Spontaneous firing properties of rat medial vestibular nucleus neurons in brain slices by infrared visual patch clamp technique

Domestic application of infrared patch clamp techniques on brain slices is limited.The key of the tech-nique is to prepare high-quality brain slices.The present paper describes the preparation procedure of brainstem slices and the spontaneous firing properties of rat medial vestibular nucleus(MVN)neurons.By infrared differ-ential interference contrast technique,neurons of rat MVN were visualized directly at the depth of 50–100 mm underneath the surface of slices.Firing activities of MVN neurons were recorded by the whole-cell patch clamp technique in artificial cerebrospinal fluid(ACSF)and low Ca^(2+)-high Mg^(2+) fluid.The firing mode was more irregular and depressive in low Ca^(2+)-high Mg2+fluid than in ACSF.According to the averaged waveform of action potentials,cells were classified as the neurons with mono-phasic after-hyperpolarization potential(AHP),and the neurons with biphasic AHP.The resting membrane potential(RMP),input resistance(Rin)and membrane capacitance(Cm)of neurons were recorded and com-pared between groups.With infrared videomicroscopy,patch clamp recordings could be made under direct obser-vation in freshly prepared brainstem slices.The discharge activities of MVN neurons were spontaneous and the fir-ing mode was modulated by extracellular calcium concen-tration.The basic membrane properties of two types of neurons were not significantly different,while the differ-ences in waveform might play a role in the segregation between tonic and kinetic cells.