Membrane potential oscillations and corticothalamic connectivity in rat associational thalamic neurons in vitro.
Thalamic relay neurons were recorded from the dorsolateral and lateroposterior nuclei of the rat thalamus in a superfused explant preparation. The mean membrane potential of these cells was -67 +/- 7 mV, input resistance 114 +/- 31 M omega and spike amplitude 75 +/- 6 mV. Low-threshold slow membrane potential oscillations (1-4 Hz) were present in about 46% of the neurons. They occurred either spontaneously or following a membrane potential perturbation. In a subpopulation of cells, we also observed a high-threshold membrane oscillation when cells were depolarized above -45 mV. This oscillation consisted of bursts of low-amplitude spikes interrupted by rhythmic after-hyperpolarizations. Stimulation of the corticothalamic pathway elicited prolonged inhibitory postsynaptic potentials in associational thalamic neurons. In the presence of picrotoxin, corticothalamic input evoked prominent excitatory postsynaptic responses that showed marked short-term synaptic plasticity. Our results suggest that associational thalamic neurons maintained in vitro have a strong tendency to exhibit membrane oscillations. In addition, they receive a direct excitatory cortical input that remained functional in explant preparation.
Hu
B
B
Loeb Research Institute, Ottawa Civic Hospital, University of Ottawa, Canada.
D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology; D008564:Membrane Potentials; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009991:Oscillometry; D051381:Rats; D013569:Synapses / Q000502:physiology; D013788:Thalamus / Q000502:physiology*