Figure 1. Experimental strategy and interpretation of findings in Pais-Vieira et al. (2013). A, Schematic of the behavioral task and setup. The diagram represents the behavioral chamber as viewed from above. B, Electrophysiological recording sites and pharmacological manipulations done during execution of the task. C, Cortical circuits and areas involved. Tactile stimuli elicit activation of the trigeminal pathway (trigeminal nuclei, thalamus and S1). This stimuli-driven activity reaches S1 cortex but corollary signals from M1 also modulate processing in S1, as described by Pais-Vieira et al. (2013). A wealth of other areas such as the prefrontal cortex, secondary sensory cortex and nucleus basalis magnocellularis also project to S1 and could provide contextual influence to the incoming sensory information. Whisker system neural circuits relevant to Pais-Vieira et al.'s work are represented by light green arrows. Neural circuits involved in attentional processing are represented by dark green arrows. Incoming sensory (Bottom-Up) inputs to S1 are highlighted in purple. Incoming Top-Down influences to S1 and thalamus are highlighted in orange. Local processing in each area is represented by circular arrows. Other brain circuits are shown in light gray in the background. TN, trigeminal nuclei; TG, trigeminal ganglion; FN, facial nucleus; POM, posterior medial nucleus of the thalamus; VPM, ventral posterior medial nucleus of the thalamus; S1, primary somatosensory (barrel) cortex; M1, primary somatosensory motor cortex; S2, secondary somatosensory cortex; PFC, prefrontal cortex; and NBM, nucleus basalis magnocellularis.