Lateralization in male rats and dopaminergic system: evidence of right-side population bias.

Recent studies have reported population right-biased lateralization in rats, although with low percentages (between 54-59%). The present study investigated the spatial preference of rats in an electrified T-maze during successive days and the influence of ascending dopaminergic systems using apomorphine, a dopamine agonist, as well as ipsilateral and contralateral lesions on the side preference. Results showed a marked right-biased lateralization at both individual and population levels (85.71% of the rats presented a behavioral asymmetry, being 80% right-biased and 20% left-biased within the lateralized group). Also, the results suggest that there is a presynaptic dominance in the contralateral dopaminergic system to the spatial preference in the T-maze and postsynaptic dominance in the ipsilateral side.