the increased complexity of behavioural and motor control throughout evolution, it has become increasingly vital for organisms to interrelate sensory cues and also process these alongside the internal state of the organism (Mausfeld, 2013). (Angelaki et al., 2009). Resultantly, the integration of information from each sensory system is essential for optimising the behavioural responses and therefore the fundamental survival of an organism. How both visual/olfactory systems function has been researched intensely in the past, thus these processes are well understood. However, it is not well understood how these two systems integrate their sensory information and what effect, if any, the sensory integration has.

In this thesis, I display evidence of olfactory stimulation being able to alter how visual stimuli are perceived by fish, with the same visual stimulus being perceived as aversive or a potential source of food with just a change of olfactory cue. Mechanistically, we have shown that olfactory stimuli may be able to influence predictions in the main visual processing centre, the optic tectum through altering both the quantity and spatiotemporal patterning of spontaneous activity. Additionally, visual stimulation can be seen to evoke responses in olfactory cells in the olfactory bulbs and olfactory epithelium. Further experimentation will be required to understand what effect this sensory integration has on perception.