東京大学 · 医学
Hirokazu Tanaka教授の研究室は、脳が運動をどのように学習・制御しているかを解明することを目的としています。特に、視覚と運動のずれに対する適応や、内部の前向きモデル(forward model)が運動制御に果たす役割に注目しており、神経生理学的・行動的・計算モデルの統合的アプローチを用いています。研究は、運動学習の一般化、時間最適化の原則、および小脳が未来の入力を予測するメカニズムの解明を柱としています。
Figures are computed from collected data and may differ slightly.
Studying how motor adaptation to visuomotor rotation for one reach direction generalizes to other reach directions can provide insight into how visuomotor maps are represented and learned in the brain. Previous psychophysical studies have concluded that postadaptation generalization is restricted to a narrow range of directions around the training direction. A population-coding model that updates the weights between narrow Gaussian-tuned visual units and motor units on each trial reproduced expe
This review surveys physiological, behavioral, and morphological evidence converging to the view of the cerebro-cerebellum as loci of internal forward models. The cerebro-cerebellum, the phylogenetically newest expansion in the cerebellum, receives convergent inputs from cortical, subcortical, and spinal sources, and is thought to perform the predictive computation for both motor control, motor learning, and cognitive functions. This predictive computation is known as an internal forward model.
Movement duration is an integral component of motor control, but nearly all extant optimization models of motor planning prefix duration instead of explaining it. Here we propose a new optimization principle that predicts movement duration. The model assumes that the brain attempts to minimize movement duration under the constraint of meeting an accuracy criterion. The criterion is task and context dependent but is fixed for a given task and context. The model determines a unique duration as a t
Ctf4 is a protein conserved in eukaryotes and a constituent of the replisome progression complex. It also plays a role in the establishment of sister chromatid cohesion. In our current study, we demonstrate that the replication checkpoint is activated in the absence of Ctf4, and that the interaction between the MCM helicase-go ichi ni san (GINS) complex and DNA polymerase alpha (Pol alpha)-primase is destabilized specifically in a ctf4Delta mutant. An in vitro interaction between GINS and DNA Po
We here provide neural evidence that the cerebellar circuit can predict future inputs from present outputs, a hallmark of an internal forward model. Recent computational studies hypothesize that the cerebellum performs state prediction known as a forward model. To test the forward-model hypothesis, we analyzed activities of 94 mossy fibers (inputs to the cerebellar cortex), 83 Purkinje cells (output from the cerebellar cortex to dentate nucleus), and 73 dentate nucleus cells (cerebellar output)
Patterns of mortality by occupational class are remarkably different between European countries and Japan and South Korea. The recently observed patterns in the latter two countries may be related to a larger impact on the higher occupational classes of the economic crisis of the late 1990s and the late 2000s, respectively, and show that a high socioeconomic position does not guarantee better health.
Socioeconomic inequalities in smoking widened between 2001 and 2016 in Japan, which indicates that health inequalities will continue to exist in near future.
When subjects adapt their reaching movements in the setting of a systematic force or visual perturbation, generalization of adaptation can be assessed psychophysically in two ways: by testing untrained locations in the work space at the end of adaptation (slow postadaptation generalization) or by determining the influence of an error on the next trial during adaptation (fast trial-by-trial generalization). These two measures of generalization have been widely used in psychophysical studies, but
Absolute inequality trends in mortality across occupations decreased in both sexes, while relative inequality trends were heterogeneous in Japan. The main drivers of narrowing and widening mortality inequalities were cerebrovascular disease and suicide, respectively. Future public health efforts will benefit from eliminating residual inequalities in mortality by considering the contribution of the causes of death and socioeconomic status stratification.
The anomalous Nernst effect (ANE) converts heat flux perpendicular to the plane into electricity, in sharp contrast with the Seebeck effect (SE), enabling mass production, large area, and flexibility of their devices through ordinary thin-film fabrication techniques. Heat flux sensors, one of the most promising applications of ANE, are powerful devices for evaluating heat flow and can lead to energy savings through efficient thermal management. In reality, however, SE caused by the in-plane heat
The effect of introducing the new JSP for interpreting trends in all-cause mortality was considered minimal. However, caution is needed when interpreting trends in some cause-specific mortality rates.
Screening for retinopathy and nephropathy was less frequent than required despite favorable conditions for access to healthcare in Japan. Suboptimal quality of care appeared to depend on provider factors as well as patient factors, such as limited access to retinopathy prevention among working-age men with diabetes.
Selection of hospitals by cancer inpatients is affected by age, cancer sites, and availability of designated cancer care hospitals in the secondary healthcare service areas where patients live.
In Japan, the decreasing trend in overall mortality continued in 2020 despite the COVID-19 pandemic. However, approximately 2% mortality increase was observed in 2021, which was attributable to COVID-19, senility, cardiovascular disease and 'other causes'. The year 2021 was a turning point of mortality trends in Japan, although continued monitoring is warranted.
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