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The Limbic System and Massage Therapy

An exciting area of research warranting more investigation. Leading edge massage-related research • Series 1

An interest in the limbic system and its relationship with massage therapy was triggered by a research article published by Canadian and Swedish scientists who discovered the system of nerves responsible for the pleasure humans derive from touch.^1,2 The connection between touch and feelings of emotion seem to occur in the limbic brain.

The limbic system controls mood and attitude. It sets the emotional tone of the mind and modulates motivation, controls appetite and sleep cycles and promotes bonding. Problems with the system lead to moodiness, irritability and clinical depression.³

The limbic system allows animals to distinguish between the agreeable and the disagreeable. Specific affective functions are developed here, such as the one that induces the females to nurse and protect their toddlers, or the one which induces these animals to develop playful moods. Emotions and feelings, like wrath, fright, passion, love, hate, joy and sadness, originate in the limbic system. This system is also responsible for some aspects of personal identity and for important functions related to memory.⁴

The limbic system is a complex set of structures that lies above and around the thalamus and just under the cerebrum (near the centre of the brain). It includes the hypothalamus, the hippocampus, the amygdala, and several other nearby areas.⁵

The olfactory cortex may be included as well. It is important to stress that all these structures interconnect intensively and none of them is solely responsible for any specific emotional state. However, some contribute more than others to this or that kind of emotion.⁴

When the limbic system is less active there is generally a positive, more hopeful state of mind. When it is overactive, negativity can take over. The limbic system provides a filter through which you interpret the events of the day.³

The hypothalamus is one of the busiest parts of the brain. It regulates your hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behaviour and more.5 It is also involved in homeostasis in that it regulates pulse, blood pressure and breathing.⁴

The hypothalamus is connected to the pituitary gland which releases hormones that regulate growth and metabolism. It also sends signals to the body to activate the fight or flight response. A dysfunction here may cause anxiety attacks.⁶

The hippocampus is important in converting short term memory into long term memory. The hippocampus allows animals to compare the conditions of a present threat with similar past experience, thus enabling it to choose the best option, in order to improve its own chances of survival.⁴

The amygdala plays an important role on the mediation and control of major affective activities like friendship, love and affection, on the expression of mood and mainly on fear, rage and aggression.^{4, 5}

Also associated with the limbic system is the ventral segmental area of the brain stem which lies just below the thalamus. Here dopamine pathways that seem to be responsible for pleasure are found.5 The thalamus does not have a primary role in emotions, but most interconnecting nerve pathways involved in emotion pass through the thalamus.3,7

Ongoing research into the limbic system may provide massage therapists with a better understanding about some of the physiological and psychological effects of their treatments. Let’s look at some of the current literature.

The limbic system receives inputs from a number of sources including the vagus nerve, brain stem, optic nerve and olfactory nerves.5 Current research has now found small tactile nerves in the skin that elicit emotional response. Olausson et al (2002) in an article published in Nature provide further clarity about the relationship between the limbic system and touch.

They studied a female patient with selective sensory nerve damage that resulted in her being unable to feel simple touch (if she does not see where her arms and legs are, she has no sense they are even there), but she was able to “feel” a light brushing stroke. This light stroking was interpreted by the patient as a pleasurable feeling and the limbic system was suspected as the physiological basis for this feeling.^1,2

There is dual tactile innervation of the human hairy skin that respond to light touch, fast conducting myelinated afferent fibers and slow-conducting unmyelinated (C) afferents. Prior to this study, the unmyelinated afferents were thought to be involved only in pain and temperature sensations. Light touch of this patient evoked a faint sensation of pleasant touch and functional MRI analysis showed activation of the insular region of the brain, but not the somatosensory areas.

The conclusion drawn was that these unmyelinated nerves may be a system of limbic touch that underlies emotional, hormonal and affiliative responses to caress-like, skin-to-skin contact between individuals.1

The findings suggest the soothing feelings humans experience when stroked or caressed do not stem from positive mental associations alone, but also from a direct physical connection between the unmyelinated afferent fibres and the area of the brain responsible for emotion.²

A recent article by Blackburn-Munro et al. (2002) in Trends in Endocrinology and Metabolism8 states that pain is a multi-dimensional process involving the physical, emotional and perceptual integration of noxious information. The physical component is relayed via the spinal cord; the emotional aspect is encoded by the limbic system which encapsulates the relationship between pain and mood. Dysfunction of the hypothalamo-pituitary-adrenal axis has been implicated in a variety of chronic pain conditions.

Hayes et al. (2000) in their research report entitled The mediating role of cutaneous sensitivity within neonatal psychoneuroimmunology hypothesized that cutaneous stimulation in the form of light stroking only (not kneading or kinesthetic massage) has a mediating role in eliciting beneficial psychoneuroimmunological coactions in the ventilated pre-term infants during the first week of post-natal life.

Their conclusion was that the sensory nerves endings in the skin receive the stimulation from the stroking actions; consequently impulses are being sent via afferent fibres to the limbic system where the sensation is interpreted by 68 per cent of the neonates as being comforting or not distressing.⁹

In a related systematic review registered with the Cochrane collaboration (2001) entitled Massage for promoting growth and development of pre-term and/or low birth weight infants found massage (rubbing, stroking and kinaesthetic stimulation) improved daily weight gain by 5 grams, however there is no evidence that gentle, still touch is of benefit. Massage intervention also appeared to reduce length of stay in hospital by 4.6 days, though there are methodological concerns about the blinding of this outcome.

Evidence that massage for pre-term infants is of benefit for developmental outcomes is weak and does not warrant wider use of pre-term infant massage. Future research should assess the effects of massage intervention on clinical outcome measure and on process-of-care outcomes.¹⁰

A randomized controlled clinical trial of massage therapy for bulimic adolescents showed that massage (slow stroke massage) patients showed greater decreases in short term measure of anxiety and depression (both self report and behaviour observation).11 Again further studies are warranted.

Further research on the limbic system and massage could explore the efficacy of different types of touch inputs in the treatment of acute and chronic pain conditions or affect disorders.

For instance, if limbic system stimulation influences psychosocial factors such as fear, anxiety, depression, could it also inhibit or foster negative pain behaviours? Further understanding of the limbic system and the peripheral pathways that send signals of emotion as a result of touch needs to be explored and translated into effective massage treatments for our patients.

Reference List

1. Olausson H, Lamarre Y, Backlund H, Morin C, Wallin BG, Starck G et al. Unmyelinated tactile afferents signal touch and project to insular cortex. Nature neuroscience 5[9]. 2002. www.nature.com/natureneuroscience
2. Nelson O. Emotion connected to touch, study finds. Link in limbic brain. National Post 2002.
3. Amen DG. Brain Function and Physiology. Limbic System (controls mood and attitude). Internet. 2003. www.brainplace.com/bp/brainsystem/limbic.asp
4. Rocha do Amaral J, Martins de Oliveira J. Limbic System: The Centre of Emotions. Brain and Mind Electronic Magazine on Neuroscience 5 [March-May]. 1998. www.epub.org.br/cm/n05/mente/limbic_i.htm
5. Boeree G. The Limbic System. Internet. 2003. www.ship.edu/cgboeree/limbicsystem.html
6. Frey K, Cameron O, Huang G, Minoshima S, Kilbourn M, Nichols TE et al. Reduced GABAA Receptor/Benzodiazepine Binding Sites in Insular Cortex of Panic Disorder Patients . Internet . 2003. http://www.academicpress.com/www/journal/nrm2002/14652.html
7. Craig AD. Spinal location of ascending lamina I axons in the Macaque monkey. J Pain 2000; 1(33):45.
8. Blackburn-Munro G, Blackburn-Munro R. Pain in the brain: are hormones to blame? Trends Endocrinology and Metabolism 2002; 14(1):20-27.
9. Hayes JA, Adamson-Mercedo EN, Perera S. The mediating role of cutaneous sensitivity within neonatal psychoneuroimmunology. Neuroendocrinol Lett 2000; 21(3):187-193.
10. Vickers A, Ohlsson A, Lacey JB, Horsley A. Massage for promoting growth and development of preterm and/or low birth weight infants. Cochrane Library Issue 3. 2001. http://www.update-software.com/abstracts/ab000390.htm
11. Field T, Schanberg S, Kuhn C, et al. Bulimic Adolescents Benefit from Massage Therapy. Adolescence 1998; 33:555-563.

note: this document has been prepared by the Sheila Kerr & Marc White, Physical Medicine Research Foundation for the College of Massage Therapists of BC (CMT) and Massage Therapists’ Association of BC (MTA). It is and remains the intellectual property of the CMT and MTA. It may not be duplicated or released in any form without the express written permission of CMT and MTA.