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How much does brain activity decrease in a hibernating Arctic ground squirrel?

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The image shows a group of Virginia big-eared bats sleeping upside down in a dark cavern. — Dormancy Virginia big-eared bats (*Corynorhinus townsendii virginianushibernating*) are true hibernators, entering a state close to death for much of the winter.

In a hibernating Arctic ground squirrel, the general electrical activity of the brain decreases by 90 percent. This reduction occurs when the animal is in a state of torpor and its brain temperature is approximately 6 °C (43 °F).1

Despite this significant drop in overall activity, specific areas of the brain responsible for regulating temperature, as well as cardiac and respiratory functions, remain active even at these low ambient temperatures.1