Incoming sensory information is first processed in the thalamocortical network. Previous studies showed that the responses generated in the nuclei of this network are behaviorally modulated, suggesting that the processing of the somatosensory information could be state dependent. Most theories, proposed to describe this response modulation have postulated that the thalamic reticular nucleus (TRN) plays a role in this response modulation. We suggest that the TRN acts as a bandpass filter whose bandwidth increases or decreases depending on the state of the animal. To test this idea, we used multineuron recordings and demonstrate, for the first time, that the responses of single neurons in the reticular nucleus are modulated by the behavior of the animal. This result, taken together with the anatomy of the thalamocortical network and previous studies on anesthetized rats, suggests that the modulation of the responses in the thalamus and cortex could be at least partially due to the TRN through a mechanism that is similar to that of a behavioral modulated filter.