Sunday, March 10, 2013

The Purring Center in Cats

Large black spots show points from which stimulation elicited purring. Small black spots show points in these sections which were stimulated without eliciting purring. Numerous other points in other sections were stimulated with negative results so far as purring was concerned (Gibbs & Gibbs, 1936).

A 1936 study by Gibbs and Gibbs identified the infundibular region (which connects the hypothalamus and the posterior pituitary) as the purring center in the cat's brain:
In the course of a study which we conducted on the convulsion threshold of various parts of the cat’s brain, a region was found which when stimulated caused purring. This reaction was so striking and the region from which it was obtained so definitely localized that we consider it worthy of a special report.

Our experiments were conducted on 400 cats.

. . .

The points stimulated in our 400 experiments were fairly well scattered through the brain (Gibbs and Gibbs, ’36). In only three cases, however, did we obtain purring as a response to stimulation. In each this was the first response to weak stimulation; it was obtained with the secondary coil at 10 cm. or more from the primary. In all three cases the tip of the needle lay in the infundibular region (see figures).


Purring can be elicited by electrical stimulation in the infundibular region of the cat’s brain.

400 cats!

Some of the 400 cats that were rescued from a market in Tianjin. 
Photograph: China Photos/Getty Images.

ADDENDUM (March 11 2013): Just to be crystal clear, the main reason the authors conducted the study in the first place was to determine seizure thresholds in different parts of the cat brain, not to find the purring center. They did not lay out the rationale for the seizure study in the purring paper, but see abstract below.

GIBBS, F. A. AND E. L. GIBBS (1936). The convulsion threshold of various parts of the cat’s brain. Arch. Neurol and Psychiat., vol. 35, pp. 109-116.

In this investigation we have attempted to determine the relative ease or difficulty with which convulsions can be produced by electrical stimulation of various parts of the cat's brain. The problem has significance because it bears directly on the question of whether or not a special part of the brain is concerned with the production of convulsions, a question of major importance to those interested in the etiology of epileptic seizures.

According to Wikipedia:
Frederic Andrews Gibbs (1903–1992) was an American neurologist who was a pioneer in the use of electroencephalography (EEG) for the diagnosis and treatment of epilepsy.


Gibbs EL, Gibbs FA. (1936). A purring center in the cat's brain. Journal of Comparative Neurology 64: 209–211.

Basal view of a human brain
(Infundibulum labeled third from the top on right).

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At March 10, 2013 5:19 AM, Anonymous Anonymous said...

I'm a bit confused. Was the purpose of the entire study solely to find the "purring center"? I hope they collected some other useful data from the 400 cats. I'm not an animal protection freak and I believe that some work in animal is necessary to gain critical knowledge that we cannot obtain from humans. However, I find this a bit disturbing.

At March 10, 2013 8:48 AM, Blogger The Neurocritic said...

Anonymous - Yes, it is a bit disturbing! Obviously, Institutional Animal Care and Use Committees weren't around in 1936.

I'm not exactly sure why they were looking at seizure thresholds in various parts of the cat brain, but that was the main purpose of the study. The authors just happened to induce purring by electrical stimulation on three occasions, which is what they reported on in this short paper. The other one is:

GIBBS, F. A. AND E. L. GIBBS. The convulsion threshold of various parts of the cat’s brain. Arch. Neurol and Psychiat., vol. 35, pp. 109-116.

At March 11, 2013 4:02 AM, Anonymous Marla Lewis said...

I was trying to figure out all along the cause of purring until I read this post. I thought it was more of an emotional feedback that caused it.

At March 11, 2013 7:14 AM, Blogger Rohit said...

This was a secondary paper from a primary study (Gibbs and Gibbs 36)

That is what the first line says... In the course of doing something different (looking at the seizure threshold of various regions in the cat brain)... three special cases emerged where stimulation causes purring, and all three were in the infundibulum, and stimulating nearby did nothing... so we note that and publish it

The publishing standards then were not as high as they are now, since we know so much more and there is so much more competition... but they did not go through 400 cats for this study

Finding convulsion threshold is good for 2 reasons: 1. It tells you about the excitability of various regions in the brain, and gives you a sense of excitatory-inhibitory balance for a particular region

2. It narrows down where you look for seizures in people who have them. Given that it was pre WW2, I am assuming we knew almost nothing about what causes seizures. So figuring out where (or even not where) would have been a huge step forward.

At March 11, 2013 11:51 AM, Blogger Taymara said...

"How your cat is making you crazy" has nothing to do with the above post other than I came across it while looking to see if cats and humans share a similar brain structure.

And speaking of articles unrelated to the Gibbs study, I'm curious why you linked to the 400 Cats (that were rescued from a market in Tianjin) article.

At March 11, 2013 12:28 PM, Blogger The Neurocritic said...

Rohit - I'll add an addendum to the main part of the post includes the other Gibbs & Gibbs 1936 study. By modern standards, it's still quite alarming that they used 400 cats in the seizure threshold study.

Taymara - I typed "400 cats" into Google image search to see if something suitable came up. There were a lot more hits than you might think...


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