排序方式: 共有24条查询结果,搜索用时 15 毫秒
21.
Equilibrium maintenance during standing in humans was investigated with a 3-joint (ankle, knee and hip) sagittal model of
body movement. The experimental paradigm consisted of sudden perturbations of humans in quiet stance by backward displacements
of the support platform. Data analysis was performed using eigenvectors of motion equation. The results supported three conclusions.
First, independent feedback control of movements along eigenvectors (eigenmovements) can adequately describe human postural
responses to stance perturbations. This conclusion is consistent with previous observations (Alexandrov et al., 2001b) that
these same eigenmovements are also independently controlled in a feed-forward manner during voluntary upper-trunk bending.
Second, independent feedback control of each eigenmovement is sufficient to provide its stability. Third, the feedback loop
in each eigenmovement can be modeled as a linear visco-elastic spring with delay. Visco-elastic parameters and time-delay
values result from the combined contribution of passive visco-elastic mechanisms and sensory systems of different modalities 相似文献
22.
Sidorina VV Merzhanova GKh Kuleshova EP Zaleshin AV 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》2012,62(2):185-196
Unit and network activity of neurons in the visual, sensorimotor, and frontal cortical areas and dorsal striatum was investigated in cats under conditions of choice of the reinforcement value depending on its delay. The animals did not differ from each other in behavior. After immediate or delayed responses cats got low- or highly-valuable reinforcement, respectively. Single-unit activity in the visual and sensorimotor cortical areas and dorsal striatum was similar during performance of immediate and delayed responses. However, significant inhibition was observed in the frontal neurons during the delay period. The network activity of visual and frontal cortex displayed smaller number of interneuronal interactions during delayed responses as compared to immediate reactions. The network activity of neurons in the brain structures under study pointed to the interstructural interaction, but only during delayed reactions, steady interneuronal communication was observed between the frontal cortex and dorsal striatum. Thus, both types of estimation of cellular activity revealed differences in the ensemble organization during different types of behavior and showed specific reactions of neuronal ensembles. 相似文献
23.
Miriam R Faria Mara S Hoshida Eloisa AV Ferro Francesca Ietta Luana Paulesu Estela Bevilacqua 《Reproductive biology and endocrinology : RB&E》2010,8(1):95
Background
Macrophage migration inhibitory factor (MIF) has special pro-inflammatory roles, affecting the functions of macrophages and lymphocytes and counter-regulating the effects of glucocorticoids on the immune response. The conspicuous expression of MIF during human implantation and early embryonic development also suggests this factor acts in reproductive functions. The overall goal of this study was to evaluate Mif expression by trophoblast and embryo placental cells during mouse pregnancy. 相似文献24.