Cats in vision research at University of Sydney

In a recent 2011 publication,(1) researchers at the University of Sydney describe one of their many experiments in which cats were subjected to experiments that attempts to understand the connections between a part of the cat brain (area 18) and the responses of their neurons to visual stimuli.

The Procedure

In this particular experiment eleven adult cats underwent highly invasive surgical procedures that included the removal of part of the skull as well as bilateral cervical sympathectomy (intentionally cutting the nerve supply to parts of the head and eyes).  During the experiments the cats’ heads were restrained in a stereotaxic device and the animals received muscle relaxants in addition to a general anaesthetic.

Prior to the actual experiment, the preparation involved the brain of each cat being exposed by way of a craniotomy (surgical removal of a portion of the skull). A plastic cylinder was glued to the skull forming a well around the craniotomy and a small opening was made in the brain matter above the recording site. A stainless steel microelectrode was positioned above it and coated with dye and slowly advanced into area 18 of the brain and lesions were made. Neuron activity was then recorded.
Pharmaceutical solutions were applied to the eyes to dilate the pupils and to retract the blinking membranes. The eyes were focused on a screen position 57cm in front of the cat using corrective lenses. Artificial pupils were positions in the centre of the dilated pupils and the optic discs of each eye were projected onto the screen.
At the end of the experiment each cat was killed and the brain removed and studied.

The stereotaxic frame

The stereotaxic frame is an odious instrument used by animal researchers.  It is a heavy duty piece of equipment - a frame of bars to hold laboratory animals - particularly cats and monkeys - immobile for indefinite periods of time.  A cat is held in place with bars secured into its ears preventing movement of the head. 

The experiment raises some important concerns that need addressing:

Animal welfare concerns

According to veterinarian Dr Andre Menache the use of a muscle relaxant is always a cause for concern because it may mask signs of pain in the animal. Thus there would need to be a very good reason for allowing muscle relaxants to be used in any study.  According to Dr Menache “the study of nerve activity in the cat brain for the sake of curiosity is not a substantive reason to subject these animals to muscle relaxant and bilateral cervical sympathectomy”.

The authors state that the cats received DAILY intramuscular injections of antibiotics, which would suggest that the animals may have undergone repeated procedures. However, this is unclear as there is no description in the article of the duration of each experimental session, nor whether the cats underwent more than one study session.

Relevance to humans

The researchers in their publication refer to the differences between the results of these types of experiments in the cat as opposed to other research using monkeys. For example the area of mapping is different in both species. However they make no mention of any relevance this research may have to humans.
In 2002 researchers (2) studying the effectiveness of a paralysed animal model for eye movement studies noted that eye-movements in paralysed animals can lead to a profound underestimate of neuronal sensitivity to visual stimuli. 

We therefore ask if an attempted simulation of a human response in an animal model, whether it be a cat or a monkey or any other non-human animal, is indeed a scientific basis for research.

Cost-benefit assessment

The Australian and New Zealand Council for the Care of Animals in Research and Teaching states that: “Using animals for scientific purposes is acceptable only when any harm done to the animals is very greatly outweighed by the benefits of their use”.  According to Dr Meanche normally, single neuron studies require one or perhaps two animals.  “It is difficult to see why 11 cats were required for the study. The study is clearly an example of basic research which is defined as “experimental or theoretical work undertaken primarily to acquire new knowledge of the underlying foundations of phenomena and observable facts, without any particular application or use in view” (OECD definition).”

It is unclear as to whether the authors could forsee any application of this work.  The publication does not provide any evidence to show that the information obtained from the killing of these 11 cats will lead to cures for people (or even animals, for that matter).

In fact in their concluding remarks the authors state that there are species differences between cats and monkeys with respect to the nerve activity studies. There is no mention in the paper by the authors of applicability to either human or veterinary medicine.

The experiment was funded by a substantial grant by the National Health and Medical Research Council (NHMRC) and the Australian Research Council (ARC) - both taxpayer funded federal organisations.


1 Romo, Wang, Zeater, Soloman, Dreher (2011) Phase sensitivities, excitatory summation fields, and silent suppressive receptive fields of single neurons in the parastriate cortex of the cat J Neurophysiol 106: 1688-1712

2 Forte, Peirce, Kraft, Krauskopf, Lennie (2002) Residual eye-movements in macaque and their effects on visual responses of neurons Visual Neuroscience 19, 31-38

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