Biology subjects

Kishi, T.

Publications and source records attributed to Kishi, T..

3 recordsLinked to original sources

bioRxiv2026

Confidence: Its Measurement, Relation to Behavior, and Neural Representation

Confidence (certainty/uncertainty about one's own decision) has attracted considerable attention in psychology, neuroscience, and artificial intelligence. Yet its relation to behavior remains unclear: Some treat confidence as a cause of behavior whereas others view it as a state controlled by environmental variables. The unobservable nature of confidence makes its measurement validation and analyses difficult. To tackle these issues, we developed a novel procedure combining a decision-making task, risk choices, and a post-task open-ended questionnaire. Point-gain/loss amounts for correct/incorrect decisions varied depending on choices between high-risk/high-return and low-risk/low-return. In the questionnaire, 90% of 16 participants reported feelings interpretable as certainty/uncertainty when making those risk choices despite no instruction about confidence, whereas 8% did so when the choices led to identical outcomes/returns. This suggests confidence is a state controlled by environmental contingencies rather than a cause of behavior. We also decoded changes in the state from electroencephalography and functional magnetic resonance imaging.

neuroscience↗

bioRxiv2021

A role of cryptochrome for magnetic field-dependent improvement of sleep quality, lifespan and motor function in Drosophila

Understanding the molecular genetic basis of animal magnet reception has been one of the big challenges in biology. Recently it was discovered that the magnetic sense of Drosophila melanogaster is mediated by the ultraviolet (UV)-A/blue light photoreceptor cryptochrome (Cry). Here, using the fruit fly as a magnet receptive model organism, we show that exposure to a specific AC magnetic field during night time affected the health of the fly. AC magnetic field exposure showed lifespan extension under starvation, sleep improvement and prevention of decreased motor function. In contrast, all the health improvement effect was not observed in cryptochrome mutant flies (cryb). We showed that AC magnetic field exposure prevented motor dysfunction in Gauchers disease model Drosophila. The data suggests that magnetic field-dependent improvement of sleep quality, lifespan and motor function is mediated through a cry-dependent pathway in animals.

animal behavior and cognition↗

bioRxiv2020

Mechanical impact on the head has an antihypertensive effect

Physical exercise is known to be beneficial for various brain functions. However, the mechanisms behind the positive effects of exercise on the brain remain to be elucidated. Here we show that passive head motion in hypertensive rats, which reproduces the mechanical accelerations generated in their heads during moderate-velocity treadmill running, decreases the expression of angiotensin II type 1 receptor (AT1R) in astrocytes in the rostral ventrolateral medulla (RVLM), thereby lowering blood pressure. Passive head motion generates interstitial fluid movement that is estimated to exert shear stress with an average magnitude of <1 Pa on the cells in the rat medulla. Fluid shear stress of a sub-Pa magnitude decreases AT1R expression in cultured astrocytes. In hypertensive rats, inhibition of interstitial fluid movement following hydrogel introduction to the RVLM eliminates the antihypertensive effects of passive head motion and treadmill running. Furthermore, vertically oscillating chair riding by hypertensive adult humans, which reproduces the mechanical accelerations generated in their heads during light jogging or fast walking, lowers their blood pressure. Our findings indicate that moderate mechanical intervention can have antihypertensive effects by modulating the function of RVLM astrocytes through interstitial fluid shear stress. We anticipate that mechanical regulation is responsible for a variety of the positive effects of physical exercise on human health, particularly those related to brain functions.

bioengineering↗