We studied the effects of reversible cooling between 35 and 7 C on membrane properties and spike generation of cells in slices of @entity35 visual cortex. Cooling led to a depolarization of the neurones and an increase of the input resistance, thus bringing the cells closer to spiking threshold. Excitability, measured with intracellular current steps, increased with cooling. Synaptic stimuli were most efficient in producing spikes at room temperature, but strong stimulation could evoke spikes even below 10 C. Spike width and total area increased with cooling, and spike amplitude was maximal between 12 and 20 C. Repetitive firing was enhanced in some cells by cooling to 20-25 C, but was always suppressed at lower temperatures. With cooling, passive @entity972 conductance decreased and the voltage-gated @entity972 current had a higher activation threshold and lower amplitude. At the same time, neither passive @entity1372 conductance nor the activation threshold of voltage-dependent @entity1372 channels changed. Therefore changing the temperature modifies the ratio between @entity972 and @entity1372 conductances, and thus alters basic membrane properties. Data from two cells recorded in slices of cat visual cortex suggest a similar temperature dependence of the membrane properties of neocortical neurones to that described above in the @entity35 . These results provide a framework for comparison of the data recorded at different temperatures, but also show the limitations of extending the conclusions drawn from in vitro data obtained at room temperature to physiological temperatures. Further, when cooling is used as an inactivation tool in vivo, it should be taken into account that the mechanism of inactivation is a depolarization block. Only a region cooled below 10 C is reliably silenced, but it is always surrounded by a domain of hyperexcitable cells.

Membrane properties and spike generation in XXXX visual cortical cells during reversible cooling.

@entity35 :: ('10116', 'Species') :: ['rat'] @entity1372 :: ('MESH:D012964', 'Chemical') :: ['sodium'] @entity972 :: ('MESH:D011188', 'Chemical') :: ['potassium']
@entity35 :: (10116,Species) :: ['rat']
