Electrical properties of neurones in the olfactory cortex slice in vitro.

Abstract

Slices of guinea pig olfactory cortex were maintained in vitro. Electrical properties of neurons in the prepyriform region were studied using single high resistance glass microelectrodes filled with potassium acetate, connected to a resistance-compensating circuit to allow passage of current through the electrode. Neurons showed a high, stable resting membrane potential (75.4 .+-. 2.7 mV, mean .+-. SD; n = 47). Input resistance measured with small depolarizing currents varied over a range of 9-280 M.OMEGA.. The time constant for decay of depolarizing potentials was 19.4 .+-. 7.5 ms (mean .+-. SD). The relationship between membrane potential and [K]out [extracellular K+ concentration] accorded with a value for PNa[Na+ permeability]:PK of 0.02. Depolarization produced repetitive action potentials (maximum frequency of 85 Hz) having peak amplitudes of +16 to +47 mV. The action potential was followed by a depolarizing after potential of about 20 mV positive to the membrane potential. In these and other respects, the prepyriform neurons appeared to behave like most other neurons in the mammalian brain, after allowing for the more stable recording conditions in this preparation.