Perception has intrigued philosophers and scientists since Aristotle ~2,300 years ago, but only recently it became technically possible to address its underlying neural mechanisms. The main scientific research approach still focuses on studying the evoked responses to a perceived sensory stimulus. However, in a state of sensory deprivation, sensory areas in the brain remain highly active. This activity, once interpreted as irrelevant noise, has been found to exhibit highly coherent spatiotemporal structures, suggesting a possible role in perception. Here, I propose to test the hypothesis that perception results as a consequence of the interaction between the dynamic internal state of the brain and the activity evoked by sensory experience. For this purpose, I shall use the zebrafish larva as the experimental model, and a multidisciplinary approach involving two-photon imaging of neural network activities with single cell resolution, behavioural assays, novel mathematical methods for data analysis and genetic engineering techniques to label and manipulate activity of specific cell types or entire networks. The zebrafish model offers the advantage of combining simultaneously all these techniques in an intact behaving vertebrate. I shall specifically examine: 1) The Neuronal representation of sensory perception 2) The role of ongoing spontaneous activity in sensory perception 3) The effect of sensory experience on perception The proposed multidisciplinary approach will shed new light on how information flows through the nervous system; how sensory stimuli are detected, processed and converted into motor behaviours. The findings of this project should provide clear hypotheses regarding analogous and poorly-understood processes in mammals. The work could therefore contribute to understanding of neurological disorders, such as tinnitus, phantom limb and other hallucinations, in which sensory experience is perceived in the absence of external stimulation.