Visual motion and form integration in the behaving ferret

Abstract

Ferrets have become a standard animal model for the development of early visual stages. Less is known about higher-level vision in ferrets, both during development and in adulthood. Here, as a step towards establishing higher-level vision research in ferrets, we used behavioral experiments to test the motion and form integration capacity of adult ferrets. Motion integration was assessed by training ferrets to discriminate random dot kinematograms (RDK) based on their direction. Task difficulty was varied systematically by changing RDK coherence levels, which allowed the measurement of motion integration thresholds. Form integration was measured analogously by training ferrets to discriminate linear Glass patterns of varying coherence levels based on their orientation. In all experiments, ferrets proved to be good psychophysical subjects that performed tasks reliably. Crucially, the behavioral data showed clear evidence of perceptual motion and form integration. In the monkey, motion and form integration are usually associated with processes occurring in higher-level visual areas. In a second set of experiments, we therefore tested whether PSS, a higher-level motion area in the ferret, could similarly support motion integration behavior in this species. To this end, we measured responses of PSS neurons to RDK of different coherence levels. Indeed, neurometric functions for PSS were in good agreement with the behaviorally derived psychometric functions. In conclusion, our experiments demonstrate that ferrets are well suited for higher-level vision research.

Significance statement The ferret is a central animal model for development because of its early parturition. To date, most visual development research in ferrets has focused exclusively on early visual stages. Here, we use behavioral experiments to demonstrate that adult ferrets are capable of visual motion and form integration. These complex visual functions are usually associated with higher-level visual areas in monkeys and ferrets. We similarly observed good agreement between the motion integration performance of neurons in PSS, a higher-level motion area in the ferret, and the behaviorally measured motion integration capacity. Our experiments in the adult ferret demonstrate that the ferret is a viable model for higher-level vision research, which provides exciting opportunities for developmental research in this species.