Layer-specific attentional modulation in the human primary somatosensory cortex.

Selective attention enhances relevant sensory inputs while filtering out distractions, yet its layer-specific effects remain poorly understood. Here, we used microvascular-specific spin-echo BOLD fMRI at 7 T to investigate attentional modulation across cortical layers in the human primary somatosensory cortex (S1) during finger and wrist stimulation. During passive, unattended stimulation, the middle and deep layers exhibited stronger signals than the superficial layer. In the attended finger region, attention significantly increased activity in the superficial layer, consistent with top-down feedback, and decreased activity in the deep layer, while leaving the middle layer unchanged. In the wrist region processing tactile or pain distractors, signals were uniformly suppressed across layers, including the thalamic-input middle layer, consistent with the impaired sensory discrimination observed in behavioral studies. Our findings reveal that attention reshapes laminar activation in S1, selectively enhancing relevant signals while suppressing irrelevant input, consistent with an attentional gating mechanism.