Noise localization ability in the Mongolian gerbil ( Meriones unguiculatus )

Understanding localization ability is essential for comparison to physiological studies of binaural neurons. Heffner and Heffner [Beh. Neuro. 102, 422 (1998)] reported relatively poor ability of the gerbil to localize a 100 ms noise burst (approximately 75% correct at 27° separation.) Their experimental setup required the gerbil to enter an observing response compartment, initiating a noise burst from one of two speakers separated by the test angle. The animal was required to respond by entering a reporting compartment, positioned 90° to the right or left, regardless of speaker location. This required mapping from speaker location to response location. In this study, response mapping was avoided in an effort to improve performance. After an observing response (jumping on a platform in the center of a circular cage), the animal responded by moving directly towards the active speaker. The results of this study were consistent with those of Heffner and Heffner at small angles of separation. [For 180° separation, this task resulted in poorer performance than the previous study, presumably due to lack of control of head orientation during stimulation, leading to front-back confusions.] In conclusion, the poor localiza tion ability of gerbils is apparently not explained by response mapping. [Work supported by NIDCD R01-DC001641.]