En del studier relatert til hudstekk behandlingen, DermoNeuroModulation:
Cutaneous afferents provide information about knee joint movements in humans
To investigate if proprioceptive information is also provided by skin mechanoreceptor afferents from skin areas related to large joints of postural importance, microneurography recordings were obtained in humans from skin afferents in the lateral cutaneous femoral nerve to study their responses to knee joint movements.
All afferents from fast and slowly adapting low-threshold mechanoreceptors, as well as C mechanoreceptors, responded to manually applied skin stretch. In contrast, the same stimulus elicited, at most, feeble responses in hair follicle receptors.
Qualitative and quantitative analyses of the responses of a subset of afferents revealed that in particular slowly adapting afferents effectively encode both static and dynamic aspects of passively imposed knee joint movements.
A previously undefined type of slowly adapting receptor (SA III) seemed particularly suited for this task whereas this does not seem to be the case for either hair follicle receptors or C mechanoreceptors.
Cortical processing of lateral skin stretch stimulation in humans.
Direction discrimination of a moving tactile stimulus requires intact dorsal columns and provides a sensitive clinical test of somatosensory dysfunction
Second somatosensory cortex (S2) was activated in the task as well as no task experiment, and there was no significant difference in cortical activation between the two experiments. Within S2 nearly all subjects had prominent activations in the caudal and superficial part, i.e., in the opercular parietal (OP) area 1.
Tactile directional sensitivity and postural control.
Tactile directional sensitivity depends on two different kinds of somatosensory information, i.e. spatiotemporal information and information about friction-induced changes in skin stretch. The objective of this study was to compare the relative contribution to postural control of these two types of information for both glabrous and hairy skin. Postural sway amplitudes and sway paths were recorded, with or without access to tactile and/or visual stabilizing stimuli. Subjects were standing on two types of surface, either solid metal or 50 mm foam plastic.
The results invite speculation that patients with poor directional sensitivity might have reduced postural stability compared with healthy individuals.
Does sympathetic nerve discharge affect the firing of myelinated cutaneous afferents in humans?
The close relation to blood flow for all types of afferents, and the different responses among SAII afferents, suggest that sympathetically mediated changes in afferent firing properties are indirect, i.e. secondary to changes in the mechanoreceptors’ tissue environment rather than to a direct sympathetic effect on the endings.
Clustering of slowly adapting type II mechanoreceptors in human peripheral nerve and skin.
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.
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.
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.