The authors would like to thank Hannah Zamore, Emily Saks, and Josh Searle for their help in establishing this operant strategy shifting paradigm in the Grafe lab. They would also like to thank Kevin Snyder for his help with the MATLAB code for analysis.

The authors have nothing to disclose.

The protocol demonstrates how to measure the effects of stress on cognitive function. Specifically, a modified operant strategy shifting paradigm is used in rodents, which measures cognitive flexibility (analogous to the Wisconsin Card Sorting Task in humans)1. Cognitive flexibility denotes the ability to adapt cognitive processing strategies to face new conditions in the environment, and it is crucial for normal daily functioning2. As human studies on cognitive flexibility are mostly limited to brain imaging11, the use of this paradigm in animals will greatly advance the understanding of effects of stress on the brain and cognition.
Stress can impair cognitive function40. In fact, this is one of the most common phenotypes in stress-related illnesses such as PTSD and MDD3,41. Moreover, there are stark sex differences in the occurrence of stress-related psychiatric illnesses5,6,7, yet there is little understanding of the neurobiology behind these biased incidences. Thus, use of this operant strategy shifting paradigm in animals of both sexes may help advance the current understanding of sex differences in psychiatry.
This operant strategy shifting task allows researchers to examine key aspects of cognition relevant to psychiatric disorders. For example, perseverative errors after experimental manipulation are calculated in this paradigm. Perseveration is observed in stress-related psychiatric disorders such as PTSD, and it impairs the ability of one to learn a new set of rules, ultimately impairing working memory3. Thus, the measure of perseverative errors is translationally relevant. Moreover, omissions in attention tasks have been noted in patients with PTSD, indicating slower cortical processing3. Accordingly, omission data from this paradigm may have clinical counterparts. In sum, cognitive flexibility measured as by this experimental paradigm models key phenotypes that are observed in psychiatric disorders.
This experimental paradigm also allows for precision in targeting neural substrates underlying cognitive flexibility. For example, the literature has indicated that the prefrontal cortex (PFC) is a crucial brain region for cognitive flexibility3, including the medial prefrontal (mPFC) and orbitofrontal cortex (OFC). Of these subregions in the PFC, the OFC is important for performance in the side reversal task34,35. These brain areas are also a key targets for stress-induced functional alterations42,43. Interestingly, the model of stress used here does appear to play a role in the subsequent performance of rodents in tests of cognitive flexibility; thus, it should be considered in the design of future experiments. These varying responses to stress point to potentially novel mechanisms by which cognition is impacted by stress. Thus, targeting specific neurotransmitters, proteins, or activation of these brain regions may shed light on how stress affects cognition in male and female rodents. Researchers can choose to manipulate these neural substrates at different timepoints in conjunction with stress or strategy shifting, or alternatively measure neural substrates after exposure to these behavioral paradigms.
This modified operant strategy shifting task has clear advantages over other cognitive flexibility paradigms used in the stress literature (i.e., the digging task12,13,14,15), which require more time and effort by the experimenter to train rodents. This procedure requires minimal oversight by the experimenter and allows multiple rats to be tested simultaneously. In addition, unlike other versions of this automated task19, the paradigm only requires 3 days of training and includes an efficient programmed data analysis.
The operant strategy shifting paradigm does have certain limitations. One limitation is that it can only test two stimulus dimensions (e.g., left or right lever vs. light cue), whereas the digging task12,13,14,15 can test a third stimulus dimension (e.g., digging media vs. odor vs. texture). However, the task described in this protocol still allows for testing of the rat&#8217;s ability to shift to different rules, which allows testing of the cognitive flexibility constructs. In addition, it is possible to add other parameters to the operant chambers to allow for a third stimulus (e.g., an odor), but this may prolong the training required for the task.
The primary advantage of this task is its simplicity and ability to pair it with stressful or pharmacological manipulations to further understand how stress affects the brain. It should be noted that this simplicity comes with an increased difficulty that subjects face while learning to lever press, compared to the ecologically relevant digging task. While this operant task is far less labor-intensive, rodents will generally require more trials to acquire this task. However, both the digging task and this paradigm engage similar neurobiological mechanisms and thus represent valid options for the examination of cognitive flexibility16,44. While there have been varied results in the literature regarding the effects of stress on cognitive flexibility using the digging task and this operant procedure23,25,27,45,46, the presented method reflects the complex effects that the type, intensity, and duration of a stressor can have on cognitive function20,21.
Another limitation of the task is that rodents are housed in closed opaque boxes; thus, behaviors other than those that are collected via the computer interface cannot be coded. For example, a high number of omissions by a rat may be due to behavioral inhibition inflicted by stress, or because the rat is asleep. Moreover, other stereotypical behaviors, such as grooming (which is particularly relevant in studying stress), may be interesting to analyze during the task. Mounting cameras in operant chambers may allow for this type of behavioral precision.
Overall, this report details the use of stress procedures in conjunction with an operant strategy shifting paradigm to further understand how stress affects the brain. It should be noted that, in addition to stress procedures and cognitive assessment in adults, research on different developmental stages may provide crucial information about the etiology of cognitive inflexibility. In addition to studying the effects of stress on cognitive flexibility, this simple and efficient operant strategy shifting paradigm can be paired with many experimental manipulations to investigate how the brain adapts to changing environments. Moreover, alternate experimental approaches can be used to study the neural basis of cognitive flexibility, including lesions, pharmacology, gene editing, and electrophysiology. As cognitive inflexibility is one of the key phenotypes in psychiatric disease, more research must be conducted to further understand its neurobiological substrates.

In humans, stressful life events can impair cognitive function (i.e, cognitive flexibility1), which denotes the ability to adapt cognitive processing strategies to face new conditions in the environment2. Impairment in cognition precipitates and exacerbates many psychiatric disorders, such as Post Traumatic Stress Disorder (PTSD) and Major Depressive Disorder (MDD)3,4. These disorders are twice as prevalent in females5,6,7,8, yet the biological basis for this disparity remains unknown. Aspects of executive functioning in humans can be assessed using the Wisconsin Card Sorting Task, a demonstration of cognitive flexibility2. Performance in this task is impaired in patients with PTSD9 and MDD10, but the neural basis of this change can only be examined by brain imaging11.
Advances in understanding how stress affects the brain have been made through the use of animal models, particularly rodents. As cognitive flexibility is affected in stress-related diseases, it is an exceptionally relevant phenotype to examine in rodents. To date, most stress neurobiology literature has used an alternative cognitive flexibility paradigm (sometimes referred to as the digging task)12,13,14,15. While this task has been extensively vetted, it requires more time and effort by the experimenter to train rodents. Adapted and described here is a well-established automated set-shifting protocol16 to assess cognitive flexibility in male and female Sprague Dawley rats using various stress models17,18. The procedure requires minimal oversight by the experimenter and allows multiple rats to be tested simultaneously. In addition, unlike other versions of this automated task19, the adaptation of this paradigm only requires 3 days of training and includes an efficient programmed data analysis.
Whether stress enhances or impairs cognitive function depends on the type, intensity, and duration of the stressor, as well as the timing of the stressor in relation to learning or executing a cognitive task20,21. Thus, the protocol incorporates stress procedures both before and after the operant training. It also examines representative results from stress studies. In addition, the brain regions underlying particular aspects of set-shifting have been well-established2,16,22; thus, the report also describes how to target and assess particular brain regions during or after the stress and strategy shifting procedures.
There has been limited research on directly examining sex differences in cognitive flexibility18,23. &#160;The protocol describes how to 1) incorporate both male and female rats into the experimental paradigm, then 2) track estrous cycles before and during the procedures in freely cycling females. Prior studies have indicated that stress before operant training can lead to sex-specific deficits in cognitive flexibility in rats17. Particularly, female rats exhibit disruptions in cognitive flexibility after stress, whereas cognitive flexibility improves in male rats after stress17. Interestingly, a major hallmark of stress-related psychiatric disorders, which have a sex-biased incidence in humans, is cognitive inflexibility. These results suggest that females may be more vulnerable to this type of cognitive impairment than males. The use of these techniques in animal models will shed light on the effects of stress on the brain and how it impairs cognition in psychiatric disorders in humans.

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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.

The adapted automated operant strategy shifting paradigm outlined above was used to determine if repeated restraint stress affects cognition in male and female Sprague Dawley rats. Representative behavioral data are described in Figure 2 below. In short, control and repeatedly restrained rats performed this operant strategy shifting test, which consisted of a series of tasks: side discrimination, side reversal, and light discrimination.
Trials to criterion for each task are depicted in Figure 2A. Typically, better performance on each task was represented by a reduced number of trials to criterion. These data indicate that, following acute restraint, males completed the side reversal task in significantly fewer trials than unstressed, control males. Conversely, stressed females required a significantly greater number of trials to complete the side reversal task. These results suggest that males exhibited improved performance following stress, whereas females exhibited impaired performance. In the light discrimination task, stress increased the number of trials to criterion compared to control females, thereby impairing performance in females but not males in this task.&#160;
The total number of errors made for each attention task is depicted in Figure 2B. Consistent with the number of trials to criterion, stressed males made significantly fewer errors than control males, whereas stressed females made more errors in the side reversal task. Furthermore, in the light discrimination task, females also made significantly more errors. In sum, these data suggest that repeated stress improves cognitive performance in males but impairs cognitive performance in females.
Total errors were further categorized into perseverative or regressive errors in Figure 2C (for a distinction between these two types of errors, refer to section 7 of the protocol). Interestingly, stressed males made fewer perseverative errors in the side reversal task than control males. On the other hand, in both the side reversal and light discrimination tasks, stressed females made a greater number of perseverative errors than control females. There were no differences between the treatment groups in the number of regressive errors made during either task.
Omissions in each trial and time to reach criterion are shown in Figure 2D (for more information on how these were calculated, refer to section 7 of the protocol). These measures were evaluated in the side reversal task only, as this task exhibited the largest sex differences. Stressed females made a higher percentage of omissions compared to all other treatment groups. In addition, while stress appeared to decrease the time to complete the side reversal task in males, stress prolonged completion of the task in females. In sum, repeated stress impaired cognitive flexibility in females but not males.
Brain substrates underlying cognitive flexibility are depicted in Figure 3. As stark sex differences were observed in the side reversal task, the brain areas underlying this task were examined to determine whether they displayed similar sex differences in neural activity. As previously discussed, lesion studies have indicated that the orbitofrontal cortex (OFC) mediates the side reversal task34. Thus, c-fos, a measure of neural activation37, was labeled in the OFC at 30 min after the completion of strategy shifting, which should have reflected performance in the side reversal task38. However, it is possible that OFC may also play a role in the extradimensional strategy shifting component of this task39. Thus, it is important to perform the sacrifice at the appropriate time to reflect brain activity during a particular task within the operant strategy shifting paradigm. Here, stress induced a significant increase in neuronal activation in the OFC of males compared to controls. However, stress induced a significant decrease in neuronal activation in the OFC of females compared to controls. Furthermore, in males, OFC activation and trials to criterion were negatively correlated; specifically, higher OFC activation was associated with fewer trials to criterion. In contrast, there was no correlation between OFC activation and performance in females, suggesting that the OFC was disengaged during these performances.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61228/61228fig1.jpg" /> 
Figure 1: Schematic of the operant strategy shifting paradigm during training and test days. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61228/61228fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61228/61228fig2.jpg" /> 
Figure 2: Representative behavioral data from operant strategy shifting paradigm. (A) Trials to criterion for each task on test day. In the side reversal task, stress improved performance in males but impaired performance in females. In the light discrimination task, stress weakened performance in females, while it did not affect males. (B) Number of errors for each task on test day. Stress reduced the number of errors made in males but increased errors in females in both side reversal and light discrimination tasks. (C) Perseverative and regressive error categorization. Stress decreased perseverative errors made in males but increased perseverative errors made in females in both side reversal and light discrimination tasks. (D) Percent trials omitted and time to criterion in the side reversal task. Stress increased the percent omissions in female rats. Stress decreased the time required by males but increased the time required by females to complete the task. Statistics were calculated using two-way ANOVA followed by Tukey&#8217;s t-test (n = 12 rats per group; error bars represent SEM; #p &#8804; 0.10, *p &#60; 0.05). This figure has been modified from a previous publication17. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61228/61228fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/61228/61228fig3.jpg" /> 
Figure 3: Representative neural activation after operant strategy shifting paradigm. (A) OFC activation after strategy shifting task. Representative images of immunohistochemical 3,3&#8217;-diaminobenzidine (DAB) staining using an antibody against c-fos in the OFC visualized using brightfield microscopy, then quantified. Stress significantly increased activation (demonstrated by the number of c-fos-expressing cells) in the OFC of males, while it decreased activation in females. Scale bar in bottom-right image panel represents 200 &#181;m. Statistics were calculated using two-way ANOVA followed by Tukey&#8217;s t-test (n = 12 rats per group, 6&#8211;8 sections of OFC analyzed per rat; error bars represent SEM; *p &#60; 0.05). (B) Trials to criterion in the side reversal task correlated with OFC activation. Males displayed a significant negative correlation, whereas females did not. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61228/61228fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Assessment of Stress Effects on Cognitive Flexibility using an Operant Strategy Shifting Paradigm at JoVE.com

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

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 ...

assessment-stress-effects-on-cognitive-flexibility-using-an-operant

Nanyang Technological University

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JoVE Journal

Behavior

3.2K Views.  Bryn Mawr College. 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.

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

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 ...

Irrelevant Stimuli and Action Control: Analyzing the Influence of Ignored Stimuli via the Distractor-Response Binding Paradigm

Selection tasks in which simple stimuli (e.g. letters) are presented and a target stimulus has to be selected against one or more distractor stimuli are frequently used in the research on human action control. One important question in these settings is how distractor stimuli, competing with the target stimulus for a response, influence actions. The distractor-response binding paradigm can be used to investigate this influence. It is particular useful to separately analyze response retrieval and distractor inhibition effects. Computer-based experiments are used to collect the data (reaction times and error rates). In a number of sequentially presented pairs of stimulus arrays (prime-probe design), participants respond to targets while ignoring distractor stimuli. Importantly, the factors response relation in the arrays of each pair (repetition vs. change) and distractor relation (repetition vs. change) are varied orthogonally. The repetition of the same distractor then has a different effect depending on response relation (repetition vs. change) between arrays. This result pattern can be explained by response retrieval due to distractor repetition. In addition, distractor inhibition effects are indicated by a general advantage due to distractor repetition. The described paradigm has proven useful to determine relevant parameters for response retrieval effects on human action.

The distractor-response binding paradigm is described. It can be used to shed light on the influence irrelevant stimuli, competing with targets for a response, can have on human action. Both response retrieval effects and distractor inhibition effects can be analyzed within the paradigm.

Selection tasks in which simple stimuli (e.g. letters) are presented and a target stimulus has to be selected against one or more distractor stimuli are ...

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 ...

Investigating the Effects of Antipsychotics and Schizotypy on the N400 Using Event-Related Potentials and Semantic Categorization

Within the field of cognitive neuroscience, functional magnetic resonance imaging (fMRI) is a popular method of visualizing brain function. This is in part because of its excellent spatial resolution, which allows researchers to identify brain areas associated with specific cognitive processes. However, in the quest to localize brain functions, it is relevant to note that many cognitive, sensory, and motor processes have temporal distinctions that are imperative to capture, an aspect that is left unfulfilled by fMRI&#8217;s suboptimal temporal resolution. To better understand cognitive processes, it is thus advantageous to utilize event-related potential (ERP) recording as a method of gathering information about the brain. Some of its advantages include its fantastic temporal resolution, which gives researchers the ability to follow the activity of the brain down to the millisecond. It also directly indexes both excitatory and inhibitory post-synaptic potentials by which most brain computations are performed. This sits in contrast to fMRI, which captures an index of metabolic activity. Further, the non-invasive ERP method does not require a contrast condition: raw ERPs can be examined for just one experimental condition, a distinction from fMRI where control conditions must be subtracted from the experimental condition, leading to uncertainty in associating observations with experimental or contrast conditions. While it is limited by its poor spatial and subcortical activity resolution, ERP recordings&#8217; utility, relative cost-effectiveness, and associated advantages offer strong rationale for its use in cognitive neuroscience to track rapid temporal changes in neural activity. In an effort to foster increase in its use as a research imaging method, and to ensure proper and accurate data collection, the present article will outline &#8211; in the framework of a paradigm using semantic categorization to examine the effects of antipsychotics and schizotypy on the N400 &#8211; the procedure and key aspects associated with ERP data acquisition.

Using event-related EEG potentials (ERPs), we investigate the effects of antipsychotic medications on abnormal semantic brain activations in healthy individuals with schizotypal traits. We use ERPs to track distinct changes in brain activity, shedding insight into the cognitive processes associated with semantic categorization.

Within the field of cognitive neuroscience, functional magnetic resonance imaging (fMRI) is a popular method of visualizing brain function. This is in ...

A Cognitive Paradigm to Investigate Interference in Working Memory by Distractions and Interruptions

Goal-directed behavior is often impaired by interference from the external environment, either in the form of distraction by irrelevant information that one attempts to ignore, or by interrupting information that demands attention as part of another (secondary) task goal. Both forms of external interference have been shown to detrimentally impact the ability to maintain information in working memory (WM). Emerging evidence suggests that these different types of external interference exert different effects on behavior and may be mediated by distinct neural mechanisms. Better characterizing the distinct neuro-behavioral impact of irrelevant distractions versus attended interruptions is essential for advancing an understanding of top-down attention, resolution of external interference, and how these abilities become degraded in healthy aging and in neuropsychiatric conditions. This manuscript describes a novel cognitive paradigm developed the Gazzaley lab that has now been modified into several distinct versions used to elucidate behavioral and neural correlates of interference, by to-be-ignored distractors versus to-be-attended interruptors. Details are provided on variants of this paradigm for investigating interference in visual and auditory modalities, at multiple levels of stimulus complexity, and with experimental timing optimized for electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) studies. In addition, data from younger and older adult participants obtained using this paradigm is reviewed and discussed in the context of its relationship with the broader literatures on external interference and age-related neuro-behavioral changes in resolving interference in working memory.

A novel cognitive paradigm is developed to elucidate behavioral and neural correlates of interference by to-be-ignored distractors versus interference by to-be-attended interruptors during a working memory task. In this manuscript, several variants of this paradigm are detailed, and data obtained with this paradigm in younger/older adult participants is reviewed.

Goal-directed behavior is often impaired by interference from the external environment, either in the form of distraction by irrelevant information that ...

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 ...

Assessment of Social Cognition in Non-human Primates Using a Network of Computerized Automated Learning Device (ALDM) Test Systems

Fagot &#38; Paleressompoulle1 and Fagot &#38; Bonte2 have published an automated learning device (ALDM) for the study of cognitive abilities of monkeys maintained in semi-free ranging conditions. Data accumulated during the last five years have consistently demonstrated the efficiency of this protocol to investigate individual/physical cognition in monkeys, and have further shown that this procedure reduces stress level during animal testing3. This paper demonstrates that networks of ALDM can also be used to investigate different facets of social cognition and in-group expressed behaviors in monkeys, and describes three illustrative protocols developed for that purpose. The first study demonstrates how ethological assessments of social behavior and computerized assessments of cognitive performance could be integrated to investigate the effects of socially exhibited moods on the cognitive performance of individuals. The second study shows that batteries of ALDM running in parallel can provide unique information on the influence of the presence of others on task performance. Finally, the last study shows that networks of ALDM test units can also be used to study issues related to social transmission and cultural evolution. Combined together, these three studies demonstrate clearly that ALDM testing is a highly promising experimental tool for bridging the gap in the animal literature between research on individual cognition and research on social cognition.

Assessment of Social Cognition in Non-human Primates Using a Network of Computerized Automated Learning Device ALDM Test Systems

Fagot &#38; Paleressompoulle1 have published an automated learning device (ALDM) aimed at testing individual cognitive abilities in semi-free ranging monkeys. The main goal of our protocol is to use a network of ALDM test units to study social cognition in non-human primates.

Fagot &#38; Paleressompoulle1 and Fagot &#38; Bonte2 have published an automated learning device (ALDM) for the study of cognitive abilities of monkeys ...

Assessing the Effects of Music Listening on Psychobiological Stress in Daily Life

Music listening is associated with stress-reducing effects. However, most of the results on music listening and stress were gathered in experimental settings. As music listening is a popular activity of daily life, it is of utmost importance to study the effects of music listening on psychobiological stress in an everyday, daily-life setting. Here, a study protocol is presented that allows the assessment of associations between music listening and psychobiological stress in daily life by noninvasively measuring salivary cortisol (as a marker of the Hypothalamic-Pituitary-Adrenal (HPA) axis) and salivary alpha-amylase (as a marker of the Autonomic Nervous System (ANS)). The protocol includes advice on the study design (e.g., sampling protocol), the materials and methods (e.g., the assessment of psychobiological stress in daily life, the assessment of music listening, and the manual), the selection of participants (e.g., the approval of the institutional review board and inclusion criteria), and the statistical analyses (e.g., the multilevel approach). The representative results provide evidence for a stress-reducing effect of music listening in daily life. Particularly, specific reasons for listening to music (especially relaxation), as well as the presence of others while doing so, increase this stress-reducing effect. At the same time, music listening in daily life differentially affects the HPA axis and ANS functioning, thus emphasizing the need for a multi-dimensional assessment of stress in daily life.

A study protocol is presented on how to assess associations between music listening and psychobiological stress (as measured by subjective stress levels, salivary cortisol, and salivary alpha-amylase) in daily life. Advice on study design, materials, methods, selection of participants, and statistical handling is provided. Representative results are presented and discussed.

Music listening is associated with stress-reducing effects. However, most of the results on music listening and stress were gathered in experimental ...

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.

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 ...

Eye Tracking During Visually Situated Language Comprehension: Flexibility and Limitations in Uncovering Visual Context Effects

The present work is a description and an assessment of a methodology designed to quantify different aspects of the interaction between language processing and the perception of the visual world. The recording of eye-gaze patterns has provided good evidence for the contribution of both the visual context and linguistic/world knowledge to language comprehension. Initial research assessed object-context effects to test&#160;theories of modularity in language processing. In the introduction, we describe how subsequent investigations have taken the role of the wider visual context in language processing as a research topic in its own right, asking questions such as how our visual perception of events and of speakers contributes to&#160;comprehension informed by&#160;comprehenders&#39; experience. Among the examined aspects of the visual context are actions, events, a speaker&#39;s gaze, and emotional facial expressions, as well as spatial object configurations. Following an overview of the eye-tracking method and its different applications, we list the key steps of the methodology in the protocol, illustrating how to successfully use it to study visually-situated language comprehension. A final section presents three sets of representative results and illustrates the benefits and limitations of eye tracking for investigating the interplay between the perception of the visual world and language comprehension.

The present article reviews an eye-tracking methodology for studies on language comprehension. To obtain reliable data, key steps of the protocol must be followed. Among these are the correct set-up of the eye tracker (e.g., ensuring good quality of the eye and head images) and accurate calibration.

The present work is a description and an assessment of a methodology designed to quantify different aspects of the interaction between language processing ...