数控凸轮

针对机械凸轮的某些不足，提出了数控凸轮的概念．介绍了数控凸轮的工作原理、实现方法及应用前景．     

Distal excitability properties of median motor axons.

Excitability properties were recorded from 14 volunteers following stimulation of the recurrent motor branch of the median nerve in the palm. Distal stimulation resulted in significantly lower strength-duration time constant and lower threshold during prolonged hyperpolarization than did wrist stimulation in the same subjects. These differences may be geometric in origin or alternatively may arise from functional changes distally, particularly reduced expression of persistent Na(+) conductances and more hyperpolarization-activated current. Excitability studies using palm stimulation provide information closer to the neuromuscular junction, where membrane properties are preferentially affected in a variety of clinical conditions.     

Viscero‐somatic reflexes in referred pain areas evoked by capsaicin stimulation of the human gut

The interaction between visceral pain and the sympathetic nervous system is only sparsely investigated in quantitative human studies. Referred visceral pain can be evoked experimentally by application of substances such as capsaicin (the pungent substance of chilli pepper) to the gut. The aim of the present study was to induce referred visceral pain from the small and large intestine in 32 volunteers via the stomal opening in patients with ileo‐ or colostomy and quantify the viscero‐somatic reflex responses in these referred pain areas by thermography and laser doppler flowmetry. Capsaicin evoked pain and referred pain areas in all subjects. In the referred pain area, the temperature increased by approximately 0.6°C (P<0.001) and the blood flow by approximately 35AU (P<0.001). Saline was used in a control experiment, and no temperature and blood flow changes were found. The present quantitative human study of viscero‐somatic reflexes showed dramatic sympathetic responses in the referred pain areas after experimentally induced gut pain.     

Corticostriatal and corticosubthalamic input zones from the presupplementary motor area in the macaque monkey: comparison with the input zones from the supplementary motor area

The presupplementary motor area (pre-SMA) is a cortical motor-related area which lies in the medial wall of the frontal lobe, immediately anterior to the supplementary motor area (SMA). This area has been considered to participate in the control of complex forelimb movements in a way different from the SMA. In an attempt to analyze the patterns of projections from the pre-SMA to the basal ganglia, we examined the distributions of pre-SMA inputs in the striatum and the subthalamic nucleus and compared them with the SMA input distributions. To detect morphologically the terminal fields from the pre-SMA and the forelimb region of the SMA, anterograde tracers were injected into such areas that had been identified electrophysiologically in the macaque monkey. Corticostriatal inputs from the pre-SMA were distributed mainly in the striatal cell bridges connecting the rostral aspects of the caudate nucleus and the putamen, as well as in their neighboring striatal portions. These input zones were located, with no substantial overlap, rostral to corticostriatal input zones from the SMA forelimb region. Corticosubthalamic input zones from the pre-SMA were almost localized in the medial aspect of the nucleus, where corticosubthalamic inputs from the SMA forelimb region were also distributed predominantly. However, the major terminal fields from the pre-SMA were centered ventrally to those from the SMA. The present results indicate that the corticostriatal and corticosubthalamic input zones from the pre-SMA appear to be segregated from the SMA-derived input zones. This implies the possibility of parallel processing of motor information from the pre-SMA and SMA in the cortico-basal ganglia circuit.     

Distribution of choline acetyltransferase and acetylcholinesterase in the vocal motor system of zebra finches

The distribution of choline acetyltransferase immunoreactivity (ChAT-IR) was surveyed in the vocal motor system of adult male and female zebra finches and was compared with the pattern of histochemical acetylcholinesterase (AChE-His). In the vocal motor system the most prominent accumulation of ChAT-IR somata was found in lobus parolfactorius (LPO) including Area X. Immunoreactive neuropil was found to be concentrated in pericellular networks of fibers in male's Area X while the corresponding area in females could not be demarcated within the LPO. The density of ChAT-IR fiber networks was much higher in LPO, paleostriatum augmentatum and in a shelf region around nucleus robustus archistriatalis (RA) than in neostriatal and hyperstriatal parts of the telencephalon. AChE positive neurons and neuropil were observed in all ChAT-IR regions and, in addition, in the vocal motor nuclei nucleus hyperstriatum ventrale pars caudalis (HVc), nucleus magnocellularis in the anterior neostriatum (MAN), nucleus interfacialis (NIF) and RA. However, none of the latter nuclei contained ChAT-IR cell bodies. They were characterized by rare ChAT-IR neuropil. MAN and RA exhibited shelf regions with a higher degree of stained fibers. The discrepancy between the localization of AChE-His and ChAT-IR can hardly be explained by different classes of ChAT isoenzymes in neurons within the basal forebrain and the neostriatal, hyperstriatal and archistriatal vocal control nuclei not detected by our antibody. On the other hand, vocal control centers while receiving cholinergic inputs, might - except for Area X - not possess cholinergic efferent projections within the telencephalon.     

Assessment of the cerebral vasomotor reactivity in internal carotid artery occlusion using a transcranial Doppler sonography and functional MRI.

BACKGROUND AND PURPOSE: Several methods are being used to assess cerebral vasomotor reactivity (CVR), including transcranial Doppler (TCD) sonography and blood oxygenation level-dependent functional magnetic resonance imaging (fMRI). The aim was to assess the correlation of TCD and fMRI in the CVR assessment. METHODS: Study group consisted of 28 patients (24 males, 4 females; aged 30-82, mean 63.1 +/- 10.0 years), presenting with 29 occluded internal carotid arteries. The TCD examination, including breath-holding/hyperventilation test (BH/HV) and breath-holding index (BHI), and fMRI examination were used for the assessment of CVR. fMRI employed a bimanual motor task within both a block paradigm and an event-related paradigm. Cohen's kappa was applied when statistically assessing correlation of the methods. RESULTS: The following correlations were found--between BH/HV and BHI 58.6%, kappa= .205; BH/HV and fMRI 65.5%, kappa= .322; BHI and fMRI 58.6%, kappa= .151; TCD (consistent result of both BH/HV and BHI test) and fMRI 70.6%, kappa= .414. CONCLUSIONS: In the evaluation of CVR, there is only a minimal correlation between the particular TCD tests (both BH/HV and BHI), and fMRI examination. However, there is a moderate correlation between TCD and fMRI in the case of congruity of both TCD tests.     

Role of Cholecystokinin in Gallbladder and Duodenal Motility in the Interdigestive State of Dogs

This study was designed to determine the role of cholecystokinin (CCK) in the motility patterns of duodenum and gallbladder in fasted conscious dogs. During the naturally occurring activity front in the duodenum a significant increase in the motility index, (MI) of the gallbladder was accompanied by a decrease in the gallbladder volume from about 28 ± 4 ml (control) to 21 ± 3 ml. Similar changes in the gallbladder were observed after intravenous bolus injections of motilin (20 to 40 ng/kg), which gave increments in plasma motilin comparable to those occurring spontaneously during the activity front but failed to affect plasma levels of CCK. Blocking of CCK receptors by L-364, 718 (0.5 to 1 mg/kg) delayed the occurrence of the spontaneous activity front in the duodenum and the accompanying alterations in the gallbladder motility. CCK receptor antagonism abolished the premature activity front induced by motilin in both the duodenum and the gallbladder, converted the fed-like pattern induced by exogenous CCK to a fasted motility pattern in the duodenum and prevented CCK-induced reduction in the gallbladder volume. Atropine (12.5 μg/kg) blocked the spontaneous activity front in the duodenum and accompanying alterations in the gallbladder motility and volume but failed to affect those induced by motilin. We conclude that the motility of the gallbladder in fasted dogs shows cyclic changes with typical reduction in the organ volume coinciding with the spontaneous or motilin-induced activity front in the duodenum, and that both CCK and muscarinic receptors are involved in the MMC-related alterations in the motor activity of the gallbladder.     

The effect of stage of Parkinson''s disease at the onset of levodopa therapy on development of motor complications

The aim of this study was to ascertain whether the stage of Parkinson's disease (PD) (according to the Hoehn and Yahr staging system) would affect the length of time between the introduction of levodopa therapy and appearance of levodopa-associated motor complications. Forty patients with clinically definite PD were studied. In all, clinical and therapeutic data were collected from the time of diagnosis to the time of levodopa-associated motor complications (i.e. dyskinesia, motor fluctuations). In 17 patients, levodopa could be started in Hoehn and Yahr stage I (H & Y-I; 16.2 months after the onset of PD), whilst in 13 patients levodopa could be started in H & Y-II (19.6 months after the onset of the disease) and in 10 in H & Y-III (45.1 months after the onset of PD). Cox proportional hazard regression model shows that the PD patients in whom the initial levodopa treatment was introduced at stage III develop both dyskinesias and motor fluctuations significantly earlier than the patients whose levodopa started in stage I and II of PD. The median interval to develop dyskinesias was 66, 72 and 24 months for patients in whom levodopa was introduced in stage I, II and III, respectively. These values were 64, 55 and 14 months for motor fluctuations. These findings add to the clinical arguments that favour an essential role of severity of PD at levodopa initiation as a risk factor for the development of levodopa-associated motor complications.     

Cobaltic lysine study of the morphology and distribution of the cranial nerve efferent neurons (motoneurons and preganglionic parasympathetic neurons) and rostral spinal motoneurons in the Japanese toad

The morphology and distribution of the cranial nerve motoneurons (except III, IV, and VI) and rostral spinal motoneurons were systematically studied in the Japanese toad (Bufo japonicus) by retrograde labelling with cobaltic lysine complex. The cobaltic lysine clearly labelled whole neurons, i.e., cell bodies, proximal and distal dendrites, and axons. The branchial motoneurons (V, VII, IX, and X) had similar morphological characteristics and formed a more-or-less continuous cell column through the brainstem. The dendrites could be grouped mainly into the dorsomedial and the ventrolateral dendritic arrays. The dorsomedial dendrites formed a dendritic plexus in the subependymal gray matter, which extended as far peripherally as beneath the ependymal layer. The ventrolateral dendrites formed a broom-like dendritic plexus in the lateral to ventrolateral white matter. They usually extended as far peripherally as the pial surface. The rostrocaudal extent of the dendritic field was also wide and usually exceeded the motor nuclear boundaries. The hypoglossal motoneurons were grouped into the dorsomedial and ventrolateral cell groups, and the latter was considered to be part of the rostral spinal motoneuron column, from their morphology and distribution. The former had well-differentiated dendrites and occupied a more medial position than the branchial motoneurons. Besides the equivalent of the dorsomedial and ventrolateral dendritic arrays of the branchial motoneurons, they had dorsal and commissural dendrites. The accessory motoneurons had morphological characteristics and a distribution pattern similar to those of the rostral spinal motoneurons rather than the branchial motoneurons. The rostral spinal motoneurons had morphological characteristics somewhat different from the branchial motoneurons and the hypoglossal motoneurons (dorsomedial group). Functional implications of the motoneuron morphology are discussed, mainly based on the present results and earlier anatomical and physiological studies of the spinal motoneurons. The present study also revealed the anatomical features of the preganglionic parasympathetic neurons supplying some cranial nerves. These neurons had small somata with less elaborate dendrites and formed an almost continuous cell column that occupied a more dorsal position than the motoneurons of the corresponding nerve. They are thought to be homologous to the salivatory nucleus and the dorsal motor nucleus of the vagus. The basic anatomical organization of the general visceral efferent column seems to be similar throughout vertebrates.