Intracellular and computational evidence for a dominant role of internal network activity in cortical computations

► The brain displays considerable spontaneous activity. ► Neurons do not respond only to external inputs, but the response is also a function of the spontaneous activity. ► The paper reviews intracellular and modeling evidence for this phenomenon. ► A scheme is proposed to reconcile apparently conflicting results. ► It is concluded that spontaneous activity should be an integral part of brain computations.