The pretectum, one of the arborization fields of retinal ganglion cells, locates in the dorsal-medial diencephalon.In the preventricular pretectum, there are monoaminergic neurons which axons project to the neuropil of the ipsilateral optic tectum.Studies on toads and salamanders indicate that the pretectum may be involved in prey discrimination and avoidance behavior.However, it still remains largely unknown how pretectal monoaminergic neurons regulate prey-relevant information processing in the retinotectal pathway in the optic tectum.As electrical stimulation of the pretectum decreased field potentials in the optic tectum of toads, we propose that the pretectum may play an inhibitory role in the retinotectal pathway via monoaminergic circuits.To test this hypothesis, we need to find anatomical evidence showing that pretectal neurons send their axon to the optic rectum and functional evidence showing that pretectal neurons can exhibit different response patterns evoked by prey-like and prey-unlike visual cues.Using immunostaining and Kaede-based photo-conversion in vivo imaging, we first found that some monoaminergic neurons in the pretectum send processes to the deep layer of tectal neuropil.In vivo whole-cell recording and extracellular recording were then made on those monoaminergic neurons.We found that those pretectal neurons showed different subtypes of responses evoked by flash and dimming stimuli.Further characterization of the input and output of those neurons will be performed at both anatomical and functional levels.