Physiology & Behavior最新文献

Individuality refers to the consistent and unique patterns of behavior, temperament, and physiological traits that vary within the same species. Individual variations arise not only because of genetic predispositions, developmental experiences, and environmental influences, but these factors also act as key drivers causing varying effects across individuals due to differences in their sensitivities and life histories. However, the molecular mechanisms underlying individual differences in physiology and behavior remain difficult to study due to the intricate interactions between influencing factors, limitations in measurement and methodology, dynamic variation with high context dependency, and even ethical considerations in human research. Drosophila melanogaster has emerged as a powerful model for dissecting the origins of inter-individual differences due to its minimal genetic variability, behavioral diversity, and accessibility for tightly controlled experimental conditions. Recent advances in genetic tools and behavioral paradigms have collectively transformed our understanding of individuality at the level of single flies. In this review, we firstly discuss the determinants of variations in individual responses in Drosophila melanogaster and how these factors further amplify behavioral diversity within a population. Secondly, we summarize the current analytical approaches that allow for the precise quantification of these subtle variations in individual physiology and behavior. Finally, we highlight the translational potential of the Drosophila model for precision medicine. By shifting the analytical framework from group means to individual variance, this review provides a mechanistic roadmap for understanding the biological basis of individual idiosyncrasy.

Taste information is transmitted to the brain via branches of cranial nerves VII (chorda tympani, CT, and greater superficial petrosal, GSP), IX (glossopharyngeal, GL), and X (superior laryngeal branch of the vagus) with each nerve innervating relatively segregated fields of taste buds on the tongue, palate, and laryngeal epithelium. Approximately 70% of taste buds reside on the tongue and are innervated by the CT or GL. Previously we found that rats offered a 5-choice cafeteria diet after combined transection of the CT and GL (2NX) ate more fat, less sugar, and larger, but fewer meals each day resulting in no net change in total daily energy intake and suggesting a role for the CT and/or GL in food choice, regulation of macronutrient intake, and satiation signaling, but the role of the individual nerves was unclear. To begin identifying the role of each nerve, this experiment aimed to interrogate the effects of transection of the GL (GLX) on food choice and meal patterns in rats offered a cafeteria diet after recovery from GLX or SHAM surgery. We found that GLX did not affect fat intake or meal patterns, but, compared with SHAM-operated controls, GLX rats had lower sugar intake, driven largely by a heightened preference for the food choice with low fat and low sugar content. These findings indicate that the GLX alone is not responsible for the elevated fat intake or meal size found in rats after 2NX, but could be solely responsible for noted reductions in sugar intake.

Environmental enrichment (EE) affects brain function and behavior in laboratory animals. In this study, we investigated the behavioral and physiological effects of short-term EE exposure on male C57BL/6J mice. Juvenile mice were housed for 2 weeks under either EE or standard environment (SE) conditions, followed by a series of behavioral tests. Compared with SE mice, EE mice displayed greater variability in nest-building behavior, with some individuals exhibiting delayed initiation. In the open field test, EE mice spent significantly more time in the center zone, suggesting reduced anxiety-like behavior. In contrast, in the elevated plus maze test, EE mice spent less time in the open arms than SE mice. No significant group differences were observed in sucrose preference or tail suspension tests. Although body weight remained unchanged between the groups, EE mice exhibited significantly increased spleen weight and decreased epididymal fat weight, indicating modest physiological changes. These findings demonstrate that EE can enhance inter-individual behavioral diversity, particularly in goal-directed behaviors such as nest building, which emerged as a sensitive and ethologically relevant behavioral outcome for detecting environmental modulation and individual variability. This diversity may serve as a useful indicator for identifying depression-like phenotypes and understanding the vulnerabilities of EE-reared individuals.

Background: Suicide prediction remains limited by the absence of objective biomarkers, particularly in adolescents with major depressive disorder (MDD), among whom suicide rates are rising. This study investigated olfactory function as a potential biomarker across groups with suicidal ideation (SI), suicide attempts (SA), and healthy controls (HC).

Methods: Olfactory performance was assessed using the standardized Sniffin' Sticks test (odor threshold, discrimination, identification, and total TDI scores) in 72 adolescents with MDD (42 with SI, and 30 with SA), and 43 matched HCs. Depression severity was controlled using Beck Depression Inventory-II (BDI-II) scores.

Results: Adolescents with suicidal thoughts and behaviors (STB) showed significantly higher odor identification (OI) than HCs (12.72 ± 1.35 vs. 11.86 ± 1.51, t = -3.19, p < 0.01). After adjusting for covariates in the ANCOVA, group differences in odor identification remained significant (F = 9.32, p < 0.01). OI independently predicted STB (OR = 1.90, 95 % CI: 1.24-3.13, p < 0.01), with strong classification accuracy (AUC = 0.913). One-way ANOVA revealed no significant group effect on odor discrimination (OD) (F = 2.34, p = 0.10).

Conclusions: Enhanced odor identification differentiates suicidal adolescents from healthy peers and predicts suicide risk with high accuracy. Stronger odor discrimination may offer protection against transition to suicidal behavior. These findings suggest olfactory testing could aid early suicide risk assessment in depressed youth.