功能磁刺激技术的研究

功能磁刺激是一种全新的生物组织刺激技术，以其可以兴奋神经肌肉的特点，及可进行深部刺激、无痛、非介入，易于操作等优点，具有广阔的应用前景。本文详细介绍了功能磁刺激技术的原理及磁刺激系统，介绍了目前磁刺激技术中线圈设计和实验研究成果，以及和我们在磁刺激镇痛方面的工作。     

微机式磁刺激系统的设计仿真与建模研究

磁刺激技术作为医学康复一种非侵入式的诊疗技术,是当前该领域国际范围的一项重要的研究课题.目前,所用的磁刺激仪存在两大问题:①磁线圈聚焦性较差;②系统能耗较大.刺激阈值所需要的能耗大,由此仪器产热并造成刺激有效性降低.本文在近几年磁刺激技术研究的基础上,运用计算机对磁刺激系统的重要模块进行了仿真,其中包括主电路与微机控制电路的仿真,并对磁刺激线圈磁场进行建模研究,为日后的研究和实践提供了有益的理论依据.     

A simple device detecting onset time of taste stimulation

A simple piece of equipment is described for recording the accurate onset time of chemical stimulation applied to the tongue surface. The equipment consists of an infrared light emitting diode, a phototransistor for monitoring the stimulus onset, and solid state logic circuits for generating electric pulses at the moment of stimulus onset.     

The perception of movements elicited by magnetic cortex stimulation depends on the site of stimulation

Previous reports suggest that magnetic cortical stimulation (MCS) of the motor cortex can elicit a sensation of movement (kinaesthesia) in paralysed limbs. To assess this sensory effect of MCS, we examined the accuracy of kinaesthetic perception of stimulus-induced right elbow flexion in six blindfolded, healthy subjects. Matching of movements elicited by MCS was compared with matching of passive elbow movements. Small flexion movements between 1.5 and 5° of angle were regularly overestimated by 50–100% when induced by MCS over the parietal cortex, whereas movements elicited by MCS over the frontal cortex or by passive elbow flexion were accurately estimated. Our results provide data compatible with the hypothesis of the existence of a central sense of movement. Activation of collateral branches projecting from the motor cortex to the sensory could be the underlying mechanism to this phenomenon.     

Regeneration of the rabbit spleen after hydrocortisone injection

The action of hydrocortisone on the rabbit spleen and the regenerative processes arising after cessation of administration of the hormone were studied. During prolonged administration of hydrocortisone the absorptive function of the reticuloendothelial system is depressed and atrophy of the spleen develops, as shown by a reduction in the weight and size of the organ. Most of the splenic follicles are converted into random clusters of lymphocytes. Pyroninophilic cells disappear from the white pulp. After cessation of the action of the hormone the animal's general condition improves, the development of the atrophic changes in the spleen is halted, the splenic follicles are restored, and the number of pyroninophilic cells in them increases. The use of a regeneration stimulator under these conditions accelerates recovery of the body weight of the animal, reversal of the atrophy of the spleen, and restoration of its normal structure.Department of Histology and Pathological Anatomy, Erevan Zooveterinary Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 12, pp. 722–725, December, 1977.     

Tris(2-hydroxyethyl)ammonium orthocresoxyacetate: A stimulator of regenerating hepatocytes

All-Union Research and Design Institute for the Meat Industry, Russian Academy of Agricultural Sciences. Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 114, No. 11, pp. 480–483, November, 1992.     

Effector innervation of melanophores of arteries at the base of the brain

During electrical stimulation of the vagus and sympathetic nerves, and in solutions of acetylcholine and noradrenalin in vitro, melanophores of arteries at the base of the cat brain change their size and shape. It is concluded that these cells have a double effector innervation.Department of Histology, Vladivostok Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 2, pp. 244–246, February, 1976.     

Electrical stimulation of the motor cortex: Theoretical considerations

The aim of this paper is to present the results of a theoretical analysis of the intracranial fields produced by electrical stimulation of the unexposed motor cortex with surface electrodes in humans. Simulations of a first approximation model of the head indicate that the intensity and the spatial configuration of the intracranial fields can be controlled, to a great extent, by proper choice of the location and of the number of the stimulating electrodes. Fields are shown to be reasonably insensitive to changes of some crucial parameters, like the number of the stimulating electrodes and the ratio between the conductivity of the skull and that of the other tissues.     

Mechanism of the stimulating action of an electric current on reparative regeneration of bone tissue

The dynamics of the ATP concentration in regenerating bone tissue was studied in experiments on rabbits after incomplete osteotomy or resection of a piece of bone and also during stimulation of reparative osteogenesis in the region of a bone defect by means of a pulsed electric current. The ATP concentration in the callus after incomplete osteotomy and during electrical stimulation was found to be higher than in regenerating bone tissue after resection of the bone fragment in the absence of stimulation. It can be concluded that improvement of the energy supply for fracture healing is an important factor in the mechanisms of the stimulating effect of an electric current on reparative regeneration of bone tissue.Laboratory of Biophysics and Radiological Department, N. N. Priorov Central Research Institute of Traumatology and Orthopedics, Ministry of Health of the USSR. Clinical Diagnostic Laboratory, A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. Moscow Energy Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR M. V. Volkov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 9, pp. 361–362, September, 1978.     

Effects of long-lasting stimulation of extensor muscle nerves on pulmonary ventilation in cats

Increments in pulmonary ventilation were shown to occur in anaesthetized cats during long-lasting stimulation of a peripherally cut extensor muscle nerve at maximal intensity for group I afferent fibers. However, these increments tended to gradually adapt to a lower value when stimuli were delivered at high frequency and constant rate whereas a tendency to potentiation, up to a steady state, occurred when stimulation was intermittent. End-tidal initially decreased with a tendency to adaptation in the case of continuous stimulation, and decreased progressively in the case of intermittent stimulation. It is concluded that the nervous mechanisms producing hyperpnoea exhibit fatigue during their constant excitation while their effects sum up during intermittent stimulation.     

Sensory mediation of female-male mounting in the rat: II. Role of tactile and conspecific cues

Although previous research has shown that olfactory cues mediate female-male mounting (FMM) in the rat, the role of other sensory modalities on FMM has not been investigated. The present study examined the display of female mounting of castrated male rats in bilevel chambers following different tactile or locomotor activity manipulations. Female rats (N = 40) were ovariectomized (OVX), primed with estrogen (E) and progesterone (P), and given either vaginocervical stimulation (VCS), flank/perineum stimulation (FPS), combined VCS and FPS, or general handling, immediately before each test with a castrated male rat for five trials. Compared to handling, the FPS females showed an increase in FMM behavior, whereas females given VCS, or combined VCS and FPS, showed a decrease in FMM behavior. A second experiment examined the effect of a 15-min delay between stimulation and testing using identical experimental and control conditions. There were no significant differences in the amount of FMM behavior between these groups. Finally, OVX rats primed with E and P were tested with castrated males that had been given injections of a ketamine/xylazine anesthetic mixture, saline, or amphetamine, to induce three levels of conspecific locomotor activity: none, moderate, or high, respectively. A positive linear relationship was found between male activity level and FMM. These data indicate that both tactile cues and cues associated with locomotor activity of the stimulus male modulate FMM.     

Effect of a pulsed electric current on the course of reparative osteogenesis

Exposure to a pulsed electric current during reparative regeneration of bone in rabbits resulted in stimulation of osteogenesis so that it predominated over fibro- and chondrogenesis to a greater degree than inthe control. The degree of mineralization of the microstructures was indistinguishable from the control.Laboratory of Biophysics, N. N. Priorov Central Scientific-Research Institute of Traumatology and Orthopedics, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR M. V. Volkov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 589–591, May, 1977.     

Action of serotonin microinjected into hypothalamic sites at which electrical stimulation produced aversive responses in the rat

A bipolar chemitrode was implanted unilaterally in the hypothalamus of the rat so that the tip rested in the medial forebrain bundle. Upon aversive electrical stimulation with pulses delivered at a rate of 2/sec, each rat learned to avoid this stimulation by depressing a lever in the test chamber. Microinjections in a volume of 0.4–0.7 μl of an artificial CSF solution or of doses of 1.0 or 5.0 μg of acetylcholine, dopamine or norepinephrine into the neuron mass directly at the tip of the electrode failed to alter the rate of avoidance responding to the electrical stimulation. However, serotonin (5-HT) microinjected similarly in a dose of 5.0 μg at the tip of the electrode caused a fourfold increase in the acceptance of this aversive electrical stimulation. It is concluded that serotonergic neurons function to attenuate punishing stimuli within the negatively reinforcing pathways located in the diencephalon.     

Comparison of descending volleys evoked by monophasic and biphasic magnetic stimulation of the motor cortex in conscious humans

The descending spinal volleys evoked by monophasic and biphasic magnetic stimulation of the motor cortex were recorded from a bipolar electrode inserted into the cervical epidural space of four conscious human subjects. The results suggest that both phases of the biphasic pulse are capable of activating descending motor output. The pattern of recruitment of descending activity depends on the intensity of the stimulus and the relative threshold of each volley to each direction of current flow.     

Spread of electrical activity at cortical level after repetitive magnetic stimulation in normal subjects

In normal subjects, focal repetitive transcranial magnetic stimulation (rTMS) of the hand motor area evokes muscle potentials (MEPs) from muscles in the hand (target muscles) and the arm (non-target muscles). In this study we investigated the mechanisms underlying the spread of MEPs induced by focal rTMS in non-target muscles. rTMS was delivered with a Magstim stimulator and a figure-of-eight coil placed over the first dorsal interosseus (FDI) motor area of the left hemisphere. Trains of 10 stimuli were given at a suprathreshold intensity (120% of motor threshold) and at frequencies of 5, 10 and 20 Hz at rest. Electromyographic (EMG) activity was recorded simultaneously from the FDI (target muscle) and the contralateral biceps muscle and from the FDI muscle ipsilateral to the side of stimulation (non-target muscle). rTMS delivered in trains to the FDI motor area of the left hemisphere elicited MEPs in the contralateral FDI (target muscle) that gradually increased in amplitude over the course of the train. Focal rTMS trains also induced MEPs in the contralateral biceps (non-target muscle) but did so only after the second or third stimulus; like target-muscle MEPs, in non-target muscle MEPs progressively increased in amplitude during the train. At no frequency did rTMS elicit MEPs in the FDI muscle ipsilateral to the site of stimulation. rTMS left the latency of EMG responses in the FDI and biceps muscles unchanged during the trains of stimuli. The latency of biceps MEPs was longer after rTMS than after a single TMS pulse. In conditioning-test experiments designed to investigate the cortical origin of the spread, a single TMS pulse delivered over the left hemisphere at an interstimulus interval (ISI) of 50, 100 and 150 ms reduced the amplitude of the test MEP evoked by a single TMS pulse delivered over the right hemisphere; and a conditioning rTMS train delivered over the left hemisphere increased the amplitude of the test MEP evoked by a single TMS pulse over the right hemisphere. A conditioning rTMS train delivered over the left hemisphere and paired magnetic shocks (test stimulus) at 3 and 13 ms ISIs over the right hemisphere reduced MEP inhibition at the 3-ms ISI but left the MEP facilitation at 13 ms unchanged. Using a control MEP size matched with that observed after a conditioning contralateral rTMS, we found that paired-pulse inhibition remained unchanged. Yet a single TMS conditioning pulse sufficiently strong to evoke a MEP in the contralateral FDI and biceps muscles simultaneously (as rTMS did) left paired-pulse inhibition unchanged. We conclude that the spread of EMG activity to non-target muscles depends on cortical mechanisms, mainly including changes in the excitability of the interneurones mediating intracortical inhibition. Electronic Publication     

Autoradiographic analysis of the effect of potassium orotate on the intensity of [5-3H]uridine and [3H]proline into wound fibroblasts

The intensity of incorporation of [5-³H]uridine into the nucleus and cytoplasm of fibroblasts during wound healing in control mice and in mice receiving potassium orotate and the intensity of incorporation of [³H]proline into the same cells and into the intercellular spaces between them were studied. Incorporation of [³H]proline was shown to take place much more intensively than that of [5-³H]uridine. A considerable increase was observed in RNA synthesis in the fibroblasts under the influence of potassium orotate, accompanied by a less marked increase in synthesis of proline-containing proteins under analogous conditions. The dynamics of the nucleo-cytoplasmic ratios revealed by autoradiographic investigation correlated with the ultrastructural changes in the fibroblasts in the course of their differentiation.Department of Pathological Anatomy, A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. V. Snezhnevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 6, pp. 615–617, June, 1979.