Correlations between the firing of supraoptic neurones in slices of rat brain.

These experiments were an attempt to study the possible interactions between cells of the supraoptic nucleus. In isolated brain slices pairs of supraoptic neurones were recorded simultaneously either with a single electrode or with two electrodes and cross-correlograms produced. Correlations were demonstrated in 22 of the 82 pairs studied and were found to be more common between closely neighbouring pairs of cells. Ten of the correlations indicated that the spikes of one cell followed spikes in the other cell. The correlations of another 10 pairs indicated that the cells were coactivated. In only 2 pairs was there a correlation indicative of an inhibitory connexion. That these correlations could result either from synaptic connexions within the nucleus, or from coactivation of cells from an extranuclear site is discussed.