In this model the rats or mice were given food and water ad libitum. The Texas A&#38;M University Baylor College of Dentistry Institutional Animal Care and Use Committee approved all the experimental protocols. Below specific settings are shown in italics and are utilized specifically for the rat TMJ arthritis model. Mice can also be utilized in this model and alternative tooth pain and myogenic orofacial pain animal models can be used as well42,43.
1. Software Settings
<ol>
	<li>Load the Animal Monitor software for the feeder units onto the computer.</li>
	<li>The Animals Monitor software is now opened by clicking on the icon and under the file menu selection choose the &#34;configuration&#34; pull down option.</li>
	<li>In the &#34;Animal Monitor Configuration&#34; window uncheck the box entitled &#34;Pellet Delivered Input&#34; (Figure 1A). 
	Note: This box is usually checked at the factory by default. Deselect this option. Once the investigator deselects this option the results are being recorded by removal of a pellet from the trough rather than when a pellet is being dispensed. 
	Note: When the &#34;Automatic File Naming&#34; box is checked the software will automatically name the files (Figure&#160;1A). This box is usually checked at the factory by default.</li>
	<li>Set the timer lights to turn on at 06:00 (6:00 am) and to turn off at 20:00 (8:00 pm). 
	Note: the hardware for the feeders units was modified so that the lights within the boxes are not controlled by the software but are wired instead to an isolated 24 hr&#160;timer. Thus, the &#34;House Light&#34; indicated on the configuration software was not functional in these examples.</li>
	<li>Select the edit pull down menu and choose Experiment. A window with the title &#34;Box 01 -&#34; appears (Figure&#160;1B).</li>
	<li>Input the file name under which the data will be saved within this window. 
	Note: if no file name is entered the data files will be automatically named by the software. Details of the experiment can be added in this window and saved with the data files. The information on the window can also be saved and used for subsequent experiments.</li>
	<li>Enter a number greater than the total time of the experiment in the entry box entitled &#34;Experiment Length (Days):&#34;. 
	Note: This will ensure that the software saves the data until the experiment is complete, a mistake can be in setting this value too short, which will stop the software from recording the data even though animals are still in the feeding modules.</li>
	<li>Enter 24 in the entry box entitled &#34;Number of Hours in a Day&#34;. 
	Note: the length can be modified to the experimenter&#39;s specifications.</li>
	<li>Enter 10 in the box entitled &#34;Meal Period End Criteria (min):&#34; 
	Note: for rats a meal was defined using a 10 min end of meal criterion based on previous studies48 (i.e.&#160;a meal was bracketed before and after by a 10 min period of no pellets being taken) and the minimum meal size was set at three pellets per meal in this software package.</li>
	<li>Enter 45 in the box entitled &#34;Pellet Size (mg)&#34;.&#160;If an individual wanted to use mice input 20 within this window.</li>
	<li>For rats add 45 mg rodent chow pellets to the feeder dispenser hopper. 
	Note: for mice add 20 mg rodent chow pellets to the chow hopper.</li>
	<li>In the &#34;Phase&#34; section of the Experiment window enter the term Day in the &#34;Name&#34; field and in the &#34;# of Hours&#34; field type 24 (Figure 1B). 
	Note: below the &#34;Phase&#34; section there are two large open fields. The first large open field will be populated by the text entered in the previous &#34;Phase&#34; and &#34;Name&#34; fields.</li>
	<li>The next large open field will have the &#34;Day Phase&#34; header Enter in the field entitled &#34;Name&#34; the word Light and enter in the field entitled &#34;Percent&#34; the number 60. 
	Note: this entered text will populate the large field below.</li>
	<li>Next enter in the field entitled &#34;Name&#34; the word Dark and enter in the field entitled &#34;Percent&#34; the number 40.&#160;Note: with these entries 60% of the day will be attributed to the light phase and 40% will be attributed to the dark phase. When the software calculates the meal patterns this information will be used. These settings typical for cycling female animals that are kept on a 14:10 light/dark cycle.</li>
	<li>Select the &#34;Set All Boxes Like This&#34; button. Save this information and then hit OK.</li>
	<li>The &#34;Start Boxes&#34; screen appears, select the feeders to activate and hit OK (Figure&#160;1C).</li>
	<li>Next the Animal Monitor Run-Time windows will appear with the meal pattern data (Figure&#160;1D). 
	Note: monitor and record the &#34;# of Pellets Dispensed&#34; from this window to determine the current health of the rat. A healthy male rat weighing around 300 g will typically eat between 300-800&#160;45 mg pellets a day.</li>
	<li>Files are generated daily and automatically saved that have a .CSV extension. Open these files to retrieve meal pattern data such as food intake, meal number, meal duration, meal size, or intermeal interval. The intervals for these meal patterns can be calculated for the entire day or for a phase of the day such as the Dark and Light phase. As noted above, the settings are for a 14:10 light/dark cycle. The raw data of when each pellet was removed from the trough is also recorded as a raw .CSV&#160;file. 
	Note: In older versions of the software a minimum meal size of 3 pellets is not used in the calculations for generating the .CSV file.&#160; Moreover, to get the average meal duration using the older software you must subtract 10 min from the values in the Average Meal Duration column of the .CSV file. 
	When the software is operating the operator can manually select the file pull down menu option and daily select &#34;save raw data&#34;. This will save the raw data for a 24 hr period rather than for the entire experiment. This raw data can be processed by alternative software at the user&#39;s discretion. 
	Note: in the results shown we used alternative software to include a minimum meal size of 3 pellets.</li>
</ol>
2. Meal Duration Assay
<ol>
	<li>Place individual rats in the sound-attenuated chambers equipped with photobeam computer-activated pellet feeders. 
	Note: in these feeding units there are graduated water bottles and waste pans in which a sheet of thick absorbent paper is placed. In the feeder dispenser hopper 45 mg rodent chow pellets can be added for rats or 20 mg rodent chow pellets can be added for mice. Chow pellets are dispensed into a V shaped feeding trough and at the bottom of this trough is a photobeam. A pellet dispensed into the trough will be detected by breaking this photobeam. Once a rat removes this pellet from the feeder trough the photobeam is restored and this signals the computer to drop another pellet. Restoration of the photobeam also triggers the computer to record the date and time and keeps a running tally of the pellets dispensed. This tally of pellets is then analyzed to determine food intake, meal number, meal duration, meal size, or intermeal interval during any part of the day using Med Assoc. Inc. software. Again the raw .CSV&#160;data file can be analyzed by outside software39,40,49-51.</li>
	<li>Record the total number of pellets eaten, the amount of water consumed and the weight of the animals to discern the general health of the rats during the experimentation.</li>
	<li>Rinse water bottles and fill with fresh water daily and add chow to the feeder hopper when needed.</li>
	<li>Dump waste pan and the thick absorbent paper beneath the cage daily and blow the dust from moving part of the feeder daily using high pressure air. 
	Note: personal protection equipment (e.g.&#160;gowns, gloves, masks, and masks) is required.</li>
	<li>Remove floors, waste pans and water bottles after the experiment is completed and wash these components. Also, remove the feeding electronics from the caging wash by hand or in a dishwasher.</li>
</ol>
3. Induction of TMJ Arthritis
<ol>
	<li>Place animals in the feeders at least 4 days before experimentation. 
	Note: this data will be reported as predays to obtain a baseline feeding behavior. Then the animals are removed from the feeder for treatment. One type of treatment was to induce an arthritic TMJ. For this model rats are injected with complete Freund&#39;s adjuvant (CFA) at 08:00 (i.e.&#160;beginning of the light phase) after the rats are anesthetized with isoflurane (5% flow).</li>
	<li>Inject 250 mg of CFA in 50 L bilaterally into the periarticular space of each TMJ. 
	Note: in the example (Figure&#160;2) 250 mg of CFA in 50 L was injected into each TMJ, but doses as low as 10 mg in volumes as small as 15 &#956;l are effective over shorter periods of time52.</li>
	<li>Inject control rats TMJ with 50 L of 0.9% saline. Note: all animals were mobile within 5 min or less after induction of anesthesia. In the event that a smaller dose of CFA is given in a lesser volume the control rats would receive this same volume of saline.</li>
</ol>

There is nothing to disclose.

TMJ patients with orofacial pain report increased pain with increased chewing time, such that, the chewing cycle lengthens the longer the individual has been chewing45,53-56. Our behavioral assay allows for similar testing in rats and mice when measuring meal duration39. A recent unpublished study suggested that von Frey filament testing had greater sensitivity than meal duration measurements, showing a significant change for a longer period but von Frey filament testing can have a reflex response c...

Animal models have been used to study pain and nociception associated with orofacial damage and or inflammation1,2, but a lack of appropriate animal models results in an incomplete understanding of the mechanisms. Although current models help us to understand various mechanisms involved in acute and chronic orofacial pain, there are strengths and weaknesses to these animal models.
Many models measure behavioral nociceptive responses for short durations. Face grooming is a known behavioral response following constriction of facial nerves3. Others studies measured facial rubbing with the ipsilateral fore or hindpaw, as well as, flinching of the head after administering formalin injections into the temporomandibular joint (TMJ) or lip4-7. Head withdrawal latencies is another model for measuring nociceptive behavior where a modified tail flick analgesia meter is used to quantitate the nociceptive response (i.e.&#160;head withdrawal) after applying heat to the shaved vibrissae pad of a rat8. Digastric and masseter muscle activity has also been recorded as a correlate of pain after glutamate injections into the TMJ9. Another study has measured changes in sleep parameters to assess nociceptive responses in male and female rats with an inflamed TMJ, these parameters included sleep latency, rapid-eye-movement (REM), percentage of non-REM sleep, and percentage of REM sleep10. Most animal models that measure behavioral nociceptive responses utilize a short time frame, i.e.&#160;minutes to hours per day11-14. In addition, most animal models testing occurs during the light phase and in a nocturnal animal, like a rat, this can cause stress which can confound the nociceptive results15-18. The above assays measure nociceptive response in varying orofacial conditions but for short duration and hence can only be used to study acute disorders. An alternative assay has used facial expression as a measure of nociception of moderate duration, but this methodology can be subjective19.
To evaluate persistent or chronic orofacial nociception some have used the application of a von Frey filament on the surface of the skin to assess mechanical sensitivity of animals subjected to nerve constriction or TMJ inflammation3,20. Liverman et al. 2009 measured withdrawal responses using graded monofilaments following CFA injections into the masseter muscle of rats 21,22. Yamazaki et al.&#160;2008 injected the TMJ with CFA and then over 14 days quantified nociceptive behaviors to mechanical or heat or cold stimulation applied over the TMJ region. Unfortunately, these nociceptive behavioral assays involve animal restraint, which produce stress hormones, learning or alternative behaviors that may interfere with the measured outcomes.
Models to measure nociception in teeth utilize the jaw opening reflex but this method can be unreliable23 or imprecise24. Electromyographic activity has been used to measure tooth nociception25, but this method typically requires that the animal be unconscious, although in one study tooth nociception was investigated in freely moving rats26. In 2008, Khan studied the relationship between dental nociception and masticatory function using a sensitive strain gauge27 but this bite duration model requires restraining the animal from normal activity 28. Bite force is a reliable measure of tooth pain in humans but because rats require training and/or restraint to measure bite force a source of stress is introduced which can produce findings with questionable physiological significance29-31
Some limitations of restraint and stress can be overcome by using an operant design to assess nociceptive behaviors. One operant model uses avoidance of an uncomfortable temperature to evaluate and characterize orofacial nociception32-35. This reward-conflict model is based on a reward of sweetened milk to induce the rodent to position its face voluntarily against a heated or cooled thermal probe34,36. However, the test requires animal training, but a strength of the assay is the data is collected in an automated fashion.&#160;
Still another animal model used nociception-induced gnawing dysfunction as an index of orofacial nociception37. However, the rodent is confined to a tube and its only escape is to gnaw through a dowel to exit. An advantage of this model is that it measures jaw function after acute or chronic jaw injury in mice. However, the rodent is confined, which adds a confounding alternate competing behavior, i.e.&#160;escape, which would be stressful and thus could influence the nociception assay results.
Meal duration has been used to measure nociception in animals with TMJ arthritis38-41, tooth pulp exposure42, and muscle damage43. A rodent who experienced orofacial nociception ate more slowly after the animal initiated a meal. Patients experiencing TMJ pain also take longer to chew their food and the cycle length shortens when TMJ pain is diminished44-46. The lengthening of meal duration when TMJ pain is present is expected to be a &#34;guarding behavior&#34;, operationally defined as nociceptive behavior47.
Meal duration measures TMJ nociception using a noninvasive method for up to 19 days in male and female rats and 6 days (longest period tested) in male mice and could be described as a biological marker of nociception38-41. In support that meal duration measures nociceptive responses, nociception can be reduced by pharmacological intervention causing the animal&#39;s meal duration to return to normal38,40,41. This was also confirmed when nociceptive neurons were destroyed using capsaicin; after nerve destruction the animals meal duration was not increased following injection of CFA into the TMJ 40.
Below is the protocol on how to obtain and statistically analyze meal duration data.

<table border="0" cellpadding="0" cellspacing="0" width="899">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:335px;">Animal Monitor software</td>
			<td style="width:92px;">Med Assoc. Inc</td>
			<td style="width:137px;">SOF-710</td>
			<td style="width:335px;">East Fairfield, VT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:335px;"></td>
			<td style="width:92px;"></td>
			<td style="width:137px;"></td>
			<td style="width:335px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Dustless Precision Pellets, Rodent, Grain-Based&#160;</td>
			<td style="width:92px;">Bio-Serv</td>
			<td>F0165</td>
			<td style="width:335px;">45 mg pellets, 50,000/box</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Dustless Precision Pellets, Rodent, Grain-Based&#160;</td>
			<td style="width:92px;">Bio-Serv</td>
			<td style="width:137px;">FO163</td>
			<td style="width:335px;">20 mg pellets</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;">Complete Freund&#39;s Adjuvant</td>
			<td style="width:92px;">Chondrex, Inc.</td>
			<td style="width:137px;">7001</td>
			<td style="width:335px;">No loger provides the 5 mg/ml concentration.&#160; Can use CFA from other sources as long as the investigator consistently uses this source</td>
		</tr>
	</tbody>
</table>

meal duration as a measure of orofacial nociceptive responses in rodents

A lengthening in meal duration can be used to measure an increase in orofacial mechanical hyperalgesia having similarities to the guarding behavior of humans with orofacial pain. To measure meal duration unrestrained rats are continuously kept in sound attenuated, computerized feeding modules for days to weeks to record feeding behavior. These sound-attenuated chambers are equipped with chow pellet dispensers. The dispenser has a pellet trough with a photobeam placed at the bottom of the trough and when a rodent removes a pellet from the feeder trough this beam is no longer blocked, signaling the computer to drop another pellet. The computer records the date and time when the pellets were taken from the trough and from this data the experimenter can calculate the meal parameters. When calculating meal parameters a meal was defined based on previous work and was set at 10 min (in other words when the animal does not eat for 10 min that would be the end of the animal&#39;s meal) also the minimum meal size was set at 3 pellets. The meal duration, meal number, food intake, meal size and inter-meal interval can then be calculated by the software for any time period that the operator desires. Of the feeding parameters that can be calculated meal duration has been shown to be a continuous noninvasive biological marker of orofacial nociception in male rats and mice and female rats. Meal duration measurements are quantitative, require no training or animal manipulation, require cortical participation, and do not compete with other experimentally induced behaviors. These factors distinguish this assay from other operant or reflex methods for recording orofacial nociception.

Meal duration is a behavioral correlate of orofacial pain and meal duration measurements have been applied to animals with TMJ arthritis (Figure 2) and tooth decay (Figure&#160;3). In one experiment, rats had TMJ arthritis after administering a high 250 mg dose of CFA and this treatment induced a significant increase in meal duration for 19 days (Figure&#160;2). A lower dose of CFA (10 mg) injected into each TMJ joint produced a smaller increase in meal duration for only...

Watch this Scientific Journal Video about Meal Duration as a Measure of Orofacial Nociceptive Responses in Rodents at JoVE.com

Meal Duration as a Measure of Orofacial Nociceptive Responses in Rodents

A lengthening in meal duration represents orofacial nociceptive behavior in rodents similar to the guarding behavior of humans with orofacial pain. Eating is a behavior that requires no training or animal manipulation, requires cortical participation, and is not competing with other experimentally induced behaviors, distinguishing this assay from alternative reflex or operant measurements.

A lengthening in meal duration can be used to measure an increase in orofacial mechanical hyperalgesia having similarities to the guarding behavior of ...

meal-duration-as-measure-orofacial-nociceptive-responses

Research

JoVE Journal

Behavior

7.5K Views.  Texas A&M University Baylor College of Dentistry. A lengthening in meal duration represents orofacial nociceptive behavior in rodents similar to the guarding behavior of humans with orofacial pain. Eating is a behavior that requires no training or animal manipulation, requires cortical participation, and is not competing with other experimentally induced behaviors, distinguishing this assay from alternative reflex or operant measurements.

Video: Meal Duration as a Measure of Orofacial Nociceptive Responses in Rodents

Using Chronic Social Stress to Model Postpartum Depression in Lactating Rodents

Exposure to chronic stress is a reliable predictor of depressive disorders, and social stress is a common ethologically relevant stressor in both animals and humans. However, many animal models of depression were developed in males and are not applicable or effective in studies of postpartum females. Recent studies have reported significant effects of chronic social stress during lactation, an ethologically relevant and effective stressor, on maternal behavior, growth, and behavioral neuroendocrinology. This manuscript will describe this chronic social stress paradigm using repeated exposure of a lactating dam to a novel male intruder, and the assessment of the behavioral, physiological, and neuroendocrine effects of this model. Chronic social stress (CSS) is a valuable model for studying the effects of stress on the behavior and physiology of the dam as well as her offspring and future generations. The exposure of pups to CSS can also be used as an early life stress that has long term effects on behavior, physiology, and neuroendocrinology.

This article describes the use of chronic resident intruder social stress as an ethologically relevant paradigm to model postpartum depression and anxiety in lactating rodents.

Exposure to chronic stress is a reliable predictor of depressive disorders, and social stress is a common ethologically relevant stressor in both animals ...

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 ...

The Attentional Set Shifting Task: A Measure of Cognitive Flexibility in Mice

Cognitive impairment, particularly involving dysfunction of circuitry within the prefrontal cortex (PFC), represents a core feature of many neuropsychiatric and neurodevelopmental disorders, including depression, post-traumatic stress disorder, schizophrenia and autism spectrum disorder. Deficits in cognitive function also represent the most difficult symptom domain&#160;to successfully treat, as serotonin reuptake inhibitors and tricyclic antidepressants have only modest effects. Functional neuroimaging studies and postmortem analysis of human brain tissue implicate the PFC as being a primary region of dysregulation in patients with these disorders. However, preclinical behavioral assays used to assess these deficits in mouse models which can be readily manipulated genetically and could provide the basis for studies of new treatment avenues have been underutilized. Here we describe the adaptation of a behavioral assay, the attentional set shifting task (AST), to be performed in mice to assess prefrontal cortex mediated cognitive deficits. The neural circuits underlying behavior during the AST are highly conserved across humans, nonhuman primates and rodents, providing excellent face, construct and predictive validity.

The goal of this protocol is to perform a behavioral assay such as the attentional set shifting task (AST) to assess prefrontal cortex-mediated cognitive flexibility in mice.

Cognitive impairment, particularly involving dysfunction of circuitry within the prefrontal cortex (PFC), represents a core feature of many ...

A Method for Remotely Silencing Neural Activity in Rodents During Discrete Phases of Learning

This protocol describes how to temporarily and remotely silence neuronal activity in discrete brain regions while animals are engaged in learning and memory tasks. The approach combines pharmacogenetics (Designer-Receptors-Exclusively-Activated-by-Designer-Drugs) with a behavioral paradigm (sensory preconditioning) that is designed to distinguish between different forms of learning. Specifically, viral-mediated delivery is used to express a genetically modified inhibitory G-protein coupled receptor (the Designer Receptor) into a discrete brain region in the rodent. Three weeks later, when designer receptor expression levels are high, a pharmacological agent (the Designer Drug) is administered systemically 30 min prior to a specific behavioral session. The drug has affinity for the designer receptor and thus results in inhibition of neurons that express the designer receptor, but is otherwise biologically inert. The brain region remains silenced for 2-5 hr (depending on the dose and route of administration). Upon completion of the behavioral paradigm, brain tissue is assessed for correct placement and receptor expression. This approach is particularly useful for determining the contribution of individual brain regions to specific components of behavior and can be used across any number of behavioral paradigms.

This protocol describes how to temporarily and remotely silence neuronal activity in discrete brain regions while rats are engaged in learning and memory tasks. The approach combines pharmacogenetics (Designer-Receptors-Exclusively-Activated-by-Designer-Drugs) with a behavioral paradigm (sensory preconditioning) that is designed to distinguish between different components of learning.

This protocol describes how to temporarily and remotely silence neuronal activity in discrete brain regions while animals are engaged in learning and ...

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.

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 ...

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 ...

Feeding Experimentation Device (FED): Construction and Validation of an Open-source Device for Measuring Food Intake in Rodents

Food intake measurements are essential for many research studies. Here, we provide a detailed description of a novel solution for measuring food intake in mice: the Feeding Experimentation Device (FED). FED is an open-source system that was designed to facilitate flexibility in food intake studies. Due to its compact and battery powered design, FED can be placed within standard home cages or other experimental equipment. Food intake measurements can also be synchronized with other equipment in real-time via FED's transistor-transistor logic (TTL) digital output, or in post-acquisition processing as FED timestamps every event with a real-time clock. When in use, a food pellet sits within FED's food well where it is monitored via an infrared beam. When the pellet is removed by the mouse, FED logs the timestamp onto its internal secure digital (SD) card and dispenses another pellet. FED can run for up to 5 days before it is necessary to charge the battery and refill the pellet hopper, minimizing human interference in data collection. Assembly of FED requires minimal engineering background, and off-the-shelf materials and electronics were prioritized in its construction. We also provide scripts for analysis of food intake and meal patterns. Finally, FED is open-source and all design and construction files are online, to facilitate modifications and improvements by other researchers.

Feeding Experimentation Device FED: Construction and Validation of an Open-source Device for Measuring Food Intake in Rodents

Feeding Experimentation Device (FED) is an open-source device for measuring food intake in mice. FED can also synchronize food intake measurements with other techniques via a real-time digital output. Here, we provide a step-by-step tutorial for the construction, validation, and usage of FED.

Food intake measurements are essential for many research studies. Here, we provide a detailed description of a novel solution for measuring food intake in ...

Noninvasive, High-throughput Determination of Sleep Duration in Rodents

Traditionally, sleep is monitored by an electroencephalogram (EEG). EEG studies in rodents require surgical implantation of the electrodes followed by a long recovery period. To perform an EEG recording, the animal is connected to a receiver, creating an unnatural tether to the head-mount. EEG monitoring is time consuming, carries risk to the animal, and is not a completely natural setting for the measurement of sleep. Alternative methods to detect sleep, particularly in a high-throughput fashion, would greatly advance the field of sleep research. Here, we describe a validated method for detecting sleep via activity-based home-cage monitoring. Previous studies have shown that sleep assessed via this method has a high degree of agreement with sleep defined by traditional EEG-based measures. Whereas this method is validated for total sleep time, it is important to note that sleep bout duration should be assessed by an EEG which has better temporal resolution. The EEG can also differentiate rapid eye movement (REM) and non-REM sleep, giving more detail about the exact nature of sleep. Nevertheless, activity-based sleep determination can be used to analyze multiple days of undisturbed sleep and to assess sleep as a response to an acute event (like stress). Here, we show the power of this system to detect the response of mice to daily intraperitoneal injections.

We describe a high-throughput method of measuring sleep by means of activity-based home-cage monitoring. This method offers advantages over traditional EEG-based methods. It is well validated for the determination of total sleep duration and can be a powerful tool to monitor sleep in rodent models of human disease.

Traditionally, sleep is monitored by an electroencephalogram (EEG). EEG studies in rodents require surgical implantation of the electrodes followed by a ...

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 ...