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11.
Christoph Börgers Martin Krupa Stan Gielen 《Journal of computational neuroscience》2010,28(3):509-526
A population of uncoupled neurons can often be brought close to synchrony by a single strong inhibitory input pulse affecting
all neurons equally. This mechanism is thought to underlie some brain rhythms, in particular gamma frequency (30–80 Hz) oscillations
in the hippocampus and neocortex. Here we show that synchronization by an inhibitory input pulse often fails for populations
of classical Hodgkin–Huxley neurons. Our reasoning suggests that in general, synchronization by inhibitory input pulses can
fail when the transition of the target neurons from rest to spiking involves a Hopf bifurcation, especially when inhibition
is shunting, not hyperpolarizing. Surprisingly, synchronization is more likely to fail when the inhibitory pulse is stronger
or longer-lasting. These findings have potential implications for the question which neurons participate in brain rhythms,
in particular in gamma oscillations. 相似文献
12.
Susy M Braun Jolanda C van Haastregt Anna J Beurskens Alexandra I Gielen Derick T Wade Jos M Schols 《BMC neurology》2010,10(1):74
Background
Within a multi-centre randomised controlled trial in three nursing homes, a process evaluation of a mental practice intervention was conducted. The main aims were to determine if the intervention was performed according to the framework and to describe the therapists' and participants' experiences with and opinions on the intervention. 相似文献13.
R Moriggi Jr HS Di Mauro SC Dias JM Matos MB Urtado NF Camar?o IV Sousa Neto DC Nascimento RA Tibana CO Assump??o J Prestes CB Urtado 《Biology of sport / Institute of Sport》2015,32(4):289-294
Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances. 相似文献
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JY Xiong SC Li YX Sun XS Zhang ZZ Dong P Zhong XR Sun 《Biology of sport / Institute of Sport》2015,32(4):295-300
Increasing evidence suggests that physical activity could delay or attenuate the symptoms of Alzheimer''s disease (AD). But the underlying mechanisms are still not fully understood. To investigate the effect of long-term treadmill exercise on the spatial memory of AD mice and the possible role of β-amyloid, brain-derived neurotrophic factor (BDNF) and microglia in the effect, male APPswe/PS1dE9 AD mice aged 4 months were subjected to treadmill exercise for 5 months with 6 sessions per week and gradually increased load. A Morris water maze was used to evaluate the spatial memory. Expression levels of β-amyloid, BDNF and Iba-1 (a microglia marker) in brain tissue were detected by immunohistochemistry. Sedentary AD mice and wildtype C57BL/6J mice served as controls. The results showed that 5-month treadmill exercise significantly decreased the escape latencies (P < 0.01 on the 4th day) and improved the spatial memory of the AD mice in the water maze test. Meanwhile, treadmill exercise significantly increased the number of BDNF-positive cells and decreased the ratios of activated microglia in both the cerebral cortex and the hippocampus. However, treadmill exercise did not significantly alleviate the accumulation of β-amyloid in either the cerebral cortex or the hippocampus of the AD mice (P > 0.05). The study suggested that long-term treadmill exercise could improve the spatial memory of the male APPswe/PS1dE9 AD mice. The increase in BDNF-positive cells and decrease in activated microglia might underpin the beneficial effect. 相似文献
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T. M. H. Dijkstra G. Schöner M. A. Giese C. C. A. M. Gielen 《Biological cybernetics》1994,71(6):489-501
When standing human subjects are exposed to a moving visual environment, the induced postural sway displays varying degrees
of coherence with the visual information. In our experiment we varied the frequency of an oscillatory visual display and analysed
the temporal relationship between visual motion and sway. We found that subjects maintain sizeable sway amplitudes even as
temporal coherence with the display is lost. Postural sway tended to phase lead (for frequencies below 0.2 Hz) or phase lag
(above 0.3 Hz). However, we also observed at a fixed frequency, highly variable phase relationships in which a preferred range
of phase lags is prevalent, but phase jumps occur that return the system into the preferred range after phase has begun drifting
out of the preferred regime. By comparing the results quantitatively with a dynamical model (the sine-circle map), we show
that this effect can be understood as a form of relative coordination and arises through an instability of the dynamics of
the action-perception cycle. Because such instabilities cannot arise in passively driven systems, we conclude that postural
sway in this situation is actively generated as rhythmic movement which is coupled dynamically to the visual motion.
Received: 7 September 1993/Accepted in revised form: 2 May 1994 相似文献