Visuoauditory Associative Memory Established with Cholecystokinin Under Anesthesia Is Retrieved in Behavioral Contexts

Plastic change in neuronal connectivity is the foundation of memory encoding. It is not clear whether the changes during anesthesia can alter subsequent behavior. Here, we demonstrated that in male rodents under anesthesia, a visual stimulus (VS) was associated with electrical stimulation of the auditory cortex or natural auditory stimulus in the presence of cholecystokinin (CCK), which guided the animals' behavior in a two-choice auditory task. Auditory neurons became responsive to the VS after the pairings. Moreover, high-frequency stimulation of axon terminals of entorhinal CCK neurons in the auditory cortex enabled LTP of the visual response in the auditory cortex. Such pairing during anesthesia also generated VS-induced freezing in an auditory fear conditioning task. Finally, we verified that direct inputs from the entorhinal CCK neurons and the visual cortex enabled the above neural plasticity in the auditory cortex. Our findings suggest that CCK-enabled visuoauditory association during anesthesia can be translated to the subsequent behavior action.

SIGNIFICANCE STATEMENT Our study provides strong evidence for the hypothesis that cholecystokinin plays an essential role in the formation of cross-modal associative memory. Moreover, we demonstrated that an entorhinal–neocortical circuit underlies such neural plasticity, which will be helpful to understand the mechanisms of memory formation and retrieval in the brain.

Cockroaches Show Individuality in Learning and Memory During Classical and Operant Conditioning

Animal personality and individuality are intensively researched in vertebrates and both concepts are increasingly applied to behavioral science in insects. However, only few studies have looked into individuality with respect to performance in learning and memory tasks. In vertebrates, individual learning capabilities vary considerably with respect to learning speed and learning rate. Likewise, honeybees express individual learning abilities in a wide range of classical conditioning protocols. Here, we study individuality in the learning and memory performance of cockroaches, both in classical and operant conditioning tasks. We implemented a novel classical (olfactory) conditioning paradigm where the conditioned response is established in the maxilla-labia response (MLR). Operant spatial learning was investigated in a forced two-choice task using a T-maze. Our results confirm individual learning abilities in classical conditioning of cockroaches that was reported for honeybees and vertebrates but contrast long-standing reports on stochastic learning behavior in fruit flies. In our experiments, most learners expressed a correct behavior after only a single learning trial showing a consistent high performance during training and test. We can further show that individual learning differences in insects are not limited to classical conditioning but equally appear in operant conditioning of the cockroach.

Positive Reinforcement Conditioning as a Tool for Frequent Minimally Invasive Blood and Vaginal Swab Sampling in African Lions (Panthera Leo)

Information regarding the physiology of African lions is scarce, mainly due to challenges associated with essential routine research procedures. The aim of this experiment was to test the possibility of training six captive lionesses by positive reinforcement conditioning (PRC) to voluntarily allow the collection of vaginal swabs and blood samples. This was done with the final goal of avoiding frequent anesthesia, and potentially stressful management during reproduction research. All lionesses mastered basic clicker and targeting principles within 2 weeks. Routine sampling was possible after 20 weeks of training, enabling the collection of about 750 vaginal swabs and 650 blood samples over 18 months. The animals remained calm and cooperative during all sessions, and demonstrated curiosity in the training. PRC training of captive lionesses proved to be a suitable, minimally invasive method for repeated collection of vaginal swabs and blood. Additionally, PRC may serve as behavioral enrichment for African lions in captive settings. Compared to chemical or physical restraining methods, this noninvasive management approach may reduce distress and physiological negative side effects, thus opening up new avenues for feline research.

High-Throughput Automated Olfactory Phenotyping of Group-Housed Mice

Behavioral phenotyping of mice is often compromised by manual interventions of the experimenter and limited throughput. Here, we describe a fully automated behavior setup that allows for quantitative analysis of mouse olfaction with minimized experimenter involvement. Mice are group-housed and tagged with unique RFID chips. They can freely initiate trials and are automatically trained on a go/no-go task, learning to distinguish a rewarded from an unrewarded odor. Further, odor discrimination tasks and detailed training aspects can be set for each animal individually for automated execution without direct experimenter intervention. The procedure described here, from initial RFID implantation to discrimination of complex odor mixtures at high accuracy, can be completed within <2 months with cohorts of up to 25 male mice. Apart from the presentation of monomolecular odors, the setup can generate arbitrary mixtures and dilutions from any set of odors to create complex stimuli, enabling demanding behavioral analyses at high-throughput.

Sex differences and the modulating effects of gonad intactness on behavioral conformity in a mouse model

Although gender differences in conformity are noticed in human studies, cultural norms and psychosocial factors inevitably affect such differences. Biological factors, especially the gonadal hormones and the brain regions involved, contributing to the sex differences in behavioral conformity remained scarcely explored. To prevent psychosocial and cultural norm confounds, intact and gonadectomized male and female mice were used to assess the modulating effects of gonadal hormones on behavioral conformity and such conformity-related brain regions using an approach of choice paradigm. Intact and gonadectomized mice' choices for the nonrewarded runway were assessed when these experimental mice were alone versus with a group, consisting of three same-sex noncagemates choosing the respective experimental mice' nonrewarded runway, in a double-J-shaped maze test. Although male and female mice exhibited comparable rewarded runway choices at the conclusion of the operant training procedures and in the test individually, male mice demonstrated greater conformity index as compared to female mice when group tested. Gonadectomy, done at their 4 or 9 weeks of age, decreased males' conformity index but did not affect females' when both sexes were group tested. Such gonadectomy did not affect the conditioning or conformity index when tested individually in either sex. Female mice had higher serum corticosterone (CORT) levels when group tested as compared to the female mice tested individually and male mice. Finally, the number of FOS-staining cells in high conformity-displaying mice was found less than it in the low conformity-performing mice in the nucleus accumbens. Taken together, we conclude that testis-derived hormones, at least, play a role in enhancing behavioral conformity in male mice. CORT and nucleus accumbal neuronal activity deserve further investigation for their involvement in behavioral conformity.

Translational approach to apathy-like behavior in mice: From the practical point of view

Apathy is a pervasive clinical phenomenon that deserves more attention at the translational and pre-clinical levels. To study apathy-like behavior in mice, we relied on an operational definition of apathy: the quantitative reduction of voluntary, goal-directed behaviors. We recently found that the chronic loss of function of a specific cell type (striatal dopamine receptor type 2-expressing medium spiny neurons, D2-MSN) in a restricted region (the ventrolateral striatum, VLS) was sufficient to induce apathy-like behavior in a food-seeking operant task. We further showed that VLS D2-MSN are activated at the preparatory period, and that optogenetic inhibition of VLS D2-MSN during that period resulted in transient decreases in instrumental motivation, strengthening the hypothesis that VLS D2-MSN mediate apathy-like behavior in mice. Mice bearing VLS D2-MSN dysfunction can thus be regarded as an apathy model for future translational studies.

Chemogenetic Silencing of Prelimbic Cortex to Anterior Dorsomedial Striatum Projection Attenuates Operant Responding

Operant (instrumental) conditioning is a laboratory analog for voluntary behavior and involves learning to make a response for a reinforcing outcome. The prelimbic cortex (PL), a region of the rodent medial prefrontal cortex, and the dorsomedial striatum (DMS), have been separately established as important in the acquisition of minimally-trained operant behavior. Despite dense anatomical connections between the two regions, experimenters have only recently linked projections from the PL to the posterior DMS (pDMS) in the acquisition of an operant response. Yet, it is still unknown if these projections mediate behavioral expression, and if more anterior regions of the DMS (aDMS), which receive dense projections from the PL, are also involved. Therefore, we utilized designer receptors exclusively activated by designer drugs (DREADDs) to test whether or not projections from the PL to the aDMS influence the expression of operant behavior. Rats underwent bilateral PL-targeted infusions of either a DREADD virus (AAV8-hSyn-hM4D(Gi)-mCherry) or a control virus (AAV8-hSyn-GFP). In addition, guide cannulae were implanted bilaterally in the aDMS. Rats were tested with both clozapine-N-oxide (CNO) (DREADD ligand) and vehicle infusions into the aDMS. Animals that had received the DREADD virus, but not the control virus, showed attenuated responding when they received CNO microinfusions into the aDMS, compared to vehicle infusions. Patch clamp electrophysiology verified the inhibitory effect of CNO on DREADDs-expressing PL neurons in acute brain slices. GFP-expressing control PL neurons were unaffected by CNO. The results add to the recent literature suggesting that connections between the PL and aDMS are important for the expression of minimally-trained operant responding.

Automated Behavioral Experiments in Mice Reveal Periodic Cycles of Task Engagement within Circadian Rhythms

High-throughput automated experiments accelerate discovery in neuroscience research and reduce bias. To enable high-throughput behavioral experiments, we developed a user-friendly and scalable automated system that can simultaneously train hundreds of mice on behavioral tasks, with time-stamped behavioral information recorded continuously for weeks. We trained 12 cages of C57BL/6J mice (24 mice, 2 mice/cage) to perform auditory behavioral tasks. We found that circadian rhythms modulated overall behavioral activity as expected for nocturnal animals. However, auditory detection and discrimination accuracy remained consistently high in both light and dark cycles. We also found a periodic modulation of behavioral response rates only during the discrimination task, suggesting that the mice periodically reduce task engagement (i.e., take “breaks”) when task difficulty increases due to the more complex stimulus–response paradigm for discrimination versus detection. Our results highlight how automated systems for continuous high-throughput behavioral experiments enable both efficient data collection and new observations on animal behavior.

Visual Discrimination, Serial Reversal, and Extinction Learning in the mdx Mouse

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy and the most common neuromuscular disorder. In addition to neuromuscular consequences, some individuals with DMD experience global intellectual dysfunction and executive dysfunction of unknown mechanistic origin. The cognitive profile of the mdx mouse, the most commonly used mouse model of DMD, has been incompletely characterized and has never been assessed using the touchscreen operant conditioning paradigm. The touchscreen paradigm allows the use of protocols that are virtually identical to those used in human cognitive testing and may, therefore, provide the most translational paradigm for quantifying mouse cognitive function. In the present study, we used the touchscreen paradigm to assess the effects of the mdx mutation on visual discrimination learning, serial reversal learning, and extinction learning. To enable measuring task-dependent learning and memory processes while holding demands on sensory-driven information processing constant, we developed equally salient visual stimuli and used them on all experimental stages. Acquisition of the initial pairwise visual discrimination was facilitated in mdx mice relative to wildtype littermates; this effect was not explained by genotypic differences in impulsivity, motivation, or motor deficits. The mdx mutation had no effect on serial reversal or extinction learning. Together, findings from this study and previous studies suggest that mdx effects on cognitive function are task-specific and may be influenced by discrimination type (spatial, visual), reward type (food, escape from a non-preferred environment), sex, and genetic background.

Separate vmPFC Ensembles Control Cocaine Self-Administration Versus Extinction in Rats

Recent studies suggest that the ventral medial prefrontal cortex (vmPFC) encodes both operant drug self-administration and extinction memories. Here, we examined whether these opposing memories are encoded by distinct neuronal ensembles within the vmPFC with different outputs to the nucleus accumbens (NAc) in male and female rats. Using cocaine self-administration (3 h/d for 14 d) and extinction procedures, we demonstrated that vmPFC was similarly activated (indexed by Fos) during cocaine-seeking tests after 0 (no-extinction) or 7 extinction sessions. Selective Daun02 lesioning of the self-administration ensemble (no-extinction) decreased cocaine seeking, whereas Daun02 lesioning of the extinction ensemble increased cocaine seeking. Retrograde tracing with fluorescent cholera toxin subunit B injected into NAc combined with Fos colabeling in vmPFC indicated that vmPFC self-administration ensembles project to NAc core while extinction ensembles project to NAc shell. Functional disconnection experiments (Daun02 lesioning of vmPFC and acute dopamine D1-receptor blockade with SCH39166 in NAc core or shell) confirm that vmPFC ensembles interact with NAc core versus shell to play dissociable roles in cocaine self-administration versus extinction, respectively. Our results demonstrate that neuronal ensembles mediating cocaine self-administration and extinction comingle in vmPFC but have distinct outputs to the NAc core and shell that promote or inhibit cocaine seeking.SIGNIFICANCE STATEMENT Neuronal ensembles within the vmPFC have recently been shown to play a role in self-administration and extinction of food seeking. Here, we used the Daun02 chemogenetic inactivation procedure, which allows selective inhibition of neuronal ensembles identified by the activity marker Fos, to demonstrate that different ensembles for cocaine self-administration and extinction memories coexist in the ventral mPFC and interact with distinct subregions of the nucleus accumbens.

The effects of age and sex on the detection of pure tones by adult CBA/CaJ mice (Mus musculus)

Age-related hearing loss (ARHL) is a neurodegenerative disorder characterized by a gradual decrease in hearing sensitivity. Previous electrophysiological and behavioral studies have demonstrated that the CBA/CaJ mouse strain is an appropriate model for the late-onset hearing loss found in humans. However, few studies have characterized hearing in these mice behaviorally using longitudinal methodologies. The goal of this research was to utilize a longitudinal design and operant conditioning procedures with positive reinforcement to construct audiograms and temporal integration functions in aging CBA/CaJ mice. In the first experiment, thresholds were collected for 8, 16, 24, 42, and 64 kHz pure tones in 30 male and 35 female CBA/CaJ mice. Similar to humans, mice had higher thresholds for high frequency tones than for low frequency pure tones across the lifespan. Female mice had better hearing acuity than males after 645 days of age. In the second experiment, temporal integration functions were constructed for 18 male and 18 female mice for 16 and 64 kHz tones varying in duration. Mice showed an increase in thresholds for tones shorter than 200 ms, reaching peak performance at shorter durations than other rodent species. Overall, CBA/CaJ mice experience ARHL for pure tones of different frequencies and durations, making them a good model for studies on hearing loss. These findings highlight the importance of using a wide range of stimuli and a longitudinal design when comparing presbycusis across different species.

H-reflex conditioning during locomotion in people with spinal cord injury

Key points

In people or animals with incomplete spinal cord injury (SCI), changing a spinal reflex through an operant conditioning protocol can improve locomotion.

All previous studies conditioned the reflex during steady‐state maintenance of a specific posture. By contrast, the present study down‐conditioned the reflex during the swing‐phase of locomotion in people with hyperreflexia as a result of chronic incomplete SCI. The aim was to modify the functioning of the reflex in a specific phase of a dynamic movement.

This novel swing‐phase conditioning protocol decreased the reflex much faster and farther than did the steady‐state protocol in people or animals with or without SCI, and it also improved locomotion.

The reflex decrease persisted for at least 6 months after conditioning ended.

The results suggest that conditioning reflex function in a specific phase of a dynamic movement offers a new approach to enhancing and/or accelerating recovery after SCI or in other disorders.

Abstract

In animals and people with incomplete spinal cord injury, appropriate operant conditioning of a spinal reflex can improve impaired locomotion. In all previous conditioning studies, the reflex was conditioned during steady‐state maintenance of a stable posture; this steady‐state protocol aimed to change the excitability of the targeted reflex pathway; reflex size gradually changed over 8–10 weeks. The present study introduces a new protocol, comprising a dynamic protocol that aims to change the functioning of the reflex pathway during a specific phase of a complex movement. Specifically, we down‐conditioned the soleus H‐reflex during the swing‐phase of locomotion in people with hyperreflexia as a result of chronic incomplete SCI. The swing‐phase H‐reflex, which is absent or very small in neurologically normal individuals, is abnormally large in this patient population. The results were clear. With swing‐phase down‐conditioning, the H‐reflex decreased much faster and farther than did the H‐reflex in all previous animal or human studies with the steady‐state protocol, and the decrease persisted for at least 6 months after conditioning ended. The H‐reflex decrease was accompanied by improvements in walking speed and in the modulation of locomotor electromyograph activity in proximal and distal muscles of both legs. These results provide new insight into the factors controlling spinal reflex conditioning; they suggest that the conditioning protocols targeting reflex function in a specific movement phase provide a promising new opportunity to enhance functional recovery after SCI or in other disorders.

In people or animals with incomplete spinal cord injury (SCI), changing a spinal reflex through an operant conditioning protocol can improve locomotion.

All previous studies conditioned the reflex during steady‐state maintenance of a specific posture. By contrast, the present study down‐conditioned the reflex during the swing‐phase of locomotion in people with hyperreflexia as a result of chronic incomplete SCI. The aim was to modify the functioning of the reflex in a specific phase of a dynamic movement.

This novel swing‐phase conditioning protocol decreased the reflex much faster and farther than did the steady‐state protocol in people or animals with or without SCI, and it also improved locomotion.

The reflex decrease persisted for at least 6 months after conditioning ended.

The results suggest that conditioning reflex function in a specific phase of a dynamic movement offers a new approach to enhancing and/or accelerating recovery after SCI or in other disorders.

Ghrelin's effects on food motivation in rats are not limited to palatable foods

The "hunger" hormone, ghrelin, is powerfully orexigenic. Even in the absence of hunger, ghrelin delivery to rats increases consumption of chow, as well as palatable foods, and increases motivated behaviour for palatable food rewards. Inspired by the finding that ghrelin increases the selection of chow in rats offered a choice diet (lard, sucrose or chow) and even in rats bingeing on a high-fat diet, we aimed to explore whether the effects of ghrelin on motivation extend to regular chow. Rats were conditioned to lever press for either chow or sucrose pellets in a progressive ratio (PR) operant conditioning task. The effect of acute i.c.v. delivery of ghrelin on both chow and sucrose self-administration was determined and compared with overnight fasting (ie, when endogenous ghrelin levels are elevated). We found that ghrelin similarly increased motivated behaviour for chow and sucrose pellets. The effect of fasting on motivated behaviour for both food pellets was comparable in magnitude to that induced by ghrelin, albeit with an earlier ceiling effect during the PR session. Devaluation experiments (in which rats are offered either food reinforcer in excess prior to PR testing) did not support the hypothesis that sucrose pellets would be more difficult to devalue (as a result of their higher incentive value) than chow pellets. When exchanging the respective pellets during a PR session, chow-conditioned rats were more motivated for sucrose pellets compared to chow pellets; however, sucrose-conditioned rats were similarly motivated for chow pellets compared to sucrose pellets. Thus, using sucrose as a reward may increase the motivation even for less palatable foods. We conclude that the impact of ghrelin on food-motivated behaviour in fed rats is not limited to palatable foods but extends to regular chow, and also that the magnitude of the effect is considerable compared to that of an overnight fast.

Evidence for a Mixed Timing and Counting Strategy in Mice Performing a Mechner Counting Task

Numerosity, or the ability to understand and distinguish between discrete quantities, was first formalized for study in animals by Mechner (1958a). Rats had to press one lever (the counting lever) n times to arm food release from pressing a second lever (the reward lever). The only cue that n presses had been made to the counting lever was the animal's representation of how many times it had pressed it. In the years that have passed since, many researchers have modified the task in meaningful ways to attempt to tease apart timing-based and count-based strategies. Strong evidence has amassed that the two are fundamentally different and separable skills but, to date, no study has effectively examined the differential contributions of the two strategies in Mechner's original task. By examining performance mid-trial and correlating it with whole-trial performance, we were able to identify patterns of correlation consistent with counting and timing strategies. Due to the independent nature of these correlation patterns, this technique was uniquely able to provide evidence for strategies that combined both timing and counting components. The results show that most mice demonstrated this combined strategy. This provides direct evidence that mice can and do use numerosity to complete Mechner's original task. A rational agent with fallible estimates of both counts made and time elapsed in making them should use both estimates when deciding when to switch to the second lever.

A Free-Operant Reward-Tracking Paradigm to Study Neural Mechanisms and Neurochemical Modulation of Adaptive Behavior in Rats

The ability to respond flexibly to changing environmental circumstances is a hallmark of goal-directed behavior, and compromised flexibility is associated with a wide range of psychiatric conditions in humans, such as addiction and stress-related disorders. To identify neural circuits and transmitter systems implicated in the provision of cognitive flexibility, suitable animal paradigms are needed. Ideally, such models should be easy to implement, allow for rapid task acquisition, provide multiple behavioral readouts, and permit combination with physiological and pharmacological testing and manipulation. Here, we describe a paradigm meeting these requirements and employ it to investigate the neural substrates and neurochemical modulation of adaptive behavior. Water-restricted rats learned to emit operant responses for positive reinforcement (water reward) within minutes in a free-operant conditioning environment. Without further training, animals were able to track changes in the reward schedule. Given prior evidence that the medial prefrontal cortex (mPFC) and the dopaminergic system are required for flexible behavior, we aimed to assess both in more detail. Silencing of mPFC compromised flexible behavior when avoidance of punishment was required. Systemic injections of the D2-receptor agonist quinpirole and the D2-receptor antagonist eticlopride had complex, differential impacts on reward seeking and adaptive behavior.

Acquisition of a simple motor skill: task-dependent adaptation and long-term changes in the human soleus stretch reflex

Changing the H reflex through operant conditioning leads to CNS multisite plasticity and can affect previously learned skills. To further understand the mechanisms of this plasticity, we operantly conditioned the initial component (M1) of the soleus stretch reflex. Unlike the H reflex, the stretch reflex is affected by fusimotor control, comprises several bursts of activity resulting from temporally dispersed afferent inputs, and may activate spinal motoneurons via several different spinal and supraspinal pathways. Neurologically normal participants completed 6 baseline sessions and 24 operant conditioning sessions in which they were encouraged to increase (M1up) or decrease (M1down) M1 size. Five of eight M1up participants significantly increased M1; the final M1 size of those five participants was 143 ± 15% (mean ± SE) of the baseline value. All eight M1down participants significantly decreased M1; their final M1 size was 62 ± 6% of baseline. Similar to the previous H-reflex conditioning studies, conditioned reflex change consisted of within-session task-dependent adaptation and across-session long-term change. Task-dependent adaptation was evident in conditioning session 1 with M1up and by session 4 with M1down. Long-term change was evident by session 10 with M1up and by session 16 with M1down. Task-dependent adaptation was greater with M1up than with the previous H-reflex upconditioning. This may reflect adaptive changes in muscle spindle sensitivity, which affects the stretch reflex but not the H reflex. Because the stretch reflex is related to motor function more directly than the H reflex, M1 conditioning may provide a valuable tool for exploring the functional impact of reflex conditioning and its potential therapeutic applications. NEW & NOTEWORTHY Since the activity of stretch reflex pathways contributes to locomotion, changing it through training may improve locomotor rehabilitation in people with CNS disorders. Here we show for the first time that people can change the size of the soleus spinal stretch reflex through operant conditioning. Conditioned stretch reflex change is the sum of task-dependent adaptation and long-term change, consistent with H-reflex conditioning yet different from it in the composition and amount of the two components.

Beyond the Activity-Based Anorexia Model: Reinforcing Values of Exercise and Feeding Examined in Stressed Adolescent Male and Female Mice

Anorexia nervosa (AN), mostly observed in female adolescents, is the most fatal mental illness. Its core is a motivational imbalance between exercise and feeding in favor of the former. The most privileged animal model of AN is the "activity-based anorexia" (ABA) model wherein partly starved rodents housed with running wheels exercise at the expense of feeding. However, the ABA model bears face and construct validity limits, including its inability to specifically assess running motivation and feeding motivation. As infant/adolescent trauma is a precipitating factor in AN, this study first analyzed post-weaning isolation rearing (PWIR) impacts on body weights and wheel-running performances in female mice exposed to an ABA protocol. Next, we studied through operant conditioning protocols i) whether food restriction affects in a sex-dependent manner running motivation before ii) investigating how PWIR and sex affect running and feeding drives under ad libitum fed conditions and food restriction. Besides amplifying ABA-elicited body weight reductions, PWIR stimulated wheel-running activities in anticipation of feeding in female mice, suggesting increased running motivation. To confirm this hypothesis, we used a cued-reward motivated instrumental task wherein wheel-running was conditioned by prior nose poke responses. It was first observed that food restriction increased running motivation in male, but not female, mice. When fed grouped and PWIR mice were tested for their running and palatable feeding drives, all mice, excepted PWIR males, displayed increased nose poke responses for running over feeding. This was true when rewards were proposed alone or within a concurrent test. The increased preference for running over feeding in fed females did not extend to running performances (time, distance) during each rewarded sequence, confirming that motivation for, and performance during, running are independent entities. With food restriction, mice displayed a sex-independent increase in their preference for feeding over running in both group-housed and PWIR conditions. This study shows that the ABA model does not specifically capture running and feeding drives, i.e. components known to be affected in AN.

When and Where Learning is Taking Place: Multisynaptic Changes in Strength During Different Behaviors Related to the Acquisition of an Operant Conditioning Task by Behaving Rats

Although it is generally assumed that brain circuits are modified by new experiences, the question of which changes in synaptic efficacy take place in cortical and subcortical circuits across the learning process remains unanswered. Rats were trained in the acquisition of an operant conditioning in a Skinner box provided with light beams to detect animals' approaches to lever and feeder. Behaviors such as pressing the lever, eating, exploring, and grooming were also recorded. Animals were chronically implanted with stimulating and recording electrodes in hippocampal, prefrontal, and subcortical sites relevant to the task. Field synaptic potentials were evoked during the performance of the above-mentioned behaviors and before, during, and after the acquisition process. Afferent pathways to the hippocampus and the intrinsic hippocampal circuit were slightly modified in synaptic strength during the performance of those behaviors. In contrast, afferent and efferent circuits of the medial prefrontal cortex were significantly modified in synaptic strength across training sessions, mostly at the moment of the largest change in the learning curve. Performance of behaviors nondirectly related to the acquisition process (exploring, grooming) also evoked changes in synaptic strength across training. This study helps to understand when and where learning is being engraved in the brain.

Probabilistic Learning by Positive and Negative Reinforcement in Generalized Anxiety Disorder

This experiment examined learning tendencies in generalized anxiety disorder (GAD) using reinforcement feedback for probabilistic outcomes. One hundred sixty-six GAD and 105 non-GAD participants were randomized to a computerized probabilistic learning task that used either negative or positive reinforcement. Participants chose between stimuli with specific probabilities of reinforcement to learn which of each pair had the highest probability. Reinforced choices either removed an angry face (negative reinforcement) or made a happy face appear (positive reinforcement). Results showed that those with GAD learned the correct probabilistic choices at a slower rate over time and to a lesser degree than control participants regardless of reinforcement type. Estimations of the likelihood of receiving a good outcome posttask were also more inaccurate for those with GAD, especially when true likelihoods were high. Furthermore, compared with control participants, those with GAD reported lower perceived reinforcement sensitivity, higher behavioral inhibition sensitivity, and higher undesirable feelings toward probabilistic learning.

A Novel Olfactometer for Efficient and Flexible Odorant Delivery

Understanding how sensory space maps to neural activity in the olfactory system requires efficiently and flexibly delivering numerous odorants within single experimental preparations. Such delivery is difficult with current olfactometer designs, which typically include limited numbers of stimulus channels and are subject to intertrial and interchannel contamination of odorants. Here, we present a novel olfactometer design that is easily constructed, modular, and capable of delivering an unlimited number of odorants in air with temporal precision and no detectable intertrial or interchannel contamination. The olfactometer further allows for the flexible generation of odorant mixtures and flexible timing of odorant sequences. Odorant delivery from the olfactometer is turbulent but reliable from trial to trial, supporting operant conditioning of mice in an odorant discrimination task and permitting odorants and concentrations to be mapped to neural activity with a level of precision equivalent to that obtained with a flow dilution olfactometer. This novel design thus provides several unique advantages for interrogating olfactory perception and for mapping sensory space to neural activity in the olfactory system.

Operant conditioning of the motor-evoked potential and locomotion in people with and without chronic incomplete spinal cord injury

Foot drop is very common among people with chronic incomplete spinal cord injury (SCI) and likely stems from SCI that disturbs the corticospinal activation of the ankle dorsiflexor tibialis anterior (TA). Thus, if one can recover or increase the corticospinal excitability reduced by SCI, motor function recovery may be facilitated. Here, we hypothesized that in people suffering from weak dorsiflexion due to chronic incomplete SCI, increasing the TA motor-evoked potential (MEP) through operant up-conditioning can improve dorsiflexion during locomotion, while in people without any injuries, it would have little impact on already normal locomotion. Before and after 24 MEP conditioning or control sessions, locomotor electromyography (EMG) and kinematics were measured. This study reports the results of these locomotor assessments. In participants without SCI, locomotor EMG activity, soleus Hoffmann reflex modulation, and joint kinematics did not change, indicating that MEP up-conditioning or repeated single-pulse transcranial magnetic stimulation (i.e., control protocol) does not influence normal locomotion. In participants with SCI, MEP up-conditioning increased TA activity during the swing-to-swing stance transition phases and ankle joint motion during locomotion in the conditioned leg and increased walking speed consistently. In addition, the swing-phase TA activity and ankle joint motion also improved in the contralateral leg. The results are consistent with our hypothesis. Together with the previous operant conditioning studies in humans and rats, the present study suggests that operant conditioning can be a useful therapeutic tool for enhancing motor function recovery in people with SCI and other central nervous system disorders. NEW & NOTEWORTHY This study examined the functional impact of operant conditioning of motor-evoked potential (MEP) to transcranial magnetic stimulation that aimed to increase corticospinal excitability for the ankle dorsiflexor tibialis anterior (TA). In people with chronic incomplete spinal cord injury (SCI), MEP up-conditioning increased TA activity and improved dorsiflexion during locomotion, while in people without injuries, it had little impact on already normal locomotion. MEP conditioning may potentially be used to enhance motor function recovery after SCI.

Ontogenesis of learning and memory: Biopsychosocial and dynamical systems perspectives

In this article, we review recent empirical and theoretical work on infant memory development, highlighting future directions for the field. We consider the state of the field since Carolyn Rovee-Collier's call for developmental scientists to "shift the focus from what to why," emphasizing the function of infant behavior and the value of integrating fractionized, highly specialized subfields. We discuss functional approaches of early learning and memory, including ecological models of memory development and relevant empirical work in human and non-human organisms. Ontogenetic changes in learning and memory occur in developing biological systems, which are embedded in broader socio-cultural contexts with shifting ecological demands that are in part determined by the infants themselves. We incorporate biopsychosocial and dynamical systems perspectives as we analyze the state of the field's integration of multiple areas of specialization to provide more holistic understanding of the contributing factors and underlying mechanisms of the development of memory.

Behavior analysts in the war on poverty: Developing an operant antipoverty program

Poverty is associated with poor health and affects many United States residents. The therapeutic workplace, an operant intervention designed to treat unemployed adults with histories of drug addiction, could form the basis for an effective antipoverty program. Under the therapeutic workplace, participants receive pay for work. To promote drug abstinence or medication adherence, participants must provide drug-free urine samples or take scheduled doses of medication, respectively, to maintain maximum pay. Therapeutic workplace participants receive job-skills training in Phase 1 and perform income-producing jobs in Phase 2. Many unemployed, drug-addicted adults lack skills they would need to obtain high-skilled and high-paying jobs. Many of these individuals attend therapeutic workplace training reliably, but only when offered stipends for attendance. They also work on training programs reliably, but only when they earn stipends for performance on training programs. A therapeutic workplace social business can promote employment, although special contingencies may be needed to ensure that participants are punctual and work entire work shifts, and social businesses do not reliably promote community employment. Therapeutic workplace participants work with an employment specialist to seek community employment, but primarily when they earn financial incentives. Reducing poverty is more challenging than promoting employment, because it requires promoting employment in higher paying, full-time and steady jobs. Although a daunting challenge, promoting the type of employment needed to reduce poverty is an important goal, both because of the obvious benefit in reducing poverty itself and in the potential secondary benefit of reducing poverty-related health disparities. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A Novel Method for Training Mice in Visuo-Tactile 3-D Object Discrimination and Recognition

Perceiving, recognizing and remembering 3-dimensional (3-D) objects encountered in the environment has a very high survival value; unsurprisingly, this ability is shared among many animal species, including humans. The psychological, psychophysical and neural basis for object perception, discrimination, recognition and memory has been extensively studied in humans, monkeys, pigeons and rodents, but is still far from understood. Nearly all 3-D object recognition studies in the rodent used the "novel object recognition" paradigm, which relies on innate rather than learned behavior; however, this procedure has several important limitations. Recently, investigators have begun to recognize the power of behavioral tasks learned through reinforcement training (operant conditioning) to reveal the sensorimotor and cognitive abilities of mice and to elucidate their underlying neural mechanisms. Here, we describe a novel method for training and testing mice in visual and tactile object discrimination, recognition and memory, and use it to begin to examine the underlying sensory basis for these cognitive capacities. A custom-designed Y maze was used to train mice to associate one of two 3-D objects with a food reward. Out of nine mice trained in two cohorts, seven reached performance criterion in about 20-35 daily sessions of 20 trials each. The learned association was retained, or rapidly re-acquired, after a 6 weeks hiatus in training. When tested under low light conditions, individual animals differed in the degree to which they used tactile or visual cues to identify the objects. Switching to total darkness resulted only in a transient dip in performance, as did subsequent trimming of all large whiskers (macrovibrissae). Additional removal of the small whiskers (microvibrissae) did not degrade performance, but transiently increased the time spent inspecting the object. This novel method can be combined in future studies with the large arsenal of genetic tools available in the mouse, to elucidate the neural basis of object perception, recognition and memory.

Token economy to improve adherence to activities of daily living

BACKGROUND

Participation in key activities of daily living (ADL), including daily bathing, physical activity, and oral hygiene, can decrease the risk of bloodstream infections, oral complications, and deconditioning in pediatric patients undergoing hematopoietic stem cell transplant (HSCT). However, many patients fail to perform ADL during their inpatient stay. To improve inpatient adherence to ADL, we tested a token economy to engage patients, families, and the clinical team in improving adherence to these important health behaviors during this critical time.

METHODS

We used a controlled before-after study design to test our hypothesis. All patients were prescribed three ADL. We used an "all or none" measurement for each component of the ADL 1-2-3 initiative to measure adherence. HSCT patients with poor ADL adherence (<20%) were eligible to receive the intervention, which consisted of rewarding patients through an ADL via a token economy.

RESULTS

Twenty-one patients participated in the study. ADL adherence for the 14 days prior to intervention in study subjects (n = 294 inpatient days) averaged 0.51 ADL per day (95% CI 0.45-0.57). In the 14 days postinitiation of the token economy intervention (n = 294 inpatient days), the average adherence was 2.5 ADL per day (95% CI 2.4-2.5; P = <0.001).

DISCUSSION

Positive reinforcement through a token economy system is associated with improved adherence to ADL in hospitalized pediatric patients who demonstrated poor ADL adherence at baseline. We believe this intervention can positively impact adherence to targeted health behaviors with the ability to correlate with improved health outcomes.