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Prediction mechanism is necessary for human visual motion to compensate a delay of sensory-motor system. In a previous study, “proactive control” was discussed as one example of predictive function of human beings, in which motion of hands preceded the virtual moving target in visual tracking experiments. To study the roles of the positional-error correction mechanism and the prediction mechanism, we carried out an intermittently-visual tracking experiment where a circular orbit is segmented into the target-visible regions and the target-invisible regions. Main results found in this research were following. A rhythmic component appeared in the tracer velocity when the target velocity was relatively high. The period of the rhythm in the brain obtained from environmental stimuli is shortened more than 10%. The shortening of the period of rhythm in the brain accelerates the hand motion as soon as the visual information is cut-off, and causes the precedence of hand motion to the target motion. Although the precedence of the hand in the blind region is reset by the environmental information when the target enters the visible region, the hand motion precedes the target in average when the predictive mechanism dominates the error-corrective mechanism.

In terms of evolution, the strategy of catching prey would have been an important part of survival in a constantly changing environment. A prediction mechanism would have developed to compensate for any delay in the sensory-motor system. In a previous study, “proactive control” was found, in which the motion of the hands preceded the virtual moving target. These results implied that the positive phase shift of the hand motion represents the proactive nature of the visual-motor control system, which attempts to minimize the brief error in the hand motion when the target changes position unexpectedly. In our study, a visual target moves in circle (13 cm diameter) on a computer screen, and each subject is asked to keep track of the target’s motion by the motion of a cursor. As the frequency of the target increases, a rhythmic component was found in the velocity of the cursor in spite of the fact that the velocity of the target was constant. The generation of a rhythmic component cannot be explained simply as a feedback mechanism for the phase shifts of the target and cursor in a sensory-motor system. Therefore, it implies that the rhythmic component was generated to predict the velocity of the target, which is a feed-forward mechanism in the sensory-motor system. Here, we discuss the generation of the rhythmic component and its roll in the feed-forward mechanism.

Background and Purpose— High-sensitivity C-reactive protein (hsCRP), a marker of inflammation, is associated with atherosclerosis, hypertensive target organ damage, and cardiovascular events. In the general Japanese population, the level of hsCRP is reported to be lower than that in Western countries, and the relationships among hsCRP, silent cerebral infarcts (SCIs), and clinical stroke events in older Japanese hypertensives remain unclear. Methods— We conducted brain MRI and measured hsCRP at baseline in 514 older Japanese hypertensives (clinic blood pressure ≥140/90 mm Hg, age ≥50 years old) who were enrolled in the Jichi Medical School ABPM Study, wave 1. They were followed up for an average of 41 months (range: 1 to 68 months, 1751 person-years) and the incidence of subsequent clinical stroke events was evaluated. Results— The subjects with SCIs at baseline (n=257) had a higher hsCRP level than those without SCIs (geometric mean hsCRP [SD range]; 0.19 [0.18 to 0.21] versus 0.14 [0.13 to 0.16] mg/L, P =0.007) after adjustment for confounding factors, and the OR for the presence of SCIs was increased with the quartile of hsCRP levels. In Cox regression analysis, the patients with above median hsCRP level (≥0.21 mg/L) (hazard ratio [HR]: 2.50, 95% CI: 1.24 to 5.00, P =0.01) and those with SCIs (HR: 4.60, 95% CI: 1.91 to 11.03, P =0.001) at baseline had independently higher risks for clinical stroke events after adjustment for age, smoking status, antihypertensive medication use, and 24-hour systolic blood pressure level. Compared with the patients with below median hsCRP level without SCIs, those with above median hsCRP level and SCIs at baseline had a higher risk for clinical stroke events (HR: 7.32, 95% CI: 2.17 to 24.76, P =0.001), although those with below median hsCRP level and SCIs (HR: 2.46, 95% CI: 0.64 to 9.47, P =0.19) and those with above median hsCRP level without SCIs (HR: 1.11, 95% CI: 0.22 to 5.55, P =0.90) did not have significant risks. Conclusion— High-sensitivity C-reactive protein is a risk factor for clinical stroke events in addition to silent cerebral infarcts in Japanese older hypertensives, indicating that the risk for clinical stroke events increases with preexisting hypertensive target organ damage in the brain and additionally with ongoing low-grade inflammation.