Growing familiarity with the test situation augments the vigilance deficit of aged rats.
Quantitative EEG profiles of aged and of young-adult Fisher-344 rats were studied over 10 consecutive recording (3 h) sessions. The individual recording sessions were spaced regularly over a 6-week period. In the aged rats, in recordings from both the frontal cortex and dorsal hippocampus, the EEG characteristics of a vigilance deficit state increased in prominence up through 8 recording sessions before a stable level was reached. A similar trend was not seen in the young-adult rats; instead, these rats showed a stable level of spectral voltage output in both leads over the entire period of the 10 recording sessions. Thus, the aged rat brain appears to suffer from a vigilance deficit state which is revealed most clearly by testing under the basal conditions brought about by thoroughly familiarizing the subjects with the test environment.
D000223:Adaptation, Psychological / Q000502:physiology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000502:physiology*; D004569:Electroencephalography; D005625:Frontal Lobe / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344