Neural correlates of a single-session massage treatment

A study from Canada investigated the immediate neurophysiological effects of different types of massage in healthy adults using functional magnetic resonance imaging (fMRI). The study suggested that that qualitatively different aspects of massage, such as the nature of human touch, can selectively modulate the activity of certain brain regions.

The researchers looked at the problem from, the resting state of the brain, which has been referred to as the default mode network and has received much attention for its importance in the generation of consciousness. These regions (i.e. insula, posterior and anterior cingulate, inferior parietal and medial prefrontal cortices) have been postulated to be involved in the neural correlates of consciousness, specifically in arousal and awareness. The researchers posit that massage would modulate these same regions given the benefits and pleasant affective properties of touch.

Healthy participants were randomly assigned to one of four conditions: 1. Swedish massage, 2. reflexology, 3. massage with an object or 4. a resting control condition. The right foot was massaged while each participant performed a cognitive association task in the scanner.

They found that the Swedish massage treatment activated the subgenual anterior and retrosplenial/ posterior cingulate cortices. This increased blood oxygen level dependent (BOLD) signal was maintained only in the former brain region during performance of the cognitive task. Interestingly, the reflexology massage condition selectively affected the retrosplenial/posterior cingulate in the resting state, whereas massage with the object augmented the BOLD response in this region during the cognitive task performance.

The most robust fMRI changes were observed with the Swedish massage treatment, which involves long and smooth strokes with an applied pressure geared towards relaxation. The impact of reflexology, which is focused upon applying pressure to specific reflex points to invoke a beneficial response at distant body regions, was restricted to the RSC/PCC brain region. In contrast, the massage with a wooden object, which involved pressure and strokes along the same areas of the foot as applied in the Swedish massage, had no significant effect on the BOLD signal in either of the brain regions. This latter finding is particularly noteworthy since it suggests the possibility that the human touch component (as opposed to the same pattern of massage with an object) had a profound influence upon the impact of the treatment.

These findings should have implications for better understanding how alternative treatments might affect resting state neural activity and could ultimately be important for devising new targets in the management of mood disorders.

BRAIN IMAGING AND BEHAVIOR Volume 6, Number 1, 77-87, DOI: 10.1007/s11682-011-9146-z