Imaging how attention modulates pain in humans using functional MRI

TLDR

Pain perception is reduced when attention is diverted from noxious stimuli, a phenomenon supported by clinical and experimental literature. The study used fMRI to identify the neural systems underlying this attentional modulation of pain. Participants performed a counting Stroop distraction while receiving intermittent painful thermal stimuli. The cognitively demanding counting Stroop task reduced pain ratings and increased activation in affective ACC and orbitofrontal cortex while decreasing activity in pain‑matrix regions such as thalamus, insula, and cognitive ACC, confirming the behavioral reduction in pain perception.

Abstract

Current clinical and experimental literature strongly supports the phenomenon of reduced pain perception whilst attention is distracted away from noxious stimuli. This study used functional MRI to elucidate the underlying neural systems and mechanisms involved. An analogue of the Stroop task, the counting Stroop, was used as a cognitive distraction task whilst subjects received intermittent painful thermal stimuli. Pain intensity scores were significantly reduced when subjects took part in the more cognitively demanding interference task of the counting Stroop than in the less demanding neutral task. When subjects were distracted during painful stimulation, brain areas associated with the affective division of the anterior cingulate cortex (ACC) and orbitofrontal regions showed increased activation. In contrast, many areas of the pain matrix (i.e. thalamus, insula, cognitive division of the ACC) displayed reduced activation, supporting the behavioural results of reduced pain perception.