Laminar distribution of gap-junctions in rat somatic cortical columns

Results about the spindle-like activity peculiarities and the dendro-dendritic gap-junctions numbers in the infragranular and supragranular layers (modules) of the rat somatic cortex columns are presented. During simultaneous recording of extracellular field potentials from the cortical columns, the following was revealed: (i) the spindle-like activity was more synchronized inside one cortical column than in different columns; (ii) in most of the experiments (9 out of 10) an amplitude of the spindle waves was two times more in the supragranular layers than in the infragranular layers. During electron microscopy investigation of the experimental objects used in the electrophysiological study, it was shown that the number of the gap-junctions was more in the supragranular columnar layers as compared with the infragranular layers (4.15% and 2.84% out of the total number of chemical synapses and gap-junctions identified in each module, respectively). The results obtained are discussed as possible structural base of the local electrotonic synchronization of the neuronal activity inside a cortical column.