Mapping quantal touch using 7 Tesla functional magnetic resonance imaging and single-unit intraneural microstimulation
- University of Nottingham, United Kingdom
- University of Gothenburg, Sweden
- Aix-Marseille University, France
- Liverpool John Moores University, United Kingdom
Figures
Figure 1
Physiological recordings from mechanoreceptive afferents and the location of afferents that were microstimulated during 7T fMRI.
Example microneurography recording (top) along with the instantaneous firing frequency (bottom) for (a) an FA1 afferent (U1; see Table 1) and (b) an SA1 afferent collected inside the 7T MR scanner …
Figure 2
Spatial localization of INMS-induced versus vibrotactile-induced responses in contralateral S1.
Activation maps related to stimulation of two different afferents in Participant 4 are rendered onto a flattened cortical patch spanning the central sulcus of the right (left of figure) and left …
Figure 3 with 1 supplement
Spread of activation across the digit ROIs identified from the somatotopy.
(a) Statistical maps (Z > 3.08, FDR-adjusted) from INMS of seven single units in participants 2, 3 and 4. In each case the activation map is rendered onto a flattened cortical patch spanning the …
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Figure 3—source data 1
Source files for plots of Z-score and Proportion of active voxels in each Digit ROI.
This matlab file contains variables for each individual unit (U4, U5, U6, U8, U9, U11) with fields ‘micro_stats’ and ‘vibro_stats’ containing a structure with the results for single unit INMS and vibrotactile stimulation of the unit’s receptive field, respectively. Each structure has the following fields: ‘zetaMean’, ‘betaSem’: (5 digits x 1)-vector containing mean Z-score (FDR-corrected) and standard error across voxels for each Digit ROI; ‘PropActVox’: (5 digits x 1)-vector containing proportion of active voxels (Z>3.08, FDR-corrected) in each Digit ROI; and ‘betaMean’, ‘betaSem’: (5 digits x 1)-vector containing mean GLM parameter estimate and standard error across voxels for each Digit ROI. GLM parameter estimates are not plot in Figure 3 but are used for subsequent group analysis.
- https://doi.org/10.7554/eLife.12812.007
Figure 3—figure supplement 1
Comparison of contralateral S1 responses to different paradigms for Participant 1.
Statistical maps overlaid on a high resolution T2*-weighted structural image. (a) Digit somatotopic maps obtained with the traveling-wave paradigm for both hands, showing the location of the maps in …
Figure 4
Group analysis (N = 7 units) of the BOLD response to INMS and vibrotactile stimulation of the unit’s receptive field, showing the stimulated digit compared to the neighboring digits.
(a) Z-scores (FDR-corrected) of INMS response in digit ROIs (defined from digit somatotopy) averaged across ROIs for the stimulated digit (N = 7) compared to neighboring digits (1st degree …
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Figure 4—source data 1
Source files for ANOVA tests.
This matlab file contains the 2D-matrices (11 x 5), related to each panel in Figure 4, that were used for the 1-way analysis of variance (performed using the ‘anova1’ matlab command). Each matrix row contains data for each of the 7 units (there are up to eleven 1st degree neighboring digit ROIs) and each matrix columns represents the ‘proximity’ to the stimulated digit ROI (stimulated digit ROI, 1st degree, 2nd degree, 3rd degree and 4th degree neighboring digit ROIs). ‘Zeta_micro’ and ‘Zeta_vibro’ are the matrices containing the Z-score (FDR-corrected) values, ‘PerVox_micro’ and ‘PerVox_vibro’ contain the proportion of active voxels (Z>3.08, FDR-corrected) and’ Beta_micro’ and ‘Beta_vibro’ contain the GLM parameter estimates for INMS and vibrotactile stimulation respectively. ANOVA results show a significant difference in mean Z-score (F4,30=14.08, p<10-5; F4,30=12.97, p<10-5), proportion of active voxels (F4,30=16.12, p<10-6; F4,30=17.64, p<10-6) and GLM parameter estimates (F4,30=13.52, p<10-5; F4,30=14.1, p<10-5) across the stimulated and neighboring digit classification (INMS; vibrotactile).
- https://doi.org/10.7554/eLife.12812.010
Figure 5
fMRI activation patterns and time courses in cortical areas.
(a) Cortical activation patterns in MNI space. Transverse slices and surface reconstructions showing areas of activation in response to INMS (red clusters) and mechanical vibrotactile stimulation …
Figure 6
Figure of the experimental setup.
The PowerLab, NeuroAmp EX and ML180 stimulator were placed just inside the magnet room at a field strength not exceeding 5 mT. Placement of the interface equipment within the magnet room was …
Tables
Table 1
Mechanoreceptive afferent units in which INMS was performed during 7T fMRI. The table details the unit type and location, as well as the frequency and perception of applied INMS. All units were …
| Participant | Unit | Type | Location | Physiology | Sensation | Frequency |
|---|---|---|---|---|---|---|
| 1 | 1 | FA1 | Palm | Yes | Buzzing | 30 Hz |
| 2 | 2 | FA1 | Base of digit 1 | Yes | Small dots | 60 Hz |
| 3 | SA1 | Middle of digit 1 | Yes | Pulling | 30 Hz | |
| 4 | SA1 | Base of digit 1 | Yes | Pulling | 30 Hz 60 Hz | |
| 5 | FA1 | Middle of digit 1 | Yes | Vibration | 60 Hz | |
| 6 | FA1 | Digit 3 fingertip | No | Tapping, vibration | 30 Hz 60 Hz 90 Hz | |
| 3 | 7 | FA1 | Base of digit 3 | Yes | Small, round point of tingle sensation | 30 Hz |
| 8 | FA1 | Digit 3 fingertip | No | Small, round point of tingle sensation | 30 Hz 60 Hz 90 Hz | |
| 4 | 9 | FA1 | Middle of digit 1 (right hand) | No | Prickle, flutter | 30 Hz |
| 10 | Undefined | Digit 4 fingertip | No | Small line* | 30 Hz | |
| 11 | FA1 | Middle of digit 4 | No | Flutter | 30 Hz |
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*A small line sensation is indicative of the simultaneous stimulation of two afferents that are in close proximity.
Table 2
Cortical areas showing significant activation to INMS of single mechanoreceptive afferents and the corresponding vibrotactile stimulation. Results show the mean and standard error across the five …
| Single unit INMS | Vibrotactile stimulation | |||||||
|---|---|---|---|---|---|---|---|---|
| ROI | No. Units | x, y, z MNI co-ordinates | Beta | Z | Voxels | Beta | Z | Voxels |
| SI R SI L | 4 3 | 54, -12, 46 -52, -12, 44 | 1.4 ± 0.2 1.2 ± 0.2 | 5.9 ± 0.5 5.6 ± 0.8 | 38 ± 7 20 ± 9 | 1.3 ± 0.3 1.6 ± 0.3 | 5.4 ± 0.3 5.2 ± 0.2 | 41 ± 12 19 ± 1 |
| BA 40 R BA 40 L | 5 4 | 60, -22, 16 -60, -22, 16 | 1.4 ± 0.2 1.5 ± 0.4 | 4.9 ± 0.2 5.3 ± 0.2 | 56 ± 5 73 ± 5 | 1.4 ± 0.1 1.4 ± 0.2 | 4.8 ± 0.2 5.0 ± 0.1 | 54 ± 7 72 ± 12 |
| BA 43 R BA 43 L | 2 3 | 60, -4, 10 -58, -12, 14 | 1.1 ± 0.4 1.0 ± 0.4 | 5.4 ± 0.1 4.8 ± 0.3 | 45 ± 6 33 ± 8 | 1.2 ± 0.4 1.7 ± 0.3 | 4.4 ± 0.2 4.2 ± 0.2 | 30 ± 20 26 ± 11 |
| SMA R SMA L | 5 5 | 4, 0, 60 -2, 0, 60 | 1.2 ± 0.2 1.2 ± 0.2 | 4.8 ± 0.3 4.5 ± 0.3 | 93 ± 27 66 ± 19 | 1.3 ± 0.2 1.2 ± 0.1 | 4.8 ± 0.2 4.5 ± 0.3 | 43 ± 21 29 ± 6 |
| PMC R PMC L | 4 5 | 54, 0, 50 -52, -2, 50 | 0.8 ± 0.2 1.1 ± 0.1 | 4.7 ± 0.2 5.5 ± 0.3 | 36 ± 11 37 ± 7 | 1.1 ± 0.2 1.2 ± 0.1 | 5.0 ± 0.2 4.3 ± 0.1 | 46 ± 9 20 ± 8 |
| M1 R M1 L | 3 2 | 54, -6, 48 -52, -6, 48 | 0.9 ± 0.2 1.5 ± 0.2 | 5.2 ± 0.5 6.3 ± 0.1 | 51 ± 20 66 ± 36 | 0.8 ± 0.2 1.3 ± 0.1 | 5.0 ± 0.7 5.3 ± 0.5 | 31 ± 10 21 ± 3 |
| PIC R PIC L | 5 5 | 46, -2, 10 -42, -2, 10 | 0.8 ± 0.2 0.8 ± 0.1 | 4.2 ± 0.2 4.4 ± 0.2 | 45 ± 12 38 ± 14 | 0.8 ± 0.2 - | 4.7 ± 0.2 - | 27 ± 3 - |
| AIC R AIC L | 4 4 | 34, 26, 4 -32, 26, 4 | 1.2 ± 0.1 1.1 ± 0.1 | 4.7 ± 0.2 4.4 ± 0.2 | 146 ± 20 106 ± 21 | - - | - - | - - |
| PPC R PPC L | 4 5 | 38, -48, 50 -38, -48, 56 | 1.2 ± 0.1 1.0 ± 0.1 | 4.4 ± 0.3 4.4 ± 0.3 | 168 ± 44 172 ± 43 | - - | - - | - - |
| PFC R | 4 | 42, 34,18 | 1.2 ± 0.2 | 4.5 ± 0.3 | 78 ± 22 | - | - | - |
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Table 2—source data 1
Source files for single unit INMS.
This matlab file contains 2D-matrices (19x5) with the results for single unit INMS for each of the 5 individual units (U1, U4, U6, U8, U11) in each of the 19 ROIs. 'BetaValues’ contains mean across voxels of the beta values, ‘Z-score’ contains the mean Z_score (FDR- corrected) across voxels and ‘NumberVoxels’ contains the number of significant active voxels (Z > 3.08, FDR-corrected) in the ROI. Table 2 summarizes the results by showing the mean and standard error across the 5 units.
- https://doi.org/10.7554/eLife.12812.013
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Table 2—source data 2
Source files for vibrotactile stimulation.
This matlab file contains 2D-matrices (19 ROIs x 5 units) with the results for vibrotactile stimulation applied to the receptive field for each of the 5 individual units (U1, U4, U6, U8, U11) in each ROI. ‘BetaValues ‘contains mean across voxels of the beta values, ‘Z_score’ contains the mean Z-score (FDR- corrected) across voxels and ‘NumberVoxels’ contains the number of significant active voxels (Z > 3.08, FDR-corrected) in the ROI. Table 2 summarizes the results by showing the mean and standard error across the 5 units.
- https://doi.org/10.7554/eLife.12812.014
