Arata Kanamaru

Optical imaging of respiratory burst activity in newborn rat medullary block preparations

We report on the optical imaging of excitation propagation induced by electrical stimulation of the nucleus tractus solitarius (NTS) area and subsequent inspiratory burst activity in the ventrolateral medulla (VLM) of a medullary block preparation. A medullary block preparation with a thickness of 1.0-1.4 mm was made from brainstems isolated from 0- to 4-day-old rats and stained with a fluorescent voltage-sensitive dye, RH795. Neuronal responses in the VLM evoked by electrical stimulation were recorded as a fluorescence change using an optical recording apparatus with a 128 x 128 photodiode array and a maximum time resolution of 0.6 ms. Motoneuronal activity was simultaneously recorded at the contralateral hypoglossal nerve roots. Neuronal excitation evoked by stimulation of the NTS area propagated to the VLM through the intermediate reticular zone (IRt). In contrast, caudal VLM stimulation induced excitation which propagated to the rostral VLM without any detectable excitation propagation in the IRt toward the NTS area from the VLM. NTS stimulation also induced an inspiratory burst activity in the hypoglossal nerve root activity with a 150-200 ms delay. Fluorescence changes corresponding to the inspiratory burst activity were observed in the VLM which coincided with the area in which the localization of many respiratory neurons had been demonstrated in previous studies using whole-brainstem preparations. The present results show the feasibility of using optical recordings for the analysis of respiratory neuron activity as well as for analysis of the transmission pathway of afferent and/or efferent information in the medulla.

Proprioceptive Chest Wall Afferents and the Effect on Respiratory Sensation

There have been a number of studies on the effects of chest wall afferents on the control of breathing. However, the effect of these afferents on respiratory sensation has been less extensively studied. The length-tension inappropriateness in the intercostal fusimotor loops (Campbell and Howell, 1963) is the most accepted possible mechanism of the sensation of breathlessness.

Movement related cortical source for elbow flexion in patients with brachial plexus injury after intercostal-musculocutaneous nerve crossing

Nine patients with brachial plexus injury whose transected musculo-cutaneous nerves had been sutured with intercostal nerves were examined and the relationship between flexion of the operated elbow and the respiratory movement were shown. Three out of nine patients showed independent control of movement from respiration after regeneration. The primary motor cortex for either flexion of the elbow to the operated side or brisk voluntary inspiration was estimated in the medial vertex region of the frontal cortex by the dipole-tracing method in these three patients. The present results suggest that patients contract the biceps muscle reinnervated by the intercostal nerve independently from respiratory movements using the same primary motor cortex with trunk movements. Functional plasticity may occur in the patients using the primary trunk motor cortex for elbow flexion.

Central histaminergic neurons regulate rabbit tracheal tension through the cervical sympathetic nerve.

We previously showed that stimulation of the posterior hypothalamus decreases tracheal tension and involves central histaminergic neurons. In the present study, we reveal that central histaminergic neurons project to the rostral ventrolateral medulla and affect cervical sympathetic nervous activity in rabbits. Administration of histamine into the fourth ventricle increased cervical sympathetic nervous activity and decreased tracheal tension. These effects were inhibited by administration of a histamine H receptor antagonist, pyrilamine, into the fourth ventricle. Unilateral injection of DL-homocysteic acid into the tuberomammillary nucleus increased cervical sympathetic nervous activity, an effect was antagonized by bilateral injection of pyrilamine into the rostral ventrolateral medulla. The pulse correlogram between the stimulation pulse applied to the tuberomammillary nucleus and the cervical sympathetic nerve activity showed a mode at 150 to 200 ms, which was reduced by pyrilamine administration into the fourth ventricle. Fibers anterogradely labeled by Phaseolus vulgaris leucoagglutinin (PHA-L) injected into the tuberomammillary nucleus were distributed in the A1, A2, C1, and C2 areas which are determined by tyrosine hydroxylase-immunohistochemistry. PHA-L positive neurons were in close contact with tyrosine hydroxylase-immunoreactive neurons in these four areas. Cell bodies in the tuberomammillary nucleus retrogradely labeled with fluorogold from the rostral ventrolateral medulla were immunoreactive with histamine. These results suggest that an excitatory efferent pathway projects from the tuberomammillary nucleus to the cervical sympathetic nerve and that the histaminergic neurons of this pathway influence tracheal tension through the rostral ventrolateral medulla.

Effect of acupuncture at the Hoku point on vibration-induced finger flexion reflex in man: comparison between press needle technique, electroacupuncture, and in-situ technique.

Effects of press needle technique (PN), electroacupuncture (EA), or in-situ technique (IS) on vibration-induced finger flexion reflex (VFR) were examined in 31 healthy adults. VFR, which is tonic finger flexion evoked by vibration applied to the finger tip, was induced by vibrating the volar side of the middle finger tip before and after acupuncture. Acupuncture was applied to the Hoku point on both sides. The three techniques, each studied on separate days, inhibited VFR and there was no significant difference in VFR inhibition among the three techniques (percentage of pre-acupuncture VFR was 71.5 +/- SE 2.2% after PN, 72.6 +/- SE 2.4% after EA, and 75.6 +/- SE 2.8% after IS). The results suggest that afferent signals from muscles contracting due to electrical stimulation had no significant effect on the reflex arcs of VFR; and that the intradermal stimulation by acupuncture played a significant role in VFR inhibition.

Vibration-induced finger flexion reflex and inhibitory effect of acupuncture on this reflex in cervical spinal cord injury patients

The vibration-induced finger flexion reflex (VFR) and the inhibitory effect of acupuncture on this reflex were studied in five cervical spinal cord injury patients (C-SCIs). VFR, which is a tonic finger flexion reflex induced by vibratory stimulation on the finger tip, was induced before and after acupuncture was carried out on the same hand. A stainless steel needle was inserted to the Hoku point. As in healthy subjects, VFR was performed and it was significantly inhibited by acupuncture in the C-SCIs; mean maximum VFR was 204.2 +/- S.E. 68.6 g before and 119.8 +/- S.E. 42.2 g after acupuncture. The present results suggest that at least part of the reflex center for VFR is located in the spinal cord and that part of VFR inhibition by acupuncture may be mediated via the spinal cord.

Sensory reinnervation of muscle receptor in human

This report describes sensory reinnervation of muscle receptors in humans. In this study, sensory function was investigated in fourteen patients with brachial plexus injury, whose musculocutaneous nerve was surgically sutured with intercostal nerves for reconstruction of elbow flexion. Tapping the intercostal nerve-reinnervated brachial biceps muscle (IC-biceps) induced somatosensory evoked potentials (IC-biceps SEP) in four patients. Tapping also induced reflex IC-biceps activity in all IC-biceps SEP (+) patients, but not in eight out of nine IC-biceps SEP (-) patients. Results show that muscle afferent fibers in the intercostal nerves reinnervated mechanoreceptors in IC-biceps, and induced both cortical sensory activity and muscle activity that indicated the classical stretch reflex.

Reconstruction of tonic vibration reflex in the biceps brachii reinnervated by transferred intercostal nerves in patients with brachial plexus injury

The transfer of intercostal nerves to musculocutaneous nerves has been performed to reconstruct elbow flexion in patients with brachial plexus injury. In nine of 15 such patients, 2-3 Hz tapping of the distal tendon of the biceps muscle reinnervated by the transferred intercostal nerves (IC-biceps) induced a mode in the correlogram between tap and EMG pulse of IC-biceps. In five of the mode-positive patients, tapping of various frequencies induced gradual augmentation of integrated EMG of IC-biceps. This reflex was consistent with the tonic vibration reflex (TVR) in normal controls. Conduction velocity and frequency property of the reflex were compatible with the speculation that rapid-conducting muscle afferents (group Ia or II or both) reinnervate mechanoreceptors, such as muscle spindles. The clinical significance of muscle sensory reinnervation is not clear; however, the reconstruction of TVR following this operation is worthy in that it confirms the specific sensory reinnervation of denervated muscle in humans.

Effect of Acupuncture at the Right Hoku Point on Bilateral Vibration-induced Finger Flexion Reflex in Man: Comparison Between In-Situ and Sparrow Pecking Technique

The purpose of this study was to compare the effect of the Sparrow Pecking (SP) technique with that of the In-Situ (IS) technique of acupuncture on vibration-induced finger flexion reflex (VFR). Subjects were 30 healthy adults. VFR, flexion movement of the vibrated finger, was induced by vibrating the volar side of the middle finger tip. The acupuncture point was the right Hoku point. Both techniques of acupuncture inhibited VFR in the ipsilateral and contralateral sides, but inhibition with SP was significantly greater than that with IS (percentage control force of VFR, mean +/- SD: with SP right, 62.1 +/- 24.6%, left, 60.6 +/- 27.9%, with IS right, 74.9 +/- 26.6%, left, 78.1 +/- 29.5%, P < 0.0005). The results suggest that SP suppresses facilitation of VFR in the reflex arcs more than IS does.

Anxiety and Respiration

Recent research on emotions has been investigated by neuropsychologists using PET and fMRJ. The location of neuronal activity during production of emotions such as happiness, sad, fear and anxiety in the human brain is becoming clear. However, emotional experiences are not only productions within the brain accompanied by physiological activity such as sweating, increasing heart rate and respiration; these activities result from an unconscious process. Respiration, one of the physiological activities, is also expressed unconsciously. The activities of breathing in and breathing out are a curious mechanism because this activity comes from the unconscious regulation of a metabolic requirement, and simultaneously expresses emotion involuntarily. In this chapter, we compare the effect of physical load and mental stress tests on metabolic outputs and respiratory timing, and demonstrate the effect of both emotional states. The results indicate that there is a correlation between anxiety levels and respiratory rate: the increase of minute ventilation involves individual anxiety. We also provide evidence that anticipatory anxiety increases respiratory rate without metabolic change and during this time dipoles are concentrated in the paralimbic area temporal pole estimated by the dipole tracing method. From our results, we discuss the relation between respiration and emotion of anxiety from psychological and physiological view points.