ASA 126th Meeting Denver 1993 October 4-8

3aPP2. Intracellular transfer functions in the apical cochlear turn: Implications for the pitch code.

Monita Chatterjee Jozef J. Zwislocki

Inst. for Sensory Res., Merrill Ln., Syracuse Univ., Syracuse, NY 13244-5290

Intra- and extracellular ac transfer functions were recorded in the 500-Hz to 1-kHz region of the Mongolian gerbil cochlea. In agreement with previous results obtained in the 2-kHz location, the best frequency decreased with increasing SPL, the shift ranging from 1/2 to 1 oct. The phase transfer function also exhibited a shift from low to high SPLs amounting to about 180 deg. Damage to the preparation resulted in smaller responses, lowered EP, a reduction in the peak shift, as well as a disappearance of the phase shift at high SPLs. The normal transfer functions demonstrate a conspicuous high-frequency notch and secondary maximum at moderate and higher intensities. The finding that, in the range between 500 Hz and 2.5 kHz, the BF is intensity-dependent, indicates that the place of maximum excitation cannot be an adequate code for pitch. It has been suggested previously with respect to the 2-kHz location, that the one intensity-independent feature of the transfer functions is the high-frequency cutoff. This seems to be approximately true for the apical turn of the gerbil also. [Work supported by NIDCD.]