Cerebral Cortex Advance Access published online on March 4, 2008
Cerebral Cortex, doi:10.1093/cercor/bhn009
Astrocytes Discriminate and Selectively Respond to the Activity of a Subpopulation of Neurons within the Barrel Cortex
1 Department of Psychiatry and Psychotherapy, Campus Benjamin Franklin, Charité-University Medicine Berlin, D-12200 Berlin, Germany, 2 Max Delbrück Center for Molecular Medicine, 13092 Berlin, Germany
Address correspondence to Prof. Dr Helmut Kettenmann, Max Delbrück Center for Molecular Medicine, Cellular Neurosciences Robert Rössle Str. 10, 13125 Berlin, Germany. Email: kettenmann{at}mdc-berlin.de.
Sensory information from single whiskers in rodents projects to defined morphological units in the cortex, the barrels. We found that astrocytes selectively respond with an increase in the cytosolic Ca2+ concentration to activation of layer 4 neurons, the input cells of the barrel columns. The neuronal Ca2+ signal also spread across barrel column borders mainly in layer 2/3, but the glutamate-mediated astrocyte response stayed restricted to the barrel column. In contrast, when interfering with inhibitory pathways by blocking either purinergic, adenosine or
-aminobutyric acidA receptors, the stimulation activated a Ca2+ response in a much larger astrocyte population no longer restricted to the borders of the barrel column. We also observed spontaneous and evoked Ca2+ activity in the synaptic target cells of layer 4 neurons, the layer 2/3 pyramidal cells, but again, we never recorded Ca2+ responses in astrocytes following activity in this neuronal population. Our data show that astrocytes can discriminate and selectively respond to the activity of a subpopulation of excitatory neurons within a given brain region. This selectivity in the astrocyte response describes a new level of complexity and integration in the reaction of astrocytes to neuronal activity.
Key Words: astrocyte barrel cortex calcium neuron–glia interaction slice
Carola Schipke and Brigitte Haas have contributed equally to this work.