ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. Adult pallid bats possess auditory capabilities similar to those of other echolocating Vespertilionids, albeit with unusually great sensitivity to frequencies below 15 kHz. 2. Newborn bats show no behavioral or neurophysiological responses to auditory stimuli. 3. Evoked potentials were detected first in a six day old bat in response to loud, low frequency sound. Absolute sensitivity and frequency range increase rapidly in the maturing bat. By 24 days, the evoked potential audiogram resembles that of an adult. 4. Except for the first week after birth, the infant bat emits only sounds with dominant frequencies it can hear. 5. The bat's auditory responsiveness is affected by low temperatures. In the anesthetized bat, cooling will produce a shift in the tuning curve toward lower frequencies. This is accompanied by a loss of sensitivity to higher frequencies with an increase in latency and a decrease in amplitude of the response. This occurred in both adult and juvenile bats. In bats less than two weeks old, all auditory responses disappear below 28 °C. 6. The high degree of temporal resolution typical of adult Vespertilionids develops gradually in bats less than two weeks old. In young bats, 40 ms or longer are required for full recovery to the second of two identical stimuli, in contrast to 4 ms in the adult. By the time a bat flies at the age of one month, good temporal resolution has developed. 7. Collicular evoked potentials are relatively insensitive to angle of incidence of the signal, but single units show sharp directionality. This appears to develop mostly after about 3 weeks of age and suggests that binaural interaction matures relatively late in development.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00666371
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