A review of the 5-Choice Serial Reaction Time (5-CSRT) task in different vertebrate models

Towards zebrafish models to unravel translational insights of obsessive-compulsive disorder: A neurobehavioral perspective

Obsessive-compulsive disorder (OCD) is a chronic and debilitating illness that has been considered a polygenic and multifactorial disorder, challenging effective therapeutic interventions. Although invaluable advances have been obtained from human and rodent studies, several molecular and mechanistic aspects of OCD etiology are still obscure. Thus, the use of non-traditional animal models may foster innovative approaches in this field, aiming to elucidate the underlying mechanisms of disease from an evolutionary perspective. The zebrafish (Danio rerio) has been increasingly considered a powerful organism in translational neuroscience research, especially due to the intrinsic features of the species. Here, we outline target mechanisms of OCD for translational research, and discuss how zebrafish-based models can contribute to explore neurobehavioral aspects resembling those found in OCD. We also identify possible advantages and limitations of potential zebrafish-based models, as well as highlight future directions in both etiological and therapeutic research. Lastly, we reinforce the use of zebrafish as a promising tool to unravel the biological basis of OCD, as well as novel pharmacological therapies in the field.

Investigating gene-environment interaction on attention in a double-hit model for Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental behavioral disorder characterized by social, communicative, and motor deficits. There is no single etiological cause for ASD, rather, there are various genetic and environmental factors that increase the risk for ASD. It is thought that some of these factors influence the same underlying neural mechanisms, and that an interplay of both genetic and environmental factors would better explain the pathogenesis of ASD. To better appreciate the influence of genetic-environment interaction on ASD-related behaviours, rats lacking a functional copy of the ASD-linked gene Cntnap2 were exposed to maternal immune activation (MIA) during pregnancy and assessed in adolescence and adulthood. We hypothesized that Cntnap2 deficiency interacts with poly I:C MIA to aggravate ASD-like symptoms in the offspring. In this double-hit model, we assessed attention, a core deficit in ASD due to prefrontal cortical dysfunction. We employed a well-established attentional paradigm known as the 5-choice serial reaction time task (5CSRTT). Cntnap2-/- rats exhibited greater perseverative responses which is indicative of repetitive behaviors. Additionally, rats exposed to poly I:C MIA exhibited premature responses, a marker of impulsivity. The rats exposed to both the genetic and environmental challenge displayed an increase in impulsive activity; however, this response was only elicited in the presence of an auditory distractor. This implies that exacerbated symptomatology in the double-hit model may situation-dependent and not generally expressed.

A novel role for phospholamban in the thalamic reticular nucleus

The thalamic reticular nucleus (TRN) is a brain region that influences vital neurobehavioral processes, including executive functioning and the generation of sleep rhythms. TRN dysfunction underlies hyperactivity, attention deficits, and sleep disturbances observed across various neurodevelopmental disorders. A specialized sarco-endoplasmic reticulum calcium (Ca2+) ATPase 2 (SERCA2)-dependent Ca2+ signaling network operates in the dendrites of TRN neurons to regulate their bursting activity. Phospholamban (PLN) is a prominent regulator of SERCA2 with an established role in myocardial Ca2+-cycling. Our findings suggest that the role of PLN extends beyond the cardiovascular system to impact brain function. Specifically, we found PLN to be expressed in TRN neurons of the adult mouse brain, and utilized global constitutive and innovative conditional genetic knockout mouse models in concert with electroencephalography (EEG)-based somnography and the 5-choice serial reaction time task (5-CSRTT) to investigate the role of PLN in sleep and executive functioning, two complex behaviors that map onto thalamic reticular circuits. The results of the present study indicate that perturbed PLN function in the TRN results in aberrant TRN-dependent phenotypes in mice (i.e., hyperactivity, impulsivity and sleep deficits) and support a novel role for PLN as a critical regulator of SERCA2 in the TRN neurocircuitry.

Acute exposure of microwave impairs attention process by activating microglial inflammation

BACKGROUND

Attention provides the foundation for cognitions, which was shown to be affected by microwave (MW) radiation. With the ubiquitous of microwaves, public concerns regarding the impact of MW radiation on attention has hence been increased. Our study aims to investigate the potential effect and mechanism of acute microwave exposure on attention.

RESULTS

We identified obvious impairment of attention in mice by the five-choice serial reaction time (5-CSRT) task. Proteomic analysis of the cerebrospinal fluid (CSF) revealed neuroinflammation and microglial activation potentially due to acute MW exposure. Moreover, biochemical analysis further confirmed microglial activation in the prefrontal cortex (PFC) of mice subjected to acute MW exposure. Finally, minocycline, a commercially available anti-inflammatory compound, attenuated neuroinflammation, inhibited the upregulation of N-methyl-D-aspartic acid receptor (NMDAR) including NR2A and NR2B, and also accelerated the attentional recovery after MW exposure.

CONCLUSIONS

We believe that microglial activation and NMDAR upregulation likely contribute to inattention induced by acute MW exposure, and we found that minocycline may be effective in preventing such process.

A Novel Role for Phospholamban in the Thalamic Reticular Nucleus

The thalamic reticular nucleus (TRN) is a critical brain region that greatly influences vital neurobehavioral processes, including executive functioning and the generation of sleep rhythms. Recently, TRN dysfunction was suggested to underlie hyperactivity, attention deficits, and sleep disturbances observed across various devastating neurodevelopmental disorders, including autism, schizophrenia and attention-deficit/hyperactivity disorder (ADHD). Notably, a highly specialized sarco- endoplasmic reticulum calcium (Ca 2+ ) ATPase 2 (SERCA2)-dependent Ca 2+ signaling network operates in the dendrites of TRN neurons to regulate their high-frequency bursting activity. Phospholamban (PLN) is a prominent regulator of the SERCA2 with an established role in maintaining Ca 2+ homeostasis in the heart; although the interaction of PLN with SERCA2 has been largely regarded as cardiac-specific, our findings challenge this view and suggest that the role of PLN extends beyond the cardiovascular system to impact brain function. Specifically, we found PLN to be expressed in the TRN neurons of the adult mouse brain and utilized global constitutive and innovative conditional genetic mouse models, in combination with 5-choice serial reaction time task (5-CSRTT) and electroencephalography (EEG)-based somnography to assess the role of PLN in regulating executive functioning and sleep, two complex behaviors that map onto thalamic reticular circuits. Overall, the results of the present study show that perturbed PLN function in the TRN results in aberrant thalamic reticular behavioral phenotypes in mice (i.e., hyperactivity, impulsivity and sleep deficits) and support a novel role for PLN as a critical regulator of the SERCA2 in the thalamic reticular neurocircuitry.

Early life cancer and chemotherapy lead to cognitive deficits related to alterations in microglial-associated gene expression in prefrontal cortex

Children that survive leukemia are at an increased risk for cognitive difficulties. A better understanding of the neurobiological changes in response to early life chemotherapy will help develop therapeutic strategies to improve quality of life for leukemia survivors. To that end, we used a translationally-relevant mouse model consisting of leukemic cell line (L1210) injection into postnatal day (P)19 mice followed by methotrexate, vincristine, and leucovorin chemotherapy. Beginning one week after the end of chemotherapy, social behavior, recognition memory and executive function (using the 5 choice serial reaction time task (5CSRTT)) were tested in male and female mice. Prefrontal cortex (PFC) and hippocampus (HPC) were collected at the conclusion of behavioral assays for gene expression analysis. Mice exposed to early life cancer + chemotherapy were slower to progress through increasingly difficult stages of the 5CSRTT and showed an increase in premature errors, indicating impulsive action. A cluster of microglial-related genes in the PFC were found to be associated with performance in the 5CSRTT and acquisition of the operant response, and long-term changes in gene expression were evident in both PFC and HPC. This work identifies gene expression changes in PFC and HPC that may underlie cognitive deficits in survivors of early life exposure to cancer + chemotherapy.

Dissection of neuronal circuits underlying sustained attention with the five-choice serial reaction time task

Attention deficits are common in psychiatric and neurological disorders. The transdiagnostic nature of impaired attention suggests a common set of underlying neural circuits. Yet, there are no circuit-based treatments such as non-invasive brain stimulation currently available due to the lack of sufficiently delineated network targets. Therefore, to better treat attentional deficits, a comprehensive functional dissection of neural circuits underlying attention is imperative. This can be achieved by taking advantage of preclinical animal models and well-designed behavioral assays of attention. The resulting findings in turn can be translated to the development of novel interventions with the goal of advancing them to clinical practice. Here we show that the five-choice serial reaction time task has greatly facilitated the study of the neural circuits underlying attention in a well-controlled setting. We first introduce the task and then focus on its application in preclinical studies on sustained attention, especially in the context of state-of-the-art neuronal perturbations.

An automated, low-latency environment for studying the neural basis of behavior in freely moving rats

BACKGROUND

Behavior consists of the interaction between an organism and its environment, and is controlled by the brain. Brain activity varies at sub-second time scales, but behavioral measures are usually coarse (often consisting of only binary trial outcomes).

RESULTS

To overcome this mismatch, we developed the Rat Interactive Foraging Facility (RIFF): a programmable interactive arena for freely moving rats with multiple feeding areas, multiple sound sources, high-resolution behavioral tracking, and simultaneous electrophysiological recordings. The paper provides detailed information about the construction of the RIFF and the software used to control it. To illustrate the flexibility of the RIFF, we describe two complex tasks implemented in the RIFF, a foraging task and a sound localization task. Rats quickly learned to obtain rewards in both tasks. Neurons in the auditory cortex as well as neurons in the auditory field in the posterior insula had sound-driven activity during behavior. Remarkably, neurons in both structures also showed sensitivity to non-auditory parameters such as location in the arena and head-to-body angle.

CONCLUSIONS

The RIFF provides insights into the cognitive capabilities and learning mechanisms of rats and opens the way to a better understanding of how brains control behavior. The ability to do so depends crucially on the combination of wireless electrophysiology and detailed behavioral documentation available in the RIFF.

Opioid abuse and SIV infection in non-human primates

Human immunodeficiency virus (HIV) and drug abuse are intertwined epidemics, leading to compromised adherence to combined antiretroviral therapy (cART) and exacerbation of NeuroHIV. As opioid abuse causes increased viral replication and load, leading to a further compromised immune system in people living with HIV (PLWH), it is paramount to address this comorbidity to reduce the NeuroHIV pathogenesis. Non-human primates are well-suited models to study mechanisms involved in HIV neuropathogenesis and provide a better understanding of the underlying mechanisms involved in the comorbidity of HIV and drug abuse, leading to the development of more effective treatments for PLWH. Additionally, using broader behavioral tests in these models can mimic mild NeuroHIV and aid in studying other neurocognitive diseases without encephalitis. The simian immunodeficiency virus (SIV)-infected rhesus macaque model is instrumental in studying the effects of opioid abuse on PLWH due to its similarity to HIV infection. The review highlights the importance of using non-human primate models to study the comorbidity of opioid abuse and HIV infection. It also emphasizes the need to consider modifiable risk factors such as gut homeostasis and pulmonary pathogenesis associated with SIV infection and opioid abuse in this model. Moreover, the review suggests that these non-human primate models can also be used in developing effective treatment strategies for NeuroHIV and opioid addiction. Therefore, non-human primate models can significantly contribute to understanding the complex interplay between HIV infection, opioid abuse, and associated comorbidities.

Thrsp Gene and the ADHD Predominantly Inattentive Presentation

There are three presentations of attention-deficit/hyperactivity disorder (ADHD): the predominantly inattention (ADHD-PI), predominantly hyperactive-impulsive (ADHD-HI), and combined (ADHD-C) presentations of ADHD. These may represent distinct childhood-onset neurobehavioral disorders with separate etiologies. ADHD diagnoses are behaviorally based, so investigations into potential etiologies should be founded on behavior. Animal models of ADHD demonstrate face, predictive, and construct validity when they accurately reproduce elements of the symptoms, etiology, biochemistry, and disorder treatment. Spontaneously hypertensive rats (SHR/NCrl) fulfill many validation criteria and compare well with clinical cases of ADHD-C. Compounding the difficulty of selecting an ideal model to study specific presentations of ADHD is a simple fact that our knowledge regarding ADHD neurobiology is insufficient. Accordingly, the current review has explored a potential animal model for a specific presentation, ADHD-PI, with acceptable face, predictive, and construct validity. The Thrsp gene could be a biomarker for ADHD-PI presentation, and THRSP OE mice could represent an animal model for studying this distinct ADHD presentation.

The translational genetics of ADHD and related phenotypes in model organisms

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder resulting from the interaction between genetic and environmental risk factors. It is well known that ADHD co-occurs frequently with other psychiatric disorders due, in part, to shared genetics factors. Although many studies have contributed to delineate the genetic landscape of psychiatric disorders, their specific molecular underpinnings are still not fully understood. The use of animal models can help us to understand the role of specific genes and environmental stimuli-induced epigenetic modifications in the pathogenesis of ADHD and its comorbidities. The aim of this review is to provide an overview on the functional work performed in rodents, zebrafish and fruit fly and highlight the generated insights into the biology of ADHD, with a special focus on genetics and epigenetics. We also describe the behavioral tests that are available to study ADHD-relevant phenotypes and comorbid traits in these models. Furthermore, we have searched for new models to study ADHD and its comorbidities, which can be useful to test potential pharmacological treatments.

Non-Human Primate Models of HIV Brain Infection and Cognitive Disorders

Human Immunodeficiency virus (HIV)-associated neurocognitive disorders are a major burden for people living with HIV whose viremia is stably suppressed with antiretroviral therapy. The pathogenesis of disease is likely multifaceted, with contributions from viral reservoirs including the brain, chronic and systemic inflammation, and traditional risk factors including drug use. Elucidating the effects of each element on disease pathogenesis is near impossible in human clinical or ex vivo studies, facilitating the need for robust and accurate non-human primate models. In this review, we describe the major non-human primate models of neuroHIV infection, their use to study the acute, chronic, and virally suppressed infection of the brain, and novel therapies targeting brain reservoirs and inflammation.

A Novel Three-Choice Touchscreen Task to Examine Spatial Attention and Orienting Responses in Rodents

Mammalian orienting behavior consists of coordinated movements of the eyes, head, pinnae, vibrissae, or body to attend to an external stimulus. The present study aimed to develop a novel operant task using a touch-screen system to measure spatial attention. In this task, rats were trained to nose-poke a light stimulus presented in one of three locations. The stimulus was presented more frequently in the center location to develop spatial attention bias toward the center stimulus. Changes in orienting responses were detected by measuring the animals' response accuracy and latency to stimuli at the lateral locations, following reversible unilateral chemogenetic inactivation of the superior colliculus (SC). Additionally, spontaneous turning and rotation behavior was measured using an open-field test (OFT). Our results show that right SC inactivation significantly increased the whole body turn angle in the OFT, in line with previous literature that indicated an ipsiversive orientating bias and the presence of contralateral neglect following unilateral SC lesions. In the touch screen orienting task, unilateral SC inactivation significantly increased bias toward the ipsilateral side, as measured by response frequency in various experimental conditions, and a very large left-shift of a respective psychometric function. Our results demonstrate that this novel touchscreen task is able to detect changes in spatial attention and orienting responses because of e.g. experimental manipulations or injury with very high sensitivity, while taking advantage of the touch screen technology that allows for high transferability of the task between labs and for open-source data sharing through https://www.mousebytes.ca.

The reuniens and rhomboid nuclei of the thalamus: A crossroads for cognition-relevant information processing?

Over the past twenty years, the reuniens and rhomboid (ReRh) nuclei, which constitute the ventral midline thalamus, have received constantly growing attention. Since our first review article about the functional contributions of ReRh nuclei (Cassel et al., 2013), numerous (>80) important papers have extended anatomical knowledge, including at a developmental level, introduced new and very original electrophysiological insights on ReRh functions, and brought novel results on cognitive and non-cognitive implications of the ReRh. The current review will cover these recent articles, more on Re than on Rh, and their contribution will be approached according to their affiliation with work before 2013. These neuroanatomical, electrophysiological or behavioral findings appear coherent and point to the ReRh nuclei as two major components of a multistructural system supporting numerous cognitive (and non-cognitive) functions. They gate the flow of information, perhaps especially from the medial prefrontal cortex to the hippocampus and back, and coordinate activity and processing across these two (and possibly other) brain regions of major cognitive relevance.

Behavioral Tasks Evaluating Schizophrenia-like Symptoms in Animal Models: A Recent Update

BACKGROUND

Schizophrenia is a serious mental illness that affects more than 21 million people worldwide. Both genetics and the environment play a role in its etiology and pathogenesis. Symptoms of schizophrenia are mainly categorized into positive, negative, and cognitive. One major approach to identify and understand these diverse symptoms in humans has been to study behavioral phenotypes in a range of animal models of schizophrenia.

OBJECTIVE

We aimed to provide a comprehensive review of the behavioral tasks commonly used for measuring schizophrenia-like behaviors in rodents together with an update of the recent study findings.

METHODS

Articles describing phenotypes of schizophrenia-like behaviors in various animal models were collected through a literature search in Google Scholar, PubMed, Web of Science, and Scopus, with a focus on advances over the last 10 years.

RESULTS

Numerous studies have used a range of animal models and behavioral paradigms of schizophrenia to develop antipsychotic drugs for improved therapeutics. In establishing animal models of schizophrenia, the candidate models were evaluated for schizophrenia-like behaviors using several behavioral tasks for positive, negative, and cognitive symptoms designed to verify human symptoms of schizophrenia. Such validated animal models were provided as rapid preclinical avenues for drug testing and mechanistic studies.

CONCLUSION

Based on the most recent advances in the field, it is apparent that a myriad of behavior tests are needed to confirm and evaluate the congruency of animal models with the numerous behaviors and clinical signs exhibited by patients with schizophrenia.

Efficient training of mice on the 5-choice serial reaction time task in an automated rodent training system

Experiments aiming to understand sensory-motor systems, cognition and behavior necessitate training animals to perform complex tasks. Traditional training protocols require lab personnel to move the animals between home cages and training chambers, to start and end training sessions, and in some cases, to hand-control each training trial. Human labor not only limits the amount of training per day, but also introduces several sources of variability and may increase animal stress. Here we present an automated training system for the 5-choice serial reaction time task (5CSRTT), a classic rodent task often used to test sensory detection, sustained attention and impulsivity. We found that full automation without human intervention allowed rapid, cost-efficient training, and decreased stress as measured by corticosterone levels. Training breaks introduced only a transient drop in performance, and mice readily generalized across training systems when transferred from automated to manual protocols. We further validated our automated training system with wireless optogenetics and pharmacology experiments, expanding the breadth of experimental needs our system may fulfill. Our automated 5CSRTT system can serve as a prototype for fully automated behavioral training, with methods and principles transferrable to a range of rodent tasks.

Channels to consciousness: a possible role of gap junctions in consciousness

The neurophysiological basis of consciousness is still unknown and one of the most challenging questions in the field of neuroscience and related disciplines. We propose that consciousness is characterized by the maintenance of mental representations of internal and external stimuli for the execution of cognitive operations. Consciousness cannot exist without working memory, and it is likely that consciousness and working memory share the same neural substrates. Here, we present a novel psychological and neurophysiological framework that explains the role of consciousness for cognition, adaptive behavior, and everyday life. A hypothetical architecture of consciousness is presented that is organized as a system of operation and storage units named platforms that are controlled by a consciousness center (central executive/online platform). Platforms maintain mental representations or contents, are entrusted with different executive functions, and operate at different levels of consciousness. The model includes conscious-mode central executive/online and mental time travel platforms and semiconscious steady-state and preconscious standby platforms. Mental representations or contents are represented by neural circuits and their support cells (astrocytes, oligodendrocytes, etc.) and become conscious when neural circuits reverberate, that is, fire sequentially and continuously with relative synchronicity. Reverberatory activity in neural circuits may be initiated and maintained by pacemaker cells/neural circuit pulsars, enhanced electronic coupling via gap junctions, and unapposed hemichannel opening. The central executive/online platform controls which mental representations or contents should become conscious by recruiting pacemaker cells/neural network pulsars, the opening of hemichannels, and promoting enhanced neural circuit coupling via gap junctions.

Revealing a compulsive phenotype in cholinergic M4-/- mice depends on the inter-trial interval initiation settings in a five choice serial reaction time task

BACKGROUND

Muscarinic acetylcholine receptor 4 (M₄) modulates dopaminergic neurotransmission and is a target for novel treatments of schizophrenia, cognitive deficits, and addiction. Impulsive and compulsive behaviors are key traits of addiction, yet the importance of M₄ receptor signaling to these traits is poorly understood. We investigated impulsive action and compulsivity by measuring premature and perseverative responses in the five choice serial reaction time task (5CSRTT). Furthermore, we hypothesized that inter-trial interval (ITI) initiation settings affected training durations and test performances in these experiments.

METHODS

M₄^-/- and wildtype mice were trained and tested on two versions of the 5CSRTT with different ITI initiation settings. One setting, the head-in condition, allowed the ITI to start while the mouse's head remained in the reward receptacle (magazine). The other setting, the head-out condition, required the mouse to remove its head from the magazine to initiate the ITI.

RESULTS AND DISCUSSION

We did not observe differences in premature or perseverative responses in M₄^-/- mice in either condition, but found evidence of reward-related compulsive behavior in M₄^-/- mice. In the head-in condition, M₄^-/- mice were slower to acquire the 5CSRTT, had more omissions, and had longer correct response latencies than wildtype mice. In the head-out condition, genotypes did not differ in training, but M₄^-/- mice showed small decreases in accuracy. Our findings demonstrate that ITI initiation settings contribute to different training durations and tested behaviors in M₄^-/- mice, suggesting ITI initiation settings are an important consideration for the general use of the 5CSRTT.

Ethanol induces maladaptive impulse control and decreased seeking behaviors in mice

Waiting impulsivity is a risk factor for many psychiatric disorders including alcohol use disorder (AUD). Highly impulsive individuals are vulnerable to alcohol abuse. However, it is not well understood whether chronic alcohol use increases the propensity for impulsive behavior. Here, we establish a novel experimental paradigm demonstrating that continuous binge-like ethanol exposure progressively leads to maladaptive impulsive behavior. To test waiting impulsivity, we employed the 5-choice serial reaction time task (5-CSRTT) in C57BL/6J male mice. We assessed premature responses in the fixed and variable intertrial interval (ITI) 5-CSRTT sessions. We further characterized our ethanol-induced impulsive mice using Open Field, y-maze, two-bottle choice, and an action-outcome task. Our results indicate that continuous binge-like ethanol exposure significantly increased premature responses when mice were tested in variable ITI sessions even during a prolonged abstinent period. Ethanol-induced impulsive mice exhibited anxiety-like behavior during chronic exposures. This behavior was also observed in a separate cohort that was subjected to 20 days of abstinence. Ethanol-treated mice were less motivated for a sucrose reward compared with air-exposed control mice, while also demonstrating reduced responding during action-outcome testing. Overall, ethanol-treated mice demonstrated increased impulsive behavior, but a reduced motivation for a sucrose reward. Although waiting impulsivity has been hypothesized to be a trait or risk factor for AUD, our findings indicate that maladaptive impulse control can also be potentiated or induced by continuous chronic ethanol exposure in mice.

Endogenous and exogenous control of visuospatial selective attention in freely behaving mice

Visuospatial selective attention has been investigated primarily in head-fixed animals and almost exclusively in primates. Here, we develop two human-inspired, discrimination-based behavioral paradigms for studying selective visuospatial attention in freely behaving mice. In the ‘spatial probability’ task, we find enhanced accuracy, sensitivity, and rate of evidence accumulation at the location with higher probability of target occurrence, and opposite effects at the lower probability location. Together with video-based 3D head-tracking, these results demonstrate endogenous expectation-driven shifts of spatial attention. In the ‘flanker’ task, we find that a second stimulus presented with the target, but with conflicting information, causes switch-like decrements in accuracy and sensitivity as a function of its contrast, and slower evidence accumulation, demonstrating exogenous capture of spatial attention. The ability to study primate-like selective attention rigorously in unrestrained mice opens a rich avenue for research into neural circuit mechanisms underlying this critical executive function in a naturalistic setting.

The authors describe behavioural tasks for the study of primate-like, endogenous and exogenous control of visuospatial selective attention in freely behaving mice.

The basolateral amygdala regulation of complex cognitive behaviours in the five-choice serial reaction time task

RATIONALE

The basolateral amygdala (BLA) plays important roles in the cognitive control in human and non-human animals. However, inconsistent findings between species have been observed and there have been relatively few detailed investigations of the cognitive properties of BLA, especially in mice.

OBJECTIVE

Our aim was to determine the role of BLA in cognition by using optogenetic manipulations.

METHODS

Male C57BL/six mice were trained and tested on the five-choice serial reaction time task (5-CSRTT), open-field test (OFT), elevated plus maze (EPM), Y-maze, and novel object recognition (NOR) test during optogenetic stimulation and inhibition of the BLA.

RESULTS

Optogenetic activation of the BLA decreased the impulsivity and increased the compulsivity of mice, whereas optogenetic inhibition of BLA had the opposite effect. Similarly, anxiety-like behaviours and spatial working memory were increased in BLA activation mice, whereas BLA inhibition decreased these behaviours. However, both BLA activation and inhibition decreased the motivation of the mice.

CONCLUSIONS

These data demonstrate that the BLA regulates impulsive action and spatial working memory, and plays a critical role in anxiety-like behaviours.

Age, but not severity of injury, mediates decline in executive function: Validation of the rodent touchscreen paradigm for preclinical models of traumatic brain injury

Increasingly, it is being recognised that traumatic brain injury (TBI) is not just an acute event but instead results in ongoing neuronal injury that may lead to chronic impairments in multiple cognitive domains. Of these, deficits in executive function are one of the more common changes reported following TBI, and are a major predictor of well-being, social function and quality of life in individuals with a history of TBI. In order to fully understand the relationship between TBI and executive dysfunction, including brain mechanisms that may account for this, experimental models are clearly needed. However, to date, there have been a lack of preclinical studies systematically comparing the effect of injury severity on executive function, particularly at long-term timepoints post-injury. Furthermore, many previous studies have not used behavioural measures that are sensitive to the full range of executive function impairments that may manifest after injury, particularly in models of diffuse axonal injury (Lv et al.). The current study aimed to investigate the temporal profile, up to 12 months post-injury, of the evolution of executive dysfunction following different severities of injury in an experimental model of DAI. In order to do so, we utilised a rodent touchscreen paradigm to administer the 5 Choice- Continuous Performance Task (5C-CPT), an extension of the 5-choice serial reaction time task (5CSRT). Interestingly, there were no differences in learning, motivation, attention, response time or impulsivity at 1 month, 6 months or 12 months post-injury in any of the TBI groups compared to sham, regardless of the initial severity of the injury. Instead, most of the effects on executive function seen at the 12 month timepoint appeared to be a result of ageing, not injury. As even the 12-month timepoint represents middle age in the rat, future studies will be needed to further probe these effects, in order to determine whether DAI may influence the presentation of executive dysfunction in older age.

Vigilance demand and the effects of stimulant drugs in a five-choice reaction-time procedure in mice

Stimulant drugs used for treating attention-deficit hyperactivity disorder (ADHD) increase signal-detection accuracy in five-choice serial reaction-time procedures. These increases may result from drug-induced increases in control exerted by the stimuli that prompt responses, which was assessed in the present study. Mice were trained with food reinforcement to nose poke into one of five holes after its illumination (signal), and effects of methylphenidate, d-amphetamine, and pentobarbital were assessed. Subsequently, the time from trial onset to signal was changed from fixed to variable for one group of subjects. A 'warning' stimulus (change in ambient lighting) preceding the signal was added for a second group. Effects of the drugs were reassessed. Dose-related increases in accuracy of signal detection (nose pokes in hole where a signal was displayed) were obtained with methylphenidate and d-amphetamine, but not with pentobarbital. When the presignal time was variable, increases in signal detection were not obtained with either stimulant. When a warning stimulus preceded the signal, the increases in accuracy were similar to those obtained without the warning stimulus. Hence, a procedure that increased vigilance demand (using a variable prestimulus period) eliminated the effects of drugs useful in treating ADHD, whereas a procedure that decreased vigilance demand (adding the warning light) had no appreciable effects on the response to stimulant drugs. Taken together, the present results suggest that the five-choice serial reaction-time has predictive validity for selecting drugs effective for treating ADHD, although effects can depend critically on the stimulus conditions used and the vigilance required by the procedure.

The Virtual-Environment-Foraging Task enables rapid training and single-trial metrics of attention in head-fixed mice

Attention - the flexible allocation of processing resources based on behavioural demands - is essential to survival. Mouse research offers unique tools to dissect the underlying pathways, but is hampered by the difficulty of accurately measuring attention in mice. Current attention tasks for mice face several limitations: Binary (hit/miss), temporally imprecise metrics, behavioural confounds and overtraining. Thus, despite the increasing scope of neuronal population measurements, insights are limited without equally precise behavioural measures. Here we present a virtual-environment task for head-fixed mice based on 'foraging-like' navigation. The task requires animals to discriminate gratings at orientation differences from 90° to 5°, and can be learned in only 3-5 sessions (<550 trials). It yields single-trial, non-binary metrics of response speed and accuracy, which generate secondary metrics of choice certainty, visual acuity, and most importantly, of sustained and cued attention - two attentional components studied extensively in humans. This allows us to examine single-trial dynamics of attention in mice, independently of confounds like rule learning. With this approach, we show that C57/BL6 mice have better visual acuity than previously measured, that they rhythmically alternate between states of high and low alertness, and that they can be prompted to adopt different performance strategies using minute changes in reward contingencies.

Affect-Driven Attention Biases as Animal Welfare Indicators: Review and Methods

Attention bias describes the differential allocation of attention towards one stimulus compared to others. In humans, this bias can be mediated by the observer's affective state and is implicated in the onset and maintenance of affective disorders such as anxiety. Affect-driven attention biases (ADABs) have also been identified in a few other species. Here, we review the literature on ADABs in animals and discuss their utility as welfare indicators. Despite a limited research effort, several studies have found that negative affective states modulate attention to negative (i.e., threatening) cues. ADABs influenced by positive-valence states have also been documented in animals. We discuss methods for measuring ADAB and conclude that looking time, dot-probe, and emotional spatial cueing paradigms are particularly promising. Research is needed to test them with a wider range of species, investigate attentional scope as an indicator of affect, and explore the possible causative role of attention biases in determining animal wellbeing. Finally, we argue that ADABs might not be best-utilized as indicators of general valence, but instead to reveal specific emotions, motivations, aversions, and preferences. Paying attention to the human literature could facilitate these advances.

Rodent Test of Attention and Impulsivity: The 5-Choice Serial Reaction Time Task

The 5-choice serial reaction time task (5-CSRTT) is employed extensively to measure attention in rodents. The assay involves animals trained to respond to a brief, unpredictable visual stimulus presented in one of five locations. The effects of experimental manipulations on response speed and choice accuracy are measured, and each related to attentional performance. The 5-CSRTT is also used to measure motor impulsivity. Adapted from a human task, the 5-CSRTT can be employed with rodents or primates, highlighting its translational value. Another strength of this procedure is its adaptability to task modification. An example is the 5-choice continuous performance task, which has both target and non-target trial types. Overall, the 5-CSRTT has proven to be valuable for drug discovery efforts aimed at identifying new agents for the treatment of central nervous system disorders and for further understanding the neurobiological processes of attention and impulsivity. Its flexibility offers considerable scope to the experimenter, and in this respect the task continues to evolve. © 2017 by John Wiley & Sons, Inc.

Assessment of Behavioral Disruption in Rats with Abdominal Inflammation Using Visual Cue Titration and the Five-choice Serial-reaction Time Task

BACKGROUND

Both acute and chronic pain result in a number of behavioral symptoms in patients, including cognitive effects such as decreased attention and working memory. Intraperitoneal administration of dilute lactic acid in rodents has been used to induce abdominal inflammation and produce effects in behavioral assays of both sensory-discriminative and affective pain modalities.

METHODS

Intraperitoneal injection of dilute lactic acid was used to study the impact of abdominal inflammation on an operant task requiring sustained visual attention in rats (N = 7 to 15/group) that adapts dynamically to performance ability. The effects of ketoprofen and morphine on lactic acid-induced impairment were compared with those on the disruptive effects of scopolamine.

RESULTS

Lactic acid impaired performance in a concentration-dependent manner, increasing the duration of cue presentation required to maintain optimal performance from 0.5 ± 0.2 s (mean ± SD) to 17.2 ± 11.4 s after the administration of 1.8% (v/v) (N = 13). The latency to emit correct responses and to retrieve the food reward were both increased by lactic acid. All effects of lactic acid injection were reversed by both ketoprofen and morphine in a dose-dependent manner. Scopolamine, however, produced dose-dependent, nonpain-related disruption in sustained attention that was not altered by either ketoprofen or morphine.

CONCLUSIONS

These data demonstrate that abdominal inflammation induced by lactic acid produces robust disruption in a visual attention-based operant task and that this disruption is reversed by analgesics. Future studies will focus on pain-related circuitry and its impact on both limbic forebrain and frontal cortical mechanisms.