| 1998, 384, Session K7, Poster |
| Responses of an octopus cell model to spike trains recorded from auditory-nerve fibers |
| *Y. Cai, J. McGee, E.J. Walsh (Boys Town National Research Hospital, Omaha, NE) |
A model of the octopus cell in the posteroventral cochlear nucleus (Cai et al. J. Neurophysiol. 78, 872-833, 1997) was studied using experimentally recorded auditory-nerve (AN) fiber spike trains.
The model has a soma, an axon and four identical dendrites. The axon and soma are each represented by a single compartment and each dendrite is represented by 20 compartments.
While both the axon and the soma compartments contain the Hodgkin-Huxley-like Na+ and K+ channels, the soma compartment contains two additional active mechanisms: the 4-AP sensitive, low-threshold K+ channel (KLT) and a Cs+-sensitive, hyperpolarization-activated inward rectifier (Ih).
The AN fiber spike trains were recorded from anesthetized cats using tone bursts of different frequencies. In this study, 80 spike train inputs, generated from responses of 8 fibers, were applied to different locations on the model. The inputs are all excitatory, with dynamics of an alpha function.
The resultant output of the model exhibits realistic onset PSTH patterns (On-I and On-L). Examination of the changes in ionic conductances on a trial by trial basis reveals that, as in the case of current injection, the Na+ channel is not inactivated, consistent with our previous conclusion that the onset response is not produced by 'depolarization block'.
The conductance of KLT undergoes the largest change, suggesting an important regulatory role of this channel. By decreasing the maximum conductance of the KLT, an On-C response pattern was simulated. Because the octopus cell and the large multipolar stellate cell (that produces the On-C pattern) share many morphological features, these results imply that the On-C pattern is probably also regulated intrinsically. |
| Supported by the NIDCD DC01007 Yidao Cai is supported, in part, by NIDCD P60 DC00982-06
|
Citation for this abstract:
Cai, Y., J. McGee, and E.J. Walsh (1998). Responses of an octopus cell model to spike trains recorded from auditory-nerve fibers. Assoc. Res. Otolaryngol. Abstr.
|
