A Computational Model of Similarity Analysis in Quality of Life Research: An Example of Studies in Poland

Due to the multidimensional structure of the results of similarity studies, their analysis is often difficult. Therefore, a compact and transparent presentation of these results is essential. The purpose of the present study is to propose a graphical representation of the results of similarity analysis in studies on the quality of life. The results are visualized on specific diagrams (maps), where a large amount of information is presented in a compact form. New similarity maps obtained using a computational method, correspondence analysis, are shown as a convenient tool for comparative studies on the quality of life of different groups of individuals. The usefulness of this approach to the description of changes of the quality of life after the retirement threshold in different domains is demonstrated. The World Health Organization Quality of Life-BREF questionnaire was used to evaluate individuals in Poland. By analyzing clusters on the similarity maps, two groups (employees and retirees) were classified according to their quality of life in different domains. By comparing the structures of the classification maps containing the information about the whole system considered, it is clearly seen which factors are important in the comparative studies. For the considered problems, the uncertainty coefficients describing the effect size and preserving the information on the symmetry of the variables that were used for the creation of the contingency tables were evaluated.

Help or flight: Neural defensive circuits promote helping under threat in humans

Helping of conspecifics under threat has been observed across species. In humans, the dominant view proposes that empathy is the key proximal mechanism driving helping motivation in a threatening context, but little is known about how one s own defensive responses to the threat may guide helping decisions. In this pre-registered study, we manipulated threat imminence to activate the entire defensive brain circuitry, and assess the impact of different defensive responses on risky helping behaviour. Forty-nine participants underwent fMRI scanning while making trial-by-trial decisions about whether or not to help a co-participant avoid aversive shocks at the risk of receiving a shock themselves. Helping decisions were prompted under imminent and distal threat, based on the spatiotemporal distance to the administration of the shock to the co-participant. We found that greater engagement of reactive fear circuits (insula, ACC, PAG) during the threat presentation led to helping decisions, whereas engagement of cognitive fear circuits (hippocampus and vmPFC) preceded decisions not to help. Relying on representational similarity analysis, we identified how the defensive circuitry uniquely represented the threat to oneself, and the distress of the co-participant during the task. Importantly, we found that the strength with which the amygdala represented the threat to oneself, and not the other s distress, predicted decisions to help. Our results demonstrate that defensive neural circuits coordinating fast escape from immediate danger may also facilitate decisions to help others, potentially by engaging neurocognitive systems implicated in caregiving across mammals. Taken together, our findings provide novel insights into the proximal basis of altruistic responding, suggesting that defensive responses may play a more important role in helping than previously understood.

Reactivation of hedonic but not sensory representations in human emotional learning

Learning which stimuli in our environment co-occur with painful or pleasurable events is critical for survival. Previous research has established the basic neural and behavioural mechanisms of aversive and appetitive conditioning; however, it is unclear what precisely is learned. Here we examined what aspects of the unconditioned stimulus (US), sensory and hedonic, are transferred to the conditioned stimulus (CS). To decode the content of brain activation patterns elicited during appetitive (soft touch) and aversive (painful touch) conditioning of faces, a novel variation of representational similarity analysis (RSA) based on theoretically driven representational patterns of interest (POIs) was applied to fMRI data. Once face associations were learned through conditioning, globally the CS reactivated US representational patterns showing conditioning dependent reactivation. More specifically, in higher order brain regions, the CS only reactivated hedonic but not sensory aspects of the US, suggesting that affective conditioning primarily carries forward the valence of the experience rather than its sensory origins.

[18F]FMCH PET/CT biomarkers and similarity analysis to refine the definition of oligometastatic prostate cancer

Background The role of image-derived biomarkers in recurrent oligometastatic Prostate Cancer (PCa) is unexplored. This paper aimed to evaluate [18F]FMCH PET/CT radiomic analysis in patients with recurrent PCa after primary radical therapy. Specifically, we tested intra-patient lesions similarity in oligometastatic and plurimetastatic PCa, comparing the two most used definitions of oligometastatic disease. Methods PCa patients eligible for [18F]FMCH PET/CT presenting biochemical failure after first-line curative treatments were invited to participate in this prospective observational trial. PET/CT images of 92 patients were visually and quantitatively analyzed. Each patient was classified as oligometastatic or plurimetastatic according to the total number of detected lesions (up to 3 and up to 5 or > 3 and > 5, respectively). Univariate and intra-patient lesions' similarity analysis were performed. Results [18F]FMCH PET/CT identified 370 lesions, anatomically classified as regional lymph nodes and distant metastases. Thirty-eight and 54 patients were designed oligometastatic and plurimetastatic, respectively, using a 3-lesion threshold. The number of oligometastic scaled up to 60 patients (thus 32 plurimetastatic patients) with a 5-lesion threshold. Similarity analysis showed high lesions' heterogeneity. Grouping patients according to the number of metastases, patients with oligometastatic PCa defined with a 5-lesion threshold presented lesions heterogeneity comparable to plurimetastic patients. Lesions within patients having a limited tumor burden as defined by three lesions were characterized by less heterogeneity. Conclusions We found a comparable heterogeneity between patients with up to five lesions and plurimetastic patients, while patients with up to three lesions were less heterogeneous than plurimetastatic patients, featuring different cells phenotypes in the two groups. Our results supported the use of a 3-lesion threshold to define oligometastatic PCa.