The Effects of Dorsal Lateral Telencephalon Lesions on Zebrafish Social Behaviour

Zebrafish are extremely social and aggregate in groups to form shoals. This social behaviour has been studied in the wild and in a laboratory setting, yet the mechanisms underlying the behaviour are unknown. There is evidence to suggest that the dorsal lateral telencephalon might play a role in shaping shoaling behaviour, being involved in modulating social behaviours and social reward associated with shoaling. In the current thesis, I adapted and combined several existing methods for performing lesions on the dorsal lateral telencephalon to create my own method to measure the role of the dorsal lateral telencephalon in social reward and shoaling behaviour. I predicted that the social reward associated with shoaling would be reduced by the lesions, thus that experimental fish would swim farther away from controls, which would disrupt the collective moment of the group. Two experimental groups, a control group, and a sham-lesioned group were behaviourally tested. The groups involved one focal fish that either received a lesion, sham-lesion or randomly picked control swimming with four other fish that did not have surgery. The group’s movements were tracked and recorded for 20 minutes over three consecutive days. Common measures of shoaling such as the nearest neighbour distance, inter-individual distance, and polarization were computed. Overall, as predicted, both experimental groups appeared to swim farther away from sham and control groups, although this effect was only seen in the first trial. There was no difference in polarization across groups. Overall, I found that the lesions to the dorsal lateral telencephalon have an effect on shoaling behaviour under certain conditions