TRANSECTION OF THE CHORDA TYMPANI AND INSERTION OF EAR PINS FOR STEREOTAXIC SURGERY - EQUIVALENT EFFECTS ON TASTE SENSITIVITY

NaCl and sucrose absolute detection thresholds were determined in rats with bilateral transection of the chorda tympani nerve (group CT) and those treated by having stereotaxic ear pins inserted into the auditory canal and through the tympanic membrane (group EP). Relative to controls, each experimental group had deficits in acquisition of the NaCl detection tasks and higher NaCl thresholds, but had no significant deficits in the sucrose detection tasks. There were no differences between the CT and EP groups on any measure of performance. The performance of rats with unilateral CT or EP treatment was identical to that of controls for high concentrations of NaCl, but somewhat poorer on near threshold concentrations. These results (A) confirm prior reports for a specific role of the CT in NaCl detection and (B) indicate that the use of ear pins in stereotaxic surgery may disrupt CT function with a resultant decrease in NaCl sensitivity.