The purpose of the present experiment was to investigate the role of auditory feedback and its impact on movement time in a standard Fitts task. Feedback was given at the moment of target acquisition. A 2-way analysis of variance found significant differences between feedback groups at all three indexes of difficulty (F(2, 40) = 156.02, p < .001). Results from a mixed-model multivariate analysis of variance for kinematic factors show significant differences in peak velocity and the location of peak velocity when comparing feedback groups. In general, the addition of auditory feedback decreased the task ID by .5.
The authors investigated the underlying processing structures for mental and physical practice. Participants mentally or physically performed 4 tasks during practice. Halfway through practice, 2 tasks were switched from mental to physical practice, or vice versa. After completing practice trials, participants performed 2 retention tests. The first retention test required memory retrieval and the second retention test reinstated the practice context and did not require memory retrieval. Measures of response initiation and execution showed discrepant findings suggesting that different processing structures underlie response initiation and execution during mental and physical practice. Findings for the switch conditions supported this interpretation suggesting that different neural structures may facilitate processing related to mental and physical practice.
Mitotic progression in eukaryotic cells depends upon the activation of cyclin-dependent kinase 1 (CDK1), followed by its inactivation through the anaphase-promoting complex (APC)/cyclosome-mediated degradation of M-phase cyclins. Previous work revealed that expression of a constitutively active CDK1 (CDK1AF) in HeLa cells permitted their division, but yielded G1 daughter cells that underwent premature S-phase and early mitotic events. While CDK1AF was found to impede the sustained activity of APC-Cdh1, it was unknown if this defect improperly stabilized mitotic substrates and contributed to the occurrence of these premature M phases. Here, we show that CDK1AF expression in HeLa cells improperly stabilized APC-Cdh1 substrates in G1-phase daughter cells, including mitotic kinases and the APC adaptor, Cdc20. Division of CDK1AF-expressing cells produced G1 daughters with an accelerated S-phase onset, interrupted by the formation of premature bipolar spindles capable of spindle assembly checkpoint function. Further characterization of these phenotypes induced by CDK1AF expression revealed that this early spindle formation depended upon premature CDK1 and Aurora B activities, and their inhibition induced rapid spindle disassembly. Following its normal M-phase degradation, we found that the absence of Wee1 in these prematurely cycling daughter cells permitted the endogenous CDK1 to contribute to these premature mitotic events, since expression of a non-degradable Wee1 reduced the number of cells that exhibited premature cyclin B1oscillations. Lastly, we discovered that Cdh1-ablated cells could not be forced into a premature M phase, despite cyclin B1 overexpression and proteasome inhibition. Together, these results demonstrate that expression of constitutively active CDK1AF hampers the destruction of critical APC-Cdh1 targets, and that this type of condition could prevent newly divided cells from properly maintaining a prolonged interphase state. We propose that this more subtle type of defect in activity of the APC-driven negative-feedback loop may have implications for triggering genome instability and tumorigenesis.
-The theoretical explanations used to explain changes in performance during motor imagery and physical practice conditions are inconsistent when memory retrieval is and is not required. This study measured performance time and workload during acquisition, a retention test requiring memory retrieval, and a retention test not requiring memory retrieval using a key-pressing task. The participants were assigned to physical practice with or without instructions to learn or motor imagery with or without instructions to learn. A diagram of the keys was presented during the practice trials and the first retention test, but was not presented during the second test. The results revealed no effect for the learning instructions or performance changes during the practice phases. However, during both retention tests participants in the physical practice conditions performed significantly faster than those in the motor imagery conditions. Also, higher levels of workload were reported for the motor imagery conditions when the retention test required memory retrieval compared to the other phases. A discussion of the implications of workload on performance is presented with respect to varying practice conditions.
726registration. Data were analyzed using univariate analysis of variance, adjusted for test center, and presented as counts per minute (cpm) as a measure of overall physical activity. RESULTS:The mean age (SD) was 71.8 (5.6) y and 71.7 (5.2) y for females and males, respectively. No gender differences in age and activity level were observed in the material. Mean (SEM) overall physical activity levels were as follows: 65-69 y (n=243) 317 (9) cpm, 70-74 y (n=146) 301 (12) cpm, 75-79 y (n=106) 237 (14) cpm, 80-85 y (n=65) 160 (18) cpm. Linear regression analysis showed that physical activity level decreased with increasing age at a rate of 9 cpm per year (B=-9.4, p<0.001).CONCLUSION: Physical activity level among Norwegian elderly decreased with increasing age, and the oldest age group (80-85 y) showed a 50% lower activity level compared to the youngest age group (65-70 y). (No relationships reported)PURPOSE: To analyze the weekly moderate-to-vigorous physical activity times (MVPAt) measured by accelerometry reported in previous studies for US adults. METHODS:Computer-based searches (MEDLINE and Web of Science) and manual searches were conducted in the English language literature from 2001 to 2010. Key words used for the computer searches were physical activity, accelerometer, accelerometry. Inclusion criteria were as follows: (a) subjects were residents of US, apparently healthy, and in the age range of 18-65 yr; (b) subjects were recruited without bias of their previous physical activity level; (c) the independent variable was the 7-day minute-by-minute MVPAt assessed by accelerometry. Research reports were excluded if there was any control of physical activity. For studies sharing the same database, only one was used for the present analysis. As population physical activity patterns might change in time, only reports for the last decade were used. The reported MVPAt (mean ± sd) and 95% confidential level were calculated. A two-sample t-test and an F-test were performed to determine the effect of sample size on reported physical activity times. RESULTS:The average reported MVPAt was 249.48 ± 83.95 min·wk -1 , and the 95% confidential interval was (211.73, 287.22 min·wk -1 ). The sample sizes of these studies ranged from 6 to 639 subjects, with two significant clusters (n < 300 vs. n > 500). Using n=300 as the cut-off point of the sample size, MVPAt of the small sample size reports (n=11) was not significantly different from MVPAt of the large sample size reports (n=8) (277.80 ± 93.28 vs. 210.53 ± 51.93 min·wk -1, p=.06, power= .47); and the variances between the small and large sample size groups were not significantly different (F10,7 = 3.23, p=.13).CONCLUSIONS: ACSM recommends at least 150 min·wk -1 moderate physical activity to maintain and promote health. This study suggests as for those reports using accelerometry, the US adults as a group appear to meet this recommendation. Similar analyses using other methods of estimation of MVPAt are needed. (No relationships reported)PURPOSE: Changes in the physique and...
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