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Hedonic, such a nice word

By Timothy Cocks Science and the world 23 Apr 2014

Dottore Alberto Gallace of the Università di Milano-Bicocca is a very clever guy. He spoke at the first PainAdelaide meeting (I recall he spoke at length about drinking beer with Lorimer Moseley), he’s published a bunch of papers with other very clever people and is the multisensory processing section editor at

The OUPblog has a nice interview with Dottore Gallace talking about his research into human touch.

“To my students I often say, where our touch begins, we are. I wanted to understand more of these topics. I wanted to compare touch with other sensory modalities. In doing that I was convinced that research on touch had to get away from the fingertips or hands and extend to the whole body surface. The more I studied this sense, the more I became interested in it. For every question answered there were many more without responses. I like touch a lot because there are many things that still need to be understood about it, and I am a rather curious person, particularly when it comes to science.

I am not sure if it’s the most important development, but what I certainly consider important is the recent study of certain neural fibres specialized in transmitting socially-relevant information via the sense of touch. That is, the C tactile afferents in humans, that are strongly activated by ‘caress like’ stimuli, might play an important role in many of our most pleasant social experiences.” 


“C Fibres” are often seen as the bad guys, and while we know that they are not “pain fibres”, they are frequently part of a discussion of pain in relation to their nociceptive properties.

But the C Tactile afferents that Dr Gallace mentions are a different kind of C fibre altogether. From a nice little, open access paper (however this one’s not authored by Dr Gallace):

“Human C-tactile (CT) afferents respond vigorously to gentle skin stroking and have gained attention for their importance in social touch. Pharmacogenetic activation of the mouse CT equivalent has positively reinforcing, anxiolytic effects, suggesting a role in grooming and affiliative behavior.

We show that CTs are unique among mechanoreceptive afferents: they discharged preferentially to slowly moving stimuli at a neutral (typical skin) temperature, rather than at the cooler or warmer stimulus temperatures

Furthermore, the CT firing frequency correlated with hedonic ratings to the same mechano-thermal stimulus only at the neutral stimulus temperature, where the stimuli were felt as pleasant at higher firing rates. We conclude that CT afferents are tuned to respond to tactile stimuli with the specific characteristics of a gentle caress delivered at typical skin temperature. This provides a peripheral mechanism for signaling pleasant skin-to-skin contact in humans, which promotes interpersonal touch and affiliative behaviour.”


I like the word hedonic. Defined as “relating to, characterized by, or considered in terms of pleasant sensations”, its one of those words that for me captures complex, multiple, sensual, intimate, tangible experiences like no other word can. It’s remarkably consistent across languages – the Germans make it their own with “hedonischen”, the French make it all fancy like with “hédonique” while the Estonians give it a nice ring with “hedoonilises”. Not to be confused with hedonism- “the pursuit of pleasure; sensual self-indulgence.” or this, a hedonic experience might be in many ways the very opposite of a pain experience.

I have had a number of psychologist friends that point out how lucky I am as a physiotherapist that I am allowed to touch people. Perhaps having this modality restricted in their interactions with people in trouble they have realised its power? I wonder if physio-/physical therapists take this a bit for granted? With so many physical therapy techniques being quite brisk, strong and robust, are we missing the opportunities to provide clients with a bit of a hedonic experience with some lighter, gentler touch? Activating those C Tactile afferents that are “tuned to respond to tactile stimuli with the specific characteristics of a gentle caress”? If you’re in the business of touching people for a living, is this worth considering? Do you/ how do you give clients a nice little hedonic buzz?


-Tim Cocks


  1. Yes Tim indeed a beautiful word and a philosophy to follow whether, in an altruistic fashion in giving to others or in imparting it on ourselves……. We are trully privaliged in that we have permission to touch……..our most powerful negotiator with pain……ones quest in life must be to enjoy the maximum of pleasure with the minimum of pain……..This should equally be our goal for our patients……

    1. timcocks0noi

      Hi David, love that line “our most powerful negotiator with pain”. Touch as a “conversation” is such a nice metaphor – it implies a two way communication, as opposed to the notion that therapists can somehow fix a person by doing something “to” them.

  2. blanaidcoveney

    Hi Tim, nice post! Your psychologist friends may have had a point! In my first week in University we had lectures from the wise Head of the School of Physiotherapy. His first words have stayed with me always. He said ” It is a honour and a privilege to be able to touch the patients. Never take it for granted”. Wise words never forgotten.

    1. timcocks0noi

      Hi Blanaid, I too can recall a similar idea voiced early on in my training regarding the privilege of touching another person – but its taken a very long time to truly understand the meaning!
      Thanks for dropping by,

  3. Nice post Tim.

    I think gentleness in treatment is of enormous importance.
    If a treatment has any degree of effort or force, it belies the
    therapist’s attitude towards treatment – one of overcoming resistance.
    We aren’t there to overcome resistance or force our agenda onto
    the patient. A therapist who is overly desirous of a “good outcome” will just cause an ugly battle to emerge.
    We are there to accept exactly “what is”. Whatever the
    patient presents us is “right”. If pain, spasm, swelling is “right”, then we just give it a brief and gentle rub with no intent to alter the course of recovery. The need to be a super-therapist is let go, and paradoxically, the most amazing outcomes happen. We’re just saying “ok, I see that hurts”.


    PS. Some psychologists used to think it was ok to touch patients. The great Carl Rogers here agrees to hold the patient’s hands. The look in her eye is a worry!! She’s besotted with him! LOL.

    1. timcocks0noi

      Hi EG
      Thanks for your comments and the link- quite an interesting conversation!
      I was reminded in writing this post of clients I have seen in the past (somewhat distant past I am happy to be able to say) that came into the clinic in quite a bit of trouble and being able to do just the lightest “treatment” – they came back reporting significant improvement after the session and since. Of course, with the improvement I could then get stuck in to doing “proper” treatment with heavier mobilisation to “loosen up those joints” – only to have them return reporting a worsening of their symptoms again……

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