Name: measurement of vibration detection threshold and tactile spatial acuity in human subjects
Uploaded: 2016-09-01T13:00:00
Description: Watch this Scientific Journal Video about Measurement of Vibration Detection Threshold and Tactile Spatial Acuity in Human Subjects at JoVE.com

The research and development leading to the above described vibration test was funded by the European Research Council (ERC, ADG 294678) and the German Research Council (grant, SFB665). Thanks go to the Max-Delbr&#252;ck-Center technical and support staff, Mr. R. Fischer, B. Neumann, and Mr. M. Pflaume, who provided invaluable assistance with the project.

The testing protocol was approved by the Charit&#233;-Universit&#228;tsmedizin Ethics Committee.
1. Vibration Detection Threshold (VDT)
<ol>
	<li>Device and Testing Protocol Assembly&#160;&#8211; Pretesting
	<ol>
		<li>Assemble the components of the device according to Figure 1A. Place a smooth-surfaced board (40 cm x 80 cm) on a table. Place the brass bar on the board.</li>
		<li>Connect the piezoelectric actuator (vibration stimulator) to the controller unit.</li>
		<li>Connect the response bo...

<ol>
	<li>Poole, K., Herget, R., Lapatsina, L., Ngo, H. D., Lewin, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+Piezo+ion+channels+to+detect+molecular-scale+movements+relevant+for+fine+touch.">Tuning Piezo ion channels to detect molecular-scale movements relevant for fine touch.</a> Nat Commun. 5, 3520 (2014).</li><li>Lechner, S. G., Lewin, G. 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H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Piezo2+is+required+for+Merkel-cell+mechanotransduction.">Piezo2 is required for Merkel-cell mechanotransduction.</a> Nature. 509 (7502), 622-626 (2014).</li><li>Ranade, S. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Piezo2+is+the+major+transducer+of+mechanical+forces+for+touch+sensation+in+mice.">Piezo2 is the major transducer of mechanical forces for touch sensation in mice.</a> Nature. 516 (7529), 121-125 (2014).</li><li>Wetzel, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+stomatin-domain+protein+essential+for+touch+sensation+in+the+mouse.">A stomatin-domain protein essential for touch sensation in the mouse.</a> Nature. 445 (7124), 206-209 (2007).</li><li>McMillin, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutations+in+PIEZO2+cause+Gordon+syndrome,+Marden-Walker+syndrome,+and+distal+arthrogryposis+type+5.">Mutations in PIEZO2 cause Gordon syndrome, Marden-Walker syndrome, and distal arthrogryposis type 5.</a> Am. J. Hum. Genet. 94 (5), 734-744 (2014).</li><li>Gandhi, M. S., Sesek, R., Tuckett, R., Bamberg, S. J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+in+vibrotactile+threshold+evaluation+techniques:+a+review.">Progress in vibrotactile threshold evaluation techniques: a review.</a> J Hand Ther. 24 (3), 240-255 (2011).</li><li>G&#252;&#231;l&#252;, B., Bolanowski, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vibrotactile+thresholds+of+the+Non-Pacinian+I+channel:+I.+Methodological+issues.">Vibrotactile thresholds of the Non-Pacinian I channel: I. Methodological issues.</a> Somatosens Mot Res. 22 (1-2), 49-56 (2005).</li><li>Lindsell, C. J., Griffin, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normative+vibrotactile+thresholds+measured+at+five+European+test+centres.">Normative vibrotactile thresholds measured at five European test centres.</a> Int Arch Occup Environ Health. 76 (7), 517-528 (2003).</li><li>Morioka, M., Griffin, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dependence+of+vibrotactile+thresholds+on+the+psychophysical+measurement+method.">Dependence of vibrotactile thresholds on the psychophysical measurement method.</a> Int Arch Occup Environ Health. 75 (1-2), 78-84 (2002).</li><li>Tannan, V., Dennis, R., Tommerdahl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+device+for+delivering+two-site+vibrotactile+stimuli+to+the+skin.">A novel device for delivering two-site vibrotactile stimuli to the skin.</a> J. Neurosci. Methods. 147 (2), 75-81 (2005).</li><li>Zwislocki, J. J., Relkin, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+a+psychophysical+transformed-rule+up+and+down+method+converging+on+a+75%+level+of+correct+responses.">On a psychophysical transformed-rule up and down method converging on a 75% level of correct responses.</a> Proc. Natl. Acad. Sci. U.S.A. 98 (8), 4811-4814 (2001).</li><li>Gescheider, G. A., Bolanowski, S. J., Pope, J. V., Verrillo, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+four-channel+analysis+of+the+tactile+sensitivity+of+the+fingertip:+frequency+selectivity,+spatial+summation,+and+temporal+summation.">A four-channel analysis of the tactile sensitivity of the fingertip: frequency selectivity, spatial summation, and temporal summation.</a> Somatosens Mot Res. 19 (2), 114-124 (2002).</li><li>Kuroki, S., Watanabe, J., Nishida, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+within-+and+cross-channel+information+to+vibrotactile+frequency+discrimination.">Contribution of within- and cross-channel information to vibrotactile frequency discrimination.</a> Brain Res. 1529, 46-55 (2013).</li><li>Levitt, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transformed+up-down+methods+in+psychoacoustics.">Transformed up-down methods in psychoacoustics.</a> J. Acoust. Soc. Am. 49 (2), (1971).</li><li>International Organization for Standardization. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+vibration-Vibrotactile+perception+thresholds+for+the+assessment+of+nerve+dysfunction-Part+1:+Methods+of+measurement+at+the+fingertips.">Mechanical vibration-Vibrotactile perception thresholds for the assessment of nerve dysfunction-Part 1: Methods of measurement at the fingertips.</a> ISO 13091-1. , (2001).</li><li>International Organization for Standardization. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+vibration-Vibrotactile+perception+thresholds+for+the+assessment+of+nerve+dysfunction-Part+2:+Analysis+and+interpretation+of+measurements+at+the+fingertips.">Mechanical vibration-Vibrotactile perception thresholds for the assessment of nerve dysfunction-Part 2: Analysis and interpretation of measurements at the fingertips.</a> ISO 13091-2. , (2003).</li><li>Holden, J. K., Nguyen, R. H., Francisco, E. M., Zhang, Z., Dennis, R. G., Tommerdahl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+device+for+the+study+of+somatosensory+information+processing.">A novel device for the study of somatosensory information processing.</a> J Neurosci Methods. 204 (2), 215-220 (2012).</li><li>G&#252;&#231;l&#252;, B., Oztek, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tactile+sensitivity+of+children:+effects+of+frequency,+masking,+and+the+non-Pacinian+I+psychophysical+channel.">Tactile sensitivity of children: effects of frequency, masking, and the non-Pacinian I psychophysical channel.</a> J Exp Child Psychol. 98 (2), 113-130 (2007).</li><li>Cohen, J. C., Makous, J. C., Bolanowski, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Under+which+conditions+do+the+skin+and+probe+decouple+during+sinusoidal+vibrations?.">Under which conditions do the skin and probe decouple during sinusoidal vibrations?.</a> Exp Brain Res. 129 (2), 211-217 (1999).</li><li>Makous, J. C., Gescheider, G. A., Bolanowski, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+static+indentation+on+vibrotactile+threshold.">The effects of static indentation on vibrotactile threshold.</a> J. Acoust. Soc. Am. 99 (5), 3149-3153 (1996).</li><li>Goldreich, D., Kanics, I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tactile+Acuity+is+Enhanced+in+Blindness.">Tactile Acuity is Enhanced in Blindness.</a> J. Neurosci. 23 (8), 3439-3445 (2003).</li><li>Peters, R. M., Goldreich, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tactile+Spatial+Acuity+in+Childhood:+Effects+of+Age+and+Fingertip+Size.">Tactile Spatial Acuity in Childhood: Effects of Age and Fingertip Size.</a> PLoS One. 8 (12), (2013).</li><li>Tong, J., Mao, O., Goldreich, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-point+orientation+discrimination+versus+the+traditional+two-point+test+for+tactile+spatial+acuity+assessment.">Two-point orientation discrimination versus the traditional two-point test for tactile spatial acuity assessment.</a> Front Hum Neurosci. 7, 579 (2013).</li><li>Goldreich, D., Wong, M., Peters, R. M., Kanics, I. 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The techniques used to evaluate VDT vary as to device specifications, hardware, and testing protocols. The International Organization for Standardization specifies the methods and procedures to analyze and interpret vibrotactile thresholds including recommendations for the various components of a vibrometer (ISO 13091-1 and 226,27) The described testing system abides to the relevant ISO recommendations for testing frequency range (4-125 Hz), method (variant of up-down staircase and forced choice), probe size (...

Specialized mechanosensory receptors in the skin mediate the perception of vibration and grating orientation. Each mechanosensory receptor type is tuned to detect distinct features of tactile stimuli1,2. This property provides the psychophysical basis for a differentiated assessment of mechanosensory function by using tests that deliver simple sinusoidal oscillations (vibration) or fine gratings. It is known that psychophysical thresholds for vibration perception are lower for high than low frequency vibration3,4. Two types of rapidly adapting mechanoreceptors associated with the Meissner and Pacinian corpuscles primarily detect low (10-40 Hz) and high (100-200 Hz) frequency vibration stimuli, respectively5. It is thought that the psychophysical thresholds for vibration perception rely to a considerable extent on the activation of these two sets of mechanoreceptors at their best frequencies6,7. Tactile spatial acuity is tested by the grating orientation task to determine the finest grating whose orientation can be discriminated by a subject7-9. Merkel cell-neurite complex afferents are essential for detecting grating orientation8,10. Interestingly, there has been considerable recent progress in our understanding of the molecular basis of how mechanoreceptors detect extremely small tactile stimuli11. Mechanosensitive ion channels like Piezo2 and modulators like STOML3 have been directly implicated in the detection of fine tactile stimuli in touch receptors12-15. There are already human patients identified with function altering mutations in the Piezo2 gene and it will be important to test whether such patients have touch deficits16. 
The determination of the vibrotactile threshold relies on the delivery of a vibrating stimulus to the skin. Vibration detection thresholds vary with the vibration frequency. Vibration frequency to detection threshold curves were described by von Bekesey, Verillo, and Bolanowski, among many others, from the 1930s up to the 1990s5,17. The devices in the early days were based on shakers and power amplifiers and several devices have been commercialized and there are a lot of variation as to choice of stimulator (testing frequency), the diameter of the probe in contact with skin, the use of a surround to limit the stimulation to one area of the skin, and the testing protocol that determines the threshold (see the following references for more detailed insight on the device and testing features)18-20. Most devices usually test one site; however, there are new devices that use vertical displacement stimulators equipped with 2 probes to deliver vibratory stimuli with separation ranges that can be varied21. Also detection thresholds are measured based on vibration frequency or intensity discrimination with continuous stimulation; or with intermittent vibration stimuli with or without a masking stimulus. Therefore, we recommend that the reader be aware of the plethora of developments in this field. 
Here, we describe the components of the device and a step-by-step guide on how to conduct psychophysical tests to estimate vibration detection threshold in human subjects. We then show how to assess tactile acuity manually by using the tactile acuity cube. We use a two-interval, forced-choice paradigm: the stimulus is always presented during one of two intervals and the subject has to indicate which interval has the vibration stimulus. We employ a transformed-rule up and down as the adaptive method that executes a threshold search by changing the stimulus intensity based on the performance during the test. Both psychophysical protocols can be used by investigators as a screening tool for evaluation of alterations in touch sensitivity.

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		<tr height="145">
			<td height="145" style="height:145px;width:115px;">Piezo actuator</td>
			<td style="width:83px;">Physik Instrument, Germany</td>
			<td style="width:221px;">P-602.1L</td>
			<td style="width:411px;">The linear piezoelectric actuator, with integrated position sensor and motion amplifier, contains a piezoceramic material that elongates and contracts when voltage is applied. The piezoelectric actuator travels up to100 &#181;m. The actuator is equipped with a flexure guide that ensures straight motion without tilting or lateral offset. The displacement is linear and calibration is done and checked by the manufacturer. It is recommended that on-axis movement of the probe be checked under the microscope. According to the manufacturer, the stimulus amplitude dampens by less than 20% at oscillating frequencies of 1000 Hz. This can be checked by using a force or displacement measuring device (e.g. force transducer from Kleindiek).</td>
			<td style="width:555px;">The linear piezoelectric actuator, with integrated position sensor and motion amplifier, contains a piezoceramic material that elongates and contracts when voltage is applied. The piezoelectric actuator travels up to100 &#181;m. The actuator is equipped with a flexure guide that ensures straight motion without tilting or lateral offset. The displacement is linear and calibration is done and checked by the manufacturer. It is recommended that on-axis movement of the probe be checked under the microscope. According to the manufacturer, the stimulus amplitude dampens by less than 20% at oscillating frequencies of 1000 Hz. This can be checked by using a force or displacement measuring device (e.g. force transducer from Kleindiek).</td>
		</tr>
		<tr height="547">
			<td height="547" style="height:546px;width:115px;">Piezo Amplifier / Servo Controller</td>
			<td style="width:83px;">Physik Instrument, Germany</td>
			<td style="width:221px;">E-665</td>
			<td style="width:411px;">E-665 amplifier/controller drives and controls the displacement of a low-voltage piezoelectric actuator in a system with sensor position feedback (SGS sensors). The servo-controller provides the option for closed loop operation. When applying sinusoidal and oscillating stimuli the amplitude signal deviates from the set amplitude starting from 500 Hz and reaches a maximum decrease of 20% at 1000Hz.&#160;&#160;</td>
			<td style="width:555px;">E-665 amplifier/controller drives and controls the displacement of a low-voltage piezoelectric actuator in a system with sensor position feedback (SGS sensors). The servo-controller provides the option for closed loop operation. When applying sinusoidal and oscillating stimuli the amplitude signal deviates from the set amplitude starting from 500 Hz and reaches a maximum decrease of 20% at 1000Hz. &#160;</td>
		</tr>
		<tr height="39">
			<td height="57" rowspan="2" style="height:57px;width:115px;">LabChart Software</td>
			<td rowspan="2" style="width:83px;">ADInstruments, USA</td>
			<td style="width:221px;">LabChart 7, MLU60/8</td>
			<td style="width:411px;">Can create, store and run macro of the psychophysical testing algorithm.&#160;</td>
			<td rowspan="2" style="width:555px;">Can create, store and run macro of the psychophysical testing algorithm.&#160;&#160;</td>
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		<tr height="18">
			<td height="18" style="height:18px;width:221px;"></td>
			<td style="width:411px;"></td>
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			<td height="35" rowspan="2" style="height:35px;width:115px;">PowerLab</td>
			<td rowspan="2" style="width:83px;">ADInstruments, USA</td>
			<td style="width:221px;">PowerLab 4/35 PL3504</td>
			<td rowspan="2" style="width:411px;">Data Acquisition Hardware. Used with LabChart software.</td>
			<td rowspan="2" style="width:555px;">Data Acquisition Hardware. Used with LabChart software.</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:18px;width:221px;"></td>
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		<tr height="60">
			<td height="60" style="height:60px;width:115px;">Brass bar</td>
			<td style="width:83px;">Custom-made</td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">Bar made of pure brass, weighs 15.5Kg. When the peizoelectric actuator is mounted on the brass bar it should exert a force of 30 g weight on skin surface.</td>
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		<tr height="35">
			<td height="35" style="height:35px;width:115px;">Monitor</td>
			<td style="width:83px;">Custom-made</td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">To mark the 1st and the 2nd interval. The monitor indicates to the subject the time intervals during which the stimulus may be presented.</td>
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		<tr height="35">
			<td height="35" style="height:35px;width:115px;">Response box</td>
			<td style="width:83px;">Custom-made</td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">The subject indicates the interval at which stimulus occurred.&#160;</td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:115px;">Board&#160;</td>
			<td style="width:83px;">Custom-made</td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">Upper surface should be smooth (Plastic), lower surface made of foam to prevent stray vibration ot be transmitted to the stimulating pobe.&#160;</td>
		</tr>
		<tr height="71">
			<td height="71" style="height:71px;width:115px;">Probe</td>
			<td style="width:83px;">Custom-made</td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">A flat circular probe with smoothed edges (thermoplastic material) attached to a screw head. The screw should be of appropriate size to be tightened directly to the moving part of piezoelectric actuator. Size of the probe can be according to preference; in our case, diameter 8.21mm and surface area 52.9mm2.</td>
		</tr>
		<tr height="39">
			<td height="39" style="height:39px;width:115px;">Labchart Script</td>
			<td style="width:83px;"></td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">Can be sent on request. See supplementary code file.&#160;</td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:115px;">Tactile Acuity Cube</td>
			<td style="width:83px;">MedCore</td>
			<td style="width:221px;"></td>
			<td colspan="2" style="width:965px;">The cube is comprised of 6 sides each containing a grating (bar and groove) whose widths are 0.75, 1.25, 1.75, 3.0, 4.5, and 6.0 mm.&#160;</td>
		</tr>
	</tbody>
</table>

measurement of vibration detection threshold and tactile spatial acuity in human subjects

Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about mechanosensory function that are relevant for clinical diagnosis as well as for basic research. Here, we describe two psychophysical tests designed to determine the vibration detection threshold (automated system) and tactile spatial acuity (handheld device). Both procedures implement a two-interval forced-choice and a transformed-rule up and down experimental paradigm. These tests have been used to obtain mechanosensory profiles for individuals from distinct human cohorts such as twins or people with sensorineural deafness.

The piezoelectric actuator provides the vibration stimulus to the subject. The vibration stimulus has a total duration of 1.8 sec and is presented only once during a trial during the first or second interval (Figure 2A). The rise and fall time at the onset and offset of the stimulus is determined by the functions (1-e-bt)&#8729;Amplitude&#8729;sine(frequency), and (e-bt)&#8729;Amplitude&#8729;sine(frequency), respectively, where b is set at 9.1. The ...

Watch this Scientific Journal Video about Measurement of Vibration Detection Threshold and Tactile Spatial Acuity in Human Subjects at JoVE.com

Measurement of Vibration Detection Threshold and Tactile Spatial Acuity in Human Subjects

Here, we present protocols to determine vibration detection thresholds and tactile acuity using psychophysical methods in man.

Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about ...

The overall goal of this psychophysical procedure is to determine the threshold for vibration detection in tactile spatial acuity. This method can help us ask some quite interesting questions about sense medicine through physiology, in particular, about the sense of touch. The main advantage of this method is that we can obtain quantitative information about mechani-sensory profiles in individuals and this information can be used for both for clinical diagnosis as well as for basic research.We first applied this method in a twin study to test whether touch traits in people are heritable. Visual demonstration of this method is critical as depiction of the procedure as well as the adaptive method we use are complex. Begin to assemble the components of the device by placing a 40 cm by 80 cm smooth surface board on a table.Then, place a brass bar on this board. Afterwards, ready the controller unit. Next, connect the response box and the monitor device to the data acquisition system.Then, screw the custom-made stimulating probe to the moving part of the piezoelectric actuator. Finally, mount the piezoelectric actuator with the probe on the balance brass bar. Begin by bringing the subject into a quiet room and seat them near the device.Inform the subject about the testing procedure and have them sign a written consent form. Then, place their arm on the board and pad the little finger with medical dough to minimize movement. Next, place the brass bar on the board and use a water level to position the probe horizontally on the little finger of the tested hand just below the nail bed.Avoid skin contact with the edges of the circular flat probe. Prior to starting the test, ensure that the procedure is understood by presenting both an easy to perceive vibration stimulus, and a hard one by varying the amplitude until the subject perceives a vibration. Then, start the test by running a script that uses a two alternative forced-choice procedure with the up-down adaptive method.For each trial, randomly administer a vibration stimulus during one of the two intervals which are visually indicated to the test subject as one or two on the screen in front of them. Ask the subject to indicate if the first or second interval contained the vibration stimulus by pressing the number one or two on the response box. Have the subject make a guess response if they are not sure when the stimulus was presented.Complete a total of six to nine trials, and repeat the same vibration stimulus at the one amplitude level at least six times consecutively. If all responses are correct, reduce the stimulus intensity level for the subsequent trial series. Based on the decision rule of the adaptive method, grant the subject more trials at the same stimulus intensity if the subject makes errors in a trial series.Reduce the stimulus intensity if the stimulus is correctly identified in at least five trials, and incorrectly in less than two trials. Increase the stimulus level if the subject makes two incorrect responses in a trial series or more than one incorrect response and fewer than five correct responses. Document the change in the direction of stimulus intensity as the reversal point.Change the stimulus intensity according to reversal point number. For example, prior to the third reversal point, Change by four intensity levels. Or at the third reversal point, change by two intensity levels.Otherwise, by one level. End testing when the subject completes a total of eight reversals. Finally calculate the vibration detection threshold or VDT by taking the median of the stimulus amplitude value of the last six reversals.Begin by providing instructions about the task in a quiet room set at a temperature between 20 and 30 degrees Celsius. Next, blindfold the subject using shielded eye glasses. Place the dominant hand on a table with the palm surface facing up.During each trial, apply the tactile acuity cube or TAC to the finger pad at one of two grating orientations. Vertically or horizontally aligned to the long axis of the finger. Apply the gratings of the TAC to the finger pad of the finger for two seconds so that the cube exerts its whole weight on the finger.Then, ask the subject to determine the orientation of the alignment before the cube is removed from their finger. Start with the largest grating at 6.0 millimeters and decrease the grating width after two correct identifications of the orientation. Then, test the next smaller width and continue with the stepping rule until the subject makes and incorrect response.Then, document this grating width as a reversal point. Increase the grating width step-wise again until the two orientations of the width are determined correctly again. Finally, end the test after the completion of 13 reversals and calculate the tactile grating orientation threshold by taking the median of the grating widths of the last 10 reversals.Here, a typical testing session to determine the vibration detection threshold at 125 Hz is shown. A decrease in stimulus intensity requires at least six sequential correct responses. Furthermore, a change in the direction of stimulus intensity marks a reversal point in the trial series track and requires at least two incorrect responses.The stimulus intensity is changed in steps of four levels when the number of reversals is less than three, followed by two levels at the third reversal, and finally one level steps to finally determine the threshold. For the tactile cube experiment, where each trial consists of two stimulations, vertical and horizontal, the threshold is 1.6 millimeters, which is the median value of the grating widths of the last 10 reversal points. Once mastered, this technique can be done in about 30 minutes, if it's done properly.After watching this video, you should get a good idea about how to measure vibration detection threshold as well as tactile acuity in humans.

measurement-vibration-detection-threshold-tactile-spatial-acuity

Research

JoVE Journal

Behavior

Quantitative Assessment of Cortical Auditory-tactile Processing in Children with Disabilities

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess children&#39;s cortical processing of light touch, speech sounds and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing children discomfort. To accomplish this we developed a dual channel, time and strength calibrated air puff stimulator that allows both tactile stimulation and sham control. We combined this with the use of event-related potential methodology to allow for high temporal resolution of signals from the primary and secondary somatosensory cortices as well as higher order processing. This methodology also allowed us to measure a multisensory response to auditory-tactile stimulation.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess infants and children&#39;s cortical processing of light touch, speech sounds, and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing discomfort in vulnerable patients.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology ...

Performing Behavioral Tasks in Subjects with Intracranial Electrodes

Patients having stereo-electroencephalography (SEEG) electrode, subdural grid or depth electrode implants have a multitude of electrodes implanted in different areas of their brain for the localization of their seizure focus and eloquent areas. After implantation, the patient must remain in the hospital until the pathological area of brain is found and possibly resected. During this time, these patients offer a unique opportunity to the research community because any number of behavioral paradigms can be performed to uncover the neural correlates that guide behavior. Here we present a method for recording brain activity from intracranial implants as subjects perform a behavioral task designed to assess decision-making and reward encoding. All electrophysiological data from the intracranial electrodes are recorded during the behavioral task, allowing for the examination of the many brain areas involved in a single function at time scales relevant to behavior. Moreover, and unlike animal studies, human patients can learn a wide variety of behavioral tasks quickly, allowing for the ability to perform more than one task in the same subject or for performing controls. Despite the many advantages of this technique for understanding human brain function, there are also methodological limitations that we discuss, including environmental factors, analgesic effects, time constraints and recordings from diseased tissue. This method may be easily implemented by any institution that performs intracranial assessments; providing the opportunity to directly examine human brain function during behavior.

Patients implanted with intracranial electrodes provide a unique opportunity to record neurological data from multiple areas of the brain while the patient performs behavioral tasks. Here, we present a method of recording from implanted patients that can be reproducible at other institutions with access to this patient population.

Patients having stereo-electroencephalography (SEEG) electrode, subdural grid or depth electrode implants have a multitude of electrodes implanted in ...

Determining Pain Detection and Tolerance Thresholds Using an Integrated, Multi-Modal Pain Task Battery

Human pain models are useful in the assessing the analgesic effect of drugs, providing information about a drug&#39;s pharmacology and identify potentially suitable therapeutic populations. The need to use a comprehensive battery of pain models is highlighted by studies whereby only a single pain model, thought to relate to the clinical situation, demonstrates lack of efficacy. No single experimental model can mimic the complex nature of clinical pain. The integrated, multi-modal pain task&#160;battery presented here encompasses the electrical stimulation task, pressure stimulation task, cold pressor task, the UVB inflammatory model which includes a thermal task and a paradigm for inhibitory conditioned pain modulation. These human pain models have been tested for predicative validity and reliability both in their own right and in combination, and can be used repeatedly, quickly, in short succession, with minimum burden for the subject and with a modest quantity of equipment. This allows a drug to be fully characterized and profiled for analgesic effect which is especially useful for drugs with a novel or untested mechanism of action.

Human pain models are valuable tools used to assess the analgesic potential of novel compounds and predict their clinical efficacy, especially when used in an integrated manner. Although implementation of these models is complex, with proper execution, the pain models described in this protocol can provide predictive and reliable results.

Human pain models are useful in the assessing the analgesic effect of drugs, providing information about a drug&#39;s pharmacology and identify ...

The (Spatial) Memory Game: Testing the Relationship Between Spatial Language, Object Knowledge, and Spatial Cognition

The memory game paradigm is a behavioral procedure to explore the relationship between language, spatial memory, and object knowledge. Using two different versions of the paradigm, spatial language use and memory for object location are tested under different, experimentally manipulated conditions. This allows us to tease apart proposed models explaining the influence of object knowledge on spatial language (e.g., spatial demonstratives), and spatial memory, as well as understanding the parameters that affect demonstrative choice and spatial memory more broadly. Key to the development of the method was the need to collect data on language use (e.g., spatial demonstratives: &#34;this/that&#34;) and spatial memory data under strictly controlled conditions, while retaining a degree of ecological validity. The language version (section 3.1) of the memory game tests how conditions affect language use. Participants refer verbally to objects placed at different locations (e.g., using spatial demonstratives: &#34;this/that red circle&#34;). Different parameters can be experimentally manipulated: the distance from the participant, the position of a conspecific, and for example whether the participant owns, knows, or sees the object while referring to it. The same parameters can be manipulated in the memory version of the memory game (section 3.2). This version tests the effects of the different conditions on object-location memory. Following object placement, participants get 10 seconds to memorize the object&#39;s location. After the object and location cues are removed, participants verbally direct the experimenter to move a stick to indicate where the object was. The difference between the memorized and the actual location shows the direction and strength of the memory error, allowing comparisons between the influences of the respective parameters.

The Spatial Memory Game: Testing the Relationship Between Spatial Language, Object Knowledge, and Spatial Cognition

We present a protocol to explore the relationship between spatial language production, spatial memory, and object knowledge. The procedure allows experimental manipulation of, and control over, conditions of object knowledge, language at instruction, and physical location, thus teasing apart cognitive and linguistic models describing interactions between these variables.

The memory game paradigm is a behavioral procedure to explore the relationship between language, spatial memory, and object knowledge. Using two different ...

Whole Body Vibration Methods with Survivors of Polio

The purpose of the original study was to examine the use of whole body vibration (WBV) on polio survivors with and without post-polio syndrome as a form of weight bearing exercise. The goal of this article is to highlight the strengths, limitations, and applications of the method used. Fifteen participants completed two intervention blocks with a wash-out period in between the blocks. Each block consisted of twice a week (four weeks) WBV interventions, progressing from 10 to 20 min per session. Low intensity (peak to peak displacement 4.53 mm, frequency 24 Hz, g force 2.21) and higher intensity (peak to peak displacement 8.82 mm, frequency 35 Hz, g force 2.76) WBV blocks were used. Pain severity significantly improved in both groups following higher intensity vibration. Walking speed significantly improved in the group who participated in higher intensity intervention first. No study-related adverse events occurred. Even though this population can be at risk of developing overuse-related muscle weakness, fatigue, or pain from excessive physical activity or exercise, the vibration intensity levels utilized did not cause significant muscle weakness, pain, fatigue, or sleep disturbances. Therefore, WBV appears to provide a safe method of weight bearing exercise for this population. Limitations included the lack of measurement of reflexes, muscular activity, or circulation, the difficulty in participant recruitment, and insufficient strength of some participants to stand in recommended position. Strengths included a standard, safe protocol with intentional monitoring of symptoms and the heterogeneity of the participants in their physical abilities. An application of the methods is the home use of WBV to reduce the barriers associated with going to a facility for weight bearing exercise for longer term interventions, and benefits for conditions such as osteoporosis, particularly for aging adults with mobility difficulties due to paralysis or weakness. Presented method may serve as a starting point in future studies.

The goal of this article is to highlight the strengths, limitations, and applications of the method used with whole body vibration on polio survivors with and without post-polio syndrome as a feasible and safe form of weight bearing exercise.

The purpose of the original study was to examine the use of whole body vibration (WBV) on polio survivors with and without post-polio syndrome as a form ...

Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile feedback (VTF). This protocol aims to test the effect of VTF on the response to incongruent visual-tactile stimuli. The tactile feedback is acquired by grasping a block and moving it across a partition. The visual feedback is a real-time virtual presentation of the moving block, acquired using a motion capture system. The congruent feedback is the reliable presentation of the movement of the block, so that the subject feels that the block is grasped and see it move along with the path of the hand. The incongruent feedback appears as the movement of the block diverts from the actual movement path, so that it seems to drop from the hand when it is actually still held by the subject, thereby contradicting the tactile feedback. Twenty subjects (age 30.2 &#177; 16.3) repeated 16 block transfers, while their hand was hidden. These were repeated with VTF and without VTF (total of 32 block transfers). Incongruent stimuli were presented randomly twice within the 16 repetitions in each condition (with and without VTF). Each subject was asked to rate the difficulty level of performing the task with and without the VTF. There were no statistically significant differences in the length of the hand paths and durations between transfers recorded with congruent and incongruent visual-tactile signals &#8211; with and without the VTF. The perceived difficulty level of performing the task with the VTF significantly correlated with the normalized path length of the block with VTF (r = 0.675, p = 0.002). This setup is used to quantify the additive or reductive value of VTF during motor function that involves incongruent visual-tactile stimuli. Possible applications are prosthetics design, smart sport-wear, or any other garments that incorporate VTF.

We present a protocol to apply incongruent visual-tactile stimuli during an object transfer task. Specifically, during block transfers, performed while the hand is hidden, a virtual presentation of the block shows random occurrences of false block drops. The protocol also describes adding vibrotactile feedback while performing the motor task.

The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile ...

Measurement of Spatial Stability in Precision Grip

The purpose of the protocol is to indirectly evaluate the direction of the finger force during manipulation of a handheld object based on the biomechanical relationships in which deviated force direction causes center of pressure (COP) replacement. To evaluate this, a thin, flexible, and high spatial resolution pressure sensor sheet is used. The system allows measurement of the COP trajectory in addition to the force amplitude and its temporal regulation. A series of experiments found that increased trajectory length reflected a sensorimotor deficit in stroke patients, and that decreased COP trajectory reflects a compensatory strategy to avoid an object slipping from the hand grip in the elderly. Moreover, the COP trajectory could also be decreased by dual task interference. This article describes the experimental procedure and discusses how finger COP contributes to an understanding of the physiology and pathophysiology of grasping.

The goal of this protocol is to measure the center of pressure (COP) replacement using a high spatial resolution sensor sheet to reflect the spatial stability in a precision grip. The use of this protocol could contribute to greater understanding of the physiology and pathophysiology of grasping.

The purpose of the protocol is to indirectly evaluate the direction of the finger force during manipulation of a handheld object based on the ...

Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training

An elevation in cardiac troponin T (cTnT), as a highly specific biomarker of cardiomyocyte damage, after moderate-intensity continuous exercise (MCE) has been described. The exercise-induced cTnT response distorts the diagnostic role of the cTnT assay. Although high-intensity interval exercise (HIE) is growing in popularity and concerns remain about its safety, available data related to cTnT release after HIE is limited, which hampers the use of HIE as a health intervention. Here, we present three representative HIE protocols [traditional HIE (repeated 4 min cycling at 90% V&#775;O2max interspersed with 3 min rest, 200 kJ/session); sprint interval exercise (SIE, repeated 1 min cycling at 120% V&#775;O2max interspersed with 1.5 min rest, 200 kJ/session); and repeated sprint exercise (RSE, 40 x 6 s all-out sprints interspersed with 9 s rest)] and one representative MCE protocol (continuous cycling exercise at an intensity of 60% V&#775;O2max, 200 kJ/session). Forty-seven sedentary, overweight young women were randomly assigned to one of four groups (HIE, SIE, RSE, and MCE). Six bouts of respective exercise were performed by every single group, with each being 48 h apart. Meanwhile, for four groups, the duration of the entire testing period was identical, being 10 days. Before and after the first and final exercise bouts, an assessment was conducted of cTnT. The current study provides a frame of reference giving a clear picture of how a specific exercise session affects the circulating cTnT concentration at the early stage of training. The information may assist with clinical interpretations of post-exercise cTnT elevation and guide the prescription of exercise, especially for HIE.

Here, we present protocols of high-intensity interval and moderate-intensity continuous exercise to observe the response of circulating cardiac troponin T (cTnT) concentration to acute exercise over 10 days. The information may assist with clinical interpretations of post-exercise cTnT elevation and guide the prescription of exercise.

An elevation in cardiac troponin T (cTnT), as a highly specific biomarker of cardiomyocyte damage, after moderate-intensity continuous exercise (MCE) has ...

Tactile Semiautomatic Passive-Finger Angle Stimulator (TSPAS)

Passive tactile perception is the ability to passively and statically perceive stimulus information coming from the skin; for example, the ability to sense spatial information is the strongest in the skin on the hands. This ability is termed tactile spatial acuity, and is measured by the tactile threshold or discrimination threshold. At present, the two-point threshold is extensively used as a measure of tactile spatial acuity, although many studies have indicated that critical deficits exist in two-point discrimination. Therefore, a computer-controlled tactile stimulus system was developed, the tactile semiautomated passive-finger angle stimulator (TSPAS), using the tactile angle discrimination threshold as a new measure for tactile spatial acuity. The TSPAS is a simple, easily operated system that applies raised angle stimuli to a subject&#39;s passive fingerpad, while controlling movement speed, distance, and contact duration. The components of the TSPAS are described in detail as well as the procedure to calculate the tactile angle discrimination threshold.

Tactile Semiautomatic Passive-Finger Angle Stimulator TSPAS

Presented is the tactile semiautomated passive-finger angle stimulator TSPAS, a new way to assess tactile spatial acuity and tactile angle discrimination using a computer-controlled tactile stimulus system that applies raised angle stimuli to a subject&#39;s passive fingerpad, while controlling for movement speed, distance, and contact duration.

Passive tactile perception is the ability to passively and statically perceive stimulus information coming from the skin; for example, the ability to ...

Calcium Imaging in Freely Behaving Caenorhabditis elegans with Well-Controlled, Nonlocalized Vibration

Nonlocalized mechanical forces, such as vibrations and acoustic waves, influence a wide variety of biological processes from development to homeostasis. Animals cope with these stimuli by modifying their behavior. Understanding the mechanisms underlying such behavioral modification requires quantification of neural activity during the behavior of interest. Here, we report a method for calcium imaging in freely behaving Caenorhabditis elegans with nonlocalized vibration of specific frequency, displacement, and duration. This method allows the production of well-controlled, nonlocalized vibration using an acoustic transducer and quantification of evoked calcium responses at single-cell resolution. As a proof of principle, the calcium response of a single interneuron, AVA, during the escape response of C. elegans to vibration is demonstrated. This system will facilitate understanding of neural mechanisms underlying behavioral responses to mechanical stimuli.

Calcium Imaging in Freely Behaving Caenorhabditis elegans with Well-Controlled, Nonlocalized Vibration

Reported here is a system for calcium imaging in freely behaving Caenorhabditis elegans with well-controlled, nonlocalized vibration. This system allows researchers to evoke nonlocalized vibrations with well-controlled properties at nano-scale displacement and to quantify calcium currents during responses of C. elegans to the vibrations.

Nonlocalized mechanical forces, such as vibrations and acoustic waves, influence a wide variety of biological processes from development to homeostasis. ...