Coordination of flipflopping neural signals and head turning during pheromone-mediated walking in a male silkworm moth Bombyx mori

Male silkworm moths, Bombyx mori, move their heads side-to-side during zigzag walking toward a source of sex pheromone. High-speed video analysis revealed that changes in walking direction were synchronized with this head turning. Thus the direction of the walking is indicated by the direction of the head turning. Head turning was regulated by neck motor neurons which innervate the cervical ventral muscles and the ventral muscles through the second cervical nerve. To determine the role of the `flipflop' state transition in spike activity carried by descending interneurons from the brain to the thoracic ganglion, we recorded pheromonal responses simultaneously from flipflop descending interneurons and a single cervical ventral 1 neck motor neuron. The activity of the cervical ventral 1 neck motor neuron was synchronized to that of the flipflop descending interneurons. The cervical ventral 1 neck motor neuron was morphologically identified using confocal imaging. Our results demonstrate that the flipflop signals play an important role in instructing turning signals during the pheromone-mediated behavior in a male B. mori. Accepted: 11 June 1998     

Cortical reorganization in training.

Plasticity within the human central motor system occurs and has been studied with transcranial magnetic stimulation in patients with amputations, spinal cord injuries, and ischemic nerve block. These studies have identified a pattern of motor system reorganization that results in enlarged muscle representation areas and large motor evoked potentials (MEPs) for muscles immediately proximal to the lesion. Some of these changes are apparent minutes after ischemic nerve block, weeks after spinal cord injury, and as early as six months after amputation.These studies motivated us to study the cortical motor reorganization after finger movement training in normals and after anastomosis of intercostal nerves to the musculocutaneous nerve in young patients with cervical root avulsions due to a traumatic motorcycle injury.     

A single pair of interneurons controls motor neuron activity during pre-ecdysis compression behavior in larval Manduca sexta

Manduca sexta molts several times as a larva (caterpillar) before becoming a pupa and then an adult moth. Each molt culminates in ecdysis behavior, during which the old cuticle is shed. Prior to each larval ecdysis, the old cuticle is loosened by pre-ecdysis behavior, which includes rhythmic, synchronous compressions of the abdomen. A previous study indicated that motor neuron activity during pre-ecdysis compression behavior is driven by an ascending neural pathway from the terminal abdominal ganglion. The present study describes a pair of interneurons, designated IN-402, that are located in the terminal ganglion and belong to the ascending pathway. Each IN-402 is synchronously active with pre-ecdysis compression motor bursts, and bilaterally excites compression motor neurons throughout the abdominal nerve cord via apparently monosynaptic connections. The pair of IN-402s appears to be the sole source of rhythmic synaptic drive to the motor neurons during the pre-ecdysis compression motor pattern. These interneurons play a key role in the production of larval pre-ecdysis behavior, and are candidates for contributing to the developmental weakening of pre-ecdysis behavior at pupation.Abbreviations A3, A4... abdominal ganglion 3, abdominal ganglion 4... - AT terminal abdominal ganglion - DN _A anterior branch of the dorsal nerve - EH eclosion hormone - EPSP excitatory postsynaptic potential     

The Impact of Motor Axon Misdirection and Attrition on Behavioral Deficit Following Experimental Nerve Injuries

Peripheral nerve transection and neuroma-in-continuity injuries are associated with permanent functional deficits, often despite successful end-organ reinnervation. Axonal misdirection with non-specific reinnervation, frustrated regeneration and axonal attrition are believed to be among the anatomical substrates that underlie the poor functional recovery associated with these devastating injuries. Yet, functional deficits associated with axonal misdirection in experimental neuroma-in-continuity injuries have not yet been studied. We hypothesized that experimental neuroma-in-continuity injuries would result in motor axon misdirection and attrition with proportional persistent functional deficits. The femoral nerve misdirection model was exploited to assess major motor pathway misdirection and axonal attrition over a spectrum of experimental nerve injuries, with neuroma-in-continuity injuries simulated by the combination of compression and traction forces in 42 male rats. Sciatic nerve injuries were employed in an additional 42 rats, to evaluate the contribution of axonal misdirection to locomotor deficits by a ladder rung task up to 12 weeks. Retrograde motor neuron labeling techniques were utilized to determine the degree of axonal misdirection and attrition. Characteristic histological neuroma-in-continuity features were demonstrated in the neuroma-in-continuity groups and poor functional recovery was seen despite successful nerve regeneration and muscle reinnervation. Good positive and negative correlations were observed respectively between axonal misdirection (p<.0001, r²=.67), motor neuron counts (attrition) (p<.0001, r²=.69) and final functional deficits. We demonstrate prominent motor axon misdirection and attrition in neuroma-in-continuity and transection injuries of mixed motor nerves that contribute to the long-term functional deficits. Although widely accepted in theory, to our knowledge, this is the first experimental evidence to convincingly demonstrate these correlations with data inclusive of the neuroma-in-continuity spectrum. This work emphasizes the need to focus on strategies that promote both robust and accurate nerve regeneration to optimize functional recovery. It also demonstrates that clinically relevant neuroma-in-continuity injuries can now also be subjected to experimental investigation.     

Frequency Distribution of F-Latencies (DFL) has Physiological Significance and Gives Distribution of Conduction Velocity (DCV) of Motor Nerve Fibres With Implications for Diagnosis

On electrical stimulation of a peripheral motor nerve, a delayed and reduced F-response is obtained, which is known to occur due to random backfiring of a few percent of the motor nerve fibres at the spinal end after antidromic conduction. F-latencies obtained from multiple stimulations vary in latency, size and shape because of this randomness. We hypothesised that, being a random process, recruitment of fibres for F-response would depend on the distribution of conduction velocity (DCV) for motor nerve fibres directly, and therefore, a frequency distribution of F-latencies (DFL) from such multiple F-responses would be an approximate mirror image of DCV, latency being inversely proportional to velocity. First, obtaining DFL from many human subjects, we have shown that this is a reproducible parameter for a nerve trunk of a subject, and hence reveals a new physiological phenomenon. DFL has a single peaked distribution, which is also expected for the DCV of a normal healthy motor nerve. To validate its hypothesised relationship to DCV further, DFLs were obtained from both median nerves of patients with unilateral carpal tunnel syndrome (CTS). The patterns of DFL from both sides remained almost the same except for a delay shift equal to that in between the two M-responses, which lends support to this hypothesis. DFL, and DCV as its suggested mirror image, appear to change systematically with certain known disorders such as cervical spondylosis, even at a subclinical stage, which needs further study. This also indicates that DFL may become a new and improved investigative diagnostic tool in neurophysiology.     

神经根型颈椎病和脊髓型颈椎病手术治疗的研究进展

颈椎病是一种临床发病率较高的退行性病变,发病原因主要是颈椎长期劳损、骨质增生或椎间盘脱出、韧带增厚等导致颈椎脊髓、神经根或椎动脉受压,进而引起一系列功能性障碍。临床普遍认为,对于已经得到明确诊断,且神经根压迫症状严重的患者,以及经保守治疗后症状无明显好转的患者应及时采取手术治疗,解除压迫状态,从而获得良好的预后。随着融合技术的进步及合成材料的改进,颈椎病的手术治疗效果也不断提高。本文对近年来国内外神经根型颈椎病和脊髓型颈椎病手术治疗的相关文献进行综述。     

Influence of peripheral targets on the expression of calcitonin gene-related peptide immunoreactivity in rat cranial motoneurones

Calcitonin gene-related peptide-like immunoreactivity (CGRP-ir) is displayed by motoneurons that innervate striated muscle but is absent from preganglionic parasympathetic motoneurons. One hypothesis to explain this is that CGRP gene expression in motoneurons is, in part, dependent on influences from the innervated organ. To test this hypothesis, we cross-anastomosed the right hypoglossal and cervical vagal nerves of rats so that the vagal motoneurons grew to innervate the musculature of the tongue. Following a recovery period of 17 to 52 weeks, the distribution of CGRP-ir in the dorsal motor vagal nucleus was determined in both cross-anastomosed animals and self-anastomosed control animals. Successful reinnervation of the tongue musculature by vagal motoneurons was demonstrated by showing that electrical stimulation of the central vagus/peripheral hypoglossal nerve produced a twitch of the tongue muscles. Motoneurones of the dorsal motor vagal nucleus, which now innervated the tongue were found to express CGRP-ir, which was evident from the double labeling of neurons with both horseradish peroxidase and CGRP-ir. Motoneurones of the dorsal motor vagal nucleus contralateral to the cross-anastomosis remained CGRP negative. Similarly, motoneurons of the dorsal motor vagal nucleus in control animals where the vagus nerve was self-anastomosed remained CGRP negative, showing that an induction of CGRP expression is not a result of nerve section itself. We suggest that a signal from the striated muscle transported retrogradely via the motor axon regulates expression of CGRP-ir in motoneurons. © 1995 John Wiley & Sons, Inc.     

Effects of α-Phenyl-N-tert-butyl Nitrone (PBN) on Compression Injury of Rat Spinal Cord

-Phenyl-N-tert-butyl Nitrone (PBN) is a free radical scavenger which recently has proved to be neuroprotective in experimental studies on focal cerebral ischemia and infarction. We therefore studied the effect of this drug in a model of moderate compression injury to rat spinal cord at the midthoracic level. The compound was given intraperitoneally 0.5 h before (100 mg/kg b.w) and at 1.5 h (50 mg/kg b.w) and 3.5 h (50 mg/kg b.w) after compression. Treated animals and controls (vehicle alone) were allowed to survive for 1 or 9 days following trauma. The functional outcome was tested by the inclined plane method and the motor performance score. By using MAP2 immuno-staining the number of nerve cell bodies in the ventral horn and the ratio of MAP2 immunostained area to area of whole section of the cord were assessed to detect loss of neurons and loss of dendrites in the compressed segment. pAPP and PGP9.5 immunostaining was used to demonstrate axonal lesions.

Treated and control rats showed at day 1 when tested with the inclined plane method a marked reduction of the capacity angle. This abnormality recovered gradually over the following days and was normalized at day 9. The motor performance score showed a marked reduction at day 1 which almost normalized at day 9. There was no difference regarding the functional outcome between rats given PBN and controls in none one of these functional tests.

The spinal cord of normal rats presented immunoreactivity to MAP2 in nerve cell bodies and dendrites but not in axons and other structures. Following compression there was at day 1 and 9 a marked loss of MAP2 immunoreactivity in dendrites and nerve cell bodies. We could not detect any difference between the PBN and the control rats regarding the degree of cell loss or degree of reduction of dendrite staining. No difference between the two groups was seen with the axonal immunostainings (βAPP and PGP9.5).

In conclusion, our study did not reveal any neuroprotective effect of PBN on the functional outcome and morphology (immunostaining to MAP2, pAPP and PGP9.5) in this model of moderate compression trauma to rat spinal cord.     

Mechanical responses of the rat uterus, cervix, and bladder to stimulation of hypogastric and pelvic nerves in vivo

Mechanical activities of the uterus, cervix, and bladder were recorded in vivo in anesthetized rats during electrical stimulation of either the hypogastric or pelvic nerve. Ovariectomized controls and hormone-treated groups were used as well as pregnant and postpartum rats. Stimulation of either hypogastric or pelvic nerve produced voltage- and frequency-dependent contractions of the three organs with no evidence of apparent inhibition. All evoked responses were completely abolished by tetrodotoxin, suggesting that these nerves are common pathways of innervation to the three organs. Atropine abolished uterine and cervical responses to both hypogastric and pelvic nerve stimulation, whereas bladder responses were only partly reduced. Hexamethonium almost totally blocked the evoked responses of the uterus and cervix. Phentolamine partly blocked uterine and cervical responses, and propranolol or physostigmine enhanced uterine and cervical responses to both hypogastric and pelvic nerve stimulation. These results suggest that motor innervation to the rat uterus and cervix is predominantly postganglionic cholinergic, with some alpha- and beta-adrenergic components, and that the bladder is innervated by mainly cholinergic and also noncholinergic nerves. Estrogen and estrogen-plus-progesterone pretreatment significantly increased the responses of uterus and cervix but not bladder. Uterine and cervical responses to either hypogastric or pelvic nerve stimulation were markedly reduced late in pregnancy and reappeared within 7 days after delivery.     

Superparamagnetic iron oxide-enhanced magnetic resonance imaging of neuroinflammation in a rat model of radicular pain

In many clinical cases of radicular pain, no noticeable neuropathology is detected by conventional medical imaging strategies. Superparamagnetic iron oxide (SPIO) nanoparticles were evaluated as magnetic resonance contrast agents to specifically detect neuroinflammation at sites of painful injury in a rat model of cervical nerve root compression. Two separate groups of rats were used: an injury group that underwent controlled transient compression of the dorsal root and a sham group that received the same surgical procedures but no injury. Precontrast magnetic resonance imaging (MRI) was performed 6 days after surgery, followed by administration of SPIO via tail vein injection. After 24 hours, T2*-weighted imaging at the site of root injury revealed a postcontrast enhancement of 72.9 ± 31%. This was significantly greater than that of injured animals prior to SPIO administration (5.3 ± 12.9%). SPIO did not generate any significant postcontrast enhancement in the nerve roots of the sham group. Histology confirmed colocalization of SPIO with macrophage at the injury site. These findings suggest that SPIO-enhanced MRI may be a valuable tool to identify otherwise undetectable nerve root compression and enable improved patient management.     

Characteristics of multisegmental monosynaptic responses of leg muscles in subjects with lumber nerve compression

The reflex motor responses of 16 symmetric leg muscles evoked by transcutaneous electric stimulation of spinal nerves at the L2-L3 or L3-L4 level were studied in subjects with signs of lumbar nerve compression. The evoked responses agreed with Ia afferent activation through monosynaptic neuronal circuits. Their monosynaptic nature was demonstrated by amplitude changes in response to a conditioning stimulus and continuous tendon vibration. Multisegmental monosynaptic responses (MMRs) of large distal flexors containing large numbers of slow motor units were subjected to the greatest modifications against a background of lumbar nerve compression.     

Visual response properties of neck motor neurons in the honeybee

Recent behavioural studies have demonstrated that honeybees use visual feedback to stabilize their gaze. However, little is known about the neural circuits that perform the visual motor computations that underlie this ability. We investigated the motor neurons that innervate two neck muscles (m44 and m51), which produce stabilizing yaw movements of the head. Intracellular recordings were made from five (out of eight) identified neuron types in the first cervical nerve (IK1) of honeybees. Two motor neurons that innervate muscle 51 were found to be direction-selective, with a preference for horizontal image motion from the contralateral to the ipsilateral side of the head. Three neurons that innervate muscle 44 were tuned to detect motion in the opposite direction (from ipsilateral to contralateral). These cells were binocularly sensitive and responded optimally to frontal stimulation. By combining the directional tuning of the motor neurons in an opponent manner, the neck motor system would be able to mediate reflexive optomotor head turns in the direction of image motion, thus stabilising the retinal image. When the dorsal ocelli were covered, the spontaneous activity of neck motor neurons increased and visual responses were modified, suggesting an ocellar input in addition to that from the compound eyes.     

Inhibitory innervation to the guinea pig trachealis muscle

The inhibitory innervation of the cervical trachea was studied in situ in anesthetized male guinea pigs. We measured effects of electrical stimulation of vagal motor and sympathetic trunk nerve fibers, during atropine, on trachealis muscle tension. Effects of direct transmural stimulation of trachealis muscle were also determined. We confirmed the dual nature of the inhibitory innervation to this muscle. Vagal motor inhibitory nerves are shown to be preganglionic. Neural transmission at the level of the ganglia is characterized by filtering of high frequency action potentials. The neurotransmitter at the myoneural junction is unidentified but is not norepinephrine. Maximal relaxation accounts for about 20-40% of maximal relaxations seen with transmural stimulation of trachealis muscle in the presence of atropine. Sympathetic trunk nerve fibers are also preganglionic. Neurotransmission at the level of the ganglia is apparently 1:1 at high-action potential frequencies. Norepinephrine released presynaptically has access to smooth muscle beta- but not alpha-receptors. Maximal adrenergic relaxations account for 60-80% of total transmural stimulation relaxations. Transmural stimulation relaxations appear to be accounted for by release of neurotransmitter from sympathetic adrenergic plus vagal nonadrenergic postganglionic nerve fibers.     

地塞米松对大鼠坐骨神经损伤后各型肌纤维运动终板恢复作用的实验研究

本实验使用１２０只Ｗｉｓｔａｒ系大鼠,采用定位、定量、定时的方法压挫坐骨神经后,给予治疗剂量的地塞米松,动态地观察损伤后红、白、中间肌纤维运动终板ＡＣｈＥ的酶组织化学及各型肌纤维运动终板超微结构的变化。结果提示,早期适量应用地塞米松对周围神经损伤后运动终板的恢复有促进作用。     

Distribution of motor and sensory fibers in the intercostal nerves. Significance in reconstructive surgery.

If the distribution of the types of nerve fibers in the various intercostal nerves is taken into consideration, an intercostal nerve segment can be an acceptable donor nerve graft for sensory and/or motor nerve replacements. We describe the distribution of motor and sensory axons in various segments of the upper and lower intercostal nerves.     

Neurocalcin-like immunoreactivity in the rat esophageal nervous system

Neurocalcin is a newly identified neuronal calcium-binding protein. We tried here to investigate the immunohistochemical distribution of neurocalcin in the rat esophagus. Nerve cell bodies having neurocalcin immunoreactivity were found throughout the myenteric plexus. In the myenteric ganglia, two types of nerve terminals showed neurocalcin immunoreactivity. One was varicose terminals containing numerous small clear vesicles and forming a synapse with nerve cells. The other terminals were characterized by laminar or pleomorphic structure and many mitochondria. These laminar terminals were supposed to be sensory receptors of the esophageal wall. In the motor endplates of the striated muscles, nerve terminals containing many small clear vesicles and mitochondria also had neurocalcin immunoreactivity. After left vagus nerve cutting under the nodose ganglia, the number of immunopositive thick nerve fibers, laminar endings and nerve terminals on the striated muscles decreased markedly. Retrograde tracing experiments using Fast Blue showed extrinsic innervation of esophagus from ambiguus nucleus, dorsal motor nucleus of vagus, superior cervical ganglia, celiac ganglia, nodose ganglia and dorsal root ganglia. In the celiac ganglia, nodose ganglia and dorsal root ganglia, retrogradely labeled nerve cells were neurocalcin-immunoreactive. Neurons in the celiac ganglia may project varicose terminals, while nodose and dorsal root neurons project laminar terminals. Although cell bodies of motoneurons in the ambiguus nucleus lacked neurocalcin immunoreactivity, these neurons may contain neurocalcin only in the nerve terminals in the motor endplates. Neurocalcin immunoreactivity is distributed in many extrinsic and intrinsic neurons in the esophagus and this protein may play important roles in regulating calcium signaling in the neurons.     

Organization of the larval pre-ecdysis motor pattern in the tobacco hornworm,Manduca sexta

The tobacco hornworm, Manduca sexta, undergoes several larval molts before transforming into a pupa and then an adult moth. Each molt culminates in ecdysis, when the old cuticle is shed. Prior to each larval ecdysis, the old cuticle is loosened by pre-ecdysis behavior, which consists of rhythmic compressions that are synchronous along the abdomen and on both body sides, and rhythmic retractions of the abdominal prolegs. Both pre-ecdysis and ecdysis behaviors are triggered by a peptide, eclosion hormone. The aim of the present study was to investigate the neural circuitry underlying larval preecdysis behavior. The pre-ecdysis motor pattern was recorded in isolated nerve cords from eclosion hormone-treated larvae, and the effects of connective transections and ionic manipulations were tested. Our results suggest that the larval pre-ecdysis compression motor pattern is coordinated and maintained by interneurons in the terminal abdominal ganglion that ascend the nerve cord without chemical synaptic relays; these interneurons make bilateral, probably monosynaptic, excitatory connections with identified pre-ecdysis motor neurons throughout the abdominal nerve cord. This model of the organization of the larval pre-ecdysis motor pattern should facilitate identification of the relevant interneurons, allowing future investigation of the neural basis of the developmental weakening of the pre-ecdysis motor pattern that accompanies the larval-pupal transformation.Abbreviations A3, A4... abdominal ganglia 3, 4... - AT terminal abdominal ganglion - ALE anterior lateral external muscle - DN dorsal nerve - DN_A anterior branch of the dorsal nerve - DN_L lateral branch of the dorsal nerve - DN_P posterior branch of the dorsal nerve - EH eclosion hormone - TP tergopleural muscle - VN ventral nerve - VN_A anterior branch of the ventral nerve - VN_L lateral branch of the ventral nerve - VN_P posterior branch of the ventral nerve     

Current issues in x-ray diagnosis of cervical osteochondrosis in the course of medical rehabilitation

The results of studying 500 patients with neurological manifestations of cervical osteochondrosis are presented. All the patients underwent in the vertical position X-ray studies in the frontal, lateral, and axial projections, as well as functional spondylography. The development of radiological signs in patients with cervical osteochondrosis and that of the morphological and functional signs of degenerative and dystrophic changes in the cervical spine are discussed. Comprehensive evaluation of osteochondrosis used criteria for cervical motor disorders and impaired disk amortizing and spinal fixing functions. The degree of intradural space compression was also estimated. The studies have yielded a new classification of osteochondrosis and recommendations at the stages of medical rehabilitation.     

THE VALUE OF ELECTROMYOGRAPHY IN NEUROLOGY

By detection of muscular fibrillation, a sign of motor nerve impairment, through electromyography, diseases of the motor nervous system can be distinguished from muscular disorders, malingering, and psychoneurotic states. The site of lesion can be determined and the degree of impairment and progress of recovery can be estimated. The method has been used successfully in amyotrophic lateral sclerosis, poliomyelitis, peripheral neuritis and neuronitis, and root compression syndrome, as also for indirect evidence in muscular dystrophy and other myopathic conditions.