Deep, chronic electrodes were implanted in the anterior and posterior hypothalamus of seven thirteen-lined ground squirrels. The electrical brain activity and heart rate were recorded as the animal's body temperature was decreased by cooling the animal in a refrigerator. Above 23°C body temperature, amplitude varied, but remained near normal. From 23° to 21°C the amplitude dropped sharply, decreasing by almost 50 per cent. Below 21 °C, the amplitude decreased more gradually. Detectable but not easily measurable activity was recorded at 11 °C. Frequency showed an initial rise, then decreased between 22° and 26°C, then increased again through 16°C. Heart rate declined slowly and the heart continued to beat even at 15°C where most recordings were terminated.
Proceedings of the Iowa Academy of Science
©1964 Iowa Academy of Science, Inc.
Johnson, James H.
"A Study of the Effects of Hypothermia on the Electrical Activity of the Hypothalamus in Citellus tridecemlineatus,"
Proceedings of the Iowa Academy of Science, 71(1), 467-473.
Available at: https://scholarworks.uni.edu/pias/vol71/iss1/71