Chemogenetic activation ofarcuate nucleus NPY and NPY/AgRP neurons increases feeding behaviour in mice.

Neuropeptide Y (NPY) plays a crucial role in controlling energy homeostasis and feeding behaviour. The role of NPY neurons located in the arcuate nucleus of the hypothalamus (Arc) in responding to homeostatic signals has been the focus of much investigation, but most studies have used AgRP promoter-driven models, which do not fully encompass Arc NPY neurons. To directly investigate NPY-expressing versus AgRP-expressing Arc neurons function, we utilised chemogenetic techniques in NPY-Cre and AgRP-Cre animals to activate Arc NPY or AgRP neurons in the presence of food and food-related stimuli. Our findings suggest that chemogenetic activation of the broader population of Arc NPY neurons, including AgRP-positive and AgRP-negative NPY neurons, has equivalent effects on feeding behaviour as activation of Arc AgRP neurons. Our results demonstrate that these Arc NPY neurons respond specifically to caloric signals and do not respond to non-caloric signals, in line with what has been observed in AgRP neurons. Activating Arc NPY neurons significantly increases food consumption and influences macronutrient selection to prefer fat intake.

A Cognitive Pathway to Persistent, Maladaptive Choice.

BACKGROUND: Correctly recognising that alcohol or other substances are causing problems is a necessary condition for those problems to spur beneficial behaviour change. Yet such recognition is neither immediate nor straightforward. Recognition that one's alcohol or drug use is causing negative consequences often occurs gradually. Contemporary addiction neuroscience has yet to make progress in understanding and addressing these recognition barriers, despite evidence that a lack of problem recognition is a primary impediment to seeking treatment. SUMMARY: Based on our recent empirical work, this article shows how recognition barriers can emerge from dual constraints on how we learn about the negative consequences of our actions. One constraint is imposed by the characteristics of negative consequences themselves. A second constraint is imposed by the characteristics of human cognition and information processing. In some people, the joint action of these constraints causes a lack of correct awareness of the consequences of their behaviour and reduced willingness to update that knowledge and behaviour when confronted with counterevidence. KEY MESSAGES: This "cognitive pathway" can drive persistent, maladaptive choice.

Translational research in punishment learning.

Punishment learning is learning of the causal relationship between responses and their adverse or undesirable consequences. Here, we review our translational approach for understanding whether, when, and how individuals differ in what they learn during punishment, and how these differences in learning may drive persistent poor or maladaptive decisions. We show that individual differences in punishment insensitivity can emerge from differences between individuals in what they learn about punishment (instrumental contingency knowledge), rather than differences in aversive valuation, reward valuation, general (impulsivity), or specific (habit) behavioral control. These differences in instrumental contingency knowledge are shared with and can be studied in other animals. Our approach has strong construct and predictive validity, providing a robust translational platform for studying how punishment learning and decision making may contribute to neuropsychiatric disorders. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

A cognitive pathway to punishment insensitivity.

Individuals differ in their sensitivity to the adverse consequences of their actions, leading some to persist in maladaptive behaviors. Two pathways have been identified for this insensitivity: a motivational pathway based on excessive reward valuation and a behavioral pathway based on autonomous stimulus-response mechanisms. Here, we identify a third, cognitive pathway based on differences in punishment knowledge and use of that knowledge to suppress behavior. We show that distinct phenotypes of punishment sensitivity emerge from differences in what people learn about their actions. Exposed to identical punishment contingencies, some people (sensitive phenotype) form correct causal beliefs that they use to guide their behavior, successfully obtaining rewards and avoiding punishment, whereas others form incorrect but internally coherent causal beliefs that lead them to earn punishment they do not like. Incorrect causal beliefs were not inherently problematic because we show that many individuals benefit from information about why they are being punished, revaluing their actions and changing their behavior to avoid further punishment (unaware phenotype). However, one condition where incorrect causal beliefs were problematic was when punishment is infrequent. Under this condition, more individuals show punishment insensitivity and detrimental patterns of behavior that resist experience and information-driven updating, even when punishment is severe (compulsive phenotype). For these individuals, rare punishment acted as a "trap," inoculating maladaptive behavioral preferences against cognitive and behavioral updating.

Pathways to the persistence of drug use despite its adverse consequences.

The persistence of drug taking despite its adverse consequences plays a central role in the presentation, diagnosis, and impacts of addiction. Eventual recognition and appraisal of these adverse consequences is central to decisions to reduce or cease use. However, the most appropriate ways of conceptualizing persistence in the face of adverse consequences remain unclear. Here we review evidence that there are at least three pathways to persistent use despite the negative consequences of that use. A cognitive pathway for recognition of adverse consequences, a motivational pathway for valuation of these consequences, and a behavioral pathway for responding to these adverse consequences. These pathways are dynamic, not linear, with multiple possible trajectories between them, and each is sufficient to produce persistence. We describe these pathways, their characteristics, brain cellular and circuit substrates, and we highlight their relevance to different pathways to self- and treatment-guided behavior change.

Role of anterior insula cortex in context-induced relapse of nicotine-seeking.

Tobacco use is the leading cause of preventable death worldwide, and relapse during abstinence remains the critical barrier to successful treatment of tobacco addiction. During abstinence, environmental contexts associated with nicotine use can induce craving and contribute to relapse. The insular cortex (IC) is thought to be a critical substrate of nicotine addiction and relapse. However, its specific role in context-induced relapse of nicotine-seeking is not fully known. In this study, we report a novel rodent model of context-induced relapse to nicotine-seeking after punishment-imposed abstinence, which models self-imposed abstinence through increasing negative consequences of excessive drug use. Using the neuronal activity marker Fos we find that the anterior (aIC), but not the middle or posterior IC, shows increased activity during context-induced relapse. Combining Fos with retrograde labeling of aIC inputs, we show projections to aIC from contralateral aIC and basolateral amygdala exhibit increased activity during context-induced relapse. Next, we used fiber photometry in aIC and observed phasic increases in aIC activity around nicotine-seeking responses during self-administration, punishment, and the context-induced relapse tests. Next, we used chemogenetic inhibition in both male and female rats to determine whether activity in aIC is necessary for context-induced relapse. We found that chemogenetic inhibition of aIC decreased context-induced nicotine-seeking after either punishment- or extinction-imposed abstinence. These findings highlight the critical role nicotine-associated contexts play in promoting relapse, and they show that aIC activity is critical for this context-induced relapse following both punishment and extinction-imposed abstinence.

A Corticothalamic Circuit Trades off Speed for Safety during Decision-Making under Motivational Conflict.

Decisions to act while pursuing goals in the presence of danger must be made quickly but safely. Premature decisions risk injury or death, whereas postponing decisions risk goal loss. Here we show how mice resolve these competing demands. Using microstructural behavioral analyses, we identified the spatiotemporal dynamics of approach-avoidance decisions under motivational conflict in male mice. Then we used cognitive modeling to show that these dynamics reflect the speeded decision-making mechanisms used by humans and nonhuman primates, with mice trading off decision speed for safety of choice when danger loomed. Using calcium imaging in paraventricular thalamus and optogenetic inhibition of the prelimbic cortex to paraventricular thalamus pathway, we show that this speed-safety trade off occurs because increases in paraventricular thalamus activity increase decision caution, thereby increasing approach-avoid decision times in the presence of danger. Our findings demonstrate that a discrete brain circuit involving the paraventricular thalamus and its prefrontal input adjusts decision caution during motivational conflict, trading off decision speed for decision safety when danger is close. We identify the corticothalamic pathway as central to cognitive control during decision-making under conflict.SIGNIFICANCE STATEMENT Foraging animals balance the need to seek food and energy against the conflicting needs to avoid injury and predation. This competition is fundamental to survival but rarely has a stable, correct solution. Here we show that approach-avoid decisions under motivational conflict involve strategic adjustments in decision caution controlled via a top-down corticothalamic pathway from the prelimbic cortex to the paraventricular thalamus. We identify a novel corticothalamic mechanism for cognitive control that is applicable across a range of motivated behaviors and mark paraventricular thalamus and its prefrontal cortical input as targets to remediate the deficits in decision caution characteristic of unsafe and impulsive choices.

Instrumental aversion coding in the basolateral amygdala and its reversion by a benzodiazepine.

Punishment involves learning the relationship between actions and their adverse consequences. Both the acquisition and expression of punishment learning depend on the basolateral amygdala (BLA), but how BLA supports punishment remains poorly understood. To address this, we measured calcium (Ca2+) transients in BLA principal neurons during punishment. Male rats were trained to press two individually presented levers for food; when one of these levers also yielded aversive footshock, responding on this punished lever decreased relative to the other, unpunished lever. In rats with the Ca2+ indicator GCaMP6f targeted to BLA principal neurons, we observed excitatory activity transients to the footshock punisher and inhibitory transients to lever-presses earning a reward. Critically, as rats learned punishment, activity around the punished response transformed from inhibitory to excitatory and similarity analyses showed that these punished lever-press transients resembled BLA transients to the punisher itself. Systemically administered benzodiazepine (midazolam) selectively alleviated punishment. Moreover, the degree to which midazolam alleviated punishment was associated with how much punished response-related BLA transients reverted to their pre-punishment state. Together, these findings show that punishment learning is supported by aversion-coding of instrumental responses in the BLA and that the anti-punishment effects of benzodiazepines are associated with a reversion of this aversion coding.

Phasic inhibition of dopamine neurons is an instrumental punisher.

It is well established that the activity of VTA dopamine neurons is sufficient to serve as a Pavlovian reinforcer but whether this activity can also serve as instrumental reinforcer is less well understood. Here we studied the effects of optogenetic inhibition of VTA dopamine neurons in instrumental conditioning preparations. We show that optogenetic inhibition of VTA dopamine neurons causes a response-specific, contingency-sensitive suppression of instrumental responding. This suppression was due to instrumental response, not Pavlovian stimulus, learning and could not be attributed to deepened instrumental extinction learning. These effects of optogenetic inhibition of VTA dopamine neurons on instrumental responding are formally similar to the effects of aversive events in instrumental preparations and show that optogenetic inhibition of VTA dopamine neurons is sufficient to serve as an instrumental punisher. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Punishment insensitivity in humans is due to failures in instrumental contingency learning.

Punishment maximises the probability of our individual survival by reducing behaviours that cause us harm, and also sustains trust and fairness in groups essential for social cohesion. However, some individuals are more sensitive to punishment than others and these differences in punishment sensitivity have been linked to a variety of decision-making deficits and psychopathologies. The mechanisms for why individuals differ in punishment sensitivity are poorly understood, although recent studies of conditioned punishment in rodents highlight a key role for punishment contingency detection (Jean-Richard-Dit-Bressel et al., 2019). Here, we applied a novel 'Planets and Pirates' conditioned punishment task in humans, allowing us to identify the mechanisms for why individuals differ in their sensitivity to punishment. We show that punishment sensitivity is bimodally distributed in a large sample of normal participants. Sensitive and insensitive individuals equally liked reward and showed similar rates of reward-seeking. They also equally disliked punishment and did not differ in their valuation of cues that signalled punishment. However, sensitive and insensitive individuals differed profoundly in their capacity to detect and learn volitional control over aversive outcomes. Punishment insensitive individuals did not learn the instrumental contingencies, so they could not withhold behaviour that caused punishment and could not generate appropriately selective behaviours to prevent impending punishment. These differences in punishment sensitivity could not be explained by individual differences in behavioural inhibition, impulsivity, or anxiety. This bimodal punishment sensitivity and these deficits in instrumental contingency learning are identical to those dictating punishment sensitivity in non-human animals, suggesting that they are general properties of aversive learning and decision-making.

The Mesolimbic Dopamine Activity Signatures of Relapse to Alcohol-Seeking.

The mesolimbic dopamine system comprises distinct compartments supporting different functions in learning and motivation. Less well understood is how complex addiction-related behaviors emerge from activity patterns across these compartments. Here we show how different forms of relapse to alcohol-seeking in male rats are assembled from activity across the VTA and the nucleus accumbens. First, we used chemogenetic approaches to show a causal role for VTA TH neurons in two forms of relapse to alcohol-seeking: renewal (context-induced reinstatement) and reacquisition. Then, using gCaMP fiber photometry of VTA TH neurons, we identified medial and lateral VTA TH neuron activity profiles during self-administration, renewal, and reacquisition. Next, we used optogenetic inhibition of VTA TH neurons to show distinct causal roles for VTA subregions in distinct forms of relapse. We then used dLight fiber photometry to measure dopamine binding across the ventral striatum (medial accumbens shell, accumbens core, lateral accumbens shell) and showed complex and heterogeneous profiles of dopamine binding during self-administration and relapse. Finally, we used representational similarity analysis to identify mesolimbic dopamine signatures of self-administration, extinction, and relapse. Our results show that signatures of relapse can be identified from heterogeneous activity profiles across the mesolimbic dopamine system and that these signatures are unique for different forms of relapse.SIGNIFICANCE STATEMENT It is axiomatic that the actions of dopamine are critical to drug addiction. Yet how relapse to drug-seeking is assembled from activity across the mesolimbic dopamine system is poorly understood. Here we show how relapse to alcohol-seeking relates to activity in specific VTA and accumbens compartments, how these change for different forms of relapse, and how relapse-associated activity relates to activity during self-administration and extinction. We report the mesolimbic dopamine activity signatures for relapse and show that these signatures are unique for different forms of relapse.

Analyzing Event-Related Transients: Confidence Intervals, Permutation Tests, and Consecutive Thresholds.

Fiber photometry has enabled neuroscientists to easily measure targeted brain activity patterns in awake, freely behaving animal. A focus of this technique is to identify functionally-relevant changes in activity around particular environmental and/or behavioral events, i.e., event-related activity transients (ERT). A simple and popular approach to identifying ERT is to summarize peri-event signal [e.g., area under the curve (AUC), peak activity, etc.,] and perform standard analyses on this summary statistic. We highlight the various issues with this approach and overview straightforward alternatives: waveform confidence intervals (CIs) and permutation tests. We introduce the rationale behind these approaches, describe the results of Monte Carlo simulations evaluating their effectiveness at controlling Type I and Type II error rates, and offer some recommendations for selecting appropriate analysis strategies for fiber photometry experiments.

Medial Orbitofrontal Cortex Regulates Instrumental Conditioned Punishment, but not Pavlovian Conditioned Fear.

Bidirectionally aberrant medial orbitofrontal cortical (mOFC) activity has been consistently linked with compulsive disorders and related behaviors. Although rodent studies have established a causal link between mOFC excitation and compulsive-like actions, no such link has been made with mOFC inhibition. Here, we use excitotoxic lesions of mOFC to investigate its role in sensitivity to punishment; a core characteristic of many compulsive disorders. In our first experiment, we demonstrated that mOFC lesions prevented rats from learning to avoid a lever that was punished with a stimulus that coterminated with footshock. Our second experiment demonstrated that retrieval of punishment learning is also somewhat mOFC-dependent, as lesions prevented the extended retrieval of punishment contingencies relative to shams. In contrast, mOFC lesions did not prevent rats from reacquiring the ability to avoid a punished lever when it was learned prior to lesions being administered. In both experiments, Pavlovian fear conditioning to the stimulus was intact for all animals. Together, these results reveal that the mOFC regulates punishment learning and retrieval in a manner that is separate from any role in Pavlovian fear conditioning. These results imply that aberrant mOFC activity may contribute to the punishment insensitivity that is observed across multiple compulsive disorders.

Punishment insensitivity emerges from impaired contingency detection, not aversion insensitivity or reward dominance.

Our behaviour is shaped by its consequences - we seek rewards and avoid harm. It has been reported that individuals vary markedly in their avoidance of detrimental consequences, that is in their sensitivity to punishment. The underpinnings of this variability are poorly understood; they may be driven by differences in aversion sensitivity, motivation for reward, and/or instrumental control. We examined these hypotheses by applying several analysis strategies to the behaviour of rats (n = 48; 18 female) trained in a conditioned punishment task that permitted concurrent assessment of punishment, reward-seeking, and Pavlovian fear. We show that punishment insensitivity is a unique phenotype, unrelated to differences in reward-seeking and Pavlovian fear, and due to a failure of instrumental control. Subjects insensitive to punishment are afraid of aversive events, they are simply unable to change their behaviour to avoid them.

Paraventricular Thalamus Controls Behavior during Motivational Conflict.

Decision-making often involves motivational conflict because of the competing demands of approach and avoidance for a common resource: behavior. This conflict must be resolved as a necessary precursor for adaptive behavior. Here we show a role for the paraventricular thalamus (PVT) in behavioral control during motivational conflict. We used Pavlovian counterconditioning in male rats to establish a conditioned stimulus (CS) as a signal for reward (or danger) and then transformed the same CS into a signal for danger (or reward). After such training, the CS controls conflicting appetitive and aversive behaviors. To assess PVT involvement in conflict, we injected an adeno-associated virus (AAV) expressing the genetically encoded Ca2+ indicator GCaMP and used fiber photometry to record population PVT Ca2+ signals. We show distinct profiles of responsivity across the anterior-posterior axis of PVT during conflict, including an ordinal relationship between posterior PVT CS responses and behavior strength. To study the causal role of PVT in behavioral control during conflict, we injected AAV expressing the inhibitory hM4Di DREADD and determined the effects of chemogenetic PVT inhibition on behavior. We show that chemogenetic inhibition across the anterior-posterior axis of the PVT, but not anterior or posterior PVT alone, disrupts arbitration between appetitive and aversive behaviors when they are in conflict but has no effect when these behaviors are assessed in isolation. Together, our findings identify PVT as central to behavioral control during motivational conflict.SIGNIFICANCE STATEMENT Animals, including humans, approach attractive stimuli and avoid aversive ones. However, they frequently face conflict when the demands of approach and avoidance are incompatible. Resolution of this conflict is fundamental to adaptive behavior. Here we show a role for the paraventricular thalamus, a nucleus of the dorsal midline thalamus, in the arbitration of appetitive and aversive behavior during motivational conflict.

Behavioral and neurobiological mechanisms of punishment: implications for psychiatric disorders.

Punishment involves learning about the relationship between behavior and its adverse consequences. Punishment is fundamental to reinforcement learning, decision-making and choice, and is disrupted in psychiatric disorders such as addiction, depression, and psychopathy. However, little is known about the brain mechanisms of punishment and much of what is known is derived from study of superficially similar, but fundamentally distinct, forms of aversive learning such as fear conditioning and avoidance learning. Here we outline the unique conditions that support punishment, the contents of its learning, and its behavioral consequences. We consider evidence implicating GABA and monoamine neurotransmitter systems, as well as corticostriatal, amygdala, and dopamine circuits in punishment. We show how maladaptive punishment processes are implicated in addictions, impulse control disorders, psychopathy, anxiety, and depression and argue that a better understanding of the cellular, circuit, and cognitive mechanisms of punishment will make important contributions to next generation therapeutic approaches.

Distinct Accumbens Shell Output Pathways Promote versus Prevent Relapse to Alcohol Seeking.

Contexts exert bi-directional control over relapse to drug seeking. Contexts associated with drug self-administration promote relapse, whereas contexts associated with the absence of self-administration protect against relapse. The nucleus accumbens shell (AcbSh) is a key brain region determining these roles of context. However, the specific cell types, and projections, by which AcbSh serves these dual roles are unknown. Here, we show that contextual control over relapse and abstinence is embedded within distinct output circuits of dopamine 1 receptor (Drd1) expressing AcbSh neurons. We report anatomical and functional segregation of Drd1 AcbSh output pathways during context-induced reinstatement and extinction of alcohol seeking. The AcbSh→ventral tegmental area (VTA) pathway promotes relapse via projections to VTA Gad1 neurons. The AcbSh→lateral hypothalamus (LH) pathway promotes extinction via projections to LH Gad1 neurons. Targeting these opposing AcbSh circuit contributions may reduce propensity to relapse to, and promote abstinence from, drug use.

Basolateral Amygdala Neurons Maintain Aversive Emotional Salience.

BLA neurons serve a well-accepted role in fear conditioning and fear extinction. However, the specific learning processes related to their activity at different times during learning remain poorly understood. We addressed this using behavioral tasks isolating distinct aspects of fear learning in male rats. We show that brief optogenetic inhibition of BLA neurons around moments of aversive reinforcement or nonreinforcement causes reductions in the salience of conditioned stimuli, rendering these stimuli less able to be learned about and less able to control fear or safety behaviors. This salience reduction was stimulus-specific, long-lasting, and specific to learning about, or responding to, the same aversive outcome, precisely the goals of therapeutic interventions in human anxiety disorders. Our findings identify a core learning process disrupted by brief BLA optogenetic inhibition. They show that a primary function of the unconditioned stimulus-evoked activity of BLA neurons is to maintain the salience of conditioned stimuli that precede it. This maintenance of salience is a necessary precursor for these stimuli to gain and maintain control over fear and safety behavior.SIGNIFICANCE STATEMENT The amygdala is essential for learning to fear and learning to reduce fear. However, the specific roles served by activity of different amygdala neurons at different times during learning is poorly understood. We used behavioral tasks isolating distinct aspects of learning in rats to show that brief optogenetic inhibition of BLA neurons around moments of reinforcement or nonreinforcement disrupts maintenance of conditioned stimulus salience. This causes a stimulus-specific and long-lasting deficit in the ability of the conditioned stimulus to be learned about or control fear responses. These consequences are the precisely goals of therapeutic interventions in human anxiety disorders. Our findings identify a core learning process disrupted by brief BLA optogenetic inhibition.