What Suffering or Sacrifice of Experimental Animals is Warranted? - Single Unit Activity in Striate Cortex of Unrestrained Cats

Abstract

The major purpose of this study was to discover whether our ability to see is determined by cells that fire in the brain to points of light in specific locations. To test this hypothesis, Hubel developed a procedure which enabled researchers to study brain activity in cats whose visual system shares similarities with the human eye and brain. First the cats were anesthetized and a hollow peg was surgically implanted into their skulls. Once the cats recovered from the anesthesia, tiny microelectrodes were inserted into the cat's brain. They track the response of cells as the cat watched special light displays.

Extended Summary Purpose of the Study

The purpose of this study was to determine whether our ability to see is determined by cells that fire in the brain (the striate cortex. This question was first examined in cats who have a visual system similar to humans. At the time this study was conducted, scientists had only been able to study brain (cortical) cell responding while cats were not conscious (under anesthesia). Hubel's experiment pioneered a new technique to study brain activity when animals were in a natural consciousness.

Hypothesis:

Scientists had previously found that cells in the eye (the retina) responded to specific points of light. Hubel wanted to determine whether there were cells in the striate region of the brain that also responded to these points of light. The primary hypothesis tested in this study was: Cells in the cat striate cortex will respond to points of light in specific locations.

Subjects:

Thirty-five cats were studied.

Procedure:

Hubel developed a technique which would allow cortical brain cell responses to be measured while cats were in a natural awake state. To do this he first anesthetized the cats and implanted a hollow peg into each of their skulls. The peg enabled Hubel to insert tiny microelectrode wires into the cat's brain once the cat recovered from the anesthesia. The electrodes recorded cortical cell responding while the cat watched a screen upon which stationary or moving points of light were displayed.

Results:

The microelectrode recordings indicated that many cells in the visual cortex respond to both stationary points of light and to points of light moving in particular directions.

Conclusions:

Hubel's findings indicated that detection of specific features of the visual world occur in the striate cortex of the cat brain. He also found that some cells only respond to stationary points of light, while other cells only respond to movement of light points in specific directions. The discovery of movement sensitive cells suggested that the visual cortex might enable cats to attend to moving objects and coordinate head and eye movements.

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Questions on Ethics of this Research

1. Explain why you think the study does or does not adequately test the researcher's hypothesis.
2. Describe how the research animals did or did not benefit from being in the study.
3. Describe how members of society might or might not benefit from the results of the study.
4. Did the surgical procedures cause harm?
5. Why was sacrificing the animal to determine if the pegs had damaged the brain scientifically justifiable?
6. Describe ways in which researchers can minimize harm to animals in this type of study and still test the experimental hypothesis.
7. Discuss whether researchers have the same obligation toward animal subjects as they have toward human subjects.
8. What are the ethical responsibilities that researchers have to animal participants?
9. Discuss how you might modify this study to further protect the rights and welfare of research participants.
10. Taking into consideration the investigators' responsibility to both science and participants, give ethical reasons for why you would or would not approve conducting this study either in its original form or with your modifications.

David H. Hubel (1959), Journal of Physiology, 147, 226-238