The responses of the cortex to sensory stimulation seem to rely on a balance between excitation and inhibition. Previous studies of such responses have largely used anaesthetized animals; now, Haider et al. report that recordings of visually evoked responses from the cortex of awake mice show much greater levels of widespread inhibition, resulting in more spatially selective and short-lived cortical responses to sensory stimulation than are seen in anaesthetized animals. This synaptic inhibition might be modulated by attention or reward-related factors to influence visual processing.