Pacemaker calcium oscillations in thalamic astrocytes in situ.

During development, astrocytes in the ventrobasal thalamus display spontaneous intracellular calcium [Ca(2+)](i) oscillations, that can lead to the excitation of adjacent thalamocortical neurons via an NMDA receptor-mediated mechanism. In this study, we show that while astrocytes usually exhibit oscillations of irregular amplitude and frequency, a subset of spontaneously active thalamic astrocytes exhibits rhythmic, i.e. pacemaker, [Ca(2+)](i) oscillations with an average frequency of 0.019 Hz. This frequency of the pacemaker oscillations is close to the modal frequency of the irregularly oscillating astrocytes, suggesting that there is a preferred frequency for astrocytic [Ca(2+)](i) oscillations. If pacemaker [Ca(2+)](i) oscillations underlie excitatory signaling to neurons, the result would be rhythmic activation of thalamocortical neurons and astrocyte-driven synchronized oscillations within neurons of the thalamocortical loop.