Directional hearing in aging rats.

The loss of the ability to localize sounds was discovered to occur in rats as a consequence of aging. Subjects were trained in a two-alternative forced-choice paradigm to press the left bar if a sound was presented from the left side and to press the right bar if sound was presented from the right side. Testing was conducted with a brief 200 msec pink noise signal. The accuracy of sound localization was measured in rats from 10 to 21 months of age. By 21 months of age the accuracy of localization had declined from greater than 90% correct to less than 69% correct. The loss of the ability to localize sounds may be involved with the onset of spatial disorientation observed in some subjects at advanced ages.