Reinforcer Delivery Research Articles

Serial engagement of distinct motor learning mechanisms to alter walking after stroke

This study asked if combining different motor learning mechanisms—adaptation and reinforcement—could produce immediate improvements in over ground walking after stroke. Fifteen adults with stroke engaged in three conditions: (1) reinforcement following adaptation, (2) reinforcement alone, and (3) adaptation alone. Adaptation involved split-belt treadmill walking to produce after-effects that reduce step asymmetry. Reinforcement involved the use of real-time auditory feedback about step length asymmetry. Auditory feedback was binary, signaling whether steps were asymmetric or equal, but not whether to shorten or lengthen either step. Change in step length asymmetry was the outcome assessed during over ground walking. Reinforcement following adaptation led to reductions in step length asymmetry that persisted into an immediate retention period. Importantly, it led to the desired pattern of lengthening the shorter step in a majority of participants. Reinforcement alone led to no significant change in step length asymmetry, and sometimes produced a non-optimal pattern of shortening the longer step. Our control condition of adaptation alone led to more transient reductions in step length asymmetry. These findings reveal the potential for utilizing serial delivery of adaptation and reinforcement to influence a complex movement in the real-world context of over ground walking, in people with stroke.

Using Programmed Schedules of Reinforcement to Increase the Variability of Reinforcer Delivery in Classroom Assistant-Implemented Variable-Ratio Schedules

Using Programmed Schedules of Reinforcement to Increase the Variability of Reinforcer Delivery in Classroom Assistant-Implemented Variable-Ratio Schedules

Using the Performance Diagnostic Checklist‐Human Services to assess and increase teacher token delivery

AbstractStaff implementation fidelity of behavioral interventions is an ongoing challenge in many educational settings. The Performance Diagnostic Checklist‐Human Services (PDC‐HS) is one tool that may be effective in identifying effective solutions to identified staff performance issues. This study examined the use of the PDC‐HS to assess and identify interventions for increasing staff delivery of token reinforcers within a Positive Behavior Interventions and Supports (PBIS) school‐wide system. Participants included five classroom teachers, ranging from 2 to 22 years of teaching experience. A concurrent multiple baseline design across participants was used including a baseline condition, implementation of a non‐indicated intervention based on the PDC‐HS, and implementation of a PDC‐HS indicated intervention. The number of teacher‐delivered tokens per school day was measured across the study. Results indicated participants' daily number of delivered tokens increased following implementation of the PDC‐HS indicated intervention.

A Method for Assessing Working Memory in Rats Using Controlled Virtual Environment.

Biological part of the investigation: In our study, young healthy Wistar rats aged 6-7 months were used. The initial stage involved habituating the experimental animals to the experimenter over a period of two weeks. The habituation process was conducted in several successive steps. First, the rats were acclimated to wearing a jacket, which is part of the apparatus that holds the animal in the experimental setup. Next, they were familiarized with the fixation system. Following this, the rats were introduced to the treadmill (a sphere), and finally, they were acclimated to the entire setup. Subsequently, the rats were gradually habituated to the virtual maze and the associated reward system through positive reinforcement. This approach helped minimize stress and facilitated their adaptation to the new conditions. The second stage involved exploring the virtual space and learning the features of the virtual maze, including walls, turns, and the end goal. During the learning phase, the animals received positive reinforcement in the form of sugared water from the automatic water dispenser for correctly performed tasks. To navigate the T-maze, the rats used visual cues such as wall color and figures on the wall. At this stage, the rats learned to use virtual space to achieve their goals. Once the rats showed evident progress in learning the virtual environment, we implemented a protocol to assess their working memory. This assessment was based on the time it took for the rats to find the maze arm that provided positive reinforcement.Engineering part of the investigation: The animal is positioned on a foam plastic sphere with a 30 cm radius, using a custom device that allows its head and paws to remain mobile. Bearing fix the sphere in place, enabling the rat to rotate freely around its vertical axis. The rat's forward and backward movements cause the sphere to rotate, simulating a treadmill. The sphere's movements are detected by two infrared sensors (adapted from optical LED mice with USB interfaces) and transmitted to a computer, which generates an image of the virtual environment - a maze with landmarks on its walls. The virtual environment, created using the Unity Real-Time 3D Development Platform, is projected onto a custom-designed dome display containing the sphere and the lab rat. The setup provided the rat with a 360° field of view. In our study, we present a setup that includes a projector, a dome display, a sphere (treadmill), a virtual T-maze, motion capture sensors, systems for securing animals to the sphere, and positive reinforcement delivery systems. We have developed an optimal protocol for immersing laboratory animals into a virtual environment and evaluating their cognitive functions, particularly working memory. The application of virtual reality in biological experiments enables more precise control over study conditions and allows for the creation of highly accurate and realistic behavioral protocols to assess cognitive functions in animals. This approach enhances our understanding of the mechanisms underlying working memory and their relationship with behavioral processes in rats and other animals.

Effects of methamphetamine on probability discounting in rats using concurrent chains

How stimulant drugs affect risky choice and the role of reinforcement magnitude has been an important question for research on impulsivity. This study investigated rats’ responding on a rapid acquisition, concurrent chains, probability discounting task under methamphetamine administration. In each block of four sessions, probability of reinforcement delivery was unequal (0.5/1.0, 1.0/0.5) or equal, (1.0/1.0, 0.5/0.5) while amount of reinforcement was constant and unequal. This allowed for an estimate of probability discounting and the magnitude effect (where larger reinforcers are discounted at a greater rate) in each block. Baseline, acute and chronic methamphetamine administration, and re-establish baseline phases were completed. Rats showed sensitivity to probability and magnitude in baseline, as well as a magnitude effect whereby preference for the larger reinforcement was greater with 100% than 50% reinforcement probability. Acute methamphetamine dose-dependently reduced the probability effect. There were no effects of chronic administration and only probability discounting was maintained in the re-establish baseline phase. This was the first procedure to find a magnitude effect with rats in a probability discounting procedure and demonstrates that acute methamphetamine reduces both the probability and magnitude effects which increases propensity for risky choice.

Substitutability of nicotine and sucrose in rats: A behavioral economic analysis

Despite considerable evidence suggesting that sweet foods are a substitute for nicotine in humans, no formal behavioral economic analysis of this interrelationship has been conducted in nonhumans. The purpose of the present study was to examine this phenomenon in rats using concurrent schedules of sucrose pellet, chow pellet, and nicotine reinforcer delivery. Rats responded on separate levers that delivered sucrose pellets, chow pellets, or nicotine infusions under concurrent fixed-ratio (FR) 1 schedules for each commodity within a closed economy. Following stable food and nicotine intake, the unit price of either sucrose or nicotine (the primary commodity) was increased while the two alternative commodities remained unchanged. Substitution was quantified using a behavioral economic cross-price model, as well as a novel commodity relation index that normalizes consumption of dissimilar commodities. Asymmetrical partial substitution was observed, wherein sucrose served as a partial substitute for nicotine, but nicotine failed to substitute for sucrose. Moreover, sucrose was a stronger partial substitute for nicotine than chow in most rats. These findings indicate that substitution of food for nicotine depends on the type of food. These findings mirror the selective increase in carbohydrate intake that can occur during smoking cessation and demonstrate a behavioral economic mechanism that may mediate it.

Effects of contingent and noncontingent reinforcement on the emotional behavior of domestic dogs (Canis familiaris)

Intermittent schedules of reinforcement are frequently used in dog training. During fixed-time (FT) schedules, reinforcement delivery is time-based and response-independent. In contrast, during fixed-interval (FI) schedules, a response produces a reinforcer if a certain amount of time has elapsed since the last reinforcer was delivered (i.e., FI schedules are time-based and response-dependent). FT schedules are typically used in noncontingent-reinforcement interventions with the aim of decreasing an undesired behavior. Although the effectiveness of these interventions has been reliably shown with human and nonhuman animal learners, little is known about the emotional behavior that is related to these contingencies. In the present study, the target behavior (stepping on a mat) of six dogs was initially trained (shaped) and maintained on a FI 15s schedule. In addition, dogs were exposed to a FT 15s schedule, a combination of FT 15s and FI 15s schedules, and an extinction-only condition (no reinforcement was delivered for the target response). We found that rates of emotional responses (e.g., lip/nose licking, vocalizing) varied in prevalence across dogs and phases. Although lip/nose licking was displayed in high rates across all dogs and phases, it was generally lower in baseline and extinction phases. This suggests that these phases produced less frustration-related behavior. The effect-size calculations for dogs engaging in pacing, sneezing, and vocalizing underscored the varied prevalence of the behaviors across phases and dogs and yielded mostly small- to medium-size effects. These results are especially relevant for the training of companion and working dogs and their well-being during training sessions. Future research should continue investigating emotional behavior in dogs across various schedules of reinforcement (e.g., variable schedules).

A systematic review of remotely delivered contingency management treatment for substance use

BackgroundSubstance use and related consequences (e.g., impaired driving, injuries, disease transmission) continue to be major public health concerns. Contingency management (CM) is a highly effective treatment for substance use disorders. Yet CM remains vastly underutilized, in large part due to implementation barriers to in-person delivery. If feasible and effective, remote delivery of CM may reduce barriers at both the clinic- and patient-level, thus increasing reach and access to effective care. Here, we summarize data from a systematic review of studies reporting remote delivery of CM for substance use treatment. MethodsWe conducted a systematic review, reported according to PRISMA guidelines. The study team identified a total of 4358 articles after deduplication. Following title and abstract screening, full-text screening, and reference tracking, 39 studies met the eligibility criteria. We evaluated the methodological quality of the included studies using the Effective Public Health Practice Project Quality tool. ResultsOf 39 articles included in the review, most (n = 26) targeted cigarette smoking, with others focusing on alcohol (n = 9) or other substance use or targeting multiple substances (n = 4). Most remotely delivered CM studies focused on abstinence (n = 29), with others targeting substance use reduction (n = 2), intervention engagement (n = 5), and both abstinence and intervention engagement (n = 3). CM was associated with better outcomes (either abstinence, use reduction, or engagement), with increasingly more remotely delivered CM studies published in more recent years. Studies ranged from moderate to strong quality, with the majority (57.5 %) of studies being strong quality. ConclusionsConsistent with in-person CM, remotely delivered CM focusing on abstinence or use reduction from substances or engagement in substance use treatment services improves outcomes at the end of treatment compared to control conditions. Moreover, remotely delivered CM is feasible across a variety of digital delivery platforms (e.g., web, mobile, and wearable), with acceptability and reduced clinic and patient burden as technological advancements streamline monitoring and reinforcer delivery.

Task parameters influence operant response variability in mice.

During operant conditioning, animals associate actions with outcomes. However, patterns and rates of operant responding change over learning, which makes it difficult to distinguish changes in learning from general changes in performance or movement. Thus, understanding how task parameters influence movement execution is essential. To understand how specific operant task parameters influenced the repetition of future operant responses, we investigated the ability of operant conditioning schedules and contingencies to promote reproducible bouts of five lever presses in mice. Mice were trained on one of the four operant tasks to test three distinct hypotheses: (1) whether a cue presented concurrently with sucrose delivery influenced the pattern of lever pressing; (2) whether requiring animals to collect earned sucrose promoted the organization of responses into bouts; and (3) whether only reinforcing bouts where interresponse time (IRT) variances were below a target promoted reproducible patterns of operant behavior. (1) Signaling reinforcer delivery with a cue increased learning rates but resulted in mice pressing the lever in fast succession until the cue turned on, rather than executing discrete bouts. (2) Requiring mice to collect the reinforcer between bouts had little effect on behavior. (3) A training strategy that directly reinforced bouts with low variance IRTs was not more effective than a traditional fixed ratio schedule at promoting reproducible action execution. Together, our findings provide insights into the parameters of behavioral training that promote reproducible actions and that should be carefully selected when designing operant conditioning experiments.

Effects of transcranial direct current stimulation on improving performance of delayed- reinforcement attentional set-shifting tasks in attention-deficit/hyperactivity disorder rat model

Behavioral flexibility (or set-shifting), which is regulated by the prefrontal cortex (PFC), is often impaired in patients with attention-deficit/hyperactivity disorder (ADHD), which is characterized by poor inhibitory control and reinforcement learning. Transcranial direct current stimulation (tDCS) has been proposed as a means of noninvasive brain stimulation and a potential therapeutic tool for modulating behavioral flexibility. Animal studies can pave the way to know if tDCS application can potentially benefit rule- and goal-based activities in ADHD. Spontaneously hypertensive rats (SHRs) and inbred Wistar–Kyoto (WKY) rats were used as an animal model of ADHD and controls, respectively, and their strategy set-shifting abilities, including initial discrimination, set-shifting, and reversal learning tasks under 0-s or 15-s reinforcer delivery delay conditions, were evaluated. The tDCS treatment had a limited effect on the performance of the SHRs and WKY rats in initial discrimination task under 0-s delay condition. Under the 15-s delay condition, the SHRs had longer lever-press reaction times and/or more trial omissions than the WKY rats did when completing set-shifting and reversal-learning tasks. Among the SHRs, tDCS treatment improved the rats’ reaction times and/or reduced their trial omissions in the set-shifting and reversal-learning tasks. Although tDCS may improve delayed reinforcement learning set-shifting performance in SHRs, further studies are required to clarify the responsible mechanism.

Equines do not live for grass alone: Training equines using social interaction as a reinforcer

Functional analysis data and previous studies on animal training have demonstrated that social interaction with humans can serve as a reinforcer for animals. Yet, some studies have demonstrated that tactile interaction (e.g., patting, petting, or scratching) is less effective or ineffective when compared to food. However, the reinforcement procedures used may account for these discrepancies. The current study investigated whether tactile interaction, in the form of petting and scratching, could be used as a reinforcer to train behaviors to two horses and a mule. First, each equine learned when reinforcement would be available and what behaviors to engage in during reinforcement delivery. Next, a series of shaping steps and a changing-criterion design were used to test whether tactile interaction could be used to shape two new behaviors, stay and come. All three equines completed reinforcement training and met the mastery criteria for training stay and come. These results demonstrate that tactile interaction can be used as a reinforcer to train equines and also suggest that details of the reinforcement delivery process may be an important consideration when tactile interaction is used as a reinforcer.

Assessing Parameters of Reinforcement on Efficiency of Acquisition: A Systematic Review.

Discrete-trial training (DTT) is a common method of instruction used in early intervention amongindividuals with autism spectrum disorder and related neurodevelopmental disorders and is an effective method of teaching different skills such as tacting, listener responding, and matching. Delivery of effective reinforcers is a key component of DTT. Although general recommendations have been made for effective reinforcement delivery in DTT, no review has synthesized the available research on the efficiency of various reinforcer parameters on efficiency of acquisition. The current systematic review assessed the efficiency of various reinforcer parameters on acquisition in DTT. Results were idiosyncratic, and a general paucity of repeated measures examining specific reinforcer parameters within and across studies was observed. In general, (1) maintaining high levels of treatment integrity, (2) delivery of tangible (i.e. leisure items) or edible reinforcers in comparison with contingent praise as a reinforcer, and (3) delivery of edible reinforcers in comparison with other topographies of reinforcement were the most successful reinforcer parameter manipulations and always resulted in more efficient skill acquisition. The results of this review provide clinicians with information regarding what reinforcer parameter manipulations may be more or less likely to support efficient acquisition. The present review also provides considerations and makes recommendations for future research.

Maintaining On-Task Behavior of Adolescents with Autism Spectrum Disorder in the Absence of an Instructor.

Despite the vast amount of research on increasing independence for individuals with autism spectrum disorder, there is a lack of research on techniques for fostering independent on-task behavior and accuracy in the absence of an instructor. Though increasing distance of the instructor and altering reinforcer delivery have been shown in a few studies to produce independence in the absence of an instructor, no study to date has compared the effects of systematic fading and complete removal of an instructor. In the current study, we evaluated the effects of three conditions on the on-task behavior and accuracy of adolescents with autism spectrum disorder: instructor present (instructor with participant and conditioned reinforcers delivered within session ), instructor absent (instructor not with the participant and no within-session conditioned reinforcers), and instructor fading (gradual, systematic fading of instructor and thinning of within-session conditioned reinforcers). Across all three participants, the intervention was effective in maintaining criterion levels of on-task behavior and accuracy. Responding generalized to novel instructors and remained high during maintenance evaluations for all participants. Clinicians rated the procedures as having high social validity.

Machine learning with a snapshot of data: Spiking neural network 'predicts' reinforcement histories of pigeons' choice behavior.

An accumulated body of choice research has demonstrated that choice behavior can be understood within the context of its history of reinforcement by measuring response patterns. Traditionally, work on predicting choice behaviors has been based on the relationship between the history of reinforcement—the reinforcer arrangement used in training conditions—and choice behavior. We suggest an alternative method that treats the reinforcement history as unknown and focuses only on operant choices to accurately predict (more precisely, retrodict) reinforcement histories. We trained machine learning models known as artificial spiking neural networks (SNNs) on previously published pigeon datasets to detect patterns in choices with specific reinforcement histories—seven arranged concurrent variable‐interval schedules in effect for nine reinforcers. Notably, SNN extracted information from a small ‘window’ of observational data to predict reinforcer arrangements. The models' generalization ability was then tested with new choices of the same pigeons to predict the type of schedule used in training. We examined whether the amount of the data provided affected the prediction accuracy and our results demonstrated that choices made by the pigeons immediately after the delivery of reinforcers provided sufficient information for the model to determine the reinforcement history. These results support the idea that SNNs can process small sets of behavioral data for pattern detection, when the reinforcement history is unknown. This novel approach can influence our decisions to determine appropriate interventions; it can be a valuable addition to our toolbox, for both therapy design and research.

Effects of environmental distractions on teachers' procedural integrity with three function-based treatments.

Past research has demonstrated the effectiveness of teacher-implemented, function-based treatments for problem behavior, but no studies have evaluated the impact of distractions on teachers' procedural integrity. In this proof-of-concept study, the experimenters employed a laboratory analog to examine the impact of distractions on levels of integrity when 5 teachers implemented 3 different treatments. Although integrity was similar across treatments when the setting was free of distractions, integrity declined for all teachers in the presence of student-driven distractions. In general, distractions had a greater impact on the integrity of differential negative reinforcement of alternative behavior (DNRA) compared to differential negative reinforcement of other behavior (DNRO) and noncontingent escape (NCE), particularly for the delivery of reinforcement. However, teachers tended to have lower levels of integrity when responding to problem behavior during DNRO. These findings support the potential viability of this approach for studying factors that impede procedural integrity in the classroom.

New Directions for Motivational Incentive Interventions for Smoking Cessation.

BackgroundMotivational incentive interventions are highly effective for smoking cessation. Yet, these interventions are not widely available to people who want to quit smoking, in part, due to barriers such as administrative burden, concern about the use of extrinsic reinforcement (i.e., incentives) to improve cessation outcomes, suboptimal intervention engagement, individual burden, and up-front costs.PurposeTechnological advancements can mitigate some of these barriers. For example, mobile abstinence monitoring and digital, automated incentive delivery have the potential to lower the clinic burden associated with monitoring abstinence and administering incentives while also reducing the frequency of clinic visits. However, to fully realize the potential of digital technologies to deliver motivational incentives it is critical to develop strategies to mitigate longstanding concerns that reliance on extrinsic monetary reinforcement may hamper internal motivation for cessation, improve individual engagement with the intervention, and address scalability limitations due to the up-front cost of monetary incentives. Herein, we describe the state of digitally-delivered motivational incentives. We then build on existing principles for creating just-in-time adaptive interventions to highlight new directions in leveraging digital technology to improve the effectiveness and scalability of motivational incentive interventions.ConclusionsTechnological advancement in abstinence monitoring coupled with digital delivery of reinforcers has made the use of motivational incentives for smoking cessation increasingly feasible. We propose future directions for a new era of motivational incentive interventions that leverage technology to integrate monetary and non-monetary incentives in a way that addresses the changing needs of individuals as they unfold in real-time.

Bringing the past into the present: Control by exteroceptive stimuli and key-peck location in a concurrent-chains procedure

We recently found that initial-link stimuli signaling trial outcomes (signals) in a concurrent-chains procedure exerted imperfect control during initial and terminal links. Here, we conducted a follow-up experiment to investigate further such imperfect control. Five pigeons worked on a concurrent-chains procedure in which one alternative led to a terminal link ending in a smaller-sooner reinforcer delivery, and the other in a larger-later reinforcer. During initial links of some trials, compound stimuli (signals) signaled the trial outcome. We assessed control by signal dimensions in Conflicting trials, in which the dimensions signaled conflicting outcomes. Unlike our previous experiment, signals remained present during terminal links. During initial links, preference favored the signaled key in Signaled trials, and the key signaled by the dimension exerting stronger control in Conflicting trials, suggesting strong signal control. Initial-link choice also depended on trial outcomes; preference was overall biased towards the smaller-sooner key. Terminal-link responding was primarily controlled by the key peck producing terminal-link entry, although some weak signal control was also evident. Thus, signal control during initial and terminal links was enhanced, and control by key-peck location during terminal links persisted, when signals remained present during terminal links. This suggests that our previous findings were partly related to temporal separation between signals and trial outcomes, and to history effects producing strong control by key-peck location.

Contingency-based delay to reinforcement following functional communication training for autistic individuals: A multilevel meta-analysis.

Functional communication training, an intervention for challenging behavior rooted in principles of applied behavior analysis, has copious empirical support dating back to the mid-1980s for autistic individuals. Recently, there has been a concerted effort to thin reinforcement delivery during functional communication training using contingency-based delays that, in turn, are designed to enhance practicality and feasibility while not compromising efficacy. In this synthesis, we meta-analyzed the literature base with the goal of investigating both combined and across type effectiveness of contingency-based delays. We also aimed to investigate moderating variables that might impact intervention outcomes. Findings showed that contingency-based delays were effective for individuals with an autism spectrum disorder diagnosis and most effective when the delay incorporated some form of positive reinforcement. In addition, differential reinforcement of alternative-based delays was overall more effective when compared to differential reinforcement of other behavior-based delays. Noteworthy moderating variables found to impact contingency-based delay efficacy included the intervention dosage and the topography of behavior. We discuss these findings and highlight directions where additional empirical research is warranted to improve our understanding about contingency-based delays for individuals diagnosed with autism spectrum disorder.

Effects of delay of reinforcement on ABA renewal

ABA renewal was assessed by decreasing response rates by means of extinction or a 12-s delay of reinforcement in one experiment with rats. In a first phase, rats were trained to lever press for water in Context A. Rats were exposed to a second phase in Context B, where lever-pressing decreased for all rats; for one group of rats, lever-pressing decreased by means of extinction, while lever-pressing decreased by means of a 12-s delay for the other group. During a third phase, both groups were once again exposed to Context A with no reinforcer deliveries for lever-pressing. Once rats were exposed to the latter phase, renewal was observed for both groups. Results suggest that delay of reinforcement can be used as an alternative procedure to help reduce behavior and mitigate relapse.

Central Thalamic-Medial Prefrontal Control of Adaptive Responding in the Rat: Many Players in the Chamber.

The medial prefrontal cortex (mPFC) has robust afferent and efferent connections with multiple nuclei clustered in the central thalamus. These nuclei are elements in large-scale networks linking mPFC with the hippocampus, basal ganglia, amygdala, other cortical areas, and visceral and arousal systems in the brainstem that give rise to adaptive goal-directed behavior. Lesions of the mediodorsal nucleus (MD), the main source of thalamic input to middle layers of PFC, have limited effects on delayed conditional discriminations, like DMTP and DNMTP, that depend on mPFC. Recent evidence suggests that MD sustains and amplifies neuronal responses in mPFC that represent salient task-related information and is important for detecting and encoding contingencies between actions and their consequences. Lesions of rostral intralaminar (rIL) and ventromedial (VM) nuclei produce delay-independent impairments of egocentric DMTP and DNMTP that resemble effects of mPFC lesions on response speed and accuracy: results consistent with projections of rIL to striatum and VM to motor cortices. The ventral midline and anterior thalamic nuclei affect allocentric spatial cognition and memory consistent with their connections to mPFC and hippocampus. The dorsal midline nuclei spare DMTP and DNMTP. They have been implicated in behavioral-state control and response to salient stimuli in associative learning. mPFC functions are served during DNMTP by discrete populations of neurons with responses related to motor preparation, movements, lever press responses, reinforcement anticipation, reinforcement delivery, and memory delay. Population analyses show that different responses are timed so that they effectively tile the temporal interval from when DNMTP trials are initiated until the end. Event-related responses of MD neurons during DNMTP are predominantly related to movement and reinforcement, information important for DNMTP choice. These responses closely mirror the activity of mPFC neurons with similar responses. Pharmacological inactivation of MD and adjacent rIL affects the expression of diverse action- and outcome-related responses of mPFC neurons. Lesions of MD before training are associated with a shift away from movement-related responses in mPFC important for DNMTP choice. These results suggest that MD has short-term effects on the expression of event-related activity in mPFC and long-term effects that tune mPFC neurons to respond to task-specific information.