Hyperactivity of indirect pathway-projecting spiny projection neurons promotes compulsive behavior.

Compulsive behaviors are a hallmark symptom of obsessive compulsive disorder (OCD). Striatal hyperactivity has been linked to compulsive behavior generation in correlative studies in humans and causal studies in rodents. However, the contribution of the two distinct striatal output populations to the generation and treatment of compulsive behavior is unknown. These populations of direct and indirect pathway-projecting spiny projection neurons (SPNs) have classically been thought to promote or suppress actions, respectively, leading to a long-held hypothesis that increased output of direct relative to indirect pathway promotes compulsive behavior. Contrary to this hypothesis, here we find that indirect pathway hyperactivity is associated with compulsive grooming in the Sapap3-knockout mouse model of OCD-relevant behavior. Furthermore, we show that suppression of indirect pathway activity using optogenetics or treatment with the first-line OCD pharmacotherapy fluoxetine is associated with reduced grooming in Sapap3-knockouts. Together, these findings highlight the striatal indirect pathway as a potential treatment target for compulsive behavior.

Closed-loop recruitment of striatal interneurons prevents compulsive-like grooming behaviors.

Compulsive behaviors have been associated with striatal hyperactivity. Parvalbumin-positive striatal interneurons (PVIs) in the striatum play a crucial role in regulating striatal activity and suppressing prepotent inappropriate actions. To investigate the potential role of striatal PVIs in regulating compulsive behaviors, we assessed excessive self-grooming-a behavioral metric of compulsive-like behavior-in male Sapap3 knockout mice (Sapap3-KO). Continuous optogenetic activation of PVIs in striatal areas receiving input from the lateral orbitofrontal cortex reduced self-grooming events in Sapap3-KO mice to wild-type levels. Aiming to shorten the critical time window for PVI recruitment, we then provided real-time closed-loop optogenetic stimulation of striatal PVIs, using a transient power increase in the 1-4 Hz frequency band in the orbitofrontal cortex as a predictive biomarker of grooming onsets. Targeted closed-loop stimulation at grooming onsets was as effective as continuous stimulation in reducing grooming events but required 87% less stimulation time, paving the way for adaptive stimulation therapeutic protocols.

Does compulsion explain addiction?

One of the leading drug addiction theories states that habits and the underlying neural process of a ventral to dorsal striatal shift are the building blocks of compulsive drug-seeking behaviour and that compulsion is the maladaptive persistence of responding despite adverse consequences. Here we discuss that compulsive behaviour as defined primarily from the perspective of animal experimentation falls short of the clinical phenomena and their neurobiological correlates. Thus for the human condition, the concept of compulsive habbits should be critically addressed and potentially revised.

Developing feasible and acceptable strategies for integrating the use of patient-reported outcome measures (PROMs) in gender-affirming care: An implementation study.

OBJECTIVE: Use CFIR guidance to create comprehensive, evidence-based, feasible, and acceptable gender-affirming care PROM implementation strategies. DESIGN, SETTING, PARTICIPANTS: A 3-Phase participatory process was followed to design feasible and acceptable strategies for integrating PROMs in gender-affirming care. In Phase 1, barriers and enablers to PROM implementation for gender-affirming care were identified from a previous systematic review and our prior qualitative study. We used the CFIR-ERIC tool to match previously identified barriers and enablers with expert-endorsed implementation strategies. In Phase 2, implementation strategy outputs from CFIR-ERIC were organised according to cumulative percentage value. In Phase 3, gender-affirming care PROM implementation strategies underwent iterative refinement based on rounds of stakeholder feedback with seven patient and public partners and a gender-affirming healthcare professional. RESULTS: The systematic review and qualitative study identified barriers and enablers to PROM implementation spanning all five CFIR domains, and 30 CFIR constructs. The top healthcare professional-relevant strategies to PROM implementation from the CFIR-ERIC output include: identifying and preparing implementation champions, collecting feedback on PROM implementation, and capturing and sharing local knowledge between clinics on implementation. Top patient-relevant strategies include: having educational material on PROMs, ensuring adaptability of PROMs, and collaborating with key local organisations who may be able to support patients. CONCLUSIONS: This study developed evidence-based, feasible, and acceptable strategies for integrating PROMs in gender-affirming care, representing evidence from a systematic review of 286 international articles, a qualitative study of 24 gender-affirming care patients and healthcare professionals, and iteration from 7 patient and public partners and a gender-affirming healthcare professional. The finalised strategies include patient- and healthcare professional-relevant strategies for implementing PROMs in gender-affirming care. Clinicians and researchers can select and tailor implementation strategies best applying to their gender-affirming care setting.

Analysis of post-market adverse events of istradefylline: a real-world study base on FAERS database.

Analyze the adverse event (AE) signals of istradefylline based on the FAERS database. By extracting large-scale data from the FAERS database, this study used various signal quantification techniques such as ROR, PRR, BCPNN, and MGPS to calculate and evaluate the ratio and association between istradefylline and specific AEs. In the FAERS database, this study extracted data from the third quarter of 2019 to the first quarter of 2023, totaling 6,749,750 AE reports. After data cleansing and drug screening, a total of 3633 AE reports related to istradefylline were included for analysis. Based on four calculation methods, this study unearthed 25 System Organ Class (SOC) AE signals and 82 potential preferred terms (PTs) related to istradefylline. The analysis revealed new AEs during istradefylline treatment, including reports of Parkinsonism hyperpyrexia syndrome (n = 3, ROR 178.70, PRR 178.63, IC 1.97, EBGM 165.63), Compulsions (n = 5, ROR 130.12, PRR 130.04, IC 2.53, EBGM 123.02), Deep brain stimulation (n = 10, ROR 114.42, PRR 114.27, IC 3.33, EBGM 108.83), and Freezing phenomenon (n = 60, ROR 97.52, PRR 96.76, IC 5.21, EBGM 92.83). This study provides new risk signals and important insights into the use of istradefylline, but further research and validation are needed, especially for those AE that may occur in actual usage scenarios but are not yet explicitly described in the instructions.

From compulsivity to compulsion: the neural basis of compulsive disorders.

Compulsive behaviour, an apparently irrational perseveration in often maladaptive acts, is a potential transdiagnostic symptom of several neuropsychiatric disorders, including obsessive-compulsive disorder and addiction, and may reflect the severe manifestation of a dimensional trait termed compulsivity. In this Review, we examine the psychological basis of compulsions and compulsivity and their underlying neural circuitry using evidence from human neuroimaging and animal models. Several main elements of this circuitry are identified, focused on fronto-striatal systems implicated in goal-directed behaviour and habits. These systems include the orbitofrontal, prefrontal, anterior cingulate and insular cortices and their connections with the basal ganglia as well as sensoriomotor and parietal cortices and cerebellum. We also consider the implications for future classification of impulsive-compulsive disorders and their treatment.

The role of psychosis and clozapine load in excessive checking in treatment-resistant schizophrenia: longitudinal observational study.

BACKGROUND: A significant proportion of people with clozapine-treated schizophrenia develop 'checking' compulsions, a phenomenon yet to be understood. AIMS: To use habit formation models developed in cognitive neuroscience to investigate the dynamic interplay between psychosis, clozapine dose and obsessive-compulsive symptoms (OCS). METHOD: Using the anonymised electronic records of a cohort of clozapine-treated patients, including longitudinal assessments of OCS and psychosis, we performed longitudinal multi-level mediation and multi-level moderation analyses to explore associations of psychosis with obsessiveness and excessive checking. Classic bivariate correlation tests were used to assess clozapine load and checking compulsions. The influence of specific genetic variants was tested in a subsample. RESULTS: A total of 196 clozapine-treated individuals and 459 face-to-face assessments were included. We found significant OCS to be common (37.9%), with checking being the most prevalent symptom. In mediation models, psychosis severity mediated checking behaviour indirectly by inducing obsessions (r = 0.07, 95% CI 0.04-0.09; P < 0.001). No direct effect of psychosis on checking was identified (r = -0.28, 95% CI -0.09 to 0.03; P = 0.340). After psychosis remission (n = 65), checking compulsions correlated with both clozapine plasma levels (r = 0.35; P = 0.004) and dose (r = 0.38; P = 0.002). None of the glutamatergic and serotonergic genetic variants were found to moderate the effect of psychosis on obsession and compulsion (SLC6A4, SLC1A1 and HTR2C) survived the multiple comparisons correction. CONCLUSIONS: We elucidated different phases of the complex interplay of psychosis and compulsions, which may inform clinicians' therapeutic decisions.

Stress and compulsive buying-shopping disorder: A scoping review.

INTRODUCTION: Theoretical frameworks of behavioral addictions mostly acknowledge the role of stress in the development and maintenance of these disorders, models of compulsive buying-shopping disorder (CBSD) however rarely incorporated stress. The association between stress and CBSD has not been reviewed yet. METHODS: A scoping review was conducted to evaluate empirical results on the association between stress and CBSD. A comprehensive search string was employed in three databases. RESULTS: 16 studies were included. Correlative studies suggested significant correlations between general perceived stress and CBSD symptom severity. Studies involving mean comparisons found higher general perceived stress levels in persons with problematic buying-shopping behavior/CBSD compared to control participants (large effects). Mixed results were found in studies involving regression/structural equation models and ecological momentary assessments. One study with a stress/negative mood induction observed more CBSD symptoms in a high stress group compared to a low stress group. DISCUSSION: The studies are heterogeneous concerning design, samples and measures. Only very few studies surpass the level of cross-sectional correlative data which limits the ability to draw clear conclusions. Future research should study the impact of experimentally induced stress on CBSD symptoms, examine the relationship between stress and CBSD longitudinally and assess objective stress markers.

Neurocomputational model of compulsivity: deviating from an uncertain goal-directed system.

Despite a theory that an imbalance in goal-directed versus habitual systems serve as building blocks of compulsions, research has yet to delineate how this occurs during arbitration between the two systems in obsessive-compulsive disorder. Inspired by a brain model in which the inferior frontal cortex selectively gates the putamen to guide goal-directed or habitual actions, this study aimed to examine whether disruptions in the arbitration process via the fronto-striatal circuit would underlie imbalanced decision-making and compulsions in patients. Thirty patients with obsessive-compulsive disorder [mean (standard deviation) age = 26.93 (6.23) years, 12 females (40%)] and 30 healthy controls [mean (standard deviation) age = 24.97 (4.72) years, 17 females (57%)] underwent functional MRI scans while performing the two-step Markov decision task, which was designed to dissociate goal-directed behaviour from habitual behaviour. We employed a neurocomputational model to account for an uncertainty-based arbitration process, in which a prefrontal arbitrator (i.e. inferior frontal gyrus) allocates behavioural control to a more reliable strategy by selectively gating the putamen. We analysed group differences in the neural estimates of uncertainty of each strategy. We also compared the psychophysiological interaction effects of system preference (goal-directed versus habitual) on fronto-striatal coupling between groups. We examined the correlation between compulsivity score and the neural activity and connectivity involved in the arbitration process. The computational model captured the subjects' preferences between the strategies. Compared with healthy controls, patients had a stronger preference for the habitual system (t = -2.88, P = 0.006), which was attributed to a more uncertain goal-directed system (t = 2.72, P = 0.009). Before the allocation of controls, patients exhibited hypoactivity in the inferior frontal gyrus compared with healthy controls when this region tracked the inverse of uncertainty (i.e. reliability) of goal-directed behaviour (P = 0.001, family-wise error rate corrected). When reorienting behaviours to reach specific goals, patients exhibited weaker right ipsilateral ventrolateral prefronto-putamen coupling than healthy controls (P = 0.001, family-wise error rate corrected). This hypoconnectivity was correlated with more severe compulsivity (r = -0.57, P = 0.002). Our findings suggest that the attenuated top-down control of the putamen by the prefrontal arbitrator underlies compulsivity in obsessive-compulsive disorder. Enhancing fronto-striatal connectivity may be a potential neurotherapeutic approach for compulsivity and adaptive decision-making.

Sex- and estrous-related response patterns for alcohol depend critically on the level of compulsion-like challenge.

Alcohol use disorder is a substantial social and economic burden. During the last years, the number of women with drinking problems has been increasing, and one main concern is that they are particularly more vulnerable to negative consequences of alcohol. However, little is known about female-specific response patterns for alcohol, and potential underlying differences in brain mechanisms, including for compulsion-like alcohol drinking (when intake persists despite adverse consequences). We used lickometry to assess behavioral microstructure in adult Wistar male and female rats (n = 28-30) during alcohol-only drinking or moderate- or higher-challenge alcohol compulsion (10 or 60 mg/l quinine in alcohol, respectively). Estrous stages were determined and related to drinking levels and patterns of responding to alcohol, as was ovariectomy. Our findings showed that females (where we didn't determine estrus stage) had similar total licks in a session as males, but significantly longer licking bouts under alcohol-only and moderate-challenge, suggesting greater persistence. Further, greater intake under alcohol-only and moderate-challenge was related to faster licking in males, while female consumption was not related to licking speed. Thus, females could have increased persistence without greater vigor, unlike males. However, under higher-challenge, faster licking did predict higher intake in females, similar to males. To better understand female higher-challenge responding, we examined drinking in relation to phases of the estrous cycle. Higher-challenge had longer bouts only in late diestrus. In addition, ovariectomy led to longer bouts only under higher-challenge, suggesting that conditions with reduced hormone levels could increase female persistence for alcohol under higher-challenge. However, ovariectomy also reduced alcohol-only and moderate-challenge drinking but did not reduce bout length. Thus, intake level and response strategy could be regulated somewhat differently by ovarian hormones. Finally, moderate-challenge licking speed was less variable during early diestrus, and we previously showed more stereotyped responding specifically under moderate-challenge in males. By combining behavioral microstructure and sex- and estrus-related changes in drinking patterns, our results suggest that females have greater persistence for alcohol under lower-challenge drinking, while late diestrus and ovariectomy unmasked greater persistence under higher-challenge. Together, our novel insights could help develop more effective and personalized treatments for problematic alcohol use.

Pathological buying on the rise? Compensative and compulsive buying in Poland in the pre- and (Post-)pandemic times.

The study concerns the development of compensative and compulsive buying in Poland comparing the results of three waves of a cross-sectional study conducted before and at the end of the COVID-19 pandemic. Six predictors of susceptibility to compensative and compulsive buying are in focus: materialism, self-esteem, gender, age, frequency of online shopping, and experience of the COVID-19 pandemic. However, the importance of the first four predictors in explaining compensative and compulsive buying is already very well described in the literature, while the novelty consists in the predictive model including the variables that describe frequency of online shopping and negative experiences related to the COVID-19 pandemic, such as coronavirus infection, hospitalization or death of a loved one. On the one hand, a stronger susceptibility to compensative and compulsive buying could be a reaction to these negative experiences of the pandemic; on the other hand, the increased frequency of online shopping as a result of the pandemic may be an important factor in the development of compensative and compulsive buying due to the easy implementation of purchase acts and weaker social control. To achieve the above research objectives, the German Compulsive Buying Indicator (GCBI) was used to measure susceptibility to compensative and compulsive buying. The data were obtained within three waves of the study (2010, 2019, 2022) based on a random sample of about 1,000 respondents representing statistically the general adult population. Drawing on this study, the prevalence of compensative and compulsive buying is observed at 12-19% and 2-4%. The predictors of GCBI are materialism, self-esteem, gender in all examined models and additionally age, frequency of online shopping, and experience of the COVID-19 pandemic in selected models. Although the findings related to the role of materialism, self-esteem, and gender in the prediction of GCBI reflect the results reported in the literature, the analogous conclusions about age, online shopping, and experiences with the COVID-19 pandemic are different from the established opinions. The commonly reported effect of age becomes statistically significant when the examined population is limited to Gens Y and Z. Although extensive online shopping co-exists with compensative and compulsive buying in the total population, the obtained data lead to reverse conclusions in the case of women's subpopulation representing Gens Y and Z. The negative experience with the COVID-19 pandemic operationalised as hospitalization of a close friend predicts GCBI, but again only in the case of representatives of Gens Y and Z, especially among women. The findings show how important the creation of appropriate intervention strategies is within the consumer policy directed to representatives of the younger generations who may develop pathological buying as a response to negative experiences such as COVID-19 pandemic. The findings can inform of the goals behind therapeutic support for compulsive buyers, and implications for social work. People affected by excessive compensative or compulsive buying need to be given opportunities to build up their strengths and growth of their psychological resources towards healthy self-esteem, which seems to be the best protection against excessive compensative and compulsive buying.

A network analysis of mechanisms of change during exposures over the course of intensive OCD treatment.

Exposure and response prevention (ERP) is an evidence-based treatment for obsessive-compulsive disorder (OCD). Theories for how it works vary in their emphasis on active mechanisms of change. The current study aimed to clarify mechanisms of change in ERP for OCD using network analysis, comparing ERP networks at the start and end of intensive treatment (partial hospital and residential). In our sample of 182 patients, the most central node in both networks was engagement with exposure, which was consistently related to greater understanding of ERP rationale, higher willingness, and less ritualization, accounting for all other variables in the network. There were no significant differences in networks between the start and end of treatment. These results suggest that nonspecific parameters like facilitating engagement in exposures without ritualizing and providing a clear rationale to clients may be key to effective treatment. As such, it may be useful for clinicians to spend adequate time underscoring the need to eliminate rituals to fully engage in exposure tasks and explaining the rationale for ERP prior to doing exposures, regardless of theoretical orientation. Nonetheless, findings represent group-level statistics and more fine-grained idiographic analyses may reveal individual-level differences with respect to central mechanisms of change. Other limitations include demographic homogeneity of our sample.

Spatio-Temporal Image-Based Encoded Atlases for EEG Emotion Recognition.

Emotion recognition plays an essential role in human-human interaction since it is a key to understanding the emotional states and reactions of human beings when they are subject to events and engagements in everyday life. Moving towards human-computer interaction, the study of emotions becomes fundamental because it is at the basis of the design of advanced systems to support a broad spectrum of application areas, including forensic, rehabilitative, educational, and many others. An effective method for discriminating emotions is based on ElectroEncephaloGraphy (EEG) data analysis, which is used as input for classification systems. Collecting brain signals on several channels and for a wide range of emotions produces cumbersome datasets that are hard to manage, transmit, and use in varied applications. In this context, the paper introduces the Empátheia system, which explores a different EEG representation by encoding EEG signals into images prior to their classification. In particular, the proposed system extracts spatio-temporal image encodings, or atlases, from EEG data through the Processing and transfeR of Interaction States and Mappings through Image-based eNcoding (PRISMIN) framework, thus obtaining a compact representation of the input signals. The atlases are then classified through the Empátheia architecture, which comprises branches based on convolutional, recurrent, and transformer models designed and tuned to capture the spatial and temporal aspects of emotions. Extensive experiments were conducted on the Shanghai Jiao Tong University (SJTU) Emotion EEG Dataset (SEED) public dataset, where the proposed system significantly reduced its size while retaining high performance. The results obtained highlight the effectiveness of the proposed approach and suggest new avenues for data representation in emotion recognition from EEG signals.

Multiple serous cavity effusion screening based on smear images using vision transformer.

Serous cavity effusion is a prevalent pathological condition encountered in clinical settings. Fluid samples obtained from these effusions are vital for diagnostic and therapeutic purposes. Traditionally, cytological examination of smears is a common method for diagnosing serous cavity effusion, renowned for its convenience. However, this technique presents limitations that can compromise its efficiency and diagnostic accuracy. This study aims to overcome these challenges and introduce an improved method for the precise detection of malignant cells in serous cavity effusions. We have developed a transformer-based classification framework, specifically employing the vision transformer (ViT) model, to fulfill this objective. Our research involved collecting smear images and corresponding cytological reports from 161 patients who underwent serous cavity drainage. We meticulously annotated 4836 patches from these images, identifying regions with and without malignant cells, thus creating a unique dataset for smear image classification. The findings of our study reveal that deep learning models, particularly the ViT model, exhibit remarkable accuracy in classifying patches as malignant or non-malignant. The ViT model achieved an impressive area under the receiver operating characteristic curve (AUROC) of 0.99, surpassing the performance of the convolutional neural network (CNN) model, which recorded an AUROC of 0.86. Additionally, we validated our models using an external cohort of 127 patients. The ViT model sustained its high-level screening performance, achieving an AUROC of 0.98 at the patient level, compared to the CNN model's AUROC of 0.84. The visualization of our ViT models confirmed their capability to precisely identify regions containing malignant cells in multiple serous cavity effusion smear images. In summary, our study demonstrates the potential of deep learning models, particularly the ViT model, in automating the screening process for serous cavity effusions. These models offer significant assistance to cytologists in enhancing diagnostic accuracy and efficiency. The ViT model stands out for its advanced self-attention mechanism, making it exceptionally suitable for tasks that necessitate detailed analysis of small, sparsely distributed targets like cellular clusters in serous cavity effusions.

Dance for the dead: The role of top-down beliefs for social cohesion and anxiety management in naturally occurring collective rituals.

Collective rituals, particularly those characterized by synchrony and pain, have been shown to yield positive social and emotional outcomes. The question arises as to whether these findings extend to low-arousal, family-centered rituals and how spiritual beliefs factor into these communal practices. This study set out to examine the interplay between belief, ritual participation, and their effects on anxiety, social cohesion, and prosocial behavior during a low-arousal collective ritual in Mikasa, Japan. Drawing upon a sample of 183 festival participants, we measured belief in ancestors using a novel scale, identifying significant and consistent associations between these beliefs and measures of social cohesion across multiple targets. Moreover, active participation as a festival dancer displayed a positive relationship with feelings of social cohesion, particularly towards other festival attendees and at the national level. On measures of prosocial behavior, ancestral beliefs were positively associated with generosity shown within the festival setting, whereas observers were less generous towards community members than a non-attending control group. Anxiety outcomes displayed a negative relationship with ancestral beliefs and ritual observation but not participation as seen in previous research, suggesting a complex interplay between rituals, emotions, and individual states. These findings provide novel insights into the importance of belief systems and active participation in shaping social bonds and behaviors in the context of collective rituals.

Current Understanding of Compulsive Sexual Behavior Disorder and Co-occurring Conditions: What Clinicians Should Know about Pharmacological Options.

Compulsive sexual behavior disorder (CSBD) has recently been recognized as a psychiatric disorder. Pharmacological treatments for CSBD have received little study and thus have limited empirical support. The main objective of the present work is to review existing literature on the efficacy of different drugs on the symptomatology of CSBD, including the subtype of problematic pornography use (PPU). The main pharmacological approaches to treating CSBD have included opioid antagonists (naltrexone and nalmefene), selective serotonin reuptake inhibitors (paroxetine, citalopram, fluoxetine, and sertraline), mood stabilizers (topiramate), tricyclic antidepressants (clomipramine), serotonin antagonist and reuptake inhibitors (nefazodone), and N-acetylcysteine. Since people with CSBD may experience different co-occurring disorders, these should be considered when choosing the best pharmacological treatment. Pharmacological therapy for CSBD/PPU has been suggested as an adjunct to psychological therapies, which, for the moment, have the most empirical evidence. However, to evaluate the efficacy of most of the drugs presented in this narrative review, data to date have only been available from case studies. Thus, empirical support is scant and generalizability of results is limited, highlighting the need for more research in this area.

Maximizing translational value in models of compulsive behavior: A commentary on Pickenhan et al. (2024).

In this issue of Cognitive, Affective, and Behavioral Neuroscience, Pickenhan et al. (2024) discuss the need for translational studies to understand features underlying obsessive-compulsive disorder (OCD). They highlight the translational value of the observing-response task (ORT) for modeling functional and maladaptive checking behaviors, a common symptom of OCD.

Compulsive rituals in Obsessive-Compulsive Disorder - A qualitative exploration of thoughts, feelings and behavioral patterns.

BACKGROUND AND OBJECTIVES: Rituals are common among healthy individuals and across cultures and often serve adaptive purposes. In individuals with obsessive-compulsive disorder (OCD), rituals become compulsive, time-consuming and distressing, and may lead to functional impairment. Previous research has examined the functions and characteristics of compulsive rituals, but there is paucity of in-depth, first-person reports about this topic. METHOD: We used a qualitative approach to explore thoughts, feelings, and behavioral patterns that characterize OCD rituals. Ten individuals with OCD participated in a semi-structured interview that focused on their most prominent compulsive ritual. The interviews were subjected to a thematic analysis. RESULTS: Eight themes emerged from the analysis and were organized in two main categories: Micro Level perspective, comprising triggers, attention, emotional changes, and stopping criteria; and Macro Level perspective, comprising feelings and perceptions, change over time, motives, and inhibitors. The findings shed light on the role of fixed rules and feelings of "completeness" in OCD rituals, the nature of emotional and attentional characteristics during rituals performance, and the evolution of compulsive rituals over time. LIMITATIONS: This study used a qualitative approach based on a small number of participants, which limits the generalizability of the findings. CONCLUSION: Our results, if replicated, may have clinical implications. The reported patterns of anxiety reduction during ritual performance may contribute to the fine-tuning of CBT for OCD. The findings concerning the nature of attention during ritual performance and the development of rituals over time may be important for understanding the mechanisms that maintain compulsive rituals.

Plectronoceratids (Cephalopoda) from the latest Cambrian at Black Mountain, Queensland, reveal complex three-dimensional siphuncle morphology, with major taxonomic implications.

The Plectronoceratida includes the earliest known cephalopod fossils and is thus fundamental to a better understanding of the origin and early evolution of this group of molluscs. The bulk of described material comes from the late Cambrian Fengshan Formation in North China with isolated occurrences in South China, Laurentia, Kazakhstan and Siberia. Knowledge of their morphology and taxonomy is limited in that most specimens were only studied as longitudinal sections, which are prone to misinterpretations due to variations in the plane of section. We describe more than 200 new specimens, which exceeds the entire hitherto published record of plectronoceratids. The material was collected by Mary Wade and colleagues during the 1970s and 1980s, from the lower Ninmaroo Formation at Black Mountain (Mount Unbunmaroo), Queensland, Australia. Despite the collecting effort, diverse notes and early incomplete drafts, Mary Wade never published this material before her death in 2005. The specimens provide novel insights into the three-dimensional morphology of the siphuncle based on abundant material, prompting a general revision of the order Plectronoceratida. We describe Sinoeremoceras marywadeae sp. nov. from numerous, well-preserved specimens, allowing investigation of ontogenetic trajectories and intraspecific variability, which in turn enables improved interpretations of the three-dimensional siphuncle morphology. The siphuncle of S. marywadeae sp. nov. and other plectronoceratids is characterised by highly oblique segments, an elongated middorsal portion of the septal neck (= septal flap) and laterally expanded segments that extend dorsally relative to the septal flap (= siphuncular bulbs). We show that this complex siphuncular structure has caused problems of interpretation because it was studied mainly from longitudinal sections, leading to the impression that there were large differences between specimens and supposed species. We revise the order Protactinoceratida and the families Protactinoceratidae and Balkoceratidae as junior synonyms of the Plectronoceratida and Plectronoceratidae, respectively. We reduce the number of valid genera from eighteen (including one genus formerly classified as an ellesmeroceratid) to three: Palaeoceras Flower, 1954, Plectronoceras Kobayashi, 1935 and Sinoeremoceras Kobayashi, 1933. We accept 10 valid species to which the 68 previously established species may be assigned. Sinoeremoceras contains 8 of the 10 plus the new species. Two species, previously referred to ellesmeroceratid genera, are transferred to Sinoeremoceras. This revised scheme groups plectronoceratids into distinct geographically and stratigraphically separated species, which better reflects biological realities and removes bias caused by preparation techniques. North China remains important containing the highest known diversity and was likely a centre of cephalopod diversification.