Poster No:
2062
Submission Type:
Abstract Submission
Authors:
Renate Schweizer1, Laura Wirth1, Nikolas Makowka1, Melanie Bueckner1, Henrike Jungeblut1
Institutions:
1Functional Imaging Laboratory, German Primate Center, Goettingen, Germany
First Author:
Renate Schweizer
Functional Imaging Laboratory, German Primate Center
Goettingen, Germany
Co-Author(s):
Laura Wirth
Functional Imaging Laboratory, German Primate Center
Goettingen, Germany
Nikolas Makowka
Functional Imaging Laboratory, German Primate Center
Goettingen, Germany
Melanie Bueckner
Functional Imaging Laboratory, German Primate Center
Goettingen, Germany
Henrike Jungeblut
Functional Imaging Laboratory, German Primate Center
Goettingen, Germany
Introduction:
This functional MRI (fMRI) study investigated the blood-oxygen-level-dependent (BOLD) signal elicited by passive tactile stimulation at the hairy skin of the arm and the glabrous skin of the palm and fingers. The glabrous skin, optimized for discriminative touch, is characterized by a high density of specialized receptors, that project via Aβ fibers to the primary somatosensory cortex (S1). In contrast, the hairy skin contains a higher density of free nerve endings (Vallbo et al., 1999), which project via unmyelinated C-tactile fibers to the insular cortex (IC). These fibers can mediate positive affective perceptions through slow, soft stroking movement across hairy skin (McGlone et al., 2007; Olausson et al., 2010). During fMRI measurements a female experimenter applied C-tactile stimulation to the arm or the hand of female participants using various materials, which were rated trial-by-trial as either "pleasant" or "neutral". These behavioral ratings were analyzed to determine whether stimulation of hairy skin is generally perceived as more "pleasant" compared to glabrous skin and to investigate the BOLD responses associated with individual perceptions of "pleasant" or "neutral" tactile experiences at the arm or at the hand.
Methods:
A total of 11 women (aged 20-28) participated in a 3T MRI session, which included a T1-weighted structural and three T2*-weighted functional measurements with either unimodal tactile stimulation of the hand, arm or unimodal visual stimulation. Visual stimulation comprised of 12 selected images of the International Affective Picture System, equally split between positive and neutral valence. Tactile stimulation utilized 12 materials (e.g. various fabrics, fur, a brush, a wooden spoon, a sponge) six of which were estimated to elicit positive affective responses and six "neutral" response. These materials were manually applied by a female experimenter in slow proximal-to-distal strokes (velocity: 10 cm/sec) to the glabrous skin at the right palm and the fingers or the hairy skin of the dorsal surface of the lower right arm. During the 12 min fMRI measurements, participants completed 36 trials, with each of the 12 materials presented three times in pseudorandom order. Each trial consisted of 6 seconds of stimulation, followed by a 4 second interval during which participants rated the stimulation as "pleasant" or "neutral" performing a single button press with either the index or the middle finger of the left hand, and concluded with a 10 second rest period. General Linear Model (GLM)-based analysis was conducted incorporating individual ratings of each stimulus as predictors for "pleasant" and "neutral" responses associate with stimulation at the arm and hand.
Results:
Ratings during fMRI measurements revealed an average of 8% increase of "pleasant" ratings for stimulation of the hairy skin of the arm compared to identical stimulation of the hand. This effect varied across stimulus materials, with one material (jersey cloth) consistently rated as "neutral" when applied to the hand but as "pleasant" when applied to the arm, highlighting the positive affective effect of the C-tactile stimulation on the hairy skin of the arm. Tactile stimulation of the hand consistently resulted in positive BOLD activation in contralateral S1, whereas stimulation of the arm elicited negative BOLD responses in contralateral S1 in eight of the 11 participants. No differences were observed between the S1 activation evoked by "pleasant" or "neutral" perceived stimulation. In IC, BOLD activation exhibited very general response patterns, with no differentiation between skin types nor between the affective valences.
Conclusions:
Tactile stimulation at the arm resulted in increased "pleasant" ratings. The negative BOLD responses with arm stimulation in S1 and the unspecific positive BOLD responses in IC suggest the need for more specific analysis approaches.
Novel Imaging Acquisition Methods:
BOLD fMRI 2
Perception, Attention and Motor Behavior:
Perception: Tactile/Somatosensory 1
Keywords:
ADULTS
Cortex
Emotions
FUNCTIONAL MRI
Somatosensory
1|2Indicates the priority used for review
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Please indicate below if your study was a "resting state" or "task-activation” study.
Task-activation
Healthy subjects only or patients (note that patient studies may also involve healthy subjects):
Healthy subjects
Was this research conducted in the United States?
No
Were any human subjects research approved by the relevant Institutional Review Board or ethics panel?
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Yes
Were any animal research approved by the relevant IACUC or other animal research panel?
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Not applicable
Please indicate which methods were used in your research:
Functional MRI
Structural MRI
For human MRI, what field strength scanner do you use?
3.0T
Which processing packages did you use for your study?
FSL
Provide references using APA citation style.
McGlone, F., Vallbo, A. B., Olausson, H., Loken, L., & Wessberg, J. (2007). Discriminative touch and emotional touch. Canadian Journal of Experimental Psychology / Revue canadienne de psychologie expérimentale, 61(3), 173–183. https://doi.org/10.1037/cjep2007019
Olausson, H., Wessberg, J., Morrison, I., McGlone, F., & Vallbo, Å. (2010). The neurophysiology of unmyelinated tactile afferents. Neuroscience Biobehavioral Reviews, 34(2), 185–191. https://doi.org/10.1016/j.neubiorev.2008.09.011
Vallbo, A. B., Olausson, H., & Wessberg, J. (1999). Unmyelinated Afferents Constitute a Second System Coding Tactile Stimuli of the Human Hairy Skin. Journal of Neurophysiology, 81(6), 2753–2763. https://doi.org/10.1152/jn.1999.81.6.2753
No