ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06
5pPP15. Representation of sinusoid ``ramps'' and ``damps'' in
auditory-nerve fibers of the goldfish.
R. Fay
M. Chronopoulos
Parmly Hear. Inst., Loyola Univ. Chicago, 6525 N. Sheridan Rd., Chicago,
IL 60626
Roy Patterson
MRC Appl. Psychol. Unit, Cambridge CB2 2EF, England
Earlier, behavioral data was presented showing that goldfish perceive
repeated, asymmetrically shaped 400-Hz tone bursts (ramps and damps)
qualitatively as humans do: Ramps are more tonelike than damps [R. Fay and R.
Patterson, 2941 (A) (1994)]. Ramps have slow rise and relatively fast
fall envelopes. Damps are ramps played backward. Single auditory-nerve fibers
were recorded in response to the same ramp and damp stimuli used in the
behavioral studies. Spike times were recorded for two presentations of six, 3-s
stimuli: Ramps with 25-, 35-, and 45-ms rise times and 5-ms fall times, and
these stimuli played backward (damps), presented at several levels. Tuning was
described using REVCOR analysis and by spike count functions of frequency at
several levels. Responsiveness was defined using the coefficient of
synchronization (R) over the carrier period, the number of spikes evoked (N),
and the statistic Z where Z=R[sup 2]N. For most fibers, R, N, and Z were
greater for ramps than for the corresponding damps. This neural behavior is
quantitatively similar to the behavioral results. The differential perception
of ramps and damps is represented within individual primary afferents. The
origins of these physiological differences will be discussed. [Work supported
by the NIDCD.]