Stimulus-Rate Sensitivity Discerns Area 3b of the Human Primary Somatosensory Cortex

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© 2015 Public Library of Science (PLoS). This is the accepted version of the following article: Hlushchuk, Yevhen & Simões-Franklin, Cristina & Nangini, Cathy & Hari, Riitta. 2015. Stimulus-Rate Sensitivity Discerns Area 3b of the Human Primary Somatosensory Cortex. PLOS ONE. Volume 10, Issue 5. 1-10. ISSN 1932-6203 (printed). DOI: 10.1371/journal.pone.0128462, which has been published in final form at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0128462.
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Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2015

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Mcode

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Language

en

Pages

1-10

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PLOS ONE, Volume 10, Issue 5

Abstract

Previous studies have shown that the hemodynamic response of the primary somatosensory cortex (SI) to electrical median nerve stimulation doubles in strength when the stimulus rate (SR) increases from 1 to 5 Hz. Here we investigated whether such sensitivity to SR is homogenous within the functionally different subareas of the SI cortex, and whether SR sensitivity would help discern area 3b among the other SI subareas. We acquired 3-tesla functional magnetic resonance imaging (fMRI) data from nine healthy adults who received pneumotactile stimuli in 25-s blocks to three right-hand fingers, either at 1, 4, or 10 Hz. The main contrast (all stimulations pooled vs. baseline), applied to the whole brain, first limited the search to the whole SI cortex. The conjunction of SR-sensitive contrasts [4 Hz − 1 Hz] > 0 and [10 Hz − 1 Hz] > 0 ([4Hz − 1Hz] + [10Hz − 1Hz] > 0), applied to the SI cluster, then revealed an anterior-ventral subcluster that reacted more strongly to both 10-Hz and 4-Hz stimuli than to the 1-Hz stimuli. No other SR-sensitive clusters were found at the group-level in the whole-brain analysis. The site of the SR-sensitive SI subcluster corresponds to the canonical position of area 3b; such differentiation was also possible at the individual level in 5 out of 9 subjects. Thus the SR sensitivity of the BOLD response appears to discern area 3b among other subareas of the human SI cortex.

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Keywords

primary somatosensory cortex, nerve stimulation, stimulus rate, fMRI

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Citation

Hlushchuk, Yevhen & Simões-Franklin, Cristina & Nangini, Cathy & Hari, Riitta. 2015. Stimulus-Rate Sensitivity Discerns Area 3b of the Human Primary Somatosensory Cortex. PLOS ONE. Volume 10, Issue 5. 1-10. ISSN 1932-6203 (printed). DOI: 10.1371/journal.pone.0128462.