Hippocampal EEG and behavior: effects of variation in body temperature and relation of EEG to vibrissae movement, swimming and shivering

Abstract

Hippocampal and neocortical EEG activity was examined in freely moving rats at normal rectal temperature and during artificial hypothermia and hyperthermia. Hippocampal rhythmical slow activity (RSA) and neocortical low voltage fast activity occurred during walking, jumping and swimming (voluntary movement), but irregular hippocampal activity and cortical spindling occurred during immobility and shivering (when it occurred in the absence of other movement). Movements of the vibrissae were not directly correlated with RSA. During voluntary movement, RSA frequency varied from 2 to 12 Hz over a temperature range of 23–42°C. RSA fell in amplitude only below about 26°C and disappeared entirely below 23°C. Simultaneously, voluntary movements also disappeared, but shivering persisted below 20°C. Neocortical spindle activity was not observed below about 30°C.