Directionality of auditory nerve fiber responses to pure tone stimuli in the grassfrog, Rana temporaria. II. Spike timing |
| |
Authors: | Morten Buhl Jørgensen Jakob Christensen-Dalsgaard |
| |
Institution: | (1) Center for Sound Communication, Biological Institute, Odense University, Campusvej 55, DK-5230 Odense M, Denmark, Fax: +45/65 93 04 57, e-mail: MBJ@DOU.DK, DK |
| |
Abstract: | We studied the directionality of spike timing in the responses of single auditory nerve fibers of the grass frog, Rana temporaria, to tone burst stimulation. Both the latency of the first spike after stimulus onset and the preferred firing phase during
the stimulus were studied. In addition, the directionality of the phase of eardrum vibrations was measured. The response latency
showed systematic and statistically significant changes with sound direction at both low and high frequencies. The latency
changes were correlated with response strength (spike rate) changes and were probably the result of directional changes in
effective stimulus intensity. Systematic changes in the preferred firing phase were seen in all fibers that showed phaselocking
(i.e., at frequencies below 500–700 Hz). The mean phase lead for stimulation from the contralateral side was approximately
140° at 200 Hz and decreased to approximately 100° at 700 Hz. These phaseshifts correspond to differences in spike timing
of approximately 2 ms and 0.4 ms respectively. The phaseshifts were nearly independent of stimulus intensity. The phase directionality
of eardrum vibrations was smaller than that of the nerve fibers. Hence, the strong directional phaseshifts shown by the nerve
fibers probably reflect the directional characteristics of extratympanic pathways.
Accepted: 23 November 1996 |
| |
Keywords: | Anura Directional hearing Spike timing Phaselocking Eardrum vibrations |
本文献已被 SpringerLink 等数据库收录! |
|