The authors acknowledge the following funding sources: the Duquesne University Faculty Development Fund grants awarded to Kimberly Szucs, PhD and Alex Kranjec, PhD and to Benedict Kolber, PhD and Matthew Kostek, PhD. We also acknowledge Rachel Sweetnich for experimental assistance and funding from the Duquesne University Pain Undergraduate Research Experience program awarded to Sweetnich (Mentors: Szucs and Kostek).

All tests with human subjects should be approved by the Institutional Review Board at the individual institution. All testing described for the current study was approved by the Duquesne University Institutional Review Board for human subject research. Training for and descriptions of each measure are as follows:
1. Cutaneous Mechanical Sensitivity Assay13
NOTE: Enrolled participants are asked to sit in a chair, with support provided for the extremity to be...

<ol>
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We have demonstrated cost-effective and simple qualitative and quantitative sensory tests that can be used to assess mechanical sensation, thermal sensation and pain, and pressure pain in human subjects. The value of these assays is their ease of implementation and low amount of necessary training time. Each experimenter received a minimal amount of training (one trial observation and one trial implementation). Thus, multiple technicians could be trained in one day. The results suggest strong inter-experimenter and withi...

Chronic pain conditions are a worldwide clinical problem. More than 1.5 billion people worldwide suffer from chronic pain, and approximately 5% of the global population suffers from neuropathic pain, with incidence rates increasing with age1. In America, it is estimated that pain affects more people than diabetes, heart disease, and cancer, combined2. While awareness of this problem is increasing, treatments are not always successful, can be expensive, and may have serious side effects, including addiction. Research on treatments is ongoing, but as pain varies greatly between individuals, pain measurement for research or diagnosis can be problematic. In particular, the reliance on qualitative approaches, such as the Visual Analog Scale (VAS), for determining treatment efficacy has been problematic because of the subjective and personal nature of pain3. As more research laboratories and smaller clinics around the world answer questions about and treat pain, measures that are accurate, consistent, portable, quantitative, and affordable are in great demand.
A key distinction in pain measurement is acute versus chronic pain. Acute pain is a normal response to injury, infection, or another noxious stimulus. Acute pain normally resolves with treatment and time, and the pain location is usually site-specific. Chronic pain, however, can be related to an initial bout of acute pain, or it can be idiopathic. Chronic pain may relate to the site of injury, but it is often widespread throughout the body4. Chronic pain can last for weeks, months, and even years, causing substantial physical, psychological, and monetary burdens on patients and their families, employers, and societies. The ability to identify and quantify pain is critical for correct diagnosis, evaluation of ongoing treatment, and development of new analgesic treatments. Quantitative and qualitative sensory testing are thus critical for diagnosis and treatment.
Several methods can be used to examine peripheral sensation and pain: nerve conduction velocity (NCV), somatosensory evoked potentials (SEP), skin biopsies, and quantitative sensory testing (QST). Clinicians also routinely use bedside neurologic sensory testing, but this testing is not calibrated and does not use a standardized set of instructions5. Exams of NCV and SEP can be informative, but compared to QST, they require highly specialized equipment, typically only examine large nerve fibers, only measure loss of function, and do not test the entire somatosensory system6,7. Skin biopsies are used to assess nerve fiber density, but compared to QST, they are invasive and require tissue processing and microscopy time, which could take several days to accomplish8. Furthermore, the biopsy only examines a small, specific area of the somatosensory system and does not test nerve function. QST measurements overcome most of the limitations of other testing methods. Recently, standardized normative data for QSTs have been made available, which further add to their utility to assess pain and neural sensation9-11. We therefore focus the current protocol on QST measures for chronic pain.
New technologies have made the assessment of pain and physical sensation (e.g., pressure and heat) precise and reliable within well-equipped laboratories that have established internal protocols12. Many of these technologies, however, are not easily portable and are cost-prohibitive for new or small research laboratories and medical clinics. Additionally, protocols for technology use are not standardized across laboratories13, which can affect reliability. Therefore, the goal of this manuscript is to demonstrate effective and reliable pain and sensory measures that can be conducted with equipment that is available in most clinics or research laboratories. The rationale for the development of the current protocol is that while many people suffer from chronic pain conditions, and accurate assessment of pain is needed for diagnosis and treatment, there are no published protocols with visual demonstrations of assays.
An example of a nearly fully automated device for testing acute pain is the Neuro Sensory Analyzer, which can reliably assess thermal pain sensation, as demonstrated by Angst et al. following a cutaneous burn in human subjects14. The unit is modular, and additional sensory testing devices can be added. In their study, Angst et al. also demonstrate pressure sensory testing with the use of Punctuated Pressure Probes, which were custom built. While these probes should offer more consistent results, few laboratories or clinics have them.
The current protocol demonstrates QST measures for chronic pain: von Frey filaments for cutaneous sensory testing, a radiant (&#34;Hargreaves&#34; method) and contact heat technique, and pressure algometry for deep tissue pain. These QST measurements are not unique. Rather, they are the most common and generally accepted measurements for human sensory testing in medical clinics, hospitals, and research laboratories13,15,16. Mechanical and thermal stimulation are used to examine cutaneous and deep sensation. These measures, furthermore, include the evaluation of both small and large fiber sensitivity for normal sensation and pain. To assess deep tissue pain (muscle), pressure algometry is used, which is the most frequently applied technique for the quantification of pain in soft tissue such as muscles17,18. Both A-delta and C fibers mediate pain induced by pressure stimulation19. Stimulation of both fibers is an advantage and a disadvantage, in that it examines multiple pathways, making it a good overall measure, but it is also less specific. To examine touch sensitivity, mechanical stimulation of skin with von Frey filaments is used because they are one of the most commonly used sensory devices in pain and medical neural clinics. Von Frey filaments stimulate A-beta fibers,20 but are not specific as both low threshold mechanoreceptors and nociceptors can be activated21. The use of these filaments has been criticized, mainly because of potential variability of the application procedure (degree of filament indention or accidental movement of the hand) and concerns that the mechanical filament characteristics may change over time22,23. This protocol addresses these issues by providing detailed instructions with a script and calibration of filaments.
For thermal pain, radiant heat using the &#34;Hargreaves&#34; method (visible light and ramping temperature) and a heat block to examine contact heat are used. Contact and radiant heat activate thermal receptors differently and can even confound one another. It has been shown that dynamic contact can inhibit thermal nociception24. This is similar to the concept of thermal referral, in which touch contributes to normal temperature perception25-27. Therefore, one measure of thermal sensation and two measures of thermal pain are included. First, radiant heat is used to determine the threshold for temperature change detection (starting from room temperature). Second, the radiant heat source is used to determine the threshold for heat pain. The detection of warm thermal change (non-nociceptive) is mediated in part by transient receptor potential (TRP) channels on C fibers, while heat pain is mediated by TRPV1/V2 and other higher-threshold channels on C and A-delta fibers28-30. At threshold determination, rapid skin heating activates first A-delta fibers, corresponding to the &#34;first pain,&#34; followed by a C fiber-mediated &#34;second pain,&#34; described as &#34;throbbing, burning, or swelling&#34;31. Heating gives a preferential activation of C fibers and is the best evaluation of second pain32. In the contact heat assay, a constant nociceptive temperature is applied to determine the qualitative intensity and affective aspects of pain.
Another variable considered in developing the QST protocol is anatomical location. For acute or location-specific pain, the anatomical site of the pain is typically used for testing. Because the protocol was designed with chronic pain conditions in mind, we take a more global approach. The protocol assesses sensation on the forearm and leg instead of the hand, as it has been shown that heat pain thresholds are significantly higher on the hand than on the forearm33 and that thermal nociception can be perceived on the hand, although less frequently and less intensely than on the forearm24. While the protocol was designed for the majority of chronic pain conditions, we caution users that some chronic pain conditions affect specific anatomical regions, and this should be taken into account when modifying the protocol for a specific patient population.
While these QST measures are the most commonly used and are accepted as some of the most reliable, they are inexpensive and common enough that most clinics and research laboratories might already have access to them, can afford them, and can transport them. This QST protocol is useful to any laboratory or clinic where measures are needed for humans with chronic pain. To date, there are currently no published visual reports demonstrating a protocol for the use and reliability of these measures. Based upon this protocol demonstration and tips on improving reliability, a laboratory or clinic could easily examine their own test-retest reliability. Because many clinics will need to utilize several technicians to measure all patients, inter-rater reliability data would be useful in selecting a protocol. We include a small set of data that suggests that the protocol has good reliability, but each clinic and laboratory is strongly advised to use this as an example, as each clinic and each patient population with chronic pain is unique.
Notes on injury risk for sensory and pain testing:
Risk of injury related to cutaneous mechanical testing is extremely rare and unlikely. Mechanical testing is safe and widely used. Risks to the individual are minimal because 1) this is not a painful or noxious stimulus; 2) subjects are instructed that they may stop any procedure at any time, with no adverse consequences; and 3) the level of sensation experienced by subjects is well below their tolerance level and threshold for pain.
Risk of injury related to thermal pain testing is minimal. Thermal testing is safe and widely used. While thermal testing does produce pain, risks to the individual are minimal because 1) the pain is transient in nature and generally subsides immediately after the procedure; 2) subjects are instructed that they may stop any procedure at any time, with no adverse consequences; and 3) the level of pain experienced by subjects is below their tolerance level. With Hargreaves thermal stimulation, there is a very slight risk of receiving a burn, but this is minimized by the following: 1) the positive lockout of stimulus parameters above 50 &#176;C; 2) the built-in shutdown system in the stimulator that prevents the delivery of prolonged or high-intensity stimuli (20 sec); and 3) the electronic thermometer that measures the temperature at the glass surface before and during each use (see below in the instrument section). Pain threshold trials will proceed only if the temperature detected at the 20 sec cutoff is &#8804;50 &#176;C.
Risk of injury related to pressure pain testing is minimal. Pressure testing is safe and widely used. While pressure testing does produce pain, risks to the individual are minimal because 1) the pain is transient in nature and generally subsides immediately after the procedure; 2) subjects are instructed that they may stop any procedure at any time, with no adverse consequences; 3) the level of pain experienced by subjects is below their tolerance level; and 4) the pain applied is never more than that subject&#39;s pain threshold, which is well below any pressure that could cause damage. A rare side effect of pressure testing is bruising at the stimulus site. In this situation, a subject should not be retested at the bruised site. The chance for bruising can be minimized by study exclusion of individuals that bruise easily or are taking blood thinners.
During the enrollment period, participants are given a full description of all sensory and pain measures that will be used. With initial consent, all participants are allowed to experience all sensory and pain measures before full enrollment. All sensory and pain assays are based on well-established assays used in both healthy human participants and in chronic pain patients34. All assays involve either innocuous (non-painful stimuli) or acute noxious stimuli (painful stimuli) that do not damage tissue. The time between different tests is &#62;5 min, to allow the subject to rest and to reduce the potential for sensory fatigue or sensitization. The sequential order of tests is the same during each testing session. Specific sites of testing are limited to the T1 dermatome on the left and right forearms and L3/S2 dermatome on the left and right calves. All sites for testing are marked with a marker, and individual sites are spread out to avoid overlapping receptive field activation (Figure 1). See the Materials and Equipment Table for the full materials list. For retest reliability studies, individual subjects were tested by two experimenters in a single day.

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	<tbody>
		<tr height="86">
			<td height="86" style="height:87px;width:224px;">Pressure Algometer / Force Dial</td>
			<td style="width:144px;">Wagner Instruments</td>
			<td style="width:111px;">FDK 20</td>
			<td style="width:427px;">The pressure algometer quantifies pressure pain threshold.&#160; It has a rubber tip attachment that is applied to the marked skin site by the investigator.&#160; The dial records the pressure and is reset after each measurement.</td>
		</tr>
		<tr height="100">
			<td height="100" style="height:100px;width:224px;">von Frey cutaneous stimulators</td>
			<td style="width:144px;">Touch Test</td>
			<td style="width:111px;">NC1275-01 through -08</td>
			<td style="width:427px;">These von Frey filaments are commonly used to examine sensitivity in research and clincial settings.&#160; Our set of 8 filaments covers a range of sensitivites.&#160; The individual filaments are 1.65 mN, 2.36 mN, 2.44 mN, 2.83 mN, 3.22 mN, 3.61 mN, 3.84 mN, 4.08 mN.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:224px;">&#34;Hargreaves&#34; apparatus, testing platform</td>
			<td style="width:144px;">Custom</td>
			<td style="width:111px;">n/a</td>
			<td style="width:427px;">One complete base and four supporting columns are used to form a platform for a sheet of safety glass through which the heat source directs heat to the subjects arm or leg that is resting on the glass.&#160; The heat lamp is placed beneath the glass.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:224px;">0.64cm Pyrex safety glass</td>
			<td style="width:144px;">DuPont</td>
			<td style="width:111px;">n/a</td>
			<td style="width:427px;">Safety glass is important to avoid injury in the unlikely event of a fracture in the glass surface.</td>
		</tr>
		<tr height="66">
			<td height="66" style="height:67px;width:224px;">Electronic thermometer / thermocouple 53 IIB</td>
			<td style="width:144px;">Fluke</td>
			<td style="width:111px;">3821062</td>
			<td style="width:427px;">The thermocouple is used for thermal testing.&#160; The thermocouple is placed on the glass underneath the subject&#39;s arm or leg and measures the temperature at the glass level.</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;">IITC Plantar Analgesia Meter&#160;</td>
			<td style="width:144px;">Life Science Inc. Woodland Hills, CA</td>
			<td style="width:111px;">390</td>
			<td style="width:427px;">This is the heat source and timer for Hargreaves testing.&#160; The unit&#39;s heat source has an &#8220;idle state&#8221; that allows exact placement of the heat source.&#160; The heat source is radiant light and the light beam is focused to the top of the glass to creates a 4X6mm intense spot on the arm or leg.</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">Examiner script</td>
			<td style="width:144px;">Custom</td>
			<td style="width:111px;">n/a</td>
			<td style="width:427px;">A written script for the examiner is used for every testing session.&#160; Because pain and sensitivity can be affected by envrionmental stresses, we attempt to maintain as much consistency as possible between subjects.&#160; The examiner reads directly from the script every time a measure is made to ensure&#160; verbal consistency.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Markers for testing site</td>
			<td>Sharpie</td>
			<td>n/a</td>
			<td style="width:427px;">Washable markers may be preferable for situations where multiple days of testing is not necessary</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">Constant heat stimulus block</td>
			<td>Benchmark Scientific</td>
			<td>BR10-00</td>
			<td>This block is digitally controlled. The surface of the block is 2x3cm.</td>
		</tr>
	</tbody>
</table>

a protocol of manual tests to measure sensation and pain in humans

Numerous qualitative and quantitative techniques can be used to test sensory nerves and pain in both research and clinical settings. The current study demonstrates a quantitative sensory testing protocol using techniques to measure tactile sensation and pain threshold for pressure and heat using portable and easily accessed equipment. These techniques and equipment are ideal for new laboratories and clinics where cost is a concern or a limiting factor. We demonstrate measurement techniques for the following: cutaneous mechanical sensitivity on the arms and legs (von-Frey filaments), radiant and contact heat sensitivity (with both threshold and qualitative assessments using the Visual Analog Scale (VAS)), and mechanical pressure sensitivity (algometer, with both threshold and the VAS). The techniques and equipment described and demonstrated here can be easily purchased, stored, and transported by most clinics and research laboratories around the world. A limitation of this approach is a lack of automation or computer control. Thus, these processes can be more labor intensive in terms of personnel training and data recording than the more sophisticated equipment. We provide a set of reliability data for the demonstrated techniques. From our description, a new laboratory should be able to set up and run these tests and to develop their own internal reliability data.

&#160;Here, we describe the implementation of cost-effective qualitative and quantitative assays to measure innocuous sensation and pain in human participants using the VAS (Figure 2). The visual representation is important, because accurate and precise results of these examinations are dependent upon correct and consistent protocol execution by the technician. Additionally, it is valuable to know if multiple technicians performing the technique as described can collect r...

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A Protocol of Manual Tests to Measure Sensation and Pain in Humans

The goal of this procedure is to demonstrate a battery of quantitative techniques for sensory and pain measurement in humans. The equipment and techniques described are commonly found in pain clinics or are easy to obtain.

Numerous qualitative and quantitative techniques can be used to test sensory nerves and pain in both research and clinical settings. The current study ...

The overall goal of this data collection procedure is to measure pressure and heat pain thresholds as well as tactile sensation in humans. These sensory measures include both quantitative measures of sensation as well as qualitative measures that help asses individuals sensory and emotional experience during testing. This method can help answer key questions in the Study of Chronic Pain Conditions by providing concrete data points to evaluate the efficacy of various therapies in the context of pain.The main advantages of these techniques are that they're easy to implement and offer reliability between experimentaters. The equipment is easily purchased, stored, and transported by most clinics and research laboratories around the world. Individuals will struggle with these methods because small changes in the time of stimulus application, placement of stimulus application, and/or application pressure can introduce significant variability in the data set.Application procedures of these tests are seemingly subjective, which can lead to inconsistent results. Visual demonstration is therefore critical to ensure accuracy and precision across multiple tests, multiple technicians, and multiple patients. Escort the subject into the testing room and have them sit on an exam table that provides arm support.Give the filament to the subject and let them gently bend it against the skin of their hand. During each trial, ask the subject to look away from their forearm. Start by applying the smallest filament at 0.078 millinewtons to the subject's forearm until it boes and ask if they feel the filament.Complete four positive trials where the filament is applied to the forearm, and one randomized negative trial where the filament is not applied, but the subject is still asked if they feel the filament. Finally, score the trials on the data form, such that if a subject detects greater than three of the positive trials, and zero of the negative trials for a filament, record that filament as the subject's mechanical sensory threshold. For a single filament, if the subject detects less than two of the positive trials, and or greater than zero of the negative trials, then start another round of five trials with the next biggest filament until the sensory threshold is reached.Begin by showing the radiant heat device to the subject and allowing them to feel the stimulus with their hand. Next, ask the subject to rest their forearm on the room temperature glass plate, which is covered with a rubber insulating sheet except for the small opening for stimulus presentation. Use a mirror to position the light source under a marked area on the subjects forearm.Then, for each trial, ask the subject to depress the stop button when they feel the temperature change. To achieve the withdraw threshold, set the device to ramp up the temperature so that the stimulus temperature reaches 47 degrees Celsius at 10 seconds. Begin by showing the constant heat block to the subject and allowing them to feel the stimulus with their hand.Next, apply the stimulus for three seconds to the marked location on the left forearm. Finally, immediately following the stimulus, ask the subject to evaluate the quality and unpleasantness of the pain using a standard zero to 10 visual analog scale. Before starting the experimental trial, allow the subject to handle the algometer, and apply the stimulus to themselves under careful supervision.Complete a pain threshold trial by placing the probe on the subject's forearm and gradually applying pressure until the stimulus transitions from innocuous pressure to painful pressure. Ask the subject to say stop when they want the stimulus removed from their forearm. Complete two trials to the forearm in two distinct sights on the right and left arm to avoid damage to a single area.Then, remove the algometer from the subject. Record the greatest applied pressure as the pressure pain threshold for the trial. Finally, to complete a constant pressure trial, apply a painful stimulus for three seconds and ask the subject to evaluate the quality and unpleasantness of the pain on two standard, zero to 10 visual analogue scales.Inform the subject that on the quality scale, zero is represented as no pain, and 10 is represented as the worst pain imaginable. On the unpleasantness scale, zero is represented as not unpleasant, and 10 is represented as the most unpleasant sensation imaginable. This intra-class correlation coefficient analysis examines the reliability between two examiners, male and female.Inter-experiment reliability was strong for mechanical, thermal, and pressure testing. Such that average inter-experiment reliability measures were all statistically significant except for the mechanical sensitivity test. In addition, all visual analogue scale results for constant heat and constant pressure, showed significant correlations between the male and female experimenters.Once mastered, these techniques can be completed in 30 minutes if performed properly. While attempting these procedures, it's important to remember to remain as consistent as possible when applying stimuli to the subject's testing areas. This is especially important for application of the Von Frey filament for cutaneous mechanical sensitivity, and the algometer for pressure sensitivity.Following these procedures, other methods that evaluate cold hypersensitivity and mechanical pain, can be performed in order to answer additional questions related to other sensory modalities that are altered in the context of pain. Quantitative sensory testing is regularly applied in pre-clinical, and clinical testing. When combined with traditional qualitative measures, the entire procedure provides a valuable snapshot of an individuals sensory and emotional experience to noxious stimuli.After watching this video, you should have a good understanding of how to measure quantitative and qualitative sensation and pain in humans. This includes tactile sensation and pain threshold for pressure and heat, as well as VAS qualitative assessments. Don't forget that working with noxious stimuli in human subjects can be hazardous, and precautions should always be taken when performing this procedure.

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Research

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Behavior

20.6K ビュー.  Duquesne University. The overall goal of this data collection procedure is to measure pressure and heat pain thresholds as well as tactile sensation in humans. These sensory measures include both quantitative measures of sensation as well as qualitative measures that help asses individuals sensory and emotional experience during testing. This method can help answer key questions in the Study of Chronic Pain Conditions by providing concrete data points to evaluate the efficacy of various therapies in the context o...

ビデオ: A Protocol of Manual Tests to Measure Sensation and Pain in Humans

Use of the Operant Orofacial Pain Assessment Device (OPAD) to Measure Changes in Nociceptive Behavior

We present an operant system for the detection of pain in awake, conscious rodents. The Orofacial Pain Assessment Device (OPAD) assesses pain behaviors in a more clinically relevant way by not relying on reflex-based measures of nociception. Food fasted, hairless (or shaved) rodents are placed into a Plexiglas chamber which has two Peltier-based thermodes that can be programmed to any temperature between 7 &deg;C and 60 &deg;C. The rodent is trained to make contact with these in order to access a reward bottle. During a session, a number of behavioral pain outcomes are automatically recorded and saved. These measures include the number of reward bottle activations (licks) and facial contact stimuli (face contacts), but custom measures like the lick/face ratio (total number of licks per session/total number of contacts) can also be created. The stimulus temperature can be set to a single temperature or multiple temperatures within a session. The OPAD is a high-throughput, easy to use operant assay which will lead to better translation of pain research in the future as it includes cortical input instead of relying on spinal reflex-based nociceptive assays.

Use of the Operant Orofacial Pain Assessment Device OPAD to Measure Changes in Nociceptive Behavior

We present a user-friendly, high-throughput operant system for the evaluation of pain behaviors in awake, conscious rodents. The Orofacial Pain Assessment Device (OPAD) can assess pain through a reward/conflict paradigm thus providing a more humane way of testing. This protocol will yield more clinically relevant and translational data from rodents.

We present an operant  system for the detection of pain in awake, conscious rodents. The Orofacial  Pain Assessment Device (OPAD) assesses pain behaviors ...

The Crossmodal Congruency Task as a Means to Obtain an Objective Behavioral Measure in the Rubber Hand Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden hand is touched. If the viewed and felt touches are given at the same time then this is sufficient to induce the compelling experience that the rubber hand is one's own hand. The RHI can be used to investigate exactly how the brain constructs distinct body representations for one's own body. Such representations are crucial for successful interactions with the external world. To obtain a subjective measure of the RHI, researchers typically ask participants to rate statements such as "I felt as if the rubber hand were my hand". Here we demonstrate how the crossmodal congruency task can be used to obtain an objective behavioral measure within this paradigm.
The variant of the crossmodal congruency task we employ involves the presentation of tactile targets and visual distractors. Targets and distractors are spatially congruent (i.e. same finger) on some trials and incongruent (i.e. different finger) on others. The difference in performance between incongruent and congruent trials - the crossmodal congruency effect (CCE) - indexes multisensory interactions. Importantly, the CCE is modulated both by viewing a hand as well as the synchrony of viewed and felt touch which are both crucial factors for the RHI.
The use of the crossmodal congruency task within the RHI paradigm has several advantages. It is a simple behavioral measure which can be repeated many times and which can be obtained during the illusion while participants view the artificial hand. Furthermore, this measure is not susceptible to observer and experimenter biases. The combination of the RHI paradigm with the crossmodal congruency task allows in particular for the investigation of multisensory processes which are critical for modulations of body representations as in the RHI.

We demonstrate how an objective measure can be employed in the widely employed rubber hand illusion paradigm. This measure is obtained by modifying the well-established crossmodal congruency task. This task allows the investigation of multisensory processes which are critical for modulations of body representations as in the rubber hand illusion.

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden ...

Studying Food Reward and Motivation in Humans

A key challenge in studying reward processing in humans is to go beyond subjective self-report measures and quantify different aspects of reward such as hedonics, motivation, and goal value in more objective ways. This is particularly relevant for the understanding of overeating and obesity as well as their potential treatments. In this paper are described a set of measures of food-related motivation using handgrip force as a motivational measure. These methods can be used to examine changes in food related motivation with metabolic (satiety) and pharmacological manipulations and can be used to evaluate interventions targeted at overeating and obesity. However to understand food-related decision making in the complex food environment it is essential to be able to ascertain the reward goal values that guide the decisions and behavioral choices that people make. These values are hidden but it is possible to ascertain them more objectively using metrics such as the willingness to pay and a method for this is described. Both these sets of methods provide quantitative measures of motivation and goal value that can be compared within and between individuals.

This article describes a set of methods for the measurement of food related motivation and food related goal values in humans.

A key challenge in studying reward processing in humans is to go beyond subjective self-report measures and quantify different aspects of reward such as ...

Disrupting Reconsolidation of Fear Memory in Humans by a Noradrenergic &#946;-Blocker

The basic design used in our human fear-conditioning studies on disrupting reconsolidation includes testing over different phases across three consecutive days. On day 1 - the fear acquisition phase, healthy participants are exposed to a series of picture presentations. One picture stimulus (CS1+) is repeatedly paired with an aversive electric stimulus (US), resulting in the acquisition of a fear association, whereas another picture stimulus (CS2-) is never followed by an US. On day 2 - the memory reactivation phase, the participants are re-exposed to the conditioned stimulus without the US (CS1-), which typically triggers a conditioned fear response. After the memory reactivation we administer an oral dose of 40 mg of propranolol HCl, a &#946;-adrenergic receptor antagonist that indirectly targets the protein synthesis required for reconsolidation by inhibiting the noradrenaline-stimulated CREB phosphorylation. On day 3 - the test phase, the participants are again exposed to the unreinforced conditioned stimuli (CS1- and CS2-) in order to measure the fear-reducing effect of the manipulation. This retention test is followed by an extinction procedure and the presentation of situational triggers to test for the return of fear. Potentiation of the eye blink startle reflex is measured as an index for conditioned fear responding. Declarative knowledge of the fear association is measured through online US expectancy ratings during each CS presentation. In contrast to extinction learning, disrupting reconsolidation targets the original fear memory thereby preventing the return of fear. Although the clinical applications are still in their infancy, disrupting reconsolidation of fear memory seems to be a promising new technique with the prospect to persistently dampen the expression of fear memory in patients suffering from anxiety disorders and other psychiatric disorders.

Disrupting Reconsolidation of Fear Memory in Humans by a Noradrenergic &amp;#946;-Blocker

Disrupting reconsolidation is a promising approach to dampen the behavioral expression of fear memory in patients with anxiety disorders or posttraumatic stress disorder. In a series of human fear conditioning studies we showed that disrupting reconsolidation by the noradrenergic &#946;-blocker propranolol is very effective in erasing conditioned fear responding.

The basic design used in our human fear-conditioning studies on disrupting reconsolidation includes testing over different phases across three consecutive ...

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.

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 ...

Force and Position Control in Humans - The Role of Augmented Feedback

During motor behaviour, humans interact with the environment by for example manipulating objects and this is only possible because sensory feedback is constantly integrated into the central nervous system and these sensory inputs need to be weighted in order meet the task specific goals. Additional feedback presented as augmented feedback was shown to have an impact on motor control and motor learning. A number of studies investigated whether force or position feedback has an influence on motor control and neural activation. However, as in the previous studies the presentation of the force and position feedback was always identical, a recent study assessed whether not only the content but also the interpretation of the feedback has an influence on the time to fatigue of a sustained submaximal contraction and the (inhibitory) activity of the primary motor cortex using subthreshold transcranial magnetic stimulation. This paper describes one possible way to investigate the influence of the interpretation of feedback on motor behaviour by investigating the time to fatigue of submaximal sustained contractions together with the neuromuscular adaptations that can be investigated using surface EMG. Furthermore, the current protocol also describes how motor cortical (inhibitory) activity can be investigated using subthreshold TMS, a method known to act solely on the cortical level. The results show that when participants interpret the feedback as position feedback, they display a significantly shorter time to fatigue of a submaximal sustained contraction. Furthermore, subjects also displayed an increased inhibitory activity of the primary cortex when they believed to receive position feedback compared when they believed to receive force feedback. Accordingly, the results show that interpretation of feedback results in differences on a behavioural level (time to fatigue) that is also reflected in interpretation-specific differences in the amount of inhibitory M1 activity.

Controlling an identical movement with position or force feedback results in different neural activation and motor behavior. This protocol describes how to investigate behavioral changes by looking at neuromuscular fatigue and how to evaluate motor cortical (inhibitory) activity using subthreshold TMS with respect to the interpretation of augmented feedback.

During motor behaviour, humans interact with the environment by for example manipulating objects and this is only possible because sensory feedback is ...

Psychophysical Tracking Method to Measure Taste Preferences in Children and Adults

The Monell two-series, forced-choice, paired-comparison tracking method provides a reliable measure of sweet taste preferences from childhood to adulthood. The method, which is identical for children, adolescents, and adults, is of short duration (&#60; 15 min), does not rely on sustained attention or place demands on memory (which would yield spurious age differences), and minimizes the impact of language development, making this method amenable to the cognitive limitations of pediatric populations. In this whole-mouth tasting method, subjects are asked to taste (without swallowing) pairs of solutions of different sucrose concentrations and to point to the solution they prefer. Each subsequent pair contains the participant&#39;s preceding preferred concentration and an adjacent stimulus concentration. The procedure continues until the subject chooses either a given concentration of sucrose when paired with both a higher and a lower concentration, or the highest or lowest concentration two consecutive times. Subjects are prevented from reaching response criteria on the basis of first or second position bias by the two-series design of the method, which counterbalances the order of solution presentation within each pair between the series (the weaker concentration is presented first in Series 1, second in Series 2). The geometric mean of the two sucrose concentrations chosen in Series 1 and 2 is an estimate of the participant&#39;s most preferred level of sucrose. Sucrose preference as determined with this laboratory-based measure has been shown to be associated with preference for sugars in foods and beverages and with taste receptor genotype, family history of alcoholism, and race/ethnicity, as well as depressive symptomatology among pediatric populations. The method has real-world relevance and has been applied to determine most preferred level of other tastes (e.g., salt), making it a valuable psychophysical tool.

Sweet taste has powerful hedonic appeal among people of all ages, particularly children. Described herein is a reliable and valid method that can be used to determine the level of sweetness most preferred, making it a valuable psychophysical tool for scientists.

The Monell two-series, forced-choice, paired-comparison tracking method provides a reliable measure of sweet taste preferences from childhood to ...

Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans

Prehension, the act of reaching to grasp an object, is central to the human experience. We use it to feed ourselves, groom ourselves, and manipulate objects and tools in our environment. Such behaviors are impaired by many sensorimotor disorders, yet our current understanding of their neural control is far from complete. Current technologies for investigating human reach-to-grasp movements often utilize motion tracking systems that can be expensive, require the attachment of markers or sensors to the hands, impede natural movement and sensory feedback, and provide kinematic output that can be difficult to interpret. While generally effective for studying the stereotypical reach-to-grasp movements of healthy sighted adults, many of these technologies face additional limitations when attempting to study the unpredictable and idiosyncratic reach-to-grasp movements of young infants, unsighted adults, and patients with neurological disorders. Thus, we present a novel, inexpensive, and highly reliable yet flexible protocol for quantifying the temporal and kinematic structure of idiosyncratic reach-to-grasp movements in humans. High speed video cameras capture multiple views of the reach-to-grasp movement. Frame-by-frame video analysis is then used to document the timing and magnitude of pre-defined behavioral events such as movement start, collection, maximum height, peak aperture, first contact, and final grasp. The temporal structure of the movement is reconstructed by documenting the relative frame number of each event while the kinematic structure of the hand is quantified using the ruler or measure function in photo editing software to calibrate 2 dimensional linear distances between two body parts or between a body part and the target. Frame-by-frame video analysis can provide a quantitative and comprehensive description of idiosyncratic reach-to-grasp movements and will enable researchers to expand their area of investigation to include a greater range of naturalistic prehensile behaviors, guided by a wider variety of sensory modalities, in both healthy and clinical populations.

This protocol describes how to use frame-by-frame video analysis to quantify idiosyncratic reach-to-grasp movements in humans. A comparative analysis of reaching in sighted versus unsighted healthy adults is used to demonstrate the technique, but the method can also be applied to the study of developmental and clinical populations.

Prehension, the act of reaching to grasp an object, is central to the human experience. We use it to feed ourselves, groom ourselves, and manipulate ...

An Electrophysiology Protocol to Measure Reward Anticipation and Processing in Children

We present a protocol designed to measure the neural correlates of reward in children. The protocol allows researchers to measure both reward anticipation and processing. Its purpose is to create a reward task that is appropriate for young children with and without autism while controlling reward properties between two conditions: social and nonsocial. The current protocol allows for comparisons of brain activity between social and nonsocial reward conditions while keeping the reward itself identical between conditions. Using this protocol, we found evidence that neurotypical children demonstrate enhanced anticipatory brain activity during the social condition. Furthermore, we found that neurotypical children anticipate social reward more robustly than children with autism diagnoses. As the task uses snacks as a reward, it is most appropriate for young children. However, the protocol may be adapted for use with adolescent or adult populations if snacks are replaced by monetary incentives. The protocol is designed to measure electrophysiological events (event-related potentials), but it may be customized for use with eye-tracking or fMRI.

This protocol is designed to measure reward anticipation and processing in young children with and without autism. Specifically, the protocol is designed to study the neural correlates of reward during social and nonsocial conditions while controlling for reward between conditions.

We present a protocol designed to measure the neural correlates of reward in children. The protocol allows researchers to measure both reward anticipation ...

Simultaneous Recordings of Cortical Local Field Potentials and Electrocorticograms in Response to Nociceptive Laser Stimuli from Freely Moving Rats

Electrocortical responses, elicited by laser heat pulses that selectively activate nociceptive free nerve endings, are widely used in many animal and human studies to investigate the cortical processing of nociceptive information. These laser-evoked brain potentials (LEPs) consist of several transient responses that are time-locked to the onset of laser stimuli. However, the functional properties of the LEP responses are still largely unknown, due to the lack of a sampling technique that can simultaneously record neural activities at the surface of the cortex (i.e., electrocorticogram [ECoG] and scalp electroencephalogram [scalp EEG]) and inside the brain (i.e., local field potential [LFP]). To address this issue, we present here an animal protocol using freely moving rats. This protocol is composed of three main procedures: (1) animal preparation and surgical procedures, (2) a simultaneous recording of ECoG and LFP in response to nociceptive laser stimuli, and (3) data analysis and feature extraction. Specifically, with the help of a 3D-printed protective shell, both ECoG and LFP electrodes implanted on the rat&#39;s skull were securely held together. During data collection, laser pulses were delivered on the rat&#39;s forepaws through gaps in the bottom of the chamber when the animal was in spontaneous stillness. Ongoing white noise was played to avoid the activation of the auditory system by the laser-generated ultrasounds. As a consequence, only nociceptive responses were selectively recorded. Using the standard analytical procedures (e.g., band-pass filtering, epoch extraction, and baseline correction) to extract stimulus-related brain responses, we obtained results showing that LEPs with a high signal-to-noise ratio were simultaneously recorded from ECoG and LFP electrodes. This methodology makes the simultaneous recording of ECoG and LFP activities possible, which provides a bridge of electrocortical signals at the mesoscopic and macroscopic levels, thereby facilitating the investigation of nociceptive information processing in the brain.

We developed a technique that simultaneously records both electrocorticography and local field potentials in response to nociceptive laser stimuli from freely moving rats. This technique helps establish a direct relationship of electrocortical signals at the mesoscopic and macroscopic levels, which facilitates the investigation of nociceptive information processing in the brain.

Electrocortical responses, elicited by laser heat pulses that selectively activate nociceptive free nerve endings, are widely used in many animal and ...