Leptin activation of dorsal raphe neurons inhibits feeding behavior.

Leptin is a homeostatic regulatory element that signals the presence of energy stores -in the form of adipocytes-which ultimately reduces food intake and increases energy expenditure. Similarly, serotonin (5-HT), a signaling molecule found in both the central and peripheral nervous systems, also regulates food intake. Here we use a combination of pharmacological manipulations, optogenetics, retrograde tracing, and in situ hybridization, combined with behavioral endpoints to physiologically and anatomically identify a novel leptin-mediated pathway between 5-HT neurons in the dorsal raphe nucleus (DRN) and hypothalamic arcuate nucleus (ARC) that controls food intake. In this study, we show that microinjecting leptin directly into the DRN reduces food intake in male Sprague-Dawley rats. This effect is mediated by leptin-receptor expressing neurons in the DRN as selective optogenetic activation of these neurons at either their ARC terminals or DRN cell bodies also reduces food intake. Anatomically, we identified a unique population of serotonergic raphe neurons expressing leptin receptors that send projections to the ARC. Finally, by utilizing in vivo microdialysis and high-performance liquid chromatography, we show that leptin administration to the DRN increases 5-HT efflux into the ARC. Overall, this study identifies a novel circuit for leptin-mediated control of food intake through a DRN-ARC pathway, utilizing 5-HT as a mechanism to control feeding behavior. Characterization of this new pathway creates opportunities for understanding how the brain controls eating behavior, as well as opens alternative routes for the treatment of eating disorders. Significance: Leptin and serotonin both play a vital role in the regulation of food intake, yet there is still uncertainty in how these two molecules interact to control appetite. The purpose of this study is to further understand the anatomical and functional connections between leptin receptor expressing neurons in the dorsal raphe nucleus, the main source of serotonin, and the arcuate nucleus of the hypothalamus, and how serotonin plays a role in this pathway to reduce food intake. Insight gained from this study will contribute to a more thorough understanding of the networks that regulate food intake, and open alternative avenues for the development of treatments for obesity and eating disorders.

Some experimental influences of lawyers' complicated questions on eyewitness confidence and accuracy.

Eyewitness evidence and the confidence the eyewitness expresses in such evidence are crucial in many criminal trials. The present study is an examination of the influence of confusing questions often used by attorneys to examine witnesses in court. Participants viewed a videotaped incident and were questioned about the incident 1 week later. Half the participants were asked questions framed in a confusing form; the remaining half were asked the same questions in straightforward language. Confusing questions reduced the participant witnesses' accuracy and suppressed the confidence-accuracy relationships compared with the condition in which simple questions were asked. However, the number of absolutely sure responses was the same in both conditions, although these responses were almost always accurate in the simplified condition, whereas in the confusing question condition, accuracy was comparatively poor. This experiment demonstrates the importance of ensuring that lawyers ask witnesses simple, clear questions.

The relationship between the medial branch of the lumbar posterior ramus and the mamillo-accessory ligament.

Gross dissection anatomical studies have investigated the course of the human lumbar posterior primary ramus and its branches. This nerve has frequently been associated with low back pain; however, the cross-sectional area of the space beneath the mamillo-accessory ligament, which is occupied by the medial branch of the posterior primary ramus, has not been clearly defined. The purpose of this study is to use a histological procedure to identify the cross-sectional area of the space beneath the mamillo-accessory ligament which is occupied by the medial branch of the posterior primary ramus as it passes en route to the zygapophyseal joint capsules. The main findings are that the medial branch of the posterior primary ramus occupies only a small percentage (approximately 3%) of the space enclosed by the mamillo-accessory ligament, and that it is surrounded by adipose tissue which provides an adequate protective "cushion" around it. Therefore, it is unlikely that the medial branch of the posterior primary ramus could be trapped beneath the mamillo-accessory ligament and cause pain.