Motor End-Plates

In the preparation of motor end-plates for class room work the use of sodium thiosulfate is suggested as a precaution against overstaining and as a regressive measure. Digestion of the connective tissue eliminates the tedious teasing and the possible destruction of the delicate nerve fibers. Mounting in a solution of gum arable makes the slides more durable than glycerin jelly for class use. Whole neuromuscular spindles may be obtained by this method.     

Tuning Multiple Motor Travel via Single Motor Velocity

Microtubule-based molecular motors often work in small groups to transport cargos in cells. A key question in understanding transport (and its regulation in vivo) is to identify the sensitivity of multiple-motor-based motion to various single molecule properties. Whereas both single-motor travel distance and microtubule binding rate have been demonstrated to contribute to cargo travel, the role of single-motor velocity is yet to be explored. Here, we recast a previous theoretical study, and make explicit a potential contribution of velocity to cargo travel. We test this possibility experimentally, and demonstrate a strong negative correlation between single-motor velocity and cargo travel for transport driven by two motors. Our study thus discovers a previously unappreciated role of single-motor velocity in regulating multiple-motor transport.     

细菌鞭毛马达——一种卓越的分子机器

鞭毛马达(flagellar motor)是一种分子旋转马达,它在细菌鞭毛的结构与功能中起着中心作用.鞭毛马达的结构已基本清楚,主要由Mot A、Mot B、Fli G、Fli M和Fli N 5种蛋白组成定子(stator)和转子(rotor),其驱动力来自于跨膜的H⁺或Na⁺流.目前对鞭毛马达的旋转动力学及旋转力矩产生机制已有初步的了解.鞭毛马达可作为研究分子旋转马达的理想模型,对其深入研究将有助于认识生物能量转化利用及细胞运动的机制并具有广泛的生物学意义.     

Motor imagery

We describe general concepts about motor imagery and differences to motor execution. The problem of controlling what the subject actually does during imagery is emphasized. A major part of the chapter is dealing with mental training by imagery and the usage of motor imagination in athletes, musicians and during rehabilitation. Data of altered representations of the body after loss of afferent information and motor representation due to limb amputation or complete spinal cord injury are demonstrated and discussed. Finally we provide an outlook on additional work about motor imagery important for further understanding of the topic.     

Motor learning

Bilateral damage of the medial temporal lobe system prevents the formation of new declarative memories but leaves intact knowledge that was acquired before damage. For motor learning, no structure has been identified that plays a comparable role for the consolidation of motor memories. The deficits of motor learning are focal and show a similar allocation to the various of motor learning are focal and show a similar allocation to the various sensorimotor subsystems, as do the corresponding non-mnemonic functions. The involvement of sensorimotor circuitries changes during motor learning so that association areas are preferentially activated in the early stages, and cerebello- and striato-motor-cortical loops are preferentially activated in the late stages of motor learning. Recent neuroanatomical and neurophysiological findings on the effects of brain lesions in human and non-human primates are discussed.     

Motor systems

The field of motor control has broadened considerably over the past decade. Increasingly detailed information has accrued about the cellular and molecular processes involved in motor pattern generation and motor learning while, at the other extreme, the comparison of studies in humans and monkeys has begun to bridge the gap between cognitive and motor functions. The most striking feature of recent research has been the intense use of electrophysiological procedures in behaving monkeys and non-invasive imaging procedures in humans to elucidate details of sensory-motor transformations and the functional roles of different brain regions in the learning, planning and execution of movements.     

Role of BDNF in Central Motor Structures and Motor Diseases

Brain-derived neurotrophic factor (BDNF), belonging to the neurotrophic family of growth factors, has a widespread distribution in the central and peripheral nervous systems. In central motor structures including the motor cortex, cerebellum, basal ganglia, and spinal cord, BDNF exerts both neurotrophic and direct electrophysiological effects via a high-affinity tyrosine receptor kinase B receptor and a common low-affinity p75 neurotrophin receptor. The underlying signaling pathways mainly involve mitogen-activated protein kinase cascades, phosphatidylinositol 3-kinase pathway, and phospholipase C-γ pathway. The loss of BDNF usually leads to neurodegeneration in these motor centers and eventually results in several severe motor diseases, such as amyotrophic lateral sclerosis, spinocerebellar ataxias, Parkinson’s disease, Huntington’s disease, as well as vestibular syndrome. In this review, we summarize the recent understanding of functions of BDNF in motor structures and suggest that BDNF may be a potent candidate for the treatment of these neurodegenerative motor diseases.