Postsynaptic potentials evoked in ventrobasal thalamus neurones by natural sensory stimuli

Intracellular recordings were made in the ventrobasal thalamus of rats anaesthetised with urethane. Postsynaptic responses were evoked by stimulation of the peripheral receptive field with an air jet of 10 ms duration. The postsynaptic response typically consisted of an excitatory postsynaptic potential (EPSP)/inhibitory postsynaptic potential (IPSP) sequence with one or more evoked action potentials. Injection of hyperpolarizing current pulses appeared to increase the EPSP amplitude, whereas depolarising current pulses caused a reduction in EPSP amplitude. These changes in EPSP amplitude were however obscured by the presence of IPSPs and a slow potential similar to a low-threshold Ca2+ spike (LTS).