Development of neural circuits for social motion perception in schooling fish.

The collective behavior of animal groups emerges from the interactions among individuals. These social interactions produce the coordinated movements of bird flocks and fish schools, but little is known about their developmental emergence and neurobiological foundations. By characterizing the visually based schooling behavior of the micro glassfish Danionella cerebrum, we found that social development progresses sequentially, with animals first acquiring the ability to aggregate, followed by postural alignment with social partners. This social maturation was accompanied by the development of neural populations in the midbrain that were preferentially driven by visual stimuli that resemble the shape and movements of schooling fish. Furthermore, social isolation over the course of development impaired both schooling behavior and the neural encoding of social motion in adults. This work demonstrates that neural populations selective for the form and motion of conspecifics emerge with the experience-dependent development of collective movement.

Understanding collective behavior through neurobiology.

A variety of organisms exhibit collective movement, including schooling fish and flocking birds, where coordinated behavior emerges from the interactions between group members. Despite the prevalence of collective movement in nature, little is known about the neural mechanisms producing each individual's behavior within the group. Here we discuss how a neurobiological approach can enrich our understanding of collective behavior by determining the mechanisms by which individuals interact. We provide examples of sensory systems for social communication during collective movement, highlight recent discoveries about neural systems for detecting the position and actions of social partners, and discuss opportunities for future research. Understanding the neurobiology of collective behavior can provide insight into how nervous systems function in a dynamic social world.

Sleeve Gastrectomy Protects Against Hypertension in Rats due to Changes in the Gut Microbiome.

INTRODUCTION: Sleeve gastrectomy (SG), results in improvement in hypertension. We have previously published that rodent SG improves hypertension independent of weight loss associated with unique shifts in the gut microbiome. We tested if the gut microbiome directly improves blood pressure by performing fecal material transfer (FMT) from post-SG rats to surgery-naïve animals. METHODS: We performed SG or Sham surgery in male, Zucker rats (n = 6-7) with obesity. Stool was collected postop from surgical donors for treatment of recipient rats. Three nonsurgical groups received daily, oral consumption of SG stool, sham stool, or vehicle alone (Nutella) for 10 wk (n = 7-8). FMT treatment was assessed for effects on body weight, food intake, oral glucose tolerance, and blood pressure. Genomic deoxyribonucleic acid of stool from donor and recipient groups were sequenced by 16S ribosomal ribonucleic acid and analyzed for diversity, abundance, and importance. RESULTS: Ten weeks of SG-FMT treatment significantly lowered systolic blood pressures in surgery-naïve, recipient rats compared to vehicle treatment alone (126.8 ± 13.3 mmHg versus 151.8 ± 12.2 mmHg, P = 0.001). SG-FMT treatment also significantly altered beta diversity metrics compared to Sham-FMT and vehicle treatment. In random forest analysis, amplicon sequence variant level significantly predicted FMT group, P = 0.01. CONCLUSIONS: We have found a direct link between gut microbial changes after SG and regulation of blood pressure. Future mechanistic studies are required to learn what specific gut microbial changes are required to induce improvements in obesity-associated hypertension and translation to clinical, metabolic surgery.