• brain;
  • gap junctions;
  • compartments;
  • neuron;
  • glia

This review describes recent progress in the identification of the molecular composition of gap junction proteins (connexins) in brain tissue. First, a general overview of gap junction function and the composition of the hemichannels (connexons) is given. Then the question of diversity of gap junction channels in the nervous system is addressed and its functional implications are discussed. Based on recent findings of gap junction mediated cell-to-cell communication we attempt to refine the concept of functionally coupled compartments in the brain. This conceptual introduction passes on to a detailed description of the coupling efficiency in glial and neuronal compartments with emphasis on innovative perspectives that allow a better understanding of gap junction function in the brain.