[Intrinsic membrane properties of rat medial vestibular nucleus neurons and their responses to simulated vestibular input signals].
OBJECTIVE
To study the membrane properties of rat medial vestibular nucleus (MVN) neurons and their firing responses to simulated input signals of peripheral vestibular system, and to discuss how the intrinsic membrane properties contribute to physiologic functions in central vestibular system.


METHODS
By using infrared differential interference contrast technique, whole-cell recordings were made from rat MVN neurons under direct observation. On the basis of their averaged action potential shapes, the MVN neurons were classified. Linear and non-linear currents were put into the neurons to simulate the input signals of peripheral vestibular system. The differences of intrinsic membrane properties and firing response dynamics were observed between two types.


RESULTS
The discharge activities were recorded in MVN neurons, which remained in low Ca2+-high Mg2+ artificial cerebrospinal fluid (ACSF). Neurons are classified as type A (33%) characterized by a single deep after-hyperpolarization (AHP) and A-like rectification, or type B (63%) characterized by double AHP, and another two neurons with all or none of the characters. The passive membrane properties were not significantly different between type A and type B neurons, while part of active membrane properties was significantly different. Both type A and B neurons well responded to simulated current inputs, but disparities existed in response range and firing dynamics.


CONCLUSIONS
The discharge activities of MVN neurons were initiated by their intrinsic membrane properties. Most MVN neurons were classified as type A and B, while several showed unrepresentative firing properties. Linear and nonlinear inputs evoked a heterogeneous range of firing responses. The differences of response range and firing dynamics between neurons may determine their different physiological functions.
Xia
Jiao
J
Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Kong
Wei-jia
WJ
Zhu
Yun
Y
Zhou
Yan
Y
Zhang
Yu
Y
Guo
Chang-kai
CK
D000200:Action Potentials; D000818:Animals; D009474:Neurons / Q000378:metabolism* / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D014726:Vestibular Nuclei / Q000166:cytology* / Q000378:metabolism / Q000502:physiology