Although the functional analysis of cortico-thalamo-cortical communication is still in its early days, there is accumulating evidence in support of an essential involvement

of “higher-order” thalamus in cortical processes. Responses of pulvinar and PoM neurons depend on input from cortex, have latencies in the same range as cortical neurons, and inherit properties resulting from cortical computations such as receptive field layout or the sensitivity for direction of motion in the case Screening Library of pulvinar (Berman et al., 2011). Conversely, two recent studies demonstrated in both the visual as well as the somatosensory domain that cortical activity critically depends on the intactness of higher-order thalamic nuclei such as the pulvinar (Theyel et al., 2010; Purushothaman et al., 2012). Considering all these features together, it is not surprising that cortico-thalamo-cortical loops have been implicated as central ingredients of higher cognitive functions. In the visual system, Capmatinib order several theories on the mechanisms of spatial attention discuss an involvement of pulvinar gating (Olshausen et al., 1993). Evidence from electrophysiological, imaging, and lesion studies together lend some support to this view, as, for example, monkeys with pulvinar lesions commonly display behavioral

changes ranging from increased reaction times to neglect-like symptoms (Petersen et al., 1987; Wilke et al., 2010). However, how pulvinar activity contributes to attentional processes in the intact animal and controls selective routing

of cortical activity remains unknown. A new study published in Science by Saalmann et al. (2012) aims to fill this gap by investigating the role of pulvinar neurons in coordinating synchronization of cortical signals in the alpha range (8–12 Hz) during visual spatial attention. Saalmann et al. (2012) performed multisite electrophysiological recordings and sampled neural activity from two adjacent midlevel cortical areas of the occipito-temporal stream, thought to be involved in the processing of visual shape and object information and a region in the ventro-lateral part of the pulvinar that they had identified using diffusion tensor imaging (DTI). To control attention, Saalmann mafosfamide et al. (2012) trained two monkeys to report the shape of a visual target stimulus presented among an array of distracters. The position of the target was cued by a preceding stimulus flashed for 100 ms at the target location followed by a brief delay period before target onset. Saalmann et al. (2012) demonstrate a cue-triggered enhancement of pulvinar responses, which is strongest during the cue presentation and sustained to a smaller extent during the delay period, most likely reflecting attentional engagement. The study does not document the cue effects on the firing rates of the cortical neurons, making it difficult to decide whether attention modulates cortical and thalamic responses to the same extent.