Neural correlates of a single-session massage treatment

D. Sliz 0 2 A. Smith 0 2 C. Wiebking 0 2 G. Northoff 0 2 S. Hayley 0 2 0 A. Smith Department of Psychology, University of Ottawa , Ottawa, ON, Canada 1 ) Department of Neuroscience, Carleton University , 1125 Colonel By Drive, Ottawa, ON , Canada K1S 5B6 2 C. Wiebking Department of Psychiatry , Otto-von-Guericke, University of Magdeburg , Magdeburg, Germany The current study investigated the immediate neurophysiological effects of different types of massage in healthy adults using functional magnetic resonance imaging (fMRI). Much attention has been given to the default mode network, a set of brain regions showing greater activity in the resting state. 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. We posit that massage would modulate these same regions given the benefits and pleasant affective properties of touch. To this end, 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. We 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. 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. - Massage therapy is a billion dollar industry in North America with approximately 8% (over four million) of North Americans using this complementary therapy on a yearly basis (Barnes et al. 2008; Park 2005). In 2007, it was estimated that out of pocket expenses for CAM therapies cost $11.9 billion dollars with over $4 million being spent on massage therapy (Nahin et al. 2009). Its use has steadily risen over the last decade, and is often used as an adjunct treatment for a number of conditions, including those involving chronic pain and distress (Sherman et al. 2009; Field 2002), as well as enhancing growth and cognitive functioning in preterm infants (Field et al. 2010; Field et al. 2008; Procianoy et al. 2010) and preschoolers (Hart et al. 1998). Emerging evidence has also indicated that massage might have beneficial effects in cancer patients by modulating immunity, and lessening pain and sleep disturbances (Russell et al. 2008; Hughes et al. 2008; Calenda 2006). In fact, 45 min of Swedish massage was reported to increase the number of circulating T lymphocytes, while reducing mitogen induced inflammatory cytokine responses and limiting hormonal variations (Rapaport et al. 2010). Yet, such findings have not been uniformly accepted, as others have failed to find such effects. For instance, a recent report revealed that 5 weeks of 30 min weekly massage did not affect peripheral cytokine or T lymphocyte responses in a group of female breast cancer patients (Krohn et al. 2011). Of particular interest to the present investigation, a recent meta-analysis (17 different studies) demonstrated that massage therapy alleviated depressive symptoms (Hou et al. 2010). Similarly, others have found that massage reduced physiological and psychological aspects of anxiety in several different populations (Field et al. 1996; Beider et al. 2007; Moyer et al. 2004). Despite the increasing research in complementary treatments such as massage, few studies have examined the neurobiological correlates of massage therapy. Of these, one study involving depressed adolescents who received a 15-min chair massage resulted in lessened right frontal EEG activation, which is known to be involved in negative affect and withdrawal tendencies (Jones and Field 1999). A recent PET study involving healthy participants, revealed that 4 min of a back massage increased cerebral blood flow (rCBF) in the left precuneus and pons and a subsequent increase was evident in bilateral precuneus and left fusiform gyrus after a further 20 min of the massage (Ouchi et al. 2006). Remarkably however, there are presently no experimental fMRI data regarding the pattern of brain region activation in response to massage therapy. To this end, the present investigation sought to evaluate the neural correlates of an acute massage session. In particular, we focus upon two brain regions that are known to be important for emotional processing and comprise critical nodes in the default mode network, the subgenual anterior cingulate cortex (sACC) and retrosplenial/posterior cingulate cortex (RSC/PCC). Over the last decade, the resting state of the brain, which has been referred to as the default mode network (DMN; Raichle et al. 2001), has received much attention for its importance in the generation of consciousness (Greicius et al. 2008; Vanhaudenhuyse et al. 2010). The DMN encompasses a set of neural networks which show positive blood oxygen level dependant (BOLD) responses when the brain is at rest (i.e. when one is sitting quietly with eyes closed and not engaged in any task) and has been postulated to play a role in self-relatedness (Schneider et al. 2008) and subjective awareness (Khalsa et al. 2009). Among the regions of the DMN, the anterior and posterior cingulate cortices (ACC and PCC, respectively) show a predominantly negative BOLD response during stimulus-induced activity and have been closely associated with self-relatedness, which refers to internal and external states that a person identifies with (i.e. ones heart rate, self-consciousness) (Northoff et al. 2010; Vanhaudenhuyse et al. 2011). Importantly, the ACC and PCC, in conjunction with the insula, are also thought to mediate changes of the peripheral autonomic nervous system and our sensation and perception of these physiological changes, which is known as interoception (Berlucchi and Aglioti 2010; Craig 2002; Wiens 2005). These changes are likely important nodes in the neural circuitry responsible for processing emotionally relevant information (Taylor et al. 2009). In fact, the closely related subgenual cingulate brain region is the site of deep brain stimulation used clinically for treatment resistant depression (Johansen-Berg et al. 2008). Since massage involves the application of an external, primarily non-self-related stimulus, it raises the question of how it might impact the PCC and ACC and default mode processing in general. The following study (...truncated)