Figure 1: Local inhibitory connections of cortical networks. Note the efferent and afferent connections indicated by arrows. In red, connections indicate glutamatergic excitation and blue connections GABAergic inhibition. Brown soma indicates an excitatory pyramidal cell (P), and blue-grey somata show inhibitory interneurons (INs). The left interneuron is integrated into a feedback inhibition loop, (FB) while the right interneuron shows feed-forward inhibition (FF). Differential targeting by the interneurons to the soma or dendrite points towards possible layer-specific actions of inhibition. Note that GABA released at the right synapse may, eventually, spill over to the neighbouring glutamatergic synapse. The global light blue staining indicates background GABA concentration that mediates tonic inhibition depending on local synaptic activity.