Biology subjects

Ritchie, J. L.

Publications and source records attributed to Ritchie, J. L..

8 recordsLinked to original sources

bioRxiv2026

ABEL: an active-learning behavior estimation and labeling platform

Detailed behavior analysis is essential for thorough characterization of ethologically relevant behaviors in model organisms, yet manual annotation of the full behavioral repertoire remains subjective, time intensive, and susceptible to observer error. Advances in machine learning have enabled high-throughput pose estimation on recorded video, but tools for behavior classification from pose and video data are still developing. Instead of hand-scoring every frame of video, experimenters can instead label a small subset of video frames and software trained through machine learning makes predictions on the rest. Here, we present an Active-learning Behavior Estimation and Labeling (ABEL) platform that uses clip-level active learning (i.e., human labeling of short video snippets) with multimodal features (pose, video, context/ROI) to train robust behavior classifiers. We rigorously validated ABEL-derived behavior predictions against expert human observers and field-standard automated software, across diverse rodent behavioral assays. Across eight assays and 45 behaviors, model training required 19.5 hours of human annotation in total, with the reviewer scoring ~8% of available video. Models trained in ABEL achieved a mean precision-recall area under the curve (PR-AUC - a 0-1 score of how well a model balances missed detections against false alarms, with 1 being perfect) of 0.90 (SD 0.09, range 0.60-0.99), with no association between performance and behavior prevalence (r = 0.20). This was aided by custom tools, Essence Extractor and UMAP Interactive Selection, for targeted discovery of high probability clips which reduce the clip review needed to find a rare behavior 6-fold relative to random sampling and 10-fold relative to labeling whole videos. As a biological validation, we assessed how ABEL-derived behaviors relate to underlying neuronal calcium dynamics. Behavior labels were tightly synced with neuronal signatures distinct from ambiguous behavior and randomly chosen, behavior-unrelated time windows (shuffle control). Together, these data indicate that ABEL provides an efficient platform for frame-precise classification of distinct ethologically relevant behaviors.

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bioRxiv2026

The role of serotonin in the orbitofrontal cortex in alcohol consumption

Binge alcohol drinking is a public health concern that can dramatically increase the risk for development of alcohol use disorder (AUD). Continued alcohol drinking in the face of negative consequences is another key feature of AUD. A better understanding of the neural circuitry that regulates these behaviors could provide insight as to novel treatments for AUD. Serotonin is a neurotransmitter that has been implicated in alcohol consumption in both human studies and animal models. The orbitofrontal cortex (OFC) is a brain region that both receives serotonergic input from the dorsal raphe and has been implicated in AUD. However, how volitional alcohol consumption impacts serotonin signaling within the OFC and how this contributes to alcohol related behaviors is unknown. Here, we show that a history of alcohol consumption alters the ability of 5-HT to hyperpolarize OFC pyramidal neurons in mice and monkeys. Consistent with this, a history of binge alcohol consumption decreases the expression of the 5-HT1A but not 5-HT2A receptor in the OFC from mice. Next, we show that deletion of the 5-HT1A receptor from the OFC increased alcohol intake and preference in male, but not female mice. Finally, we found that 5-HT1A receptor deletion led to increased quinine-adulterated alcohol intake, a measure of aversion-resistant drinking, in both male and female mice. Altogether, we identified serotonin signaling in the OFC as key target for modulation of binge and compulsive alcohol consumption.

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bioRxiv2026

Chronic oral fentanyl consumption produces dynamic behavioral adaptations during abstinence in female mice

RationaleThe opioid epidemic continues to be driven by synthetic opioids, particularly fentanyl, yet the long-term behavioral manifestations of withdrawal remain poorly characterized. Women exhibit unique vulnerabilities to opioid use disorder, including greater susceptibility to withdrawal-related symptoms and relapse, suggesting that defining the behavioral adaptations that emerge during prolonged fentanyl abstinence may identify mechanisms underlying female-specific relapse vulnerability. Thus, we used an oral fentanyl drinking model to longitudinally examine nociceptive, affective, and exploratory behaviors across chronic exposure and abstinence in female mice. MethodsAdult female C57BL/6J mice underwent a modified 5-week Drinking-in-the-Dark paradigm with 4-hour daily access to fentanyl (30 {micro}g/mL) or water. Somatic withdrawal was assessed following naloxone-precipitated withdrawal. Thermal and mechanical nociception, sucrose preference, exploratory behavior, acoustic startle, nest building, and locomotor activity were evaluated during fentanyl exposure and throughout one month of abstinence. ResultsFemale mice exhibited robust naloxone-precipitated somatic withdrawal, confirming physiological effects of opioid drinking. Chronic fentanyl exposure produced transient thermal hyperalgesia during weeks 2-4 of drinking that resolved by the final week, but re-emerged after 30 days of abstinence. After 30 days of abstinence, we also found increased mechanical sensitivity. During early abstinence, fentanyl-exposed mice exhibited increased sucrose consumption and greater exploration of anxiogenic environments without alterations in general locomotion. Increased exploratory behavior persisted into prolonged abstinence and was partially rescued in mice who previously received naloxone. Additionally, fDID mice exhibited impaired nesting behavior, while prior naloxone-precipitated withdrawal improved nest-building performance. ConclusionsWe demonstrate that chronic opioid exposure, precipitated withdrawal trials, and duration of abstinence interact to shape protracted withdrawal phenotypes in female mice that extend well beyond drug exposure. These results provide insight into persistent withdrawal symptoms that may shape relapse vulnerability using a novel translationally relevant framework.

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bioRxiv2025

Selective dysregulation of serotonin dynamics in the anterior cingulate cortex and central amygdala following binge alcohol consumption

Serotonin (5HT) is a critical modulator of brain function and behavior that is dysregulated in alcohol use disorder (AUD). The anterior cingulate cortex (ACC) and central nucleus of the amygdala (CeA) play distinct roles in AUD and undergo functional changes in 5HT signaling following binge drinking, but our understanding of real-time 5HT dynamics in these structures is lacking. We hypothesized that binge drinking would elicit brain-region specific dysfunction in 5HT dynamics during appetitive and aversive stimuli processing. Using fiber photometry with the GRAB5HT sensor, we identified distinct reward and aversion 5HT signaling motifs in the ACC and CeA. Consumption of alcohol and other tastants elicited a suppression of GRAB5HT signal in the ACC and an increase in 5HT signal in the CeA. In contrast, aversive stimuli similarly increased 5HT in both structures. The effect of binge drinking on 5HT function was surprisingly non-uniform, producing brain-region, sex-, and stimulus-specific dysfunction in 5HT signaling that dramatically shifted across weeks of alcohol experience. This suggests that adaptations in 5HT signaling are specific to neural circuits underlying discrete functions. Optogenetically stimulating 5HT terminals in the ACC and CeA increased avoidance behavior without being overtly rewarding or aversive, and stimulating 5HT release in the ACC blunted alcohol drinking. Together, these data identify distinct 5HT reward and aversion signaling motifs in the ACC and CeA and highlight early binge drinking as a critical stage of 5HT adaptation and a potential window for therapeutic intervention.

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bioRxiv2025

Adolescent alcohol exposure disrupts extinction learning and retrosplenial cortex physiology in adult males

Adolescent binge drinking can lead to a myriad of issues in adulthood, including psychiatric comorbidities that worsen clinical prognosis. Efforts to understand the effects of adolescent alcohol exposure on later health outcomes have unveiled lasting effects on physiology of brain regions critical for associative learning processes, including the hippocampus and prefrontal cortex (PFC). Here, we tested the hypothesis that adolescent alcohol exposure would produce lasting alterations in physiology within the retrosplenial cortex (RSC), another region critical for associative learning that is reciprocally connected to the hippocampus and PFC. In support of this hypothesis, we found that adolescent intermittent ethanol (AIE) vapor exposure resulted in lasting reductions in intrinsic excitability in RSC pyramidal cells of adult mice. Importantly, these changes were sex-specific, occurring in males but not females. This work suggests that the RSC may be a key, vulnerable locus to the detrimental effects of adolescent alcohol.

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bioRxiv2025

Lateral hypothalamus CRFR1 regulation of chronic binge drinking: divergence along anterior-posterior axis

Binge alcohol drinking increases the risk of developing an alcohol use disorder (AUD) and comorbid psychopathology. The lateral hypothalamus (LH) is a brain structure that integrates cognitive and sensory information to tightly regulate motivated behavior, including binge drinking. Importantly, LH function is vulnerable to modulation by the pro-stress neuropeptide corticotropin-releasing factor (CRF), and acute antagonism of CRF receptor 1 (CRFR1) in the LH blunts binge drinking. However, the role of LH CRFR1 in chronic binge drinking is unknown. We used genetically targeted knockdown (KD) of CRFR1 in the LH of male and female mice followed by three weeks of binge drinking using the "Drinking in the Dark" (DID) model. CRFR1 KD in the posterior LH increased alcohol consumption, independent of sex, with no effect of KD in the anterior LH. Consistent with this, total alcohol consumption was negatively correlated with the location of CRFR1 KD in the LH along the anterior-posterior axis. CRFR1 KD did not alter water consumption or body weight, suggesting the effects of CRFR1 KD on alcohol consumption were not due to broad disruption of fluid intake or homeostatic function. In contrast to the observed effects on binge drinking, CRFR1 KD increased anxiety-like behavior and blunted sucrose preference, independent of KD location in the LH. Our findings provide foundational insight into LH function in the context of AUD and prompt further investigation into the divergent roles that distinct circuitry or cell populations along the anterior-posterior axis of the LH may play in binge drinking. HighlightsO_LICRFR1 knockdown in posterior LH increased alcohol drinking independent of sex C_LIO_LIAlcohol intake negatively correlated with AP location of CRFR1 knockdown in LH C_LIO_LICRFR1 knockdown was anxiogenic with more pronounced effects in females C_LIO_LISucrose preference was blunted by CRFR1 knockdown C_LI

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bioRxiv2024

Dorsal Raphe to Basolateral Amygdala Corticotropin-Releasing Factor Circuit Regulates Cocaine-Memory Reconsolidation

Environmental stimuli elicit drug craving and relapse in cocaine users by triggering the retrieval of strong cocaine-related contextual memories. Retrieval can also destabilize drug memories, requiring reconsolidation, a protein synthesis-dependent storage process, to maintain memory strength. Corticotropin-releasing factor (CRF) signaling in the basolateral amygdala (BLA) is necessary for cocaine-memory reconsolidation. We have hypothesized that a critical source of CRF in the BLA is the dorsal raphe nucleus (DR) based on its neurochemistry, anatomical connectivity, and requisite involvement in cocaine-memory reconsolidation. To test this hypothesis, male and female Sprague-Dawley rats received adeno-associated viruses to express Gi-coupled designer receptors exclusively activated by designer drugs (DREADDs) selectively in CRF neurons of the DR and injection cannulae directed at the BLA. The rats were trained to self-administer cocaine in a distinct environmental context then received extinction training in a different context. They were then briefly re-exposed to the cocaine-predictive context to destabilize (reactivate) cocaine memories. Intra-BLA infusions of the DREADD agonist deschloroclozapine (DCZ; 0.1 mM, 0.5 L/hemisphere) after memory reactivation attenuated cocaine-memory strength, relative to vehicle infusion. This was indicated by a selective, DCZ-induced and memory reactivation-dependent decrease in drug-seeking behavior in the cocaine-predictive context in DREADD-expressing males and females at test compared to respective controls. Notably, BLA-projecting DR CRF neurons that exhibited increased c-Fos expression during memory reconsolidation co-expressed glutamatergic and serotonergic neuronal markers. Together, these findings suggest that the DRCRF [->] BLA circuit is engaged to maintain cocaine-memory strength after memory destabilization, and this phenomenon may be mediated by DR CRF, glutamate, and/or serotonin release in the BLA.

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bioRxiv2021

Optogenetic inhibition of the dorsal hippocampus CA3 region during early-stage cocaine-memory reconsolidation disrupts subsequent context-induced cocaine seeking in rats

The dorsal hippocampus (DH) is key to the long-term maintenance of cocaine memories following retrieval-induced memory destabilization; even though, it is not the site of protein synthesis-dependent memory reconsolidation. Here, we took advantage of the temporal and spatial specificity of an optogenetic manipulation to examine the role of the cornu ammonis 3 subregion of the DH (dCA3) in early-stage cocaine-memory reconsolidation. Male Sprague-Dawley rats expressing eNpHR3.0 in the DH were trained to self-administer cocaine in a distinct context and underwent extinction training in a different context. Rats then received a 15-min memory-reactivation session, to destabilize cocaine memories and trigger reconsolidation, or remained in their home cages (no-reactivation controls). Optogenetic inhibition of the dCA3 for 1 h immediately, but not 1 h, after memory reactivation resulted in cocaine-memory impairment as indicated by reduction in drug-seeking behavior selectively in the cocaine-paired context 3 d later, at test, relative to responding in no-inhibition, no-reactivation, and no-eNpHR3.0 controls. Cocaine-memory impairment was associated with reduced c-Fos expression, an index of neuronal activation, in the dCA3 stratum lucidum (SL) and stratum pyramidale (SP) at test. Based on these observations and extant literature, we postulate that recurrent circuits in the SP are activated during early-stage memory reconsolidation to maintain labile cocaine memories prior to protein synthesis-dependent restabilization in another brain region, such as the basolateral amygdala. Furthermore, SL and SP interneurons may enhance memory reconsolidation by limiting synaptic noise in the SP and also contribute to recall as elements of the updated cocaine engram or retrieval links.

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