Image from ProjectManhattan (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
You probably already knew that fevers can cause some people to develop seizures. According to the National Institutes of Health, these so-called 'febrile seizures' can happen at temperatures of 102.2 degrees F and above and are most-often seen in children. The good news is that this type of seizure is usually short and does not often cause any long-term damage to the brain.
In a new study published in Physiological Reports, Researchers at Emory University (Atlanta, Georgia) and University of Western Ontario (London, Ontario) wanted to know how fevers affect brain function. What they found was that fevers caused some neurons in the gray matter of the brain to fail even after an action potential was initiated. These findings may help explain how febrile seizures develop as well as why some people may experience confusion and fatigue with a fever. They also found that younger animals tended to be more susceptible to these fever-induced failures than older animals as they experienced failures with only mild fevers whereas higher temperatures were needed before failures were seen in older individuals.
Sources:
http://www.ninds.nih.gov/disorders/febrile_seizures/detail_febrile_seiz…
Pekala D, Szkudlarek H, Raastad M. Typical gray matter axons in mammalian brain fail to conduct action potentials faithfully at fever‐like temperatures.