Skin stretch research: Simon Gandevia

[Diane]

I learned about the work of Simon Gandevia lately, and think his work needs to be brought here to the dermoneuromodulation forum. He's a prolific researcher. I'll be bringing more of his material here as time goes by, but for now, here is an initial offering (http://jn.physiology.org/cgi/content/short/00191.2005v1?ck=nck): When delivered alone, strong skin stretch evoked illusory elbow flexion in 5/10 subjects (9°±4°). Simultaneous strong skin stretch and vibration increased the illusory elbow flexion for the group by 1.5 times, compared to vibration (p<0.05). For the knee, vibration was applied over the patellar tendon and skin stretch over the thigh. Skin stretch alone evoked illusory knee flexion in 3/10 subjects (8°±4°) and when delivered during vibration, perceived knee flexion increased for the group by 1.4 times, compared with vibration (p<0.05). Hence inputs from cutaneous receptors, muscle receptors, and combined inputs from both receptors likely subserve kinesthesia at joints throughout the body.

I'm very pleased to read this. I now feel closer to pulling up the appropriate hook for that paper I've been struggling with most of this year.

[Diane]

It's been a long time since I googled "skin stretch". Seems there's plenty out there (http://scholar.google.com/scholar?q=Skin+stretch&hl=en&lr=lang_en|lang_es&scoring=r&as_ylo=2002) on the topic.

[Diane]

Here is a great link (http://www.hubmed.org/search.cgi?q=gandevia+skin&sort=date) to Gandevia that Matthias sent.

[Diane]

I realized earlier today that Gandevia was the second author listed in this Henderson paper (http://www.somasimple.com/forums/showpost.php?p=29858&postcount=1) on the insular cortex that is so interesting.

[Diane]

Here are three more papers (full access) Gandevia was involved in. They are from the 80's.

[Diane]

This isn't Gandevia, but should be quite interesting for kinesio taping people I think. Legs/feet/ankles feel better with a small strip of tape placed around the back of the heel, medial to lateral. I think rehab research in Japan is quite advanced.

article (http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=17276004&ordinalpos=12&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum)

1: Neurosci Lett. 2007 Mar 30;415(3):294-8. Epub 2007 Jan 21.

Facilitation of the soleus stretch reflex induced by electrical excitation of plantar cutaneous afferents located around the heel.
Sayenko DG, Vette AH, Kamibayashi K, Nakajima T, Akai M, Nakazawa K.

Department of Rehabilitation for Movement Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa 359-8555, Japan. sayenko@rehab.go.jp

Previous studies have demonstrated that plantar cutaneous afferents can adjust motoneuronal excitability, which may contribute significantly to the control of human posture and locomotion. However, the role of plantar cutaneous afferents with respect to their location specificity in modulating the mechanically induced stretch reflex still remains unclear. In the present study, it was hypothesized that electrical stimulation of the ipsilateral heel region of the foot is followed by a modulation of spinal excitability, leading to a facilitation of the soleus motor output. The study was performed to investigate the effect of excitation of plantar cutaneous afferents located around the heel on the soleus stretch reflex. The soleus stretch reflex was evoked by rotating the ankle joint in dorsiflexion direction at two different angular velocities of 50 and 200 degrees s(-1). A conditioning pulse train of non-noxious electrical stimulation was delivered to the plantar surface of the heel at different conditioning test intervals ranging from 5 to 100 ms. Excitation of plantar cutaneous afferents around the heel resulted in a pronounced facilitation of the soleus stretch reflex with magnitude and time course comparable for both velocities. This facilitation was manifested by a significant increase of reflex size for conditioning test intervals from 30 to 70 ms. The observed effect implies a potential functional role of cutaneous afferents in balance control conditions where the ankle is naturally disturbed, e.g., during step reactions to external perturbations.

[Diane]

Here is another juicy paper (http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=9549505&ordinalpos=12&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum) to do with Ruffini endings.
1: Brain. 1998 Feb;121 ( Pt 2):265-79.

Clustering of slowly adapting type II mechanoreceptors in human peripheral nerve and skin.

Wu G, Ekedahl R, Hallin RG.
Department of Medical Laboratory Sciences and Technology, Huddinge University Hospital, Karolinska Institute, Sweden.

The intrafascicular organization of human peripheral nerves was studied with percutaneous microneurography in the median, radial and peroneal nerves with one-surface or two-surface thin diameter concentric needle electrodes. Data from 33 recording sites containing 47 slowly adapting type II (SAII) units were analysed. At many sites two, sometimes even three, neighbouring SAII units were recorded from the explored nerve fascicle and they had adjacent or even overlapping cutaneous receptive fields. Among pairs of SAII units found at the same site, one unit often had ongoing discharge, whereas the other was silent under resting conditions. The neighbouring SAII units were optimally activated by stretching the skin in different directions. Stretching the same skin area in different directions produced different unit recruitment. Clustered SAII units were often found in sites where Pacinian afferents and skin sympathetic activity were also recorded. No significant difference was observed in the degree of grouping of SAII units either between recordings obtained with one-surface versus two-surface electrodes or between glabrous and hairy skin. The data do not support the notion that myelinated fibres are randomly organized in peripheral nerve fascicles. Instead, the findings suggest that SAII units tend to be clustered in human peripheral nerves. Furthermore, the response of groups of SAII units to skin stretch suggests that they play a role in proprioception. Dual channel recordings with two-surface concentric needle electrodes may provide a novel approach to study fibre organization in human peripheral nerves and the behaviour of groups of nerve fibres.

Thank you, Wu, Ekedahl, and Hallin. :thumbs_up

[Diane]

Here is a little table I made (OK, borrowed and modified), highlighting Ruffini's - it shows them to be the ones responding to lateral skin stretch.

[EricM]

Looks like perpendicular force stimulates Merkels, also slow adapting and present in all skin. Could these be part of the mechanism accounting for pain relief upon the application of 'digital ischaemic pressure' for 'trigger points?'

[Diane]

Maybe. Do the 'trigger points' stay away after? In my experience, pain spots dull out but come right back with direct pressure. With skin stretch, they stay away to a much greater extent.

[Diane]

Here is a link Matthias sent (http://www.hubmed.org/search.cgi?q=gandevia+skin&sort=date) me ages ago now.

[Diane]

Here are a few more articles (http://www.somasimple.com/forums/showthread.php?p=43798#post43798) by Gandevia.. just housekeeping.