An optic-fiber photocell detector for measuring tongue protrusion in the rat: Evaluation of recovery from localized cortical lesions

A technique for measuring tongue protrusion during licking by rats is described. Liquid is automatically dispensed onto a shelf in front of the rats' cage. An array of 16 optic fibers spaced at 1 mm intervals act as photo detectors to measure tongue protrusion. The fibers activate relays connected to a microcomputer that counts individual beam breaks. The system permits the measurement of large numbers of consecutive tongue protrusions during training and testing of control and brain-damaged rats. It is shown that ventral frontal cortical lesions disrupt tongue protrusion more severely than posterior neocortex removal or dorsal frontal ablations. Complete frontal cortex lesions permit no sparing or recovery of tongue protrusion.