Name: new variations for strategy set-shifting in the rat
Uploaded: 2017-01-23T13:00:00
Description: Watch this Scientific Journal Video about New Variations for Strategy Set-shifting in the Rat at JoVE.com

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...

<ol>
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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acetylcholine+actions+in+the+dorsomedial+striatum+support+the+flexible+shifting+of+response+patterns.">Acetylcholine actions in the dorsomedial striatum support the flexible shifting of response patterns.</a> Neurobiology of Learning and Memory. 80, 257-267 (2003).</li><li>Ravizza, S. M., Carter, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shifting+set+about+task+switching:+Behavioral+and+neural+evidence+for+distinct+forms+of+cognitive+flexibility.">Shifting set about task switching: Behavioral and neural evidence for distinct forms of cognitive flexibility.</a> Neuropsychologia. 46, 2924-2935 (2008).</li><li>Rushworth, M. F. S., Hadland, K. A., Paus, T., Sipila, P. 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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.

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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 ...

Behavior flexibility is critical for survival in this changing world. One of the behavior paradigms testing this ability is set-shifting task which is being used for both primates and rodent. This task requires attentional shift from one stimulus dimension to another for changing behavioral strategy.In a typical version of the rat set-shifting task animals have to attend to a previously irrelevant stimulus dimension. However, during real life situation, we often change our action strategy by paying attention not only to the previously irrelevant stimulus dimension, but also to the other stimuli, such as completely novel and historically relevant cue. In this article, we introduce new variation of the rat set-shifting task.We need three different conditions for the set shift. In all three conditions, the same change in behavioral strategy is required which include two phases, an initial response strategy and a subsequent switch to a visual cue strategy. During the response strategy, a reward is given when the correct lever is pressed.The lever remains the same throughout this phase. Next, a change to the visual cue strategy occurs when a new rule to obtain a reward is applied, as animals are required to select the lever on which a visual cue is illuminated. In Condition one, no light is given in an initial response and animals have to attend to a novel light cue.In Condition two, a light cue indicates the correct side in the initial response strategy, but this cue is not necessarily used for making a choice. In this case, the animals attend to a historically relevant cue. In Condition three, the visual cue randomly appears above either lever, regardless if it's correct or not, so it has to be ignored.This case requires that the animals have to attend to the previously irrelevant cue in the next visual cue strategy. On arrival of animals, groups of two or three rats are housed together. After a week, they are each moved into individual cages and food restricted.Five days before experiments, they are gently handled daily for five minutes. Each operant chamber is composed of a house light, a pure tone generator, two identical visual cue indicators, two levers, and a food tray. On the first day of experiments, animals are put into an operant chamber for 20 minutes of habituation.Once animals have been assigned to a particular chamber, all the behavioral tasks are performed there. After habituation, 10-15 pellets are given when returned to their home cage, allowing the animals to become familiar with a reward. The following day, magazine training begins.Here, a total of 20 pellets are given to each animal at a rate of one pellet per minute. The next stage is a continuous reinforcement schedule. Here animals can obtain one pellet by pressing a lever once.This continues until they receive 60 rewards or 40 minutes pass in each session. When animals have completed a session for at least two consecutive days, they proceed to the next phase. Here animals are trained on the lever press trial.The trial commences with a three second tone. Two seconds after the tone ceases, either the left or right lever is presented. The animals are required to press the lever within ten seconds to obtain a reward.They perform 80 trials per session with an inter-trial interval of 20-30 seconds. When they make fewer than ten omissions out of 80 trials, they proceed to the last training session. The Side Bias Test determines the animal's preference for either lever.A successful trial occurs when there are at least two lever presses on each of the left and right levers. First, animals need to choose one lever to receive a reward. This selected side is counted.In the next attempt, they are required to choose the opposite side to their first choice to obtain a reward. If they respond to the same side, no reward is given and the trial is continued until animals press the other side. This test has seven trials and enables us to define each animal's side preference.From this point on, the testing session begins. A daily session has 80 trials. In this session, animals have to respond to one side of the levers that is the opposite to their preference.Similar to the performed lever press trial training, two seconds after the tone delivery, two levers are presented, and animals are allowed to make a choice. If it's correct, they obtain a reward. If they respond to the other side, the trial is counted as an incorrect trial and no reward is given.When animals do not respond within ten seconds, the trial is counted as an omission. This initial learning of the response strategy is continued for four days. In this phase, there are three different conditions which differ in how a visual cue is presented.In Condition one, no light cue is given. In Condition two, a light cue is illuminated on the correct side, but animals do not have to use this cue because they learn this strategy based on lever location. In Condition three, a light cue is randomly presented either on the left or right side, which is an irrelevant light cue.After animals have learned a response strategy based on the lever location, the behavioral rule changes to a visual cue strategy. In Condition one, animals must attend to a completely novel stimulus. In Condition two, they must attend to a previously relevant cue.In Condition three, animals must attend to a previous irrelevant cue. Importantly, all the conditions require the same change in behavioral strategy. In this visual cue learning, the number and type of errors are analyzed in detail.First, taking all the trials in which a light cue is illuminated on the opposite side of the previously correct lever, if animals respond to the previously correct lever, this error is classified as either a perseverative or regressive error. To separate those errors, the number of errors in a ten trial moving window is counted by advancing the window one trial at a time. Perseverative errors are scored until animals make fewer than eight errors out of the ten trial window.After this point, subsequent errors are regarded as regressive errors. In contrast, never-reinforced errors are scored when animals make a response to the previously incorrect lever in which a light cue did not exist. Using these new variations in behavioral experimental design our recent study compared intact rats against rats with selective lesions of the striatal cholinergic interneurons.The lesion animals were intact in acquisition of initial response strategy. As well, they did not show a significant decline in the percentage of correct responses across three conditions and in any treatment after the set-shift. However, careful analysis of error types indicated differences.When cholinergic interneurons of the ventral striatum were ablated, animals scored more perseverative errors when they had to shift their attention to a novel stimulus. On the other hand, animals with a loss of cholinergic interneurons of the dorsal medial striatum were more perseverative to the old strategy when they had to attend to the previously irrelevant stimulus. Furthermore, this condition and associated impairment of decreased number of never-reinforced errors was observed.In contrast, neither lesion affected a behavioral shift in which the light cue remained relevant. These results indicate that the ventral cholinergic system appears to be needed when attention to a novel stimulus is required, whereas the dorsal medial cholinergic system may be important when attention to a previously irrelevant cue is needed. Here we introduced a new variation of the set-shifting task for testing behavioral flexibility in the rat.We believe application of these new paradigms make it possible to further understand neural mechanism underlying a flexible control of actions upon a change in behavioral rules.

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Research

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Behavior

A Procedure to Study the Effect of Prolonged Food Restriction on Heroin Seeking in Abstinent Rats

In human drug addicts, exposure to drug-associated cues or environments that were previously associated with drug taking can trigger relapse during abstinence. Moreover, various environmental challenges can exacerbate this effect, as well as increase ongoing drug intake.
The procedure we describe here highlights the impact of a common environmental challenge, food restriction, on drug craving that is expressed as an augmentation of drug seeking in abstinent rats.
Rats are implanted with chronic intravenous i.v. catheters, and then trained to press a lever for i.v. heroin over a period of 10-12 days. Following the heroin self-administration phase the rats are removed from the operant conditioning chambers and housed in the animal care facility for a period of at least 14 days. While one group is maintained under unrestricted access to food (sated group), a second group (FDR group) is exposed to a mild food restriction regimen that results in their body weights maintained at 90% of their nonrestricted body weight. On day 14 of food restriction the rats are transferred back to the drug-training environment, and a drug-seeking test is run under extinction conditions (i.e.&#160;lever presses do not result in heroin delivery).
The procedure presented here results in a highly robust augmentation of heroin seeking on test day in the food restricted rats. In addition, compared to the acute food deprivation manipulations we have used before, the current procedure is a more clinically relevant model for the impact of caloric restriction on drug seeking. Moreover, it might be closer to the human condition as the rats are not required to go through an extinction-training phase before the drug-seeking test, which is an integral component of the popular reinstatement procedure.

A procedure that allows a demonstration of robust augmentation of drug seeking in food-restricted rats is described. Following heroin self-administration training, rats go through an abstinence period, in a drug-free environment, during which they are mildly food restricted. Drug seeking is then tested in the drug-associated environment.

In human drug addicts, exposure to drug-associated cues or environments that were previously associated with drug taking can trigger relapse during ...

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 ...

Moderate Prenatal Alcohol Exposure and Quantification of Social Behavior in Adult Rats

Alterations in social behavior are among the major negative consequences observed in children with Fetal Alcohol Spectrum Disorders (FASDs). Several independent laboratories have demonstrated robust alterations in the social behavior of rodents exposed to alcohol during brain development across a wide range of exposure durations, timing, doses, and ages at the time of behavioral quantification. Prior work from this laboratory has identified reliable alterations in specific forms of social interaction following moderate prenatal alcohol exposure (PAE) in the rat that persist well into adulthood, including increased wrestling and decreased investigation. These behavioral alterations have been useful in identifying neural circuits altered by moderate PAE1, and may hold importance for progressing toward a more complete understanding of the neural bases of PAE-related alterations in social behavior. This paper describes procedures for performing moderate PAE in which rat dams voluntarily consume ethanol or saccharin (control) throughout gestation, and measurement of social behaviors in adult offspring.

The goal of the protocol presented here is to describe procedures to expose rats to moderate levels of alcohol during prenatal brain development and to quantify resulting alterations in social behavior during adulthood.

Alterations in social behavior are among the major negative consequences observed in children with Fetal Alcohol Spectrum Disorders (FASDs). Several ...

Infant Auditory Processing and Event-related Brain Oscillations

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net application, recording, dynamic brain response analysis, and representative results.

High-density electroencephalography (dEEG) is being used increasingly to study brain development and plasticity in the early years of life. Here we present an application of sophisticated analysis techniques that builds on traditional EEG recording to understand the oscillatory dynamics of rapid auditory processing in the infant brain.

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral ...

Using the Activity-based Anorexia Rodent Model to Study the Neurobiological Basis of Anorexia Nervosa

Anorexia nervosa (AN) is a psychiatric illness characterized by excessively restricted caloric intake and abnormally high levels of physical activity. A challenging illness to treat, due to the lack of understanding of the underlying neurobiology, AN has the highest mortality rate among psychiatric illnesses. To address this need, neuroscientists are using an animal model to study how neural circuits may contribute toward vulnerability to AN and may be affected by AN. Activity-based anorexia (ABA) is a bio-behavioral phenomenon described in rodents that models the key symptoms of anorexia nervosa. When rodents with free access to voluntary exercise on a running wheel experience food restriction, they become hyperactive &#8211; running more than animals with free access to food. Here, we describe the procedures by which ABA is induced in adolescent female C57BL/6 mice. On postnatal day 36 (P36), the animal is housed with access to voluntary exercise on a running wheel. After 4 days of acclimation to the running wheel, on P40, all food is removed from the cage. For the next 3 days, food is returned to the cage (allowing animals free food access) for 2 hr daily. After the fourth day of food restriction, free access to food is returned and the running wheel is removed from the cage to allow the animals to recover. Continuous multi-day analysis of running wheel activity shows that mice become hyperactive within 24 hr following the onset of food restriction. The mice run even during the limited time during which they have access to food. Additionally, the circadian pattern of wheel running becomes disrupted by the experience of food restriction. We have been able to correlate neurobiological changes with various aspects of the animals&#8217; wheel running behavior to implicate particular brain regions and neurochemical changes with resilience and vulnerability to food-restriction induced hyperactivity.

Here we present a protocol to induce activity-based anorexia (ABA) in female adolescent mice. ABA is a condition of hyperactivity evoked by imposing food restriction on rodents with access to a running wheel. This phenomenon is being used as a model to study the underlying neurobiology of anorexia nervosa.

Anorexia nervosa (AN) is a psychiatric illness characterized by excessively restricted caloric intake and abnormally high levels of physical activity. A ...

Ultrasound Images of the Tongue: A Tutorial for Assessment and Remediation of Speech Sound Errors

Diagnostic ultrasound imaging has been a common tool in medical practice for several decades. It provides a safe and effective method for imaging structures internal to the body. There has been a recent increase in the use of ultrasound technology to visualize the shape and movements of the tongue during speech, both in typical speakers and in clinical populations. Ultrasound imaging of speech has greatly expanded our understanding of how sounds articulated with the tongue (lingual sounds) are produced. Such information can be particularly valuable for speech-language pathologists. Among other advantages, ultrasound images can be used during speech therapy to provide (1) illustrative models of typical (i.e.&#160;&#34;correct&#34;) tongue configurations for speech sounds, and (2) a source of insight into the articulatory nature of deviant productions. The images can also be used as an additional source of feedback for clinical populations learning to distinguish their better productions from their incorrect productions, en route to establishing more effective articulatory habits.
Ultrasound feedback is increasingly used by scientists and clinicians as both the expertise of the users increases and as the expense of the equipment declines. In this tutorial, procedures are presented for collecting ultrasound images of the tongue in a clinical context. We illustrate these procedures in an extended example featuring one common error sound, American English /r/. Images of correct and distorted /r/ are used to demonstrate (1) how to interpret ultrasound images, (2) how to assess tongue shape during production of speech sounds, (3), how to categorize tongue shape errors, and (4), how to provide visual feedback to elicit a more appropriate and functional tongue shape. We present a sample protocol for using real-time ultrasound images of the tongue for visual feedback to remediate speech sound errors. Additionally, example data are shown to illustrate outcomes with the procedure.

Ultrasound imaging can be used to display the shape and movements of the tongue in real time during speech. The images can be used to determine the nature of speech sound errors. Visual feedback of the tongue can be used to facilitate improvements in speech sound production in clinical populations.

Diagnostic ultrasound imaging has been a common tool in medical practice for several decades. It provides a safe and effective method for imaging ...

Stereotactically-guided Ablation of the Rat Auditory Cortex, and Localization of the Lesion in the Brain

The rat auditory cortex (AC) is becoming popular among auditory neuroscience investigators who are interested in experience-dependence plasticity, auditory perceptual processes, and cortical control of sound processing in the subcortical auditory nuclei. To address new challenges, a procedure to accurately locate and surgically expose the auditory cortex would expedite this research effort. Stereotactic neurosurgery is routinely used in pre-clinical research in animal models to engraft a needle or electrode at a pre-defined location within the auditory cortex. In the following protocol, we use stereotactic methods in a novel way. We identify four coordinate points over the surface of the temporal bone of the rat to define a window that, once opened, accurately exposes both the primary (A1) and secondary (Dorsal and Ventral) cortices of the AC. Using this method, we then perform a surgical ablation of the AC. After such a manipulation is performed, it is necessary to assess the localization, size, and extension of the lesions made in the cortex. Thus, we also describe a method to easily locate the AC ablation postmortem using a coordinate map constructed by transferring the cytoarchitectural limits of the AC to the surface of the brain.The combination of the stereotactically-guided location and ablation of the AC with the localization of the injured area in a coordinate map postmortem facilitates the validation of information obtained from the animal, and leads to a better analysis and comprehension of the data.

We describe a method for the stereotactically-guided location, exposure, and ablation of the auditory cortex in rats. The localization of the ablation is assessed using a coordinate map postmortem.

The rat auditory cortex (AC) is becoming popular among auditory neuroscience investigators who are interested in experience-dependence plasticity, ...

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 ...

Efficiently Recording the Eye-Hand Coordination to Incoordination Spectrum

The objective analysis of eye movements has a significant history and has been long proven to be an important research tool in the setting of brain injury. Quantitative recordings have a strong capacity to screen diagnostically. Concurrent examinations of the eye and upper limb movements directed toward shared functional goals (e.g., eye-hand coordination) serve as an additional robust biomarker-laden path to capture and interrogate neural injury, including acquired brain injury (ABI). While quantitative dual-effector recordings in 3-D afford ample opportunities within ocular-manual motor investigations in the setting of ABI, the feasibility of such dual recordings for both eye and hand is challenging in pathological settings, particularly when approached with research-grade rigor. Here we describe the integration of an eye tracking system with a motion tracking system intended primarily for limb control research to study a natural behavior. The protocol enables the investigation of unrestricted, three-dimensional (3D) eye-hand coordination tasks. More specifically, we review a method to assess eye-hand coordination in visually guided saccade-to-reach tasks in subjects with chronic middle cerebral artery (MCA) stroke and compare them to healthy controls. Special attention is paid to the specific eye- and limb-tracking system properties in order to obtain high fidelity data from participants post-injury. Sampling rate, accuracy, permissible head movement range given anticipated tolerance and the feasibility of use were several of the critical properties considered when selecting an eye tracker and an approach. The limb tracker was selected based on a similar rubric but included the need for 3-D recording, dynamic interaction and a miniaturized physical footprint. The quantitative data provided by this method and the overall approach when executed correctly has tremendous potential to further refine our mechanistic understanding of eye-hand control and help inform feasible diagnostic and pragmatic interventions within the neurological and rehabilitative practice.&#160;

Cerebral injury can damage both ocular and somatic motor systems. Characterization of motor control post-injury affords biomarkers that assist in disease detection, monitoring, and prognosis. We review a method to measure eye-hand movement control in health and in pathologic incoordination, with look-and-reach paradigms to assess coordination between eye and hand.

The objective analysis of eye movements has a significant history and has been long proven to be an important research tool in the setting of brain ...

Transcranial Direct Current Stimulation for Online Gamers

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that applies a weak electric current to the scalp to modulate neuronal membrane potentials. Compared to other brain stimulation methods, tDCS is relatively safe, simple, and inexpensive to administer.
Since excessive online gaming can negatively affect mental health and daily functioning, developing treatment options for gamers is necessary. Although tDCS over the dorsolateral prefrontal cortex (DLPFC) has demonstrated promising results for various addictions, it has not been tested in gamers. This paper describes a protocol and a feasibility study for applying repeated tDCS over the DLPFC and neuroimaging to examine the underlying neural correlates in gamers.
At baseline, individuals who play online games report average weekly hours spent on games, complete questionnaires on addiction symptoms and self-control, and undergo brain 18F-&#64258;uoro-2-deoxyglucose positron emission tomography (FDG-PET). The tDCS protocol consists of 12 sessions over the DLPFC for 4 weeks (anode F3/cathode F4, 2 mA for 30 min per session). Then, a follow-up is conducted using the same protocol as the baseline. Individuals who do not play online games receive only baseline FDG-PET scans without tDCS. Changes of clinical characteristics and asymmetry of regional cerebral metabolic rate of glucose (rCMRglu) in the DLPFC are examined in gamers. In addition, asymmetry of rCMRglu is compared between gamers and non-gamers at baseline.
In our experiment, 15 gamers received tDCS sessions and completed baseline and follow-up scans. Ten non-gamers underwent FDG-PET scans at the baseline. The tDCS reduced addiction symptoms, time spent on games, and increased self-control. Moreover, abnormal asymmetry of rCMRglu in the DLPFC at baseline was alleviated after tDCS.
The current protocol may be useful for assessing treatment efficacy of tDCS and its underlying brain changes in gamers. Further randomized sham-controlled studies are warranted. Moreover, the protocol can be applied to other neurological and psychiatric disorders.

We present a protocol and a feasibility study for applying transcranial direct current stimulation (tDCS) and neuroimaging assessment in online gamers.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that applies a weak electric current to the scalp to modulate ...