Responses of pontine neurons of the big brown bat, Eptesicus fuscus, to temporally patterned sound pulses.
Under free field stimulation conditions, this study examined the responses of pontine neurons of Eptesicus fucus to temporally patterned sound pulses by means of repetitive single pulses and pulse trains. Among 93 pontine neurons isolated, 90 always discharged less than 5 impulses to sound pulses presented during this study and 3 discharged impulses throughout the whole duration of each presented pulse. Responses to sound pulses at different repetition rates were examined in 65 neurons. The number of impulses of individual neurons discharged to each pulse varied within a given repetition rate and among different repetition rates. Although these pontine neurons showed different degrees of habituation to high repetition rates, more than 25% could follow the highest repetition rate tested (100 pps). However, they did not always discharge maximal number of impulses to this repetition rate. The total number of impulses discharged by a neuron was also affected by pulse duration. Thus, each pontine neuron discharged maximally to a specific combination of pulse repetition rate and duration. Using a 50% difference between the maximal and minimal responses as a criterion, the function with respect to repetition rate and duration can be described as band-pass, high-pass, all-pass and irregular. These response properties reflect more those of inferior collicular neurons than auditory cortical neurons. This study also showed that response latencies of pontine neurons examined were lengthened by increasing pulse repetition rate and duration. In addition, whereas minimum thresholds of pontine neurons were elevated by increasing repetition rate, they were lowered by increasing pulse duration.
Wu
M I
MI
Division of Biological Sciences, University of Missouri-Columbia 65211, USA.
Jen
P H
PH
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology*; D002685:Chiroptera; D007245:Inferior Colliculi / Q000166:cytology / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D011149:Pons / Q000166:cytology / Q000502:physiology*; D012016:Reference Values