64
JERALD J. BERNSTEIN
mately -24 dB. At 100 Hz the threshold to response rose to f 4 dB, and
at 2400 Hz the threshold level was f35.5 dB. In the grunt the threshold
at 1100 Hz was about +43 dB and at 600 Hz at -4 dB. At frequencies
below 600 Hz there was a high variability in the threshold values
obtained. There appeared to be a significant drop in threshold following
repeated testing of the animals. This threshold drop was as much as
28 dB at frequencies of 100 Hz. These results were interpreted as being
a mechanism for two acoustic detecting systems. That is, there were two
sense modalities for receiving pressure waves and displacements which
perhaps could be the inner ear and lateral line.
Goldfish have been classically conditioned to sound followed by a
food reward ( Enger, 1966). Sound pressure thresholds for frequencies
600-700 Hz and lower were dependent upon the distance of the fish
from the sound source. There were no significant threshold differences
at high levels of stimulation. The lowest thresholds (-42 to -45 dB)
were at 1000-1500 Hz which were found to increase to -10 dB for
5000 Hz and to -6 dB ( 2 meters distance) or -38 dB (0.1 meter distance) for 50 Hz (Enger, 1966).
Enger (1963) used the sculpin, Cottus scorpius, a nonostariophysid,
for microelectrode recording from the various branches of the auditory
nerve. The sound stimuli were usually pure tones of 1-2 sec duration.
A wide variety of frequencies were used between 60 and 500 Hz delivered at many intcnsities. Microelectrodes were used to record single unit
activity in the utricular, saccular, and lagenar branches of the auditory
nerve.
The spontaneous activity of the units in the three branches of the
nerve were of four response types: units which showed the regular
activity, units which showed burst activity, units which showed irregular
activity, and units that were not active (Fig. 9). More than half of the
units responded to the pure tones (Enger, 1963). This response consisted
of the initiation of action potentials in units without spontaneous activity
and of increased discharge rates in units with regular or irregular spontaneous activity. The units with spontaneous burst activity showed a
disruption of this activity into a regular discharge pattern of the same
frequcncy as the stimulus tone used to activate the unit. The action
potentials from single units were usually monophasic, positive spikes,
but occasionally they were positive-negative spikes with the positive
phase having the highest amplitude. The spike recorded from these units
were all alike in appearance, had constant amplitudes, bore an all-ornone relationship to stimulus intensity, and disappeared immediately
upon a slight movement of the recording electrode. Amplitudes were
from less than 1 to 12 mV with durations from 1 to 2 msec. Units of the
JERALD J. BERNSTEIN
mately -24 dB. At 100 Hz the threshold to response rose to f 4 dB, and
at 2400 Hz the threshold level was f35.5 dB. In the grunt the threshold
at 1100 Hz was about +43 dB and at 600 Hz at -4 dB. At frequencies
below 600 Hz there was a high variability in the threshold values
obtained. There appeared to be a significant drop in threshold following
repeated testing of the animals. This threshold drop was as much as
28 dB at frequencies of 100 Hz. These results were interpreted as being
a mechanism for two acoustic detecting systems. That is, there were two
sense modalities for receiving pressure waves and displacements which
perhaps could be the inner ear and lateral line.
Goldfish have been classically conditioned to sound followed by a
food reward ( Enger, 1966). Sound pressure thresholds for frequencies
600-700 Hz and lower were dependent upon the distance of the fish
from the sound source. There were no significant threshold differences
at high levels of stimulation. The lowest thresholds (-42 to -45 dB)
were at 1000-1500 Hz which were found to increase to -10 dB for
5000 Hz and to -6 dB ( 2 meters distance) or -38 dB (0.1 meter distance) for 50 Hz (Enger, 1966).
Enger (1963) used the sculpin, Cottus scorpius, a nonostariophysid,
for microelectrode recording from the various branches of the auditory
nerve. The sound stimuli were usually pure tones of 1-2 sec duration.
A wide variety of frequencies were used between 60 and 500 Hz delivered at many intcnsities. Microelectrodes were used to record single unit
activity in the utricular, saccular, and lagenar branches of the auditory
nerve.
The spontaneous activity of the units in the three branches of the
nerve were of four response types: units which showed the regular
activity, units which showed burst activity, units which showed irregular
activity, and units that were not active (Fig. 9). More than half of the
units responded to the pure tones (Enger, 1963). This response consisted
of the initiation of action potentials in units without spontaneous activity
and of increased discharge rates in units with regular or irregular spontaneous activity. The units with spontaneous burst activity showed a
disruption of this activity into a regular discharge pattern of the same
frequcncy as the stimulus tone used to activate the unit. The action
potentials from single units were usually monophasic, positive spikes,
but occasionally they were positive-negative spikes with the positive
phase having the highest amplitude. The spike recorded from these units
were all alike in appearance, had constant amplitudes, bore an all-ornone relationship to stimulus intensity, and disappeared immediately
upon a slight movement of the recording electrode. Amplitudes were
from less than 1 to 12 mV with durations from 1 to 2 msec. Units of the