Laminar Representations of Vibrotactile Stimuli with Varying Frequency in S1: a 7T fMRI Study

Poster No:

2565 

Submission Type:

Abstract Submission 

Authors:

Ji-Hyun Kim1, Sohyun Han2, Seulgi Eun2, Junsuk Kim3, Sung-Phil Kim4

Institutions:

1Ulsan National Institute and Technology, Ulsan, AS, 2Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon, AK, 3Dong-Eui University, Busan, AK, 4Ulsan National Institute of Science and Technology, Ulsan, AK

First Author:

Ji-Hyun Kim  
Ulsan National Institute and Technology
Ulsan, AS

Co-Author(s):

Sohyun Han  
Center for Neuroscience Imaging Research, Institute for Basic Science (IBS)
Suwon, AK
Seulgi Eun  
Center for Neuroscience Imaging Research, Institute for Basic Science (IBS)
Suwon, AK
Junsuk Kim  
Dong-Eui University
Busan, AK
Sung-Phil Kim  
Ulsan National Institute of Science and Technology
Ulsan, AK

Introduction:

Slow adapting receptors (SA) respond to light touch and flutter and rapid adapting receptors (RA) sense high-frequency vibration [1]. Early animal studies showed that tactile sensations from SA and RA elicit different activation patterns within a laminar structure in primary somatosensory cortex (S1) [2][3]. In contrast, little is known about receptor-specific layer organization in the human S1. A recent study has revealed layer-specific activation in the human S1 using high-, and low-frequency tactile stimuli [4]. In line with this finding, the present study aims to uncover laminar activation patterns in response to various vibrotactile frequencies. To this end, we use high-resolution (0.7 mm) fMRI at 7T with a novel vibrating stimulation apparatus.

Methods:

Twenty healthy volunteers (12 male, 26.94 ± 3.2 years old) participated in this study. All neuroimaging measurements were performed on a 7T scanner (MAGNETOM Terra, Siemens Healthineers, Erlangen, Germany), equipped with a single channel transmitter and a 32-channel receiver head coil (NOVA Medical, Wilmington, MA). We used a multi-contrast VASO-BOLD sequence [5] with slices aligned to participants' central sulcus between motor and sensory cortices. The imaging parameters were set as follows: 0.7-mm isotropic resolution, in-plane reduction factor (Rin-plane¬) = 3, field of view (FOV) = 154 × 154 mm2, 12 slices, and TI1/TI2 = 67.14/2390.9 ms. Seven different frequency stimuli were used in the study (2~38 Hz, step size 6 Hz), which were created by piezoelectric devices equipped with 6-mm diameter electrodes (Dancerdesign, St. Helens, UK). In the experiment, we conducted eight runs for each participant to obtain VASO images. In a run, each of the seven vibrotactile stimuli were randomly presented twice, constituting fourteen task trials. Each trial consisted of a task block (10 s) followed by a rest block (20 s). Participants received a sustained vibrotactile stimulus passively during the task block. Vibrating stimuli were served on the left index fingertip. To localize the brain regions that specify participants' index finger, one of the task trials was used before the main experiment. The region of interest was set to tightly fit BA 3b in S1. Layer and columnar analyses were conducted by the software LAYNII (https://github.com/layerfMRI/LAYNII).

Results:

Results: We confirmed that the vibrating stimuli activated BA 3a and 2 in contralateral S1. Compared to BOLD, VASO showed a noticeable signal drop as it neared the CSF. Similar to the previous study [4], we could find a peak activation in layer 4 in VASO in response to stimuli under 20 Hz, but not in BOLD. Also, the profile of activations across cortical layers separated by each frequency showed a tendency that the activation of the layers closer to CSF gradually increased as the frequency increased. Specifically, the high-frequency stimuli (32 Hz and 38 Hz) did not elicit peak activations in layer 4.

Conclusions:

We explored the laminar activation patterns varying with vibrotactile frequency using the high-resolution fMRI at 7T with VASO-BOLD sequence. We confirmed the previous study's result of peak activations in layer 4 during vibrotactile stimulation [4]. Moreover, we found that activation patterns across layers varied with frequency such that superficial layers were more activated than middle layers as frequency increased. Our results may suggest structural characteristics of S1 for vibrotactile frequency.

Modeling and Analysis Methods:

Activation (eg. BOLD task-fMRI)

Novel Imaging Acquisition Methods:

BOLD fMRI
Non-BOLD fMRI 2

Perception, Attention and Motor Behavior:

Perception: Tactile/Somatosensory 1

Keywords:

Cortical Columns
Cortical Layers
Data analysis
MRI
NORMAL HUMAN
Perception
Somatosensory
Touch

1|2Indicates the priority used for review

My abstract is being submitted as a Software Demonstration.

No

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 any human subjects research approved by the relevant Institutional Review Board or ethics panel? NOTE: Any human subjects studies without IRB approval will be automatically rejected.

Yes

Was any animal research approved by the relevant IACUC or other animal research panel? NOTE: Any animal studies without IACUC approval will be automatically rejected.

Not applicable

Please indicate which methods were used in your research:

Functional MRI

For human MRI, what field strength scanner do you use?

7T

Which processing packages did you use for your study?

AFNI
SPM
FSL
Other, Please list  -   LAYNII(https://github.com/layerfMRI/LAYNII)

Provide references using author date format

1. Conor C. E. (1990), 'Tactile roughness: neural codes that account for psychophysical magnitude estimates', Journal of Neuroscience, vol. 10, no. 12, pp. 3823-3826
2. Mountcastle V. B. (1957), 'Modality and topographic properties of single neurons of cat’s somatic sensory cortex', Journal of Neurophysiology, vol. 20, no. 4, pp. 408-434
3. Sur M. (1981), 'Modular segregation of functional cell classes within the postcentral somatosensory cortex of monkeys', Science, vol. 212, no. 4498, pp. 1059-1061
4. Yang J. (2019), 'High-resolution fMRI maps of columnar organization in human primary somatosensory cortex', Paper presented at: 27th Annual Meeting of ISMRM; May, 2019; Montreal, Canada. Abstract 617
5. Lu H. (2003), 'Functional magnetic resonance imaging based on changes in vascular space occupancy', Magnetic Resonance in Medicine, vol. 50, no. 2, pp. 263-274