This study was supported by Human Frontier Science Program and the Sasakawa Scientific Research Grant from the Japan Science Society.

All procedures for the use of animals were approved by the Animal Care and Use Committee at the Okinawa Institute of Science and Technology.
1. Animals
<ol>
	<li>Obtain male Long-Evans rats (250-300 g on arrival).</li>
	<li>Upon arrival, house a group of two or three rats together for a week and later separate them into individual cages. Note that this experimental design involves food-restriction and needs to hold an animal in each cage to control the amount food consumed.</li>
	<li>Provide all animals with food and water ad libitum, and house them under standard conditions (12 hr/12 hr light/dark cycle, at 23 &#176;C).</li>
	<li>5 days before the beginning of behavioral experiments, food-restrict animals at approximately 85% of their average weight with free access to water throughout experiments.</li>
	<li>Handle animals for 5 min a day for a minimum of 5 days before the beginning of experiments in order to familiarize them with an experimenter.</li>
</ol>
2. Hardware and Software for Behavioral Tests and Analyses
<ol>
	<li>Hardware
	<ol>
		<li>Use an operant chamber equipped with a sound attenuating box.</li>
		<li>The chamber is incorporated with several additional attachments: two receptacle levers on the front panel, two light cues just above the levers, a magazine spot with a sensor for detection of head entry between two levers, a food dispenser, a pure tone generator and a house light on the rear panel.</li>
	</ol>
	</li>
	<li>Software
	<ol>
		<li>Control all the behavioral events under a programmed code written by Trans IV software. Use Med-PC IV software to signal and detect all the behavioral events during training and a test.</li>
		<li>Use Trans IV for writing code for behavioral testing. Open a new file for writing.</li>
		<li>Once the program is written, translate and compile it within the software. Modify the code if errors are detected and retry.</li>
		<li>Upon successful debugging of a program, check if user&#39;s code works properly by conducting a trial-run before actual initiation of experiments.</li>
		<li>Using MED-PC IV, run behavioral experiments. Open the software, click &#34;open session&#34; and assign a single program to each box.</li>
		<li>After all the programs have been properly assigned to each box, send signals necessary to start experiments.</li>
		<li>After the completion of the task, save data as clicking &#34;Save Data&#34; or write code to automatically save data (for details, see programmer&#39;s manual for MED-PC IV).</li>
		<li>Once data is exported to a designated folder, rename the data as acquisition date and animal ID numbers for later use. The collected data is imported into Matlab for behavioral analyses described below (Protocol, 3.7).</li>
	</ol>
	</li>
</ol>
3. Behavioral Training and Testing
<ol>
	<li>Habituation and Magazine training.
	<ol>
		<li>Present no levers to animals during those phases.</li>
		<li>During the habituation phase, place animals in an operant chamber for 20 minutes a day. On the same day, give 10 sucrose pellets (45 mg) to animals in their home cage, which familiarize them to the sucrose reward.</li>
		<li>Next, begin magazine training. Place animals in the chamber and give 20 sucrose pellets (1 pellet per a minute) to the animals, providing an opportunity to learn the location of the food tray and acquisition of the pellets. 
		NOTE: Those phases can be skipped due to potential confusion of animals on obtaining a pellet without an operant response, even though we adopted them to make animals familiarized with a chamber and eating from a food tray.</li>
	</ol>
	</li>
	<li>Continuous reinforcement schedule
	<ol>
		<li>Train animals on a continuous reinforcement schedule to obtain a reward by pressing a lever. A session of this training lasts until 60 pellets have been received (60 lever-presses) or 40 min has elapsed.</li>
		<li>Present either the left or right lever throughout the first half of a session (until 30 pellets are obtained), followed by the presentation of the opposite lever during the second half. The order is alternated on a daily basis.</li>
		<li>Continue this reinforcement schedule until animals have successfully obtained 60 rewards for at least 2 consecutive days. Note that there may be high variability among animals of how quickly they make the first lever-press and this may affect the progress of reinforcement. In this case, put a few sucrose pellets on a presented lever to motivate them to approach toward the lever when no response has been made over the first session. 
		NOTE: A possible alternative is to put sucrose pellets when the lever is first presented to animals in order to make the completion of this phase faster.</li>
	</ol>
	</li>
	<li>Time schedule for a trial in lever-press training and testing.
	<ol>
		<li>Start a single trial with a 3 sec (s) tone.</li>
		<li>2 sec after the termination of tone, present two levers and allow animals to press either lever within 10 sec. In case that no response is made within 10 s, retract both levers and count this trial as an omission trial.</li>
		<li>In the case of the lever press training, present only a single lever on either side.</li>
		<li>In most of experimental conditions, there was a light stimulus above one of levers. Turn the light cue on immediately after the tone ceases and turn off when animals have either made a response or in 10 sec after lever insertion when no response has been made.</li>
		<li>Set inter-trial intervals at 20~30 sec.</li>
	</ol>
	</li>
	<li>Lever-press training
	<ol>
		<li>In this training phase, present no light to animals.</li>
		<li>Train animals under lever-press training for 5-8 sessions with the same time schedule for a trial as testing sessions described below.</li>
		<li>In this training, present either left or right lever randomly, and the lever has to be pressed within 10 sec after the lever is presented, or the trial is counted as an omission without a response. A session for the lever press training comprised of 80 trials.</li>
		<li>Once the animals have scored fewer than 10% of omissions out of 80 trials, move them to the following side-bias test.</li>
	</ol>
	</li>
	<li>Side-bias test
	<ol>
		<li>Perform a side-bias test to determine the animal&#39;s preference to either left or right lever1. A trial entails two lever-presses on both sides.</li>
		<li>Place animals in an operant chamber and allow them to choose either lever. In the next attempt, animals have to select the opposite lever in order to obtain a reward. If animal&#39;s second attempt is on the same side of the first response, give no reward and continue the trial until a response is made on the opposite side.</li>
		<li>Conduct a total of 7 trials to determine animal&#39;s side preference.</li>
	</ol>
	</li>
	<li>Testing.
	<ol>
		<li>A daily session consists of 80 trials.</li>
		<li>Prepare three different conditions for set-shifting procedures as shown in Figure 1.</li>
		<li>All the three conditions require animals to similarly change behavioral strategies from choosing one lever that is consistently on the same side (Phase 1, response strategy) to following a light cue that indicates a correct side (Phase 2, visual cue strategy).</li>
		<li>Begin with initial learning of a response strategy (Phase 1) for 4 sessions, in which animals have to press a lever based on the location of levers. In this phase, set the correct side to the lever opposite to their preference based on a preliminary side-bias test as mentioned above.</li>
		<li>Next, commence visual cue learning (Phase 2) for 10 sessions. A light cue illuminated above either lever indicates a correct lever. In this shifting phase, three different patterns of attentional shifts can be compared among three experimental conditions as described below (3.3.6-3.3.8).</li>
		<li>In set-shift condition 1 (Figure 1A), give no light in phase 1, but a light cue indicates the correct side in phase 2. In condition 1, therefore, animals need to attend to a novel stimulus.</li>
		<li>In set-shift condition 2 (Figure 1B), present a light cue above the correct lever in phase 1, and again in phase 2. In this condition, the light cue had been relevant, but not necessarily required for making a choice in phase 1. Thus animals have to attend to a previously relevant cue.</li>
		<li>In set-shift condition 3 (Figure 1C), turn on a light cue randomly above either left or right lever in phase 1. Thus it has to be ignored. In phase 2 animals are required to pay attention to the light stimulus that has been previously irrelevant.</li>
	</ol>
	</li>
	<li>Behavioral analysis.
	<ol>
		<li>Throughout sessions, measure the percentage of correct responses on a daily basis, excluding omission trials.</li>
		<li>Count errors accumulated during 10 sessions of visual cue learning and classify them into perseverative, regressive or never-reinforced errors as described in a previous study1. There, a detailed analysis of error types suggests separate functions in set-shifting.</li>
		<li>Define perseverative errors as incorrect responses to the previously correct lever while animal&#39;s performance was still below chance level4,6,13,14,15. Similar criteria have been used in previous studies1,3,7,11.</li>
		<li>Based on a principled way, determine the criterion to separate between perseverative and regressive errors as the point at which the animal first scored fewer than 8 out of 10 incorrect responses (probability of making 8/10 errors or more = 0.054, based on cumulative binomial distribution) in a moving window of 10 trials.</li>
		<li>In order to find this point, start calculating a moving average of the 10 trial window from 1st trial and then advance it by one trial at a time until &#60;8/10 errors are measured. Conduct this analysis across all trials in which a light cue is illuminated above the previously incorrect lever during visual cue strategy.</li>
		<li>Define all the subsequent errors committed after this point as regressive errors.</li>
		<li>During visual cue learning, count never-reinforced errors when animals responded to a previously incorrect lever on which the light cue was not illuminated. Divide them into an early or late portion based on the learning phase; errors made in the first half of 10 sessions (session 1-5) are considered early and those in the second half (session 6-10) are regarded as late ones.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

We developed new variations on the established set-shifting paradigm for use in rats. Using those paradigms, cholinergic lesions of the striatum were found to impair set-shifting, suggesting a specific role of striatal cholinergic interneurons in set-shifting: suppression of an old rule and facilitation of exploration for a new rule. The effects differed between dorsomedial and ventral striatum, in accordance with the different role of these structures in learning.
A set-shifting task has been...

Behavioral flexibility is a key requirement for survival in a changing world. One of the established behavioral paradigms for testing this ability is set-shifting, in which a shift of attention from one stimulus dimension to another is necessary for changing action strategies after a change in rule. Several brain regions such as the prefrontal cortex and striatum are implicated in set-shifting2,3,4,5. Neural mechanisms for this function have been investigated across several species including humans5, monkeys6 and rats1,7,8,9. However, the rat versions of set-shifting tasks have not been as extensively developed. The cost-effectiveness of rats, their appropriate size for stereotaxic surgery, and the availability of recently developed genetic methods10, motivate further development of set-shifting paradigms for use in rats.
A typical set-shifting paradigm for rats requires a change between two behavioral strategies: for example, a response strategy and a visual-cue strategy. Rats initially have to choose one of two available options (such as left or right levers in an operant automated version1 or left or right arms in a T-maze version7,8,9,11). After a set shift, they have to switch to using a visual-cue strategy, such as a light cue indicating the correct side. In those conventional set-shifting tasks, it is necessary to shift attention from one stimulus dimension to another dimension that had been previously irrelevant.
In addition to changing to a dimension that had been previously irrelevant, there is also the logical possibility that a stimulus was previously relevant, or previously absent and now novel. Real life situations in nature may entail attention to a novel, or historically relevant but not crucial cue. Therefore, we considered these subtypes of set-shift, in a new variation of rodent set-shifting based on a previously established automated set-shifting task1.
We have recently demonstrated the use of the new version of set-shifting paradigms in an experiment to determine the effect of neurochemically specific lesions of the striatum12. In our previous study, we targeted cholinergic interneurons releasing acetylcholine (ACh) of the dorsomedial or ventral striatum since ACh and those subregions have been implicated in behavioral flexibility. All the experimental conditions demanded the same strategic shift but each involved different types of attentional shift: to a novel, previously relevant or previously irrelevant cue. We here describe detailed procedures of the paradigms, and highlight representative results suggesting that striatal cholinergic systems play a fundamental role in set-shifting, which is dissociable between different striatal subregions depending on behavioral contexts12.

<table><tbody><tr><td>Standard Modular Test Chamber</td><td>Med Associates</td><td>ENV-008</td><td></td></tr><tr><td>Low Profile Retractable Response Lever</td><td>Med Associates</td><td>ENV-112CM</td><td></td></tr><tr><td>Stimulus Light for Rat</td><td>Med Associates</td><td>ENV-221M</td><td></td></tr><tr><td>Switchable Dual Pellet/Dipper Receptacle for Rat</td><td>Med Associates</td><td>ENV-202RM-S</td><td></td></tr><tr><td>Head Entry Detector for Rat Receptacles</td><td>Med Associates</td><td>ENV-254-CB</td><td></td></tr><tr><td>Modular Pellet Dispenser; 45 mg for Rat</td><td>Med Associates</td><td>ENV-203M-45</td><td></td></tr><tr><td>Sonalert Module for Rat</td><td>Med Associates</td><td>ENV-223AM</td><td>4.5 kHz available (ENV-223HAM)</td></tr><tr><td>House Light for Rat Chambers</td><td>Med Associates</td><td>ENV-215M</td><td></td></tr><tr><td>SmartCtrl Interface Module, 8 input/16 output</td><td>Med Associates</td><td>DIG-716B</td><td></td></tr><tr><td>SmartCtrl Connection Panel, 8 input/16 output</td><td>Med Associates</td><td>SG-716B</td><td></td></tr><tr><td>45 mg Tablet-Fruit Punch</td><td>TestDiet</td><td>1811255</td><td>Several flavors available</td></tr></tbody></table>

new variations for strategy set-shifting in the rat

Behavioral flexibility is crucial for survival in changing environments. Broadly defined, behavioral flexibility requires a shift of behavioral strategy based on a change in governing rules. We describe a strategy set-shifting task that requires an attentional shift from one stimulus dimension to another. The paradigm is often used for testing cognitive flexibility in primates. However, the rodent version has not been as extensively developed. We have recently extended an established set-shifting task in the rat1 by requiring attention to different stimuli according to context. All the experimental conditions required animals to choose either a left or right lever. Initially, all animals had to choose on the basis of the location of the lever. Subsequently, a change in the rule occurred, which required a shift in set from location-based rule to a rule in which the correct lever was indicated by a light cue. We compared performance on three different versions of the task, in which the light stimulus was either novel, previously relevant, or previously irrelevant. We found that specific neurochemical lesions selectively impaired the ability to make particular types of set shift as measured by the performance on the different versions of the task.

We used the strategy set-shifting task described above to investigate the role of cholinergic interneurons in behavioral flexibility. We compared the effect on the task of an immunotoxin-induced selective lesion of cholinergic interneurons in dorsomedial (DMS), ventral striatum (VS) and saline-injected control. All animals had to switch from choosing a lever based on the side (left or right), to choosing based on a cue light above the correct lever. We used three experimental conditions of set-shift in which the cue ligh...

Watch this Scientific Journal Video about New Variations for Strategy Set-shifting in the Rat at JoVE.com

New Variations for Strategy Set-shifting in the Rat

Set-shifting, a form of behavioral flexibility, requires an attentional shift from one stimulus dimension to another. We extended an established rodent set-shifting task1 by requiring attention to different stimuli according to context. The task was combined with specific lesions to identify neuron subtypes underlying a successful shift.

Behavioral flexibility is crucial for survival in changing environments. Broadly defined, behavioral flexibility requires a shift of behavioral strategy ...

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8.1K Views.  Okinawa Institute of Science and Technology. Set-shifting, a form of behavioral flexibility, requires an attentional shift from one stimulus dimension to another. We extended an established rodent set-shifting task1 by requiring attention to different stimuli according to context. The task was combined with specific lesions to identify neuron subtypes underlying a successful shift.

Video: New Variations for Strategy Set-shifting in the Rat

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 ...

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 Double-H Maze: A Robust Behavioral Test for Learning and Memory in Rodents

Spatial cognition research in rodents typically employs the use of maze tasks, whose attributes vary from one maze to the next. These tasks vary by their behavioral flexibility and required memory duration, the number of goals and pathways, and also the overall task complexity. A confounding feature in many of these tasks is the lack of control over the strategy employed by the rodents to reach the goal, e.g., allocentric (declarative-like) or egocentric (procedural) based strategies. The double-H maze is a novel water-escape memory task that addresses this issue, by allowing the experimenter to direct the type of strategy learned during the training period. The double-H maze is a transparent device, which consists of a central alleyway with three arms protruding on both sides, along with an escape platform submerged at the extremity of one of these arms.
Rats can be trained using an allocentric strategy by alternating the start position in the maze in an unpredictable manner (see protocol 1; &#167;4.7), thus requiring them to learn the location of the platform based on the available allothetic cues. Alternatively, an egocentric learning strategy (protocol 2; &#167;4.8) can be employed by releasing the rats from the same position during each trial, until they learn the procedural pattern required to reach the goal. This task has been proven to allow for the formation of stable memory traces.
Memory can be probed following the training period in a misleading probe trial, in which the starting position for the rats alternates. Following an egocentric learning paradigm, rats typically resort to an allocentric-based strategy, but only when their initial view on the extra-maze cues differs markedly from their original position. This task is ideally suited to explore the effects of drugs/perturbations on allocentric/egocentric memory performance, as well as the interactions between these two memory systems.

The goal of this protocol is to investigate spatial cognition in rodents. The double-H water maze is a novel test, which is particularly useful to elucidate the different components of learning, consolidation and memory, as well as the interplay of memory systems.

Spatial cognition research in rodents typically employs the use of maze tasks, whose attributes vary from one maze to the next. These tasks vary by their ...

Acquisition of a High-precision Skilled Forelimb Reaching Task in Rats

Movements are the main measurable output of central nervous system function. Developing behavioral paradigms that allow detailed analysis of motor learning and execution is of critical importance in order to understand the principles and processes that underlie motor function. Here we present a paradigm to study movement acquisition within a daily session of training (within-session) representing the fast learning component and primary acquisition as well as skilled motor learning over several training sessions (between-session) representing the slow learning component and consolidation of the learned task. This behavioral paradigm increases the degree of difficulty and complexity of the motor skill task due to two features: First, the animal realigns its body prior to each pellet retrieval forcing renewed orientation and preventing movement execution from the same angle. Second, pellets are grasped from a vertical post that matches the diameter of the pellet and is placed in front of the cage. This requires a precise grasp for successful pellet retrieval and thus prevents simple pulling of the pellet towards the animal. In combination with novel genetics, imaging and electrophysiological technologies, this behavioral method will aid to understand the morphological, anatomical and molecular underpinnings of motor learning and memory.

A paradigm is presented to analyze the acquisition of a high-precision skilled forelimb reaching task in rats.

Movements are the main measurable output of central nervous system function. Developing behavioral paradigms that allow detailed analysis of motor ...

An Operant Intra-/Extra-dimensional Set-shift Task for Mice

Alterations in executive control and cognitive flexibility, such as attentional set-shifting abilities, are core features of several neuropsychiatric diseases. The most widely used neuropsychological tests for the evaluation of attentional set-shifting in human subjects are the Wisconsin Card Sorting Test (WCST) and the CANTAB Intra-/Extra-dimensional set shift task (ID/ED). These tasks have proven clinical relevance and have been modified and successfully adapted for research in animal models. However, currently available tasks for rodents present several limitations, mainly due to their manual-based testing procedures, which are hampering translational advances in psychiatric medicine. To overcome these limitations and to better mimic the original version in primates, we present the development of a novel operant-based two-chamber ID/ED "Operon" task for rodents. We demonstrated the effectiveness of this novel task to measure different facets of cognitive flexibility in mice including attentional set formation and shifting, and reversal learning. Moreover, we show the high flexibility of this task in which three different perceptual dimensions can be manipulated with a high number of stimuli cues for each dimension. This novel ID/ED Operon task can be an effective preclinical tool for drug testing and/or large genetic screening relevant to the study of executive dysfunction and cognitive symptoms found in psychiatric disorders.

Attentional set-shifting cognitive abnormalities are a core feature of many psychiatric diseases. Here, we present the development of a novel automatic system for the effective study of attentional set-shifting abilities, executive functions and other cognitive abilities in mice with high translational validity to human studies.

Alterations in executive control and cognitive flexibility, such as attentional set-shifting abilities, are core features of several neuropsychiatric ...

The Structure of Skilled Forelimb Reaching in the Rat: A Movement Rating Scale

Skilled reaching for food is an evolutionary ancient act and is displayed by many animal species, including those in the sister clades of rodents and primates. The video describes a test situation that allows filming of repeated acts of reaching for food by the rat that has been mildly food deprived. A rat is trained to reach through a slot in a holding box for food pellet that it grasps and then places in its mouth for eating. Reaching is accomplished in the main by proximally driven movements of the limb but distal limb movements are used for pronating the paw, grasping the food, and releasing the food into the mouth. Each reach is divided into at least 10 movements of the forelimb and the reaching act is facilitated by postural adjustments. Each of the movements is described and examples of the movements are given from a number of viewing perspectives. By rating each movement element on a 3-point scale, the reach can be quantified. A number of studies have demonstrated that the movement elements are altered by motor system damage, including damage to the motor cortex, basal ganglia, brainstem, and spinal cord. The movements are also altered in neurological conditions that can be modeled in the rat, including Parkinson's disease and Huntington's disease. Thus, the rating scale is useful for quantifying motor impairments and the effectiveness of neural restoration and rehabilitation. Because the reaching act for the rat is very similar to that displayed by humans and nonhuman primates, the scale can be used for comparative purposes. from a number of viewing perspectives. By rating each movement element on a 3-point scale, the reach can be quantified. A number of studies have demonstrated that the movement elements are altered by motor system damage, including damage to the motor cortex, basal ganglia, brainstem, and spinal cord. The movements are also altered in neurological conditions that can be modeled in the rat, including Parkinson's disease and Huntington's disease. Thus, the rating scale is useful for quantifying motor impairments and the effectiveness of neural restoration and rehabilitation.

Experiments on animals were performed in accordance with the guidelines and regulations set forth by the University of Lethbridge Animal Care Committee in accordance with the regulations of the Canadian Council on Animal Care.

The skilled reaching scale divides the movement by a forelimb in a reach for food act into composite elements each of which are evaluated with a three-point scale. The rating scale is described for a normal rat and can be applied toward evaluating neurological motor disorders.

Skilled reaching for food is an evolutionary ancient act and is displayed by many animal species, including those in the sister clades of rodents and ...

Biology

Peering into the Dynamics of Social Interactions: Measuring Play Fighting in Rats

Play fighting in the rat involves attack and defense of the nape of the neck, which if contacted, is gently nuzzled with the snout. Because the movements of one animal are countered by the actions of its partner, play fighting is a complex, dynamic interaction. This dynamic complexity raises methodological problems about what to score for experimental studies. We present a scoring schema that is sensitive to the correlated nature of the actions performed. The frequency of play fighting can be measured by counting the number of playful nape attacks occurring per unit time. However, playful defense, as it can only occur in response to attack, is necessarily a contingent measure that is best measured as a percentage (#attacks defended/total # attacks X 100%). How a particular attack is defended against can involve one of several tactics, and these are contingent on defense having taken place; consequently, the type of defense is also best expressed contingently as a percentage. Two experiments illustrate how these measurements can be used to detect the effect of brain damage on play fighting even when there is no effect on overall playfulness. That is, the schema presented here is designed to detect and evaluate changes in the content of play following an experimental treatment.

Play fighting in the rat involves attack and defense of the nape of the neck, which if contacted, is gently nuzzled with the snout. Because the movements of one animal are countered by the actions of its partner, play fighting is a complex, dynamic interaction. This dynamic complexity raises methodological problems about what to score for experimental studies. We present a scoring schema that is sensitive to the correlated nature of the actions performed. Two experiments illustrate how these measurements can be used to detect the effect of brain damage on play fighting even when there is no effect on overall playfulness. That is, the schema presented here is designed to detect and evaluate changes in the content of play following an experimental treatment.

Play fighting in the rat involves attack and defense of the nape of the neck, which if contacted, is gently nuzzled with the snout. Because the movements ...

Neuroscience

A Task for Assessing the Impact of a Partner on the Speed and Accuracy of Motor Performance in Rats

To our knowledge, no study has examined the effect of mere presence on accuracy of performance in animals. Therefore, we developed an experimental task to measure rats&#8217; motor performance (speed and accuracy) in a social condition. Rats were trained to run on a runway and pull down a lever at the end of the runway. In testing, rats performed the task solitarily (single) or in the presence of a confederate rat beyond the lever (pair or a social condition). As indices of the performance speed, we measured the time needed to start running, run through the runway, and pull down the lever. As the index of performance accuracy, we counted the number of trials in which rats could pull down the lever during their first attempt. One-way and two-way repeated-measure analyses of variance were used to analyze the data. This run-and-pull task enabled us to examine the effect of the presence of another conspecific on both speed and accuracy of motor performance in one experiment. The results showed that rats performed the task faster but less accurately in pair sessions than in single sessions. This protocol would be a valid animal model to examine the effect of mere presence on speed and accuracy of motor performance in rats.

A procedure to measure the speed and accuracy of rats&rsquo; motor performance in a social condition is described. The protocol enables us to investigate the effect of the mere presence of others on speed and accuracy of motor performance in one experiment.

To our knowledge, no study has examined the effect of mere presence on accuracy of performance in animals. Therefore, we developed an experimental task to ...

Assessment of Stress Effects on Cognitive Flexibility using an Operant Strategy Shifting Paradigm

Stress affects cognitive function. Whether stress enhances or impairs cognitive function depends on several factors, including the 1) type, intensity, and duration of the stressor; 2) type of cognitive function under study; and 3) timing of the stressor in relation to learning or executing the cognitive task. Furthermore, sex differences among the effects of stress on cognitive function have been widely documented. Described here is an adaptation of an automated operant strategy shifting paradigm to assess how variations in stress affect cognitive flexibility in male and female Sprague Dawley rats. Specifically, restraint stress is used before or after training in this operant-based task to examine how stress affects cognitive performance in both sexes. Particular brain areas associated with each task in this automated paradigm have been well-established (i.e., the medial prefrontal cortex and orbitofrontal cortex). This allows for targeted manipulations during the experiment or the assessment of particular genes and proteins in these regions upon completion of the paradigm. This paradigm also allows for the detection of different types of performance errors that occur after stress, each of which has defined neural substrates. Also identified are distinct sex differences in perseverative errors after a repeated restraint stress paradigm. The use of these techniques in a preclinical model may reveal how stress affects the brain and impairs cognition in psychiatric disorders, such as post-traumatic stress disorder (PTSD) and major depressive disorder (MDD), which display marked sex differences in prevalence.

Stressful life events impair cognitive function, increasing the risk of psychiatric disorders. This protocol illustrates how stress affects cognitive flexibility using an automated operant strategy shifting paradigm in male and female Sprague Dawley rats. Specific brain areas underlying particular behaviors are discussed, and translational relevance of results are explored.

Stress affects cognitive function. Whether stress enhances or impairs cognitive function depends on several factors, including the 1) type, intensity, and ...

A Complex Diving-For-Food Task to Investigate Social Organization and Interactions in Rats

For many species, where status is a vital motivator that can affect health, social hierarchies influence behavior. Social hierarchies that include dominant-submissive relationships are common in both animal and human societies. These relationships can be affected by interactions with others and with their environment, making them difficult to analyze in a controlled study. Rather than a simple dominance hierarchy, this formation has a complicated presentation that allows rats to avoid aggression. Status can be stagnant or mutable, and results in complex societal stratifications. Here we describe a complex diving-for-food task to investigate rodent social hierarchy and behavioral interactions. This animal model may allow us to assess the relationship between a wide range of mental illnesses and social organization, as well as to study the effectiveness of therapy on social dysfunction.

This protocol describes a method of examining social hierarchy in a rat model. Rats perform a complex diving-for-food task in which they form a distinct hierarchy according to their willingness to dive underwater and swim to obtain a food pellet. This method is used to understand decision making and social relationships among highly social animals in small groups.