Attention to a painful cutaneous laser stimulus modulates electrocorticographic event-related desynchronization in humans

To test the hypothesis that attention to painful cutaneous laser stimuli enhances event-related desynchronization (ERD) in cortical regions receiving nociceptive input. We used wavelet time–frequency analysis and bandpass filtering to measure ERD quantitatively in subdural electrocorticographic recordings while subjects either attended to, or were distracted from, a painful cutaneous laser stimulus. ERD were observed over primary somatosensory and parasylvian (PS) cortices in all 4 subjects, and over medial frontal cortex in 1 subject. Laser-evoked potentials were also observed in all 3 regions. In all subjects, ERD was more widespread and intense, particularly over PS, during attention to laser stimuli (counting stimuli) than during distraction from the stimuli (reading for comprehension). These findings suggest that pain-associated ERD is modulated by attention, particularly over PS. This study suggests that thalamocortical circuits are involved in attentional modulation of pain because of the proposed role of these circuits in the mechanisms of ERD.