New study uses ferrets to model higher-level vision

By SHIRLEY MARINO LEE | October 10, 2019

A recent study by Hopkins researchers revealed that ferrets are well-suited for higher-level vision research. This was discovered in light of their performance when faced with behavioral tests that assessed the motion and form integration capacity of adult ferrets.

It is well known that ferrets are good models for the development of early visual stages, so the goal of the research was to see whether ferrets would also serve as good models of higher-level vision.

In order to assess the motion integration ability of ferrets, the researchers trained female ferrets to discriminate random dot kinematograms (RDK) based on their direction. In addition, they measured the threshold of motion integration in ferrets by varying the task difficulty through changes in the RDK coherence levels. The researchers used an analogous method to test form integration by training female ferrets to discriminate linear glass patterns based on their orientation. The results of these experiments showed evidence of perceptual motion and form integration in the ferrets. 

Monkeys are widely used models of higher-level vision, and their abilities for motion and form integration are associated with processes which occur in areas of their brains dedicated to higher-level vision. 

Previous ferret studies have found a higher visual area in their brains which is involved in motion processing. This area is called PSS. With this knowledge, the researchers decided to test whether this area was involved in supporting motion integration behavior in ferrets. In order to test this, they measured the response of neurons found in the PSS of the ferret brain to RDKs of differing coherence levels. The result of this measurement was an observed agreement between motion integration performance of PSS neurons and the behaviorally measured motion integration capacity of ferrets.

The results of these experiments establish ferrets as a good model for further research with the goal of expanding current understanding of higher-level vision. During an interview with The News-Letter, sophomore Kennedy Onuoha, who is majoring in Molecular and Cellular Biology, expressed her belief that this is an important discovery for future research.

“The addition of ferrets as models of high-level vision adds to the variety of model organisms that can be chosen for research studies. By having a variety of model organisms we’ll be able to study what might cause differences in the visual systems of these species and this will broaden our understanding of this topic,” Kennedy said.

Additionally, she believes this discovery will allow for new kinds of tests to be developed which will expand on the kinds of data that can be gathered to study the visual system.

The researchers who led this study are part of the Nielsen Laboratory, which forms part of both the Solomon H. Snyder Department of Neuroscience at the med campus and the Zanvyl Krieger Mind/Brain Institute at the Homewood Campus. 

The Nielsen Laboratory is mainly interested in understanding how visual information is transformed through the different processing stages. They conduct a variety of experiments to understand the structure and function of circuits between primary and higher-level visual areas. Additionally, they investigate how those circuits develop and their plasticity in the adult brain through techniques such as two-photon calcium imaging, extracellular recordings, psychophysics and immunohistochemistry.

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