Biology subjects

Murai, A.

Publications and source records attributed to Murai, A..

3 recordsLinked to original sources

bioRxiv2024

Metabolic mode estimated by breathing reflects long-term motor memory

Respiration is a crucial metabolic process that converts macronutrients, carbohydrates and fats, and oxygen (O2) into energy and carbon dioxide (CO2) to support motor actions. In addition to the energy demands of movements, the brain is a significant energy consumer, accounting for approximately 20% of the bodys total energy expenditure and relying primarily on carbohydrates for neural activity and plasticity. However, it is not known whether O2-CO2 gas composition in breathing can serve as an indicator of neural activity and plasticity as they can for movement intensity. In the human reaching movement tasks, we evaluated time-constants of sensorimotor learning while recording O2-CO2 gas exchange. We computed the respiratory exchange ratio (RER), indicating which carbohydrate or fat is used preferentially, and found that the RER was unaffected by the execution and learning of reaching movements and that it was stable within individuals but varied across individuals. Interestingly, using computational modeling to identify short and long-time constants of sensorimotor learning, individual RER levels correlated with the magnitude of long-term, but not short-term memory. Furthermore, to experimentally manipulate the individual RER, we provided 200 kcal of glucose immediately before the task. Surprisingly, this simple intervention dramatically increased 24-hour retention by 21%. Together, the RER served as a remarkable proxy for long-term motor memory, and glucose intake shifted the physiological idling state for sensorimotor learning.

neuroscience↗

bioRxiv2024

Augmenting visual errors or variability does not enhance motor learning in remote web application tasks

Laboratory experiments employing robotic manipulandum are far from achieving their goal of helping people improve their motor learning. Remote experiments using web applications are an effective tool for bridging the gap between robotic manipulandum experiments in the laboratory and general motor tasks outside. However, the influence of interventions that increase error or variability in remote motor tasks on motor learning has not yet been determined. In this study, we aimed to elucidate the effects of interventions that visually increase errors and variability in remote experiments using web applications. In particular, 48 people participated in a web-based study on the cursor-manipulation of motor tasks using laptops. Three motor tasks (visuomotor-rotation reaching, virtual curling, and virtual ball-throwing tasks) were conducted, and each task consisted of 120 trials a day conducted for three days in this study. For each task, no intervention was provided on Day 1 and the intervention to augment motor error or variability was provided on Days 2 and 3. Differences between the groups in post-intervention test trials were examined using statistical analyses. Contrary to our expectations, the interventions of error-augmentation did not exhibit positive effects in Experiments 1 and 2, which could be attributed to a lack of haptic and proprioceptive information or inaccuracies in movement kinematics. In addition, the interventions of variability-augmentation did not exhibit positive effects in Experiment 3, which could be attributed to the complex dynamics in the relationship between perceived body movements and motor outcomes. Further research is required to identify the differences between the conditions when the interventions are effective or ineffective. Moreover, interventions must be developed to further improve general motor skills.

neuroscience↗

bioRxiv2022

Mimicking seasonal changes in light-dark cycle and ambient temperature modulates gut microbiome in mice under the same dietary regimen

To better adapt to seasonal environmental changes, physiological processes and behaviors are regulated seasonally. The gut microbiome interacts with the physiology, behavior, and even the diseases of host animals, including humans and livestock. Seasonal changes in gut microbiome composition have been reported in several species under natural environments. Dietary content significantly affects the composition of the microbiome, and, in the natural environment, the diet varies between different seasons. Therefore, understanding the seasonal regulatory mechanisms of the gut microbiome is important for understanding the seasonal adaptation strategies of animals. Herein, we examined the effects of changing day length and temperature, which mimic summer and winter conditions, on the gut microbiome of laboratory mice. Principal coordinate analysis and analysis of the composition of microbiomes of 16S rRNA sequencing data demonstrated that the microbiomes of the cecum and large intestine showed significant differences between summer and winter mimicking conditions. Similar to previous studies, a daily rhythm was observed in the composition of the microbiome. Furthermore, the phylogenetic investigation of communities by reconstruction of unobserved states predicted seasonal changes in several metabolic pathways. Changing day length and temperature can affect the composition of the gut microbiome without changing dietary contents.

physiology↗