This research was supported by NASA (NNX15AC17G to CMD), and by NASA cooperative agreement NCC 9-58 (E000010 to CMD, NBPF02802 and NBPF04201 to RDH) with the National Space Biomedical Research Institute.

Laboratory animal care was according to Public Health Service (PHS) Policy on the Humane Care and Use of Laboratory Animals. All procedures were carried out in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. The Institutional Animal Care and Use Committee of the Johns Hopkins University approved the protocol and all procedures. Johns Hopkins also maintains accreditation of their program by the Association for the Assessment and Accreditation of Laborator...

<ol>
	<li>Dinges, D. F., Orne, M. T., Whitehouse, W. G., Orne, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+placement+of+a+nap+for+alertness:+contributions+of+circadian+phase+and+prior+wakefulness.">Temporal placement of a nap for alertness: contributions of circadian phase and prior wakefulness.</a> Sleep. 10, 313-329 (1987).</li><li>Dinges, D. F., Powell, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microcomputer+analyses+of+performance+on+a+portable,+simple+visual+RT+task+during+sustained+operations.">Microcomputer analyses of performance on a portable, simple visual RT task during sustained operations.</a> Behav Res Method Inst Comp. 17, 652-655 (1985).</li><li>Kribbs, N. 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P., 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=Caffeine+eliminates+psychomotor+vigilance+deficits+from+sleep+inertia.">Caffeine eliminates psychomotor vigilance deficits from sleep inertia.</a> Sleep. 24 (7), 813-819 (2001).</li><li>Blatter, K., 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=Gender+and+age+differences+in+psychomotor+vigilance+performance+under+differential+sleep+pressure+conditions.">Gender and age differences in psychomotor vigilance performance under differential sleep pressure conditions.</a> Behav Brain Res. 168 (2), 312-317 (2006).</li><li>Lim, J., Dinges, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sleep+deprivation+and+vigilant+attention.">Sleep deprivation and vigilant attention.</a> Annals of the New York Academy of Sciences. 1129, 305-322 (2008).</li><li>Basner, M., 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=Mars+520-d+mission+simulation+reveals+protracted+crew+hypokinesis+and+alterations+of+sleep+duration+and+timing.">Mars 520-d mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing.</a> Proc Natl Acad Sci U S A. 110, 2635-2640 (2013).</li><li>Christie, M. A., 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=Microdialysis+elevation+of+adenosine+in+the+basal+forebrain+produces+vigilance+impairments+in+the+rat+psychomotor+vigilance+task.">Microdialysis elevation of adenosine in the basal forebrain produces vigilance impairments in the rat psychomotor vigilance task.</a> Sleep. 31, 1393-1398 (2008).</li><li>Christie, M. A., McKenna, J. T., Connolly, N. P., McCarley, R. W., Strecker, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=24+hours+of+sleep+deprivation+in+the+rat+increases+sleepiness+and+decreases+vigilance:+introduction+of+the+rat-psychomotor+vigilance+task.">24 hours of sleep deprivation in the rat increases sleepiness and decreases vigilance: introduction of the rat-psychomotor vigilance task.</a> J. Sleep Res. 17, 376-384 (2008).</li><li>Oonk, M., Davis, C. J., Krueger, J. M., Wisor, J. P., Van Dongen, H. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rodent+model+of+the+human+psychomotor+vigilance+test:+Performance+comparisons.">A rodent model of the human psychomotor vigilance test: Performance comparisons.</a> J Neurosci Methods. 259, 57-71 (2016).</li><li>Lim, 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=Imaging+brain+fatigue+from+sustained+mental+workload:+an+ASL+perfusion+study+of+the+time-on-task+effect.">Imaging brain fatigue from sustained mental workload: an ASL perfusion study of the time-on-task effect.</a> Neuroimage. 49, 3426-3435 (2010).</li><li>Tucker, A. M., Basner, R. C., Stern, Y., Rakitin, B. 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S., Parasuraman, R., Matthews, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vigilance+requires+hard+mental+work+and+is+stressful.">Vigilance requires hard mental work and is stressful.</a> Hum Factors. 50, 433-441 (2008).</li><li>Blatter, K., 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=Gender+and+age+differences+in+psychomotor+vigilance+performance+under+differential+sleep+pressure+conditions.">Gender and age differences in psychomotor vigilance performance under differential sleep pressure conditions.</a> Behav Brain Res. 168, 312-317 (2006).</li><li>Raymann, R. J., Van Someren, E. 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The methodology described herein results in rPVT performances in rats that compare favorably in many aspects to the typical PVT performance reported in the human literature. Using the present techniques, one can quickly train rats to perform the rPVT, and the performances obtained with these techniques are characterized by clear discriminations (i.e., high levels of correct responding, low levels of both premature responding and lapses). Further, the reaction time distributions obtained with the rPVT are quite s...

The human psychomotor vigilance test (PVT) is a widely used, well-validated tool for measuring vigilance and sustained attention in humans, and was originally developed by Dinges et al. 1-3 for assessing the stability in reaction times and attention (e.g., errors in terms of premature responses and lapses in attention), both within sessions as a whole and across time within individual sessions. Over the years, the human PVT has been modified and updated4-11 to track temporal changes in various aspects attention, and has been demonstrated to be sensitive to changes in sleep deprivation and fatigue, and is affected by drug use and age of subjects12,13. The PVT is a seemingly simple procedure in which a subject briefly touches a screen when a stimulus (typically an LED number display) appears randomly in time, typically after 2 - 10 s. In the human version, the number display is incremented in ms and stopped when the screen is touched, thus indicating the subject&#39;s reaction time (RT). Decreases in vigilance are indicated by 1) slowed reaction times, 2) an increase in lapses (termed &#34;errors of omission&#34; in the human literature, and usually defined as RTs that are &#62; 500 ms in length), and 3) an increase in premature responding (termed &#34;errors of commission&#34; or &#34;false starts&#34; in the human literature). Other measures can also be obtained with the PVT for examining such variables as gender and age differences; for a review of these measures, see Basner and Dinges4. Finally, the PVT has been employed in the general area of human risk assessment, and has been successfully used under a wide range of operational areas that include the military, aviation and railway industries, first responders, and extreme environments such as NASA&#39;s Extreme Environment Missions Operations (NEEMO), the international Mars500 Project14, and on the International Space Station (ISS). On the ISS, the PVT is called the &#34;Reaction Self-Test&#34; and is employed to provide astronauts with individualized fatigue-related feedback (e.g., changes in RTs or lapses in attention).
The human PVT has been in use for decades, as have rodent versions of simple reaction time tasks (which are somewhat similar). It has been only recently, however, that a direct rodent counterpart to the human PVT has been reported in the literature. Christie and colleagues described a version of the human PVT for rats, and reported decreases in vigilance following sleep deprivation15,16. Additional recent studies have reported versions of the rPVT17-19. These reports have described changes in sustained attention following various sleep deprivation techniques; however, the data from these studies have also reported high levels of premature responding (e.g., in some cases, more than 40% of the total number of responses); such performances are quite unlike any PVT performances with humans. Such a large difference in rodent vs. human performances are likely due to differences in specific parameters employed in the human vs. the rodent versions of the PVT; for example, the Christie et al. study employed a randomly varying 3 - 7 s foreperiod, while a human PVT normally employs a 2 - 10 s foreperiod (although see Basner et al.5 for a 3-min version of the human PVT that uses a 1 - 4 s foreperiod). The use of relatively short foreperiod values can often result in animals &#34;timing&#34; their responses, and thus can promote, via accidental reinforcement, increased numbers of premature responses, as have been reported in the current rodent rPVT studies.
The version of the rPVT described here is based on our previously published article20, and provides a detailed description of the techniques and procedures involved. It differs from previously published versions of the rPVT in the following respects: 1) rats were trained with variable foreperiod values of 3 - 10 s, and 2) rats had to respond quickly, since only responses within a short response window (also termed a &#34;limited hold&#34;) following stimulus onset were reinforced (1.5 s in the present study; 3.0 s in the previous published versions of the rPVT). Using these modifications as well as brief timeouts for incorrect responding resulted in greater levels of stimulus control, as indicated by significant improvements in accuracy and reduced levels of premature responding. The present report also describes predictable changes in performance variables (e.g., lapses in attention, RTs) that parallel those seen in humans when examining vigilance decrements21, and when examining other performance measures including the human &#34;time on task&#34; effect and the response-stimulus interval (RSI) effect that is observed in the human PVT22.
The final version of the rPVT described here begins by turning on a house light (see Figure 1). After a variable interval (foreperiod) of 3 - 10 s elapses, the nose-poke key is illuminated for a maximum of 1.5 s. (To insure an equal distribution of foreperiods durations, values are randomly generated without replacement from a list of 36 possible values that range from 3 to 10 s, based on 200 ms increments.) Illumination of the nosepoke key is the signal for an animal to respond, and a response that occurs between 150 to 1,500 ms following the light onset is reinforced with a 45-mg pellet. After a reinforced response, both the nose-poke key light and the house light are turned off and a 1 s inter-trial interval (ITI; house light off) ensues. Nose-pokes at before light onset produce an 8 s timeout (TO) from the experimental contingencies that is signaled by extinguishing the house light. If no responses occur within the 1.5 s response window, both the nosepoke light and house light are turned off, and a 1 s ITI ensues. The next scheduled foreperiod value for the subsequent trial begins after either the 1 s ITI or the 8 s TO, whichever occurred during the prior trial. Sessions are conducted daily (5 days/week), normally consist of about 200 trials, and end after 30 min. This results with each trial having a duration of about 7.5 s, on average.
Shaping stable baseline performance on the rPVT is accomplished by 1) initially adapting a rat to take food pellets out of the food tray in the chamber, 2) hand-shaping a rat to respond on a nose poke key by reinforcing successive approximations to the final nose poke response, and 3) conducting daily sessions where the parameters of the rPVT procedure (i.e., foreperiod, ITI, TO, and key-illumination times) are gradually adjusted over a session, depending on how well each rat is performing during each session (described in detail below).

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			<td height="126" style="height:126px;width:315px;">Modular rat operant chamber with stainless steel grid floor</td>
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the rodent psychomotor vigilance test (rpvt): a method for assessing neurobehavioral performance in rats and mice

The human Psychomotor Vigilance Test (PVT) is a widely used procedure for measuring changes in fatigue and sustained attention. The present article describes a rodent version of the PVT&#8212;termed the &#34;rPVT&#34;&#8212;that measures similar aspects of attention (i.e., performance accuracy, motor speed, premature responding, and lapses in attention). Data are presented that demonstrate both the short- and long-term usefulness of the rPVT when employed with laboratory rats. Rats easily learn the rPVT, and learning to perform the basic procedure takes less than two weeks of training. Once acquired, rat performances in the rPVT show a high degree of similarity to these same performance measures in the human PVT, including similarities in, lapses in attention, reaction times, vigilance decrements across session time (i.e., the human &#34;time-on-task&#34; effects), and the response-stimulus interval (RSI) effect described for humans. Thus the rPVT can be an extremely valuable tool for assessing the effects of a wide range of variables on sustained attention quite similar to human PVT performances, and thus can be useful for developing novel treatments for neurobehavioral dysfunctions.

Baseline Rat rPVT Performances
With the parameters detailed here, 86.7% of the 122 male rats reached the final rPVT parameters within an average of 9.0 (SD = 10.13; n = 122) computer-automated training sessions (described in 4.1 - 4.9 rPVT Training; in our experience, only approximately 2% of rats will not acquire the rPVT). Using the current methodology, rats averaged 73.4% correct responding, 18.6% lapses in attention, and 10.6% ...

Watch this Scientific Journal Video about The Rodent Psychomotor Vigilance Test rPVT: A Method for Assessing Neurobehavioral Performance in Rats and Mice at JoVE.com

The Rodent Psychomotor Vigilance Test rPVT: A Method for Assessing Neurobehavioral Performance in Rats and Mice

A rat version of the human Psychomotor Vigilance Test (PVT) is described that measures aspects of attention similar to those measured with the human PVT, including aspects of human vigilance such as performance accuracy, motor speed, premature responding, and lapses in attention.

The Rodent Psychomotor Vigilance Test (rPVT): A Method for Assessing Neurobehavioral Performance in Rats and Mice

The human Psychomotor Vigilance Test (PVT) is a widely used procedure for measuring changes in fatigue and sustained attention. The present article ...

The overall goal of this protocol is to measure aspects of attention in rats and mice, similar to those measured by the human Psychomotor Vigilance Test, such as accuracy, motor speed, and vigilance. This method can help answer key questions regarding neurobehavioral performances in rodents, including the effects of lesions, pharmacological manipulations, genetic modifications, and sleep deprivation or restriction. The main advantage of this technique is that it provides a stable baseline for assessing the effects of a wide variety of experimental manipulations.To pretrain the rodents, first assign each animal to an operant chamber, where it will be tested each day at approximately the same time, prior to daily feeding. It is critical that the behavioral data be examined each day before moving them to the next training step. If it is not done at the right time, the result will be poor performance.Prepare the operant chamber by loading the pellet dispenser with food pellets. Then deliver 10 to 20 food pellets to the food receptacle in the chamber. Then, weigh the animal, in this case a rat, and place it in the operant chamber.For pre-training, the experimental parameters should be low, fixed values. Once started, the computer program controls the presentation of the house lights, the nose poke key illumination, and automatic dispensing of food pellets. Use settings that will give the animal ample time to explore and be rewarded, such as 10 seconds of nose poke key illumination.Once the rat finishes the food pellets, start to manually shape the rat's behavior. Leave the cubicle open and watch the rat's behavior. Using a handheld switch wired to the feeder, provide pellets as quickly as possible after the rat performs the desired behavior.Shape successive approximations of the desired behavior. For example, once the rat reliably retrieves food pellets from the food receptacle, shape it to move to the left after retrieving a food pellet, towards the nose poke key. During the shaping process, keep the computer program running and controlling the house light, nose poke key, and feeder.Thus, if the rat pokes the key, the computer program reinforces the behavior automatically. After the session, count the total number of pellets the rat receives, and subtract this total mass of food from the rat's daily food allotment. 30 minutes or more after the session, feed the rat the remainder of its daily rations.Clean the operant chamber daily with a gentle disinfectant. Use 70%ethanol sparingly. Check the nose poke key functionality daily, and clean it as needed.Pretrain each rat until it scores at least 40 computer reinforced responses on the illuminated key and retrieves each food pellet. Usually two or three half hour sessions will be enough. Once the rat's behavior is shaped, train the rat with an initial two second, foreperiod interval, and two second timeout.Illuminate the nose poke key as long as needed to get a response, such as nine seconds. This is the limited hold value of the program. Use the timeout as a punishment for premature responses, or when the rat responds prior to the illumination of the nose poke key.During the timeout, the rat has no opportunity to earn food. Proceed by running the 30 minute session. Once the rat completes eight out of 10 correct trials at the current foreperiod value, have the computer increase the foreperiod value and timeout by a tenth of a second.And also, shorten the limited hold value by a tenth of a second. These tenth of a second increases to the foreperiod and timeout values, and decreases to the limited hold values, occur repeatedly within each session as the rat completes eight out of 10 correct trials at each foreperiod value. Once the 30 minute session is over, record the maximum foreperiod length achieved by the rat in a session, and how many pellets were earned.As during pretraining, subtract the amount of food consumed from the rat's daily allotment. The next day, start the 30 minute training session with a foreperiod that is 300 milliseconds slower than the maximum value achieved in the previous session. As the rat achieves eight out of 10 correct trials at each foreperiod value, the computer program will continue to automatically increase this value just as the day before.When the timeout reaches eight seconds, and the limited hold reaches 1.5 seconds, advance these variables no further. The foreperiod can get as long as tolerated. Analyze the rat's daily performance as the percentage of correct trials, premature trials, and misses.Rats commonly maintain an average of 40 to 90%correct responses with steady improvement. Once the rat reaches a foreperiod of 10 seconds or more, vary every foreperiods in the trial from seven and 10 seconds, while keeping the other parameters fixed at eight and 1.5 seconds. When a rat is able to get 70%of the trials correct, with a variable foreperiod, extend the range of the variable foreperiod to five to 10 seconds.This often occurs within a session, so it is good to keep a close eye on the data. Again, after the rat is able to complete 70%of the trials successfully, broaden the variable foreperiod range to three to 10 seconds. It is really important that the rat get 70%or better success before advancing the degree of difficulty.Because some rats will adopt a strategy of responding randomly, instead of waiting for the stimulus. With the parameters detailed here, 86.7%of 122 male rats reached the final rPVT parameters within an average of of nine computer automated training sessions. The reaction time of rats was then compared to that of humans performing the PVT.Like humans, rats show the expected sharp rise in reaction times at the lower values, with a longer rightward tail at the higher values. As seen in the human PVT, the rats'response speed decreases over time on task, which indicates a vigilance decrement, or a decrease in performance, as the amount of time performing the task increases. Foreperiod time had a significant impact on the rats'performance.At lower foreperiod values, performance was slower and contained a greater percentage of lapses. However, as the foreperiod time increased, correct responding decreased while reaction times were faster, and the percentage of premature responses increased. After watching this video, you should have a good understanding of how to train rats and mice to accurately perform a rodent version of the human PVT, and obtain stable, consistent performances on a daily basis for months.Once mastered, this technique can be used to train rodents to perform the rodent PVT within 10 to 15 days, and produce stable performances thereafter.

the-rodent-psychomotor-vigilance-test-rpvt-method-for-assessing

Research

JoVE Journal

Behavior

The Successive Alleys Test of Anxiety in Mice and Rats

The plus-maze was derived from the early work of Montgomery. He observed that rats tended to avoid the open arms of a maze, preferring the enclosed ones. Handley, Mithani and File et al. performed the first studies on the plus-maze design we use today, and in 1987 Lister published a design for use with mice. 
Time spent on, and entries into, the open arms are an index of anxiety; the lower these indices, the more anxious the mouse is. Alternatively, a mouse that spends most of its time in the closed arms is classed as anxious. 
One of the problems of the plus-maze is that, while time spent on, and entries into, the open arms is a fairly unambiguous measure of anxiety, time in the central area is more difficult to interpret, although time spent here has been classified as &#x201C;decision making&#x201D;. In many tests central area time is a considerable part of the total test time.
Shepherd et al. produced an ingenious design to eliminate the central area, which they called the &#x201C;zero maze&#x201D;. However, although used by several groups, it has never been as widely adopted as the plus-maze. 
In the present article I describe a modification of the plus-maze design that not only eliminates the central area but also incorporates elements from other anxiety tests, such as the light-dark box and emergence tests. It is a linear series of four alleys, each having increasing anxiogenic properties. It has given similar results to the plus-maze in general. Although it may not be more sensitive than the plus-maze (more data is needed before a firm conclusion can be reached on this point), it provides a useful confirmation of plus-maze results which would be useful when, for example, only a single example of a mutant mouse was available, as, for example, in ENU-based mutagenesis programs.

The plus-maze measures anxiety-like behaviour in rodents. There are two opposite closed and two opposite open arms; anxious rodents avoid the open arms. The central area is neither completely open nor closed, so time spent here is ambiguous and difficult to interpret. Here a modification of the plus-maze protocol eliminating this area is described.

The plus-maze was derived from the early work of Montgomery. He observed that rats tended to avoid the open arms of a maze, preferring the enclosed ones.  ...

Contextual and Cued Fear Conditioning Test Using a Video Analyzing System in Mice

The contextual and cued fear conditioning test is one of the behavioral tests that assesses the ability of mice to learn and remember an association between environmental cues and aversive experiences. In this test, mice are placed into a conditioning chamber and are given parings of a conditioned stimulus (an auditory cue) and an aversive unconditioned stimulus (an electric footshock). After a delay time, the mice are exposed to the same conditioning chamber and a differently shaped chamber with presentation of the auditory cue. Freezing behavior during the test is measured as an index of fear memory. To analyze the behavior automatically, we have developed a video analyzing system using the ImageFZ application software program, which is available as a free download at http://www.mouse-phenotype.org/. Here, to show the details of our protocol, we demonstrate our procedure for the contextual and cued fear conditioning test in C57BL/6J mice using the ImageFZ system. In addition, we validated our protocol and the video analyzing system performance by comparing freezing time measured by the ImageFZ system or a photobeam-based computer measurement system with that scored by a human observer. As shown in our representative results, the data obtained by ImageFZ were similar to those analyzed by a human observer, indicating that the behavioral analysis using the ImageFZ system is highly reliable. The present movie article provides detailed information regarding the test procedures and will promote understanding of the experimental situation.

This article presents a protocol for a contextual and cued fear conditioning test using a video analyzing system to assess fear learning and memory in mice.

The contextual and cued fear conditioning test is one of the behavioral tests that assesses the ability of mice to learn and remember an association ...

Assessing Functional Performance in the Mdx Mouse Model

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential pharmaceutical compounds and gene therapy approaches have progressed into clinical trials. With improvement in muscle function being the most important end point in these trials, a lot of emphasis has been placed on setting up reliable, reproducible, and easy to perform functional tests to pre clinically assess muscle function, strength, condition, and coordination in the mdx mouse model for DMD. Both invasive and noninvasive tests are available. Tests that do not exacerbate the disease can be used to determine the natural history of the disease and the effects of therapeutic interventions (e.g. forelimb grip strength test, two different hanging tests using either a wire or a grid and rotarod running). Alternatively, forced treadmill running can be used to enhance disease progression and/or assess protective effects of therapeutic interventions on disease pathology. We here describe how to perform these most commonly used functional tests in a reliable and reproducible manner. Using these protocols based on standard operating procedures enables comparison of data between different laboratories.

Assessing Functional Performance in the Mdx Mouse Model

The primary outcome measure in clinical trials for neuromuscular disorders is generally improved muscle function. Therefore, assessing the effect of potential therapeutic compounds on muscle performance pre clinically in mouse models is of great importance. We here describe several functional tests to address this.

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential ...

Operant Procedures for Assessing Behavioral Flexibility in Rats

Executive functions consist of multiple high-level cognitive processes that drive rule generation and behavioral selection. An emergent property of these processes is the ability to adjust behavior in response to changes in one&#8217;s environment (i.e., behavioral flexibility). These processes are essential to normal human behavior, and may be disrupted in diverse neuropsychiatric conditions, including schizophrenia, alcoholism, depression, stroke, and Alzheimer&#8217;s disease. Understanding of the neurobiology of executive functions has been greatly advanced by the availability of animal tasks for assessing discrete components of behavioral flexibility, particularly strategy shifting and reversal learning. While several types of tasks have been developed, most are non-automated, labor intensive, and allow testing of only one animal at a time. The recent development of automated, operant-based tasks for assessing behavioral flexibility streamlines testing, standardizes stimulus presentation and data recording, and dramatically improves throughput. Here, we describe automated strategy shifting and reversal tasks, using operant chambers controlled by custom written software programs. Using these tasks, we have shown that the medial prefrontal cortex governs strategy shifting but not reversal learning in the rat, similar to the dissociation observed in humans. Moreover, animals with a neonatal hippocampal lesion, a neurodevelopmental model of schizophrenia, are selectively impaired on the strategy shifting task but not the reversal task. The strategy shifting task also allows the identification of separate types of performance errors, each of which is attributable to distinct neural substrates. The availability of these automated tasks, and the evidence supporting the dissociable contributions of separate prefrontal areas, makes them particularly well-suited assays for the investigation of basic neurobiological processes as well as drug discovery and screening in disease models.

The ability to assess executive functions such as behavioral flexibility in rats is useful for investigating the neurobiology of cognition in both intact animals and disease models. Here we describe automated tasks for assessing strategy shifting and reversal learning, which are particularly sensitive to disruptions in prefrontal cortical networks.

Executive functions consist of multiple high-level cognitive processes that drive rule generation and behavioral selection. An emergent property of these ...

The Modified Hole Board - Measuring Behavior, Cognition and Social Interaction in Mice and Rats

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure multiple dimensions of unconditioned behavior in small laboratory mammals (e.g., mice, rats, tree shrews and small primates). This paradigm is a valuable alternative for the use of a behavioral test battery, since a broad behavioral spectrum of an animal&#8217;s behavioral profile can be investigated in one single test.
The apparatus consists of a box, representing the &#8216;protected&#8217; area, separated from a group compartment. A board, on which small cylinders are staggered in three lines, is placed in the center of the box, representing the &#8216;unprotected&#8217; area of the set-up. The cognitive abilities of the animals can be measured by baiting some cylinders on the board and measuring the working and reference memory. Other unconditioned behavior, such as activity-related-, anxiety-related- and social behavior, can be observed using this paradigm. Behavioral flexibility and the ability to habituate to a novel environment can additionally be observed by subjecting the animals to multiple trials in the mHB, revealing insight into the animals&#8217; adaptive capacities.
Due to testing order effects in a behavioral test battery, na&#239;ve animals should be used for each individual experiment. By testing multiple behavioral dimensions in a single paradigm and thereby circumventing this issue, the number of experimental animals used is reduced. Furthermore, by avoiding social isolation during testing and without the need to food deprive the animals, the mHB represents a behavioral test system, inducing if any, very low amount of stress.

This protocol describes the modified hole board, which is a behavioral test set-up that comprises the characteristics of an open field and a traditional hole board. This set-up enables the differential analysis of unconditioned behavior of small laboratory mammals as well as the analysis of cognitive abilities.

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure ...

The Social Dimension of Stress: Experimental Manipulations of Social Support and Social Identity in the Trier Social Stress Test

In many situations humans are influenced by the behavior of other people and their relationships with them. For example, in stressful situations supportive behavior of other people as well as positive social relationships can act as powerful resources to cope with stress. In order to study the interplay between these variables, this protocol describes two effective experimental manipulations of social relationships and supportive behavior in the laboratory. In the present article, these two manipulations are implemented in the Trier Social Stress Test (TSST)&#8212;a standard stress induction paradigm in which participants are subjected to a simulated job interview. More precisely, we propose (a) a manipulation of the relationship between different protagonists in the TSST by making a shared social identity salient and (b) a manipulation of the behavior of the TSST-selection committee, which acts either supportively or unsupportively. These two experimental manipulations are designed in a modular fashion and can be applied independently of each other but can also be combined. Moreover, these two manipulations can also be integrated into other stress protocols and into other standardized social interactions such as trust games, negotiation tasks, or other group tasks.

Previous research on the social dimension of stress has focused on two important variables: social identity and social support. This protocol introduces an effective experimental manipulation of these two social variables and describes their implementation in a standard stress induction paradigm (Trier Social Stress Test).

In many situations humans are influenced by the behavior of other people and their relationships with them. For example, in stressful situations ...

A Method to Test the Effect of Environmental Cues on Mating Behavior in Drosophila melanogaster

An individual's sexual drive is influenced by genotype, experience and environmental conditions. How these factors interact to modulate sexual behaviors remains poorly understood. In Drosophila melanogaster, environmental cues, such as food availability, affect mating activity offering a tractable system to investigate the mechanisms modulating sexual behavior. In D. melanogaster, environmental cues are often sensed via the chemosensory gustatory and olfactory systems. Here, we present a method to test the effect of environmental chemical cues on mating behavior. The assay consists of a small mating arena containing food medium and a mating couple. The mating frequency for each couple is continuously monitored for 24 h. Here we present the applicability of this assay to test environmental compounds from an external source through a pressurized air system as well as manipulation of the environmental components directly in the mating arena. The use of a pressurized air system is especially useful to test the effect of very volatile compounds, while manipulating components directly in the mating arena can be of value to ascertain a compound's presence. This assay can be adapted to answer questions about the influence of genetic and environmental cues on mating behavior and fecundity as well as other male and female reproductive behaviors.

A Method to Test the Effect of Environmental Cues on Mating Behavior in Drosophila melanogaster

We demonstrate an assay to analyze the environmental and genetic cues that influence mating behavior in the fruit fly Drosophila melanogaster.

An individual's sexual drive is influenced by genotype, experience and environmental conditions. How these factors interact to modulate sexual behaviors ...

The Knob Supination Task: A Semi-automated Method for Assessing Forelimb Function in Rats

Tasks that accurately measure dexterity in animal models are critical to understand hand function. Current rat behavioral tasks that measure dexterity largely use video analysis of reaching or food manipulation. While these tasks are easy to implement and are robust across disease models, they are subjective and laborious for the experimenter. Automating traditional tasks or creating new automated tasks can make the tasks more efficient, objective, and quantitative. Since rats are less dexterous than primates, central nervous system (CNS) injury produces more subtle deficits in dexterity, however, supination is highly affected in rodents and crucial to hand function in primates. Therefore, we designed a semi-automated task that measures forelimb supination in rats. Rats are trained to reach and grasp a knob-shaped manipulandum and turn the manipulandum in supination to receive a reward. Rats can acquire the skill within 20 &plusmn; 5 days. While the early part of training is highly supervised, much of the training is done without direct supervision. The task reliably and reproducibly captures subtle deficits after injury and shows functional recovery that accurately reflects clinical recovery curves. Analysis of data is performed by specialized software through a graphical user interface that is designed to be intuitive. We also give solutions to common problems encountered during training, and show that minor corrections to behavior early in training produce reliable acquisition of supination. Thus, the knob supination task provides efficient and quantitative evaluation of a critical movement for dexterity in rats.

This manuscript describes a semi-automated task that quantifies supination in rats. Rats reach, grasp, and supinate a spherical manipulandum. The rat is rewarded with a pellet if the turn angle exceeds a criterion set by the user. This task increases throughput, sensitivity to injury, and objectivity compared to traditional tasks.

Tasks that accurately measure dexterity in animal models are critical to understand hand function. Current rat behavioral tasks that measure dexterity ...

A New Method for Inducing a Depression-Like Behavior in Rats

Contagious depression is a phenomenon that is yet to be fully recognized and this stems from insufficient material on the subject. At the moment, there is no existing format for studying the mechanism of action, prevention, containment, and treatment of contagious depression. The purpose of this study, therefore, was to establish the first animal model of contagious depression.
Healthy rats can contract depressive behaviors if exposed to depressed rats. Depression is induced in rats by subjecting them to several manipulations of chronic unpredictable stress (CUS) over 5 weeks, as described in the protocol. A successful sucrose preference test confirmed the development of depression in the rats. The CUS-exposed rats were then caged with na&#239;ve rats from the contagion group (1 na&#239;ve rat/2 depressed rats in a cage) for an additional 5 weeks. 30 social groups were created from the combination of CUS-exposed rats and na&#239;ve rats.
This proposed depression-contagion protocol in animals consists mainly of cohabiting CUS-exposed and healthy rats for 5 weeks. To ensure that this method works, a series of tests are carried out - first, the sucrose preference test upon inducing depression to rats, then, the sucrose preference test, alongside the open field and forced-swim tests at the end of the cohabitation period. Throughout the experiment, rats are given tags and are always returned to their cages after each test.
A few limitations to this method are the weak differences recorded between the experimental and control groups in the sucrose preference test and the irreversible traumatic outcome of the forced swim test. These may be worth considering for suitability before any future application of the protocol. Nonetheless, following the experiment, na&#239;ve rats developed contagion depression after 5 weeks of sharing the same cage with the CUS-exposed rats.

This protocol describes a new model by which healthy rats could contract depression over a given time periodthrough contagion by exposure to chronic unpredictable stressed (CUS) rats.

Contagious depression is a phenomenon that is yet to be fully recognized and this stems from insufficient material on the subject. At the moment, there is ...

A Behavioral Test Battery for the Repeated Assessment of Motor Skills, Mood, and Cognition in Mice

Pharmacological and toxicological studies in neurodegeneration require comprehensive behavioral analysis in mice because motor dysfunctions and dysfunctions in mood and cognition are common and often shared symptoms in neurodegenerative diseases. Shown here is a behavioral test battery for motor, mood, and cognition, which can be repeatedly tested in a longitudinal study. This battery assesses the overall behavioral phenotype in mice by examining each domain of behavior with at least two independent well-accepted tests (i.e., open-field test and rotarod test for motor function, social interaction test, elevated plus maze test, and forced swim test for emotional function, and Morris water maze test and novel object recognition test for cognitive function). Therefore, this sensitive and comprehensive test battery is a powerful tool for the study of behavioral alternation in neurodegeneration.

A comprehensive behavioral test battery of motor skills, mood&#8212;including social interaction, depression, and anxiety&#8212;and cognition is designed for the repeated assessment of neurodegeneration-related behavioral changes in mice.