In contrast to the hippocampus it has been shown that glutamatergic excitation of pyramidal neurons in the neocortex is substantially controlled by group 2 metabotropic glutamate receptors (mGluRs). To assess whether activation of group 2 mGluRs could change the balance between different neocortical microcircuits we studied the target cell-specific regulation of glutamatergic excitation by group 2 mGluRs. Modulation of extracellularly evoked compound EPSCs by the selective group 2 mGluR agonist DCG-4 (1 microM) was studied in four main types of neurons in layer 2/3 in acute brain slices of the adult mouse motor cortex (34°C): pyramidal neurons; Parvalbumin- positive, fast-spiking interneurons; Martinotti cells and neurogliaform cells. Cell types were identified on the basis of their electrophysiological properties and separated by cluster analysis. In addition, the electrophysiological classification was confirmed by morphological and immunocytochemical analysis. We found that DCG-4 depressed EPSC amplitudes to about 50 % in all types of neurons indicating the prominent role of group 2 mGluRs controlling neocortical network activity and a lack of target cell-specificity of group 2 mGluR-mediated regulation of glutamatergic synapses in the neocortex.