Ultra-late EEG potential evoked by preferential activation of unmyelinated tactile afferents in human hairy skin

Ackerley, Rochelle; Eriksson, Elin Svedlund; Wessberg, Johan

doi:10.1016/j.neulet.2013.01.004

Cited by 45 publications

(52 citation statements)

References 118 publications

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“…It was hypothesized that consistent with the stronger conscious percept and higher amplitude sympathetic skin response previously reported (Olausson et al, , ; Pawling, Trotter, Trotter, McGlone, & Walker, ), a larger amplitude P300 will be measured in response to Aβ‐targeted (30 cm/s) versus CT‐targeted (3 cm/s) touch. Secondly, consistent with the previous report of Ackerley et al (), CT optimal (3 cm/s) stroking is hypothesized to evoke a ULP over frontal electrodes, while 30 cm/s strokes, a stronger stimulus for Aβs, will not. Finally, we explored whether, in line with previous psychophysical and fMRI data (Croy et al, ; Voos et al ), cortical responses to CT‐targeted touch are correlated with self‐reported levels of autistic traits.…”

Section: Introductionsupporting

confidence: 84%

“…This ultra‐late potential (ULP), first identified as a specific response to laser evoked stimulation of C‐nociceptive fibres is recorded over frontal brain regions (Bragard, Chen, & Plaghki, ; Bromm & Lorenz, ; Bromm, Neitzel, Tecklenburg, & Treede, ; Valeriani et al, ). A ULP evoked by CT‐targeted touch has also been reported (Ackerley, Eriksson, & Wessberg, ) in response to brush strokes delivered to the ventral surface of the forearm at a CT‐optimal velocity (Ackerley et al, ). The ULP peaked around 2700 ms after initial skin contact and continued throughout the brushing stimulus.…”

Section: Introductionmentioning

confidence: 72%

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Autistic traits modulate cortical responses to affective but not discriminative touch

Haggarty

Malinowski

McGlone

et al. 2020

Eur J of Neuroscience

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The sense of touch is primarily considered a discriminative and exteroceptive sense, facilitating the detection, manipulation and exploration of objects, via an array of low‐threshold mechanoreceptors and fast conducting A‐beta (Aβ) afferents. However, a class of unmyelinated, low‐threshold mechanoreceptors identified in the hairy skin of mammals have been proposed to constitute a second, anatomically distinct system coding the affective qualities of touch. Unlike Aβs, which increase their firing rate linearly with the velocity of a stimulus moving across their receptive field, the response of these C‐tactile afferents (CTs) is described by an inverted ‘U’ curve fit, responding optimally to a skin temperature stimulus moving at between 1 and 10 cm/s. Given the distinct velocity tuning of these fast and slow touch fibres, here we used event‐related potentials to compare the time course of neural responses to 1st (fast) and 2nd (slow) touch systems. We identified a higher amplitude P300 in response to fast, Aβ‐targeted, versus slow CT‐targeted, stroking touch. In contrast, we identified a previously described, C‐fibre specific, ultra‐late potential (ULP) associated with CT‐targeted input. Of special note as regards the function of CTs is that the amplitude of the ULP was negatively correlated with self‐reported levels of autistic traits, which is consistent with the hypothesized affective and social significance of this response. Taken together, these findings provide further support for distinct discriminative and affective touch systems and suggests the temporal resolution of EEG provides an as yet underutilized tool for exploring individual differences in response sensitivity to CT‐targeted touch.

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Section: Introductionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 72%

Autistic traits modulate cortical responses to affective but not discriminative touch

Haggarty

Malinowski

McGlone

et al. 2020

Eur J of Neuroscience

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“…In comparison, there is no clinical test for tactile pleasantness; however, this may give a functional insight into the workings of the CT and C-fiber systems. A feasible way of testing the cortical signature of CT fiber function was proposed using controlled stroking with combined electroencephalography (Ackerley et al, 2012b), where an ultra-slow, late cortical potential was seen over more frontal areas.…”

Section: Introductionmentioning

confidence: 99%

Touch perceptions across skin sites: differences between sensitivity, direction discrimination and pleasantness

Ackerley¹,

Carlsson²,

Wester³

et al. 2014

Front. Behav. Neurosci.

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186

159

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Human skin is innervated with different tactile afferents, which are found at varying densities over the body. We investigate how the relationships between tactile pleasantness, sensitivity and discrimination differ across the skin. Tactile pleasantness was assessed by stroking a soft brush over the skin, using five velocities (0.3, 1, 3, 10, 30 cm s−1), known to differentiate hedonic touch, and pleasantness ratings were gained. The ratings velocity-profile is known to correlate with firing in unmyelinated C-tactile (CT) afferents. Tactile sensitivity thresholds were determined using monofilament force detection and the tactile discrimination level was obtained in the direction discrimination of a moving probe; both tasks readily activate myelinated touch receptors. Perceptions were measured over five skin sites: forehead, arm, palm, thigh and shin. The assessment of tactile pleasantness over the skin resulted in a preference for the middle velocities (1–10 cm s−1), where higher ratings were gained compared to the slowest and fastest velocities. This preference in tactile pleasantness was found across all the skin sites, apart from at the palm, where no decrease in pleasantness for the faster stroking velocities was seen. We find that tactile sensitivity and discrimination vary across the skin, where the forehead and palm show increased acuity. Tactile sensitivity and discrimination levels also correlated significantly, although the tactile acuity did not relate to the perceived pleasantness of touch. Tactile pleasantness varied in a subtle way across skin sites, where the middle velocities were always rated as the most pleasant, but the ratings at hairy skin sites were more receptive to changes in stroking velocity. We postulate that although the mechanoreceptive afferent physiology may be different over the skin, the perception of pleasant touch can be interpreted using all of the available incoming somatosensory information in combination with central processing.

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“…what, when and where. CT afferents convey gentle touch; however, there is a delay of 41.5 s before the touch information is processed in the brain, due to the slow conduction along the unmyelinated axon (Ackerley et al, 2013). These afferents are hypothesised to signal hedonic information about touch such as pleasantness, which is less useful for precise sensorimotor integration, although likely plays a role in the control and motivation of behaviour, such as driving the need to seek pleasurable, interactive social touch .…”

Section: From the Periphery To The Brainstemmentioning

confidence: 99%

The role of tactile afference in shaping motor behaviour and implications for prosthetic innovation

Ackerley

Kavounoudias

2015

Neuropsychologia

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The present review focusses on how tactile somatosensory afference is encoded and processed, and how this information is interpreted and acted upon in terms of motor control. We relate the fundamental workings of the sensorimotor system to the rehabilitation of amputees using modern prosthetic interventions. Our sense of touch is central to our everyday lives, from allowing us to manipulate objects accurately to giving us a sense of self-embodiment. There are a variety of specialised cutaneous mechanoreceptive afferents, which differ in terms of type and density according to the skin site. In humans, there is a dense innervation of our hands, which is reflected in their vast over-representation in somatosensory and motor cortical areas. We review the accumulated evidence from animal and human studies about the precise interplay between the somatosensory and motor systems, which is highly integrated in many brain areas and often not separable. The glabrous hand skin provides exquisite, discriminative detail about touch, which is useful for refining movements. When these signals are disrupted, such as through injury or amputation, the consequences are considerable. The development of sensory feedback in prosthetics offers a promising avenue for the full integration of a missing body part. Real-time touch feedback from motor intentions aids in grip control and the ability to distinguish different surfaces, even introducing the possibility of pleasure in artificial touch. Thus, our knowledge from fundamental research into sensorimotor interactions should be used to develop more realistic and integrative prostheses.

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Ultra-late EEG potential evoked by preferential activation of unmyelinated tactile afferents in human hairy skin

Cited by 45 publications

References 118 publications

Autistic traits modulate cortical responses to affective but not discriminative touch

Autistic traits modulate cortical responses to affective but not discriminative touch

Touch perceptions across skin sites: differences between sensitivity, direction discrimination and pleasantness

The role of tactile afference in shaping motor behaviour and implications for prosthetic innovation

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