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Adaptation of cortical activity to sustained pressure stimulation on the fingertip.

Chung YG, Han SW, Kim HS, Chung SC, Park JY, Wallraven C, Kim SP - BMC Neurosci (2015)

Bottom Line: Along with these studies, we hypothesized that somatosensory cortical activity in the human brain also exponentially decreased during tactile adaptation.Our results revealed that the degrees of activation in the contralateral primary and secondary somatosensory cortices exponentially decreased over time and that intra- and inter-hemispheric inter-regional functional connectivity over the regions associated with tactile perception also linearly decreased or increased over time, during pressure stimulation.These results indicate that cortical activity dynamically adapts to sustained pressure stimulation mediated by SA-I afferents, involving changes in the degrees of activation on the cortical regions for tactile perception as well as in inter-regional functional connectivity among them.

View Article: PubMed Central - PubMed

Affiliation: Department of Brain and Cognitive Engineering, Korea University, Anam-5ga, Seongbuk-gu, Seoul, 136-713, Republic of Korea. uskeywest@korea.ac.kr.

ABSTRACT

Background: Tactile adaptation is a phenomenon of the sensory system that results in temporal desensitization after an exposure to sustained or repetitive tactile stimuli. Previous studies reported psychophysical and physiological adaptation where perceived intensity and mechanoreceptive afferent signals exponentially decreased during tactile adaptation. Along with these studies, we hypothesized that somatosensory cortical activity in the human brain also exponentially decreased during tactile adaptation. The present neuroimaging study specifically investigated temporal changes in the human cortical responses to sustained pressure stimuli mediated by slow-adapting type I afferents.

Methods: We applied pressure stimulation for up to 15 s to the right index fingertip in 21 healthy participants and acquired functional magnetic resonance imaging (fMRI) data using a 3T MRI system. We analyzed cortical responses in terms of the degrees of cortical activation and inter-regional connectivity during sustained pressure stimulation.

Results: Our results revealed that the degrees of activation in the contralateral primary and secondary somatosensory cortices exponentially decreased over time and that intra- and inter-hemispheric inter-regional functional connectivity over the regions associated with tactile perception also linearly decreased or increased over time, during pressure stimulation.

Conclusion: These results indicate that cortical activity dynamically adapts to sustained pressure stimulation mediated by SA-I afferents, involving changes in the degrees of activation on the cortical regions for tactile perception as well as in inter-regional functional connectivity among them. We speculate that these adaptive cortical activity may represent an efficient cortical processing of tactile information.

No MeSH data available.


Related in: MedlinePlus

Linear decreases in inter-regional functional connectivity during pressure stimulation. The correlation coefficients (y-axis) in the inter-hemispheric (cBA3-iBA40 with p < 0.01 and iBA40-cBA13 with p < 0.001), ipsilateral (iBA40-iBA13 with p < 0.05 and iBA40-iBA5 with p < 0.05), and local cSI (cBA1-cBA2 with p < 0.01) connections significantly decreased during 15 s pressure stimulation. The correlation coefficients in one of the contralateral connections (cBA3-cBA5 with p < 0.05) significantly increased during 15 s pressure stimulation (linear regression analysis between the correlation coefficients and stimulus duration). Other thirty connections showed no significant change over time
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Fig4: Linear decreases in inter-regional functional connectivity during pressure stimulation. The correlation coefficients (y-axis) in the inter-hemispheric (cBA3-iBA40 with p < 0.01 and iBA40-cBA13 with p < 0.001), ipsilateral (iBA40-iBA13 with p < 0.05 and iBA40-iBA5 with p < 0.05), and local cSI (cBA1-cBA2 with p < 0.01) connections significantly decreased during 15 s pressure stimulation. The correlation coefficients in one of the contralateral connections (cBA3-cBA5 with p < 0.05) significantly increased during 15 s pressure stimulation (linear regression analysis between the correlation coefficients and stimulus duration). Other thirty connections showed no significant change over time

Mentions: The functional connectivity analysis revealed that Fisher-transformed correlation coefficients of the five connections, including cBA3-iBA40, cBA1-cBA2, iBA40-cBA13, iBA40-iBA13, and iBA40-iBA5, linearly decreased with time during 15 s pressure stimulation. Remarkably, it also revealed that the correlation coefficient in one connection of cBA3-cBA5 linearly increased with time (Fig. 4). The rates of decrease in the correlation coefficients were −0.008 s−1 in cBA3-iBA40 (r2 = 0.95, p < 0.01), −0.009 s−1 in cBA1-cBA2 (r2 = 0.94, p < 0.01), −0.003 s−1 in iBA40-cBA13 (r2 = 0.98, p < 0.001), −0.009 s−1 in iBA40-iBA13 (r2 = 0.87, p < 0.05), and −0.003 s−1 in iBA40-iBA5 (r2 = 0.84, p < 0.05). The rate of increase in the correlation coefficient was 0.003 s−1 in cBA3-cBA5 (r2 = 0.81, p < 0.05). The other thirty connections showed no significant change in the correlation coefficient over time.Fig. 4


Adaptation of cortical activity to sustained pressure stimulation on the fingertip.

Chung YG, Han SW, Kim HS, Chung SC, Park JY, Wallraven C, Kim SP - BMC Neurosci (2015)

Linear decreases in inter-regional functional connectivity during pressure stimulation. The correlation coefficients (y-axis) in the inter-hemispheric (cBA3-iBA40 with p < 0.01 and iBA40-cBA13 with p < 0.001), ipsilateral (iBA40-iBA13 with p < 0.05 and iBA40-iBA5 with p < 0.05), and local cSI (cBA1-cBA2 with p < 0.01) connections significantly decreased during 15 s pressure stimulation. The correlation coefficients in one of the contralateral connections (cBA3-cBA5 with p < 0.05) significantly increased during 15 s pressure stimulation (linear regression analysis between the correlation coefficients and stimulus duration). Other thirty connections showed no significant change over time
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4625848&req=5

Fig4: Linear decreases in inter-regional functional connectivity during pressure stimulation. The correlation coefficients (y-axis) in the inter-hemispheric (cBA3-iBA40 with p < 0.01 and iBA40-cBA13 with p < 0.001), ipsilateral (iBA40-iBA13 with p < 0.05 and iBA40-iBA5 with p < 0.05), and local cSI (cBA1-cBA2 with p < 0.01) connections significantly decreased during 15 s pressure stimulation. The correlation coefficients in one of the contralateral connections (cBA3-cBA5 with p < 0.05) significantly increased during 15 s pressure stimulation (linear regression analysis between the correlation coefficients and stimulus duration). Other thirty connections showed no significant change over time
Mentions: The functional connectivity analysis revealed that Fisher-transformed correlation coefficients of the five connections, including cBA3-iBA40, cBA1-cBA2, iBA40-cBA13, iBA40-iBA13, and iBA40-iBA5, linearly decreased with time during 15 s pressure stimulation. Remarkably, it also revealed that the correlation coefficient in one connection of cBA3-cBA5 linearly increased with time (Fig. 4). The rates of decrease in the correlation coefficients were −0.008 s−1 in cBA3-iBA40 (r2 = 0.95, p < 0.01), −0.009 s−1 in cBA1-cBA2 (r2 = 0.94, p < 0.01), −0.003 s−1 in iBA40-cBA13 (r2 = 0.98, p < 0.001), −0.009 s−1 in iBA40-iBA13 (r2 = 0.87, p < 0.05), and −0.003 s−1 in iBA40-iBA5 (r2 = 0.84, p < 0.05). The rate of increase in the correlation coefficient was 0.003 s−1 in cBA3-cBA5 (r2 = 0.81, p < 0.05). The other thirty connections showed no significant change in the correlation coefficient over time.Fig. 4

Bottom Line: Along with these studies, we hypothesized that somatosensory cortical activity in the human brain also exponentially decreased during tactile adaptation.Our results revealed that the degrees of activation in the contralateral primary and secondary somatosensory cortices exponentially decreased over time and that intra- and inter-hemispheric inter-regional functional connectivity over the regions associated with tactile perception also linearly decreased or increased over time, during pressure stimulation.These results indicate that cortical activity dynamically adapts to sustained pressure stimulation mediated by SA-I afferents, involving changes in the degrees of activation on the cortical regions for tactile perception as well as in inter-regional functional connectivity among them.

View Article: PubMed Central - PubMed

Affiliation: Department of Brain and Cognitive Engineering, Korea University, Anam-5ga, Seongbuk-gu, Seoul, 136-713, Republic of Korea. uskeywest@korea.ac.kr.

ABSTRACT

Background: Tactile adaptation is a phenomenon of the sensory system that results in temporal desensitization after an exposure to sustained or repetitive tactile stimuli. Previous studies reported psychophysical and physiological adaptation where perceived intensity and mechanoreceptive afferent signals exponentially decreased during tactile adaptation. Along with these studies, we hypothesized that somatosensory cortical activity in the human brain also exponentially decreased during tactile adaptation. The present neuroimaging study specifically investigated temporal changes in the human cortical responses to sustained pressure stimuli mediated by slow-adapting type I afferents.

Methods: We applied pressure stimulation for up to 15 s to the right index fingertip in 21 healthy participants and acquired functional magnetic resonance imaging (fMRI) data using a 3T MRI system. We analyzed cortical responses in terms of the degrees of cortical activation and inter-regional connectivity during sustained pressure stimulation.

Results: Our results revealed that the degrees of activation in the contralateral primary and secondary somatosensory cortices exponentially decreased over time and that intra- and inter-hemispheric inter-regional functional connectivity over the regions associated with tactile perception also linearly decreased or increased over time, during pressure stimulation.

Conclusion: These results indicate that cortical activity dynamically adapts to sustained pressure stimulation mediated by SA-I afferents, involving changes in the degrees of activation on the cortical regions for tactile perception as well as in inter-regional functional connectivity among them. We speculate that these adaptive cortical activity may represent an efficient cortical processing of tactile information.

No MeSH data available.


Related in: MedlinePlus