Brain temperature- and behavior-related changes in the dentate gyrus field potential during sleep, cold water immersion, radiant heating, and XXXX anesthesia.

@entity73 @entity4774 @entity735 @entity35 @entity7939 @entity25
The field potential evoked in the dentate gyrus (DG) by stimulation of the perforant path (PP) is known to vary with ongoing behavior and with brain temperature. To further study these phenomena chronic stimulating and recording electrodes were implanted into the PP and DG of @entity35 , and a thermistor was implanted into the contralateral homotopic DG. Field potentials and brain temperature records were made during (1) @entity25 ( @entity25 ), (2) radiant heating, (3) immersion in cool water, (4) a control session during which no manipulations were made, and (5) under @entity4774 anesthesia. In another group of @entity35 field potentials were recorded during (1) baseline immobile wakefulness, (2) @entity25 , (3) before @entity25 or after gentle awakening from @entity25 ( @entity735 and presence of intermittent @entity73 ), (4) immobile wakefulness, and (5) 24 h later. Findings were that field @entity7939 decreased and population spike (PS) amplitude increased by up to 60% of baseline values during conditions in which brain temperature was reduced ( @entity25 , immersion in cool water, @entity4774 anesthesia). Conversely, @entity7939 increased and PS amplitude decreased by up to 100% of baseline values during conditions in which brain temperature increased (awakening from @entity25 , radiant heating, and warming after immersion in cool water or @entity4774 anesthesia). Product moment correlations between brain temperature and field potential measures confirmed the statistical reliability of these findings and accounted for up to 77% of the variance. These findings confirm the robust effect on hippocampal field potentials of brain temperature changes due to exogenous heating and cooling, and extend this effect to anesthetic- and sleep-induced brain temperature changes. They also identify a state that behaviorally resembles quiet wakefulness but resembles @entity25 in terms of neocortical EEG, brain temperature, and hippocampal field potential measures. The findings indicate the need to control for brain temperature-mediated changes in hippocampal research that uses the dentate gyrus field potential as a dependent measure.
