Temperature-dependent changes in visual evoked potentials of rats.

The effects of alterations in body temperature on flash and pattern reversal evoked potentials (FEPs and PREPs) were examined in hooded rats whose thermoregulatory capacity was compromised with lesions of the preoptic/anterior hypothalamic area and/or cold restraint. Body temperature, measured with a rectal thermometer, was manipulated via exposure to different ambient temperatures. To describe the data, a model was used in which both linear and quadratic relationships could be estimated. PREP amplitudes were not significantly influenced by body temperature over the range of 27-42 degrees C, although in one experiment FEP amplitudes did show a linear decline as temperatures fell below approximately 30 degrees C. Both FEP and PREP latencies were strongly influenced by temperature and became progressively longer as body temperature was lowered. The non-linear component affecting latencies became more prominent as body temperature decreased. These data demonstrate the temperature dependence of FEP and PREP latencies independent of anesthetic or other drugs.