1. Neuroscience
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Tactile sensory channels over-ruled by frequency decoding system that utilizes spike pattern regardless of receptor type

  1. Ingvars Birznieks  Is a corresponding author
  2. Sarah McIntyre
  3. Hanna Maria Nilsson
  4. Saad S Nagi
  5. Vaughan G Macefield
  6. David A Mahns
  7. Richard M Vickery
  1. Faculty of Medicine, UNSW Sydney, Australia
  2. Neuroscience Research Australia, Australia
  3. Western Sydney University, Australia
  4. Linköping University, Sweden
  5. School of Medicine, Western Sydney University, Australia
  6. The Baker Heart and Diabetes Institute, Australia
Research Article
Cite this article as: eLife 2019;8:e46510 doi: 10.7554/eLife.46510
5 figures, 1 table and 1 additional file

Figures

Detection thresholds.

(A) Vibrotactile detection thresholds on the finger across frequency ranges for sinusoidal and pulsatile stimuli (n = 12). Shaded area represent ± 95% confidence intervals. (B) An example of the sinusoidal and pulsatile waveforms.

https://doi.org/10.7554/eLife.46510.002
Figure 2 with 1 supplement
Point of subjective equality (PSE) obtained using two interval forced choice paradigm.

The test stimulus was either sinusoidal or pulsatile presented at 20 Hz and 40 Hz. The test stimulus was compared with a range of comparison frequencies: 10, 14, 18, 22, 26, 30 Hz with 20 Hz test stimulus; and 25, 31, 37, 43, 49, 55 Hz with 40 Hz test stimulus. Black horizontal lines represent mean ± 95% confidence intervals (n = 12).

https://doi.org/10.7554/eLife.46510.004
Figure 2—source data 1

PSE values for individual subjects.

https://doi.org/10.7554/eLife.46510.006
Figure 2—figure supplement 1
Insensitivity of frequency rating to changes in stimulus amplitude.

Results are shown for five subjects (n = 5), who conducted the same experimental protocol illustrated in Figures 2 and 3 at 40 Hz, but with two different amplitudes (randomly interleaved) for the comparison frequencies. For the sinusoidal comparisons, the standard was 60 µm, and the comparisons were 40 µm (sine low) and 90 µm (sine high). For the pulsatile comparisons, the standard was 6 µm, and the comparisons were 3 µm (pulse low) and 10 µm (pulse high). Mean values for PSE and Weber fraction for each condition with 95% CI were:

40 Hz comparisonsPSEWeber Fraction
sine low38.8 (37.1 - 40.5) Hz0.15 (0.11 - 0.19)
sine high42.8 (38.5 – 47.0) Hz0.14 (0.10 - 0.19)
pulse low40.3 (38.5 - 42.2) Hz0.17 (0.11 - 0.24)
pulse high39.0 (37.7 - 40.3) Hz0.15 (0.09 - 0.21)
https://doi.org/10.7554/eLife.46510.005
The Weber's fraction of just noticeable difference in frequency.

For details refer to legend of Figure 2.

https://doi.org/10.7554/eLife.46510.008
Experimental protocols.

(A) Structure of the detection threshold task. (B) Structure of the frequency perception task. (C) Point of subjective equality (PSE) determined on the psychometric curve.

https://doi.org/10.7554/eLife.46510.010
Afferent responses with 20 Hz stimuli.

(A) FAII afferent response to pulsatile stimuli 3 µm in amplitude. (B) FAI afferent response to sinusoidal stimuli 150 µm in amplitude. (C–D) The same FAI afferent as in B, response to pulsatile stimuli at various amplitudes: no response with 25 µm (subthreshold) stimulus; sporadic firing at 30 µm; and entrainment at 35 µm. Note that firing pattern in A, B and E is identical regardless of stimulus or afferent type.

https://doi.org/10.7554/eLife.46510.011

Tables

Table 1
Amplitudes and frequencies used in each experimental condition.
https://doi.org/10.7554/eLife.46510.007
ConditionTest stimulusComparison stimulusComparison frequencies
PP20 Hz, Pulsatile, 3 µm
40 Hz, Pulsatile, 3 µm
Pulsatile, 3 µm
Pulsatile, 3 µm
10, 14, 18, 22, 26, 30 Hz
25, 31, 37, 43, 49, 55 Hz
SS20 Hz, Sinusoidal, 150 µm
40 Hz, Sinusoidal, 40 µm
Sinusoidal, 150 µm
Sinusoidal, 40 µm
10, 14, 18, 22, 26, 30 Hz
25, 31, 37, 43, 49, 55 Hz
SP20 Hz, Sinusoidal, 150 µm
40 Hz, Sinusoidal, 40 µm
Pulsatile, 3 µm
Pulsatile, 3 µm
10, 14, 18, 22, 26, 30 Hz
25, 31, 37, 43, 49, 55 Hz

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