Sensory information is actively acquired and processed in the brain. This is particularly evident in the rodent whisker sensorimotor pathway, where the animal actively moves its whiskers back and forth during exploratory tactile behaviour. Sensory processing in the somatosensory neocortex has been shown to depend strongly upon ongoing behaviour. This state-dependent activity might arise through specific modulation of cortical activity or the differences in sensory processing might relate to changes earlier in the sensory network. In order to investigate this, we need to understand what changes occur in the somatosensory thalamic nuclei, through which sensory inputs transit to the barrel cortex. Here we propose to make whole-cell recordings from neurons in the somatosensory thalamic nuclei in the behaving mouse to investigate changes in spontaneous membrane potential dynamics and sensory processing during different behaviours. Our experiments will focus on uncovering the differential roles of the somatosensory thalamic nuclei in processing sensory information and how they are influenced by different behaviours. Of equal important we will investigate the thalamic contribution to the regulation of brain states. These data will shed light on the membrane potential dynamics underlying state-dependent sensory processing providing clear and well-defined data from identified neurons.