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Mental-sweating response (MSR) was observed in the palm when the subject was asked to perform a mentally stressful task such as memory recall or mental calculation. About 4 s before the development of MSR, small MSR-related wavelets (MSR wavelets) and large waves were randomly generated on electroencephalograph. After differentiating the two types of waves, we calculated locations of the current dipole of MSR wavelets using the two-dipole model of the SSB/dipole tracing method. The result showed that one current dipole of MSR wavelets was consistently located in the hippocampus while the other dipole was widely dispersed in the cortex during memory recall and mental calculation.

Preceding mental sweating response (MSR) during mental stress, small wavelets and large waves are observed on EEG. In the present study, locations of current sources of the large waves were estimated. The results revealed that the current dipole was estimated around the orbits, reflecting activity of the eyelid or eye muscles.

Using a realistic, 3-shell head model including the scalp (S), skull (S) and brain (B) with conductivity ratios of 1:1/80:1, respectively, the electrical activity in the human brain recorded by conventional electroencephalography was approximated by 1 or 2 equivalent current dipoles. The dipole locations and vector moments were stimulated by minimizing the squared difference between the potentials actually recorded from the scalp and those theoretically calculated from the equivalent dipoles. The validity of this dipole tracing method (the DT of the SSB head model) was tested in patients with focal epileptic seizures undergoing presurgical evaluation with intracranial subdural strip electrodes. Weak currents were passed through 1 or 2 pairs of subdural electrodes to create artificial dipoles. The dipole estimations correctly distinguished between single and double generator sources, but there were certain dislocations of the calculated dipoles. The average error of dislocation was found to be 8.5 mm for the 1-dipole model. That for the 2-dipole model was 6 mm for one of the components and 18 mm for the other. It was concluded that the DT method of the SSB head model can be a valuable clinical tool in 3-dimensional localization of focal epileptic discharges in the human brain.

We measured the mental sweating response (MSR) and the skin sympathetic nerve activity (SSNA). Mental arithmetic or recall questions first elicited SSNA and then elicited MSR. MSR was used as the trigger point of time 0 ms to average EEGs. The averaged EEGs contained slow wave fluctuations, which occurred 5 s prior to the MSR onset. The current source locations of the MSR-related potentials were estimated by EEG dipole tracing method in two subjects. Mental stress activated the inferior frontal gyrus 5.5 s prior to the MSR and then 0.5 s later, the lateral part of the hippocampus in a subject, and they activated the medial part of the amygdala 5 s prior to the MSR in another subject. Indirect contact of the brain with the mind associated with mental questions was discussed.

The electric source locations of interictal spikes recorded with depth electrodes were estimated by the dipole tracing (DT) method. Three-dimensional coordinates of the active surfaces of the depth electrodes and head geometry of the patient were measured from frontal and saggital X-ray images and by a special device, respectively. The estimated dipole locations were superimposed on MR images of the patients. The dipole locations estimated in the hippocampal or parahipocampal regions successively moved in a small limited region during the interictal spike's peak. It was suggested that an interictal spike is composed of summated equivalent dipoles generated by hypersynchronization of a cluster of neurons, and that the timing of such hyperexcitation is more or less delayed because of electrical propagation along neuronal clusters which might be separated by sclerotic tissues.

A new dipole tracing method, based on a realistic head model, was used to determine dipole locations and vector moments of interictal convexity sharp waves recorded (with conventional EEG technique) from the right fronto-temporal region in a patient with partial complex seizures. When the dipole locations in the head model were compared to MRI scans, the majority of the sharp wave dipoles were found to be located in the right hippocampal area. For individual sharp waves, the hippocampal dipoles moved along tracks corresponding to the vector moment directions, suggesting that the electrical sources of the convexity sharp waves were somato-dendritic currents which spread rapidly from one neuron group to the next in the hippocampal area. Previous long-term subdural recording had shown seizure onset in this area. After right-sided anterior temporal lobectomy including the hippocampus the patient has been seizure-free for three months.

A patient with major neurological deficits 5 years after a left cerebral infarction underwent correlative EEG, MRI and PET studies of cerebral blood flow and oxygen metabolism. The EEG showed abnormal slow electroencephalographic activity in the frontopolar region. The intracranial location of the slow electrical activity was estimated, as an equivalent current dipole, by using a newly developed dipole tracing (DT) method. The DT analysis showed that the dipole equivalent of the slow wave is approximately located at the frontal part of the left cingulate gyrus, away from the margins of the infarction and enlarged left lateral ventricle demonstrated by MRI, and in a region with intact oxygen consumption rate. The genesis of the slow wave is discussed.

Measurement of the reaction γ+ p → p +π 0 +π 0 was performed in the medium energy region up to 1,160 MeV by detecting the recoil proton and one of the decay gamma-rays from the neutral pions. The cross section is very small below 650 MeV and is consistent with the prediction given by the static theory. The cross section beyond 650 MeV, however, increases steeply with photon energy and has a value of about 20 µb at 900 MeV and about 40 µb at 1,000 MeV.

The ventral or dorsal root of the rat was placed on 12 electrodes arranged side by side at 0.4 mm intervals. Impulse conduction along the fiber was displayed using unidimensional latency-topography, which corresponds to the relation between latency and electrode distance. The relation revealed step-like displacement, which implies saltatory conduction of the impulse. Since the distance between the plateaux correspond to internodal length, the conduction velocity could be calculated from the length and the time differences between plateaux. It was found from 36 observations that : (i) mean internodal length was 0.92 +/- 0.13 mm (range 0.70--1.25 mm); (ii) mean conduction velocity was 76.1 +/- 20.7 m/s; and (iii) the correlation coefficient of conduction velocity and internodal length was statistically significant at r = 0.38 (P less than 0.025), so the longer the internodal length, the higher the conduction velocity.

Conduction of an action potential along skeletal muscle fibers was graphically displayed by unidimensional latency-topography, UDLT. Since the slopes of the equipotential line were linear and the width of the line was constant, it was possible to calculate conduction velocity from the slope. To determine conduction direction of the muscle action potential elicited by electric stimulation applied directly to the muscle, surface recording electrodes were placed on a two-dimensional plane over a human muscle. Thus a bi-dimensional topography was obtained. Then, twelve or sixteen surface electrodes were placed linearly along the longitudinal direction of the action potential conduction which was disclosed by the bi-dimensional topography. Thus conduction velocity of muscle action potential in man, calculated from the slope, was for m. brachioradialis, 3.9 +/- 0.4 m/s; for m. biceps brachii, 3.6 +/- 0.2 m/s; for m. sternocleidomastoideus, 3.6 +/- 0.4 m/s. By using a tungsten microelectrode to stimulate the motor axons, a convex-like equipotential line of an action potential in UDLT was obtained from human muscle fibers. Since a similar pattern of UDLT was obtained from experiments on isolated frog muscles, in which the muscle action potential was elicited by stimulating the motor axon, it was assumed that the maximum of the curve corresponds to the end-plate region, and that the slopes on both sides indicate bi-directional conduction of the action potential.

The effect of acupuncture on the grasp reflex caused by mechanical vibrations of fingers produced by a cylinder-type vibrator (120 Hz) was studied in healthy man. As the hand grasped the vibrator during vibration, the volar surface of all fingers was simultaneously stimulated, resulting in a gradually increased force of the grasp, the vibration-induced grasp reflex (VGR). The VGR was inhibited by acupuncture with needles inserted into three acupuncture points (Shou Sanli, Chicheng and Szutu), but not into other sites in the hand.

Through intracellular observations of the cat spinal motoneuron both mono- and polysynaptic reflex arcs were shown to participate in repetitive activation of stretch reflex. Experiments were performed on 25 cats anesthetized by intraperitoneal (i.p.) injection of 3 cc/kg of a mixture of 1% chloralose and 10% urethane. Driving of the motoneuronal discharges accomplished by electric stimulation (16-100 Hz) of the gastrocnemius lateralis and medialis nerves. Repeated electric stimulation of muscle nerves elicited monosynaptic "vibratory" EPSPs and a polysynaptic "augmenting" EPSP in the motoneuron. The firing of the motoneuron occurred when a temporal summation of the "vibratory" EPSPs was sufficiently obtained. The discharge frequency of motoneuron, MNf, was expressed as a product of electrostimulus frequency, Sf, and reciprocal of an integer, n, i.e. MNf=(1/n)Sf. An increase in the stimulus intensity resulted in a dimimution of the vibratory EPSP and a remarkable increase of n. This was assumed to be due to an inhibitory process produced by the Group II fibers. The minimum value of integer n was always a determinant factor for the maximum value of MNf which was referred to as the "preferred" frequency of the motoneuron. Long-lasting electric stimulation of muscle nerves was followed by a more remarkable recruitment of the augmenting EPSP which made the motoneuron attain its critical threshold of firing. Motoneuronal spikes elicited by such a large augmenting EPSP were not locked to the Ia impulses. Unlocked spikes were observed only in a later stage of electric stimulation of Ia fibers.

By using a new method, unidimensional latency-topography, which shows the saltatory conduction pattern of an impulse along peripheral nerve fibers, the internodal length, internodal conduction time and conduction velocity were determined from the L5 ventral and/or dorsal root filaments of clioquinol-treated rats (CTR). The saltatory conduction pattern was preserved in most of the CTR fibers tested, but was not seen in some fibers. A positive correlation was seen between the conduction velocity and the internodal length in the nerve fibers of both the normal rats and CTR. Although there was no difference in the internodal length between normal rats and CTR, conduction velocities determined in CTR fibers were lower than those in normal rat fibers. Myelin length was calculated from the saltatory conduction pattern in the topography to represent the functional length of the saltatory conduction. The functional myelin length of the CTR fiber was shorter than that of normal rats. Shortening of the functional myelin length in CTR is due to the widening of the Ranvier node, which corresponds to the exposure of the Ranvier node, i.e. demyelination. It was concluded that the decrease in conduction velocity in CTR fibers was due to exposure which caused delayed excitation at the Ranvier nodes.

A new computer-aided method was developed to estimate the location of an electric source generator (e.g. a current dipole) in the human brain. Brain activity such as somatosensory evoked potentials was recorded with 21 surface electrodes over the scalp. To solve the inverse problem, it was assumed that only one dipole is elicited at a given time, and that the head is embedded in an infinite and homogeneous conductor. The exact geometry of the human head was measured from 17 slices of CT-images of a real head to arrange a human head model. A dipole with a given moment and location is assumed in the head model. Potential distribution elicited by the dipole is compared with potential distribution which was the actual recorded one. The optimal dipole location was calculated, using the simplex method. Hence, the optimal dipole moment was obtained. The accuracy of estimation as an equivalent dipole was expressed in terms of dipolarity.

The energy spectra of photoproduced π + and π - from C, Al, Ca, and Cu have been measured at 90° in the laboratory system using 250-MeV bremsstrahlung. The pions were detected by a magnetic spectrometer. The π - /π + yield ratios obtained from the measured spectra and the A-dependence of the cross sections are discussed as a function of the pion kinetic energy.

Measurement of the photoproduced two neutral pions from hydrogen was performed up to 730 MeV by detecting the both pions by means of thier decay gamma rays in coincidence. The differential cross section, we obtained, around 600 MeV is close to zero within our statistics and is consistent with the static model calculation. The cross section around 700 MeV, however, is about 0.25 µ b /(sterad) 2 at θ π 1 =θ π 2 =55° in the laboratory system.

1. Both in human subjects and monkeys, the tonic vibration reflex, TVR, was observed during vibratory stimulation of the muscle. In the latter, TVR reaches its maximum soon after vibratory application.2. In the monkey, unitary EMG was recorded during vibratory stimulation and nonsequential interspike interval histograms were obtained. Intervals of unitary EMG were shown to occur on the principle of integer multiplication of the vibratory cyclic time.3. A gradual increase or decrease of TVR during vibratory stimulation in the human subject or the monkey is effected by the EMG discharges of shorter or longer firing intervals which occur on this principle.4. Both in human subjects and monkeys, the TVR becomes larger with the higher range of vibratory frequency. Beyond a certain vibratory frequency the TVR shows a gradual decrease. The relationship between the TVR and the vibratory frequency was called the TVR-f relation. There is an optimal frequency of vibratory stimulation for producing the largest TVR tension.5. The size of the reflex tension from TVR-f relation depends on the discharge frequency of the unitary EMG, which occurs according to the principle of the integer multiplication of original vibratory cyclic time.

1. Tonic activation of muscular activity was observed during forced vibration of the gastrocnemius and soleus muscles in the decerebrate cat. Such tonic activity was not observed in the tibialis anterior muscle.2. Intervals of both unitary EMG and motoneuronal spikes were shown to occur according to the principle of integer multiplication of vibratory cyclic time.3. Gradual recruitment of tonic vibration reflex (vibratory facilitation) was found to survive after the cessation of vibratory stimulation (postvibratory facilitation).4. Nonsequential interspikes revealed that gradual tonic recriutment is effected by the spikes with a shorter firing interval.5. Muscle activities during TVR may be effected by PTP with some excitatory frequency associated with that of the applied vibration.6. Postvibratory facilitation did not correlate with the vibratory frequency. The firing of such phases may be determined by the intrinsic repetition rate of the individual motoneuron.

1. Vibratory stimuli from 25-500c/s were applied to the cat's triceps surae muscle. The group Ia discharge from the muscle spindle was obtained from the dorsal root filament.2. The new term “response ratio”, which shows the number of spikes res ponding to one cycle of vibration, was used and this ratio observed at every vibratory frequency.3. There were sometimes a few gaps or valleys in the response's ratiofrequency curve, the frequency of which showed simple integral relations, such as one to two or two to three.4. The discharge patterns at every frequency changed in a staircase manner.5. It was discussed that these phenomena may be due to the physical properties of each muscle spindle.

The muscle spindle is a very sensitive recording instrument and is here found to change its level of excitability, despite de-efferentation, after tendon taps or submaximal contraction, as shown by prolonged changes in its frequency of discharge. It is suggested that this effect often is due to mechanical displacement, but since it is influenced by injection of Flaxedil, the intrafusal end plates may well be spontaneously active in the normal state. Flaxedil causes full paralysis of extrafusal motor end plates at a time when intrafusal gamma end plates are far less influenced.

The aim of this paper is to find a mathematical expression for the inherent properties of muscle spindles as indicators of phasic changes. Rate of change of muscle extension and rate of change of interval between two successive spindle discharges have been measured and plotted, one against the other. Their ratio has been found constant at different rates of stretch. This is the spindle constant, defined in the paper.

The relationship between vibration and human motor unit spikes elicited by reflex and voluntary actions was studied by means of cross-correlograms. Using this method motor unit spikes could be classified into two categories, locked spikes with good correlation to vibratory frequency and unlocked ones with poor correlation to vibratory frequency.1. Inter-spike intervals of the locked spikes were integer multiples of the cyclic time of the vibration used. This suggests that the locked spikes are elicited by the firing of α-motoneurons that are activated by monosynaptic transmission of Ia vibratory afferents.2. Locked spikes are only elicited immediately after vibratory application. Spike frequency soon attains its maximum and frequency plateau level is then maintained.3. Unlocked spikes are slow in appearance and a gradual increase of their spike frequency is a characteristic feature. Increase of the total motor unit spike frequency is therefore attained by the recruitment of unlocked spikes even without apparent increase in the frequency of the locked spikes. This mechanism is held to explain the gradual increment of the tonic vibration reflex activity.4. It is suggested on the basis of previous work (HOMMA and KANDA, 1973) that polysynaptic transmission caused by sustained Ia vibratory afferent activity elicits a slowly increasing EPSP which is directly responsible for the unlocked spikes.5. Vibration superposed upon a voluntary effort elicits a considerable increase of locked spikes. These may be the sum of motor unit spikes activated by vibratory Ia impulses and other Ia impulses whose firing had become locked to the vibratory stimuli though originally driven by the gamma loop mobilized by voluntary command.6. It is thus maintained that the unlocked spikes are elicited either by direct voluntary a-activation or by the polysynaptic slowly rising EPSP.7. Data collected in the present study revealed that the ratio between unlocked and r-loop driven spikes was 1: 2.4. Since alpha-gamma linkage characterises voluntary command, an α-γ co-activation ratio of 1/2.4 in a light voluntary contraction suggests that under the circumstances indirect loop-activation would be dominant.

Surface electromyographic (EMG) activity was recorded from the rectus femoris, vastus medialis, biceps femoris, gastrocnemius and tibialis anterior in the human lower extremity while subjects performed bicycling movements over a range of constant pedalling velocities. Kinematics of knee and hip cyclical movements were analyzed from 16 mm film. The reciprocal pattern of activation in agonist and antagonist muscles and timing of EMG initiation relative to knee joint were studied. Reciprocal activation of rectus femoris and biceps femoris muscles was generally observed to occur during the mid-extension or mid-flexion phase of knee movements. This timing of activation pattern coincided well with the period of peak angular velocity and zero angular acceleration. As pedalling speeds approached maximum, activation times of the bifunctional, biarticular rectus femoris, biceps and gastrocnemius muscles were considerably advanced in phase relative to knee joint angles, whereas, EMG initiation of monofunctional, single joint, tibalis anterior and vastus medialis muscles maintained a relatively stable knee position-activation time relationship. At higher velocities, biceps femoris EMG activity was characterized as having a double burst pattern of activation. A less distinctive double burst pattern was seen in the rectus femoris EMG at higher cycling speeds. EMG pattern analysis of the rectus and biceps femoris muscles revealed an earlier onset of activity for both muscles during maximum cycling velocities, relative to cyclical phases of the knee joint angle. Considerable overlapping of the EMG bursts was seen beyond pedalling rates of 1 Hz. Co-contraction between rectus femoris and biceps femoris muscles could be observed during the acceleration period involving an abrupt switch to maximum pedalling performance. When co-contraction was observed, the joint angular acceleration curves observed during the knee flexion period accounted for a larger portion of a single cycle, and were more irregular than the angular accelerations observed during knee extension.

It is known that the vibration-induced grasp reflex (VGR) is inhibited by the insertion of needles into the acupuncture points. Effects of intravenous administration of naloxone on acupuncture inhibition of the VGR were studied in human subjects to determine if acupuncture inhibition of the VGR might be mediated by endogenous opioids. Acupuncture inhibition of the VGR was partly reversed by the administration of naloxone. The VGR is mediated by a polysynaptic pathway through which the acupuncture inhibition that is reversed by naloxone is considered to occur. We conclude that the facilitatory influence of interneurons on motoneurons in the VGR was reduced by endogenous opioids to inhibit the VGR.

It has been known that primary spindle impulses elicited by stimulation of gamma fusimotor fibers follow the rhythm of the stimulation (Kuffler et al., 1951). This is called ‘driving’ and is thought to be due to rapid contraction of the nuclear chain fibers (Crowe and Matthews, 1964; Bessou et al., 1968). Nakajima (1975) showed that during the stimulation of a static fusimotor fiber at 100 Hz, a peak appeared in the cross-correlograms between the stimulus pulses and the primary spindle impulses. This means that each stimulus to a static fusimotor fiber evokes one primary spindle impulse which is time-locked to the stimulus pulse. Using various kinds of regular stimulation frequencies, Hulliger (1979) described modulated distribution of primary spindle impulses in poststimulus histograms, and analyzed the relation between the root mean square deviation of the modulation and stimulation frequency. In the relationship it became clear that the degree of modulation depends on stimulation frequency. But not all static fusimotor action drives primary spindle endings (Crowe and Matthews, 1964; Brown et al., 1965; Bessou et al., 1968). On stimulation, static fusimotor fibers that produce no peaks or modulation are found in cross-correlograms or in poststimulus histograms (Nakajima, 1975; Hulliger, 1979).

Using the dipole-tracing method, the source generators of N 18 , P 22 and P 40 of the somatosensory evoked potential (SEP) were estimated as the equivalent dipole. After voluntary action of the thumb flexion, no changes were observed in N 18 or P 40 , but the amplitude of P 22 was suppressed. The after-effects of intention accompanied by a voluntary action or the subject's awareness that electrical stimulation will be given after the voluntary action were treated as ‘awareness’. By subtracting the pure SEP from SEP during ‘awareness’, it was found that the equivalent dipole of ‘awareness’ of P 22 was located at the same region of pure P 22 , but the vector was of opposite orientation. ‘Awareness’ attenuated the perceptive potential of SEP like P 22 generated in the cortex.

Experiments were performed on anemically decerebrated cats. Motoneuronal activity in the spinal cord was intracellularly or extracellulary recorded and muscle vibration or electrical stimulation of the peripheral nerve was applied for 1 s every 2 s. Such stimulation elicited monosynaptic responses and afterdischarge, a response which lasts after cessation of the stimuli. Stimulus frequencies from 50 to 200 Hz were effective in eliciting the afterdischarge, while frequencies higher or lower than this range of stimulation were ineffective. The interspike intervals of the motoneuron afterdischarge were almost constant and did not correspond to the stimulus frequency. The mean intervals obtained from the motoneurons examined ranged from 70 to 120 ms. Power spectrum analysis of the membrane potential ripples recorded immediately after stimulation revealed increased activity at 38 and 62 Hz components. Since the spike interval of the afterdischarge in this motoneuron was 80 ms, the interval was almost equal to 5- and 3-fold the cyclic time of the increased frequency components. This indicates that the interval of afterdischarge was determined by the specifically increased frequency components of the membrane potential ripples.

Based on data obtained from intracellular recordings of cat alpha-motoneurons in the stretch reflex, the firing process of these motoneurons was computer-simulated. The impulse response EPSP (IR-EPSP) was simulated to correspond to a monosynaptic mass EPSP elicited by a spindle afferent volley, while the returning potential was simulated to correspond to a potential gradient rising toward an augmenting depolarization of the membrane (augmentative EPSP) after motoneuronal spike generation. The IR-EPSPs were generated by input at random intervals and added to each other, linearly, on the returning potential. As soon as the resultant potential attained the critical threshold level, Vth, motoneuron firing occurred. Then IR-EPSPs were again added to the returning potential until another motoneuron firing occurred. This process was repeated continuously, and the time relation between input and output, lag-time distribution (PT(T)), was determined Distribution of the bias potential, PV(v), from which the motoneuron spike triggering EPSP started to rise, was also calculated. The relations between PT(T), PV(v) and a waveform of the IR-EPSP were obtained analytically. The relation indicated that the shape of PT(T) corresponds to a time derivative of the rising phase of the IR-EPSP if the PV(v) distribution is uniform. In this study, we investigated the possibility of making the PV(v) distribution uniform.

Nerve impulses are generally regarded as spike train and analyzed by use of various kinds of so-called time series analyses. Cross-correlation analysis is used to reveal temporal and/or spatial relationships between more than two spike trains in the neuronal circuit, in which two neurons are synaptically connected or two neurons are independent but receive a common input. Three main characteristics of discharge dependency between two neurons become clear from the cross-correlation histogram: 1) the direction of dependency; 2) the latency of interaction; and 3) the type of functional connections between the neurons. We reviewed the cross-correlation analysis from these points of view: 1) what is cross-correlation analysis; 2) what are primary and secondary effects; 3) what kinds of functional information can be obtained from the shape of the primary effect; 4) how sensitively cross-correlation can detect neuronal interaction; 5) how to express quantitatively the primary effect; 6) what kinds of extension technique are available from cross-correlation; and 7) research trends using cross-correlation analysis.

Conduction velocity (CV) of an action potential recorded from a single muscle fiber of the frog was measured with a new method, unidimensional latency-topography, and electrical membrane constants were determined for the same muscle fiber. CV = 1.96 +/- 0.27 m/sec (n = 52) at about 20 degrees C. Temperature coefficient of CV: Q10 = 2.0. Electrical membrane constants in the same muscle fibers (n = 52): lambda = 3.25 +/- 0.83 mm, tau = 33.4 +/- 14.3 msec, Cm = 6.09 +/- 2.13 mu F/cm2, D = 129.4 +/- 28.9 micron (mean +/- S.D.). The CV decreased linearly with increment of time constant, tau, and membrane capacity per unit area, Cm. The space constant, lambda, and the fiber diameter of the muscle fiber, D, did not correlate with CV. It was concluded that the T-system, which contributes largely to membrane capacity, has a great influence on the CV.

The ligamentum patellae in human subjects was tapped by a random triangular waveform, while single primary spindle afferent spikes were recorded from the femoral nerve. Cross-correlation between the primary spindle afferent spikes and the taps revealed a prominent peaked distribution of the discharge probability. The cross-correlograms showed that response time from the onsets of taps to the afferent spike was 7.5 +/- 0.6 msec in 6 units and that the width between the feet of the peaked distribution was 3.3 +/- 0.2 msec in 6 units. The width of the peak implies jitter of the response time of the primary spindle spikes which appear to correspond with the time-to-peak of generator potentials elicited by the taps in primary endings of muscle spindles. Integration of the peaked distribution showed a slow slope at the beginning and near the summit and a steep slope on the way. This curve is assumed to represent the rising phase of the generator potentials in primary spindle endings.

1. Firing patterns of Ia afferents and motoneuron efferents were recorded while subjecting homonymous de-efferented triceps surae muscle to vibration applied longitudinally to the tendon.2. The amplitude of vibration (ΔL) necessary to elicit the preferred firing rate of each motoneuron was noted over a wide range (20 to 180cps) of vibration frequencies (f). This permitted the plotting of a ΔL-f curve for each motoneuron, the area above the curve being termed the “response area” and the frequency associated with the minimal ΔL being termed the “optimal frequency” of vibration. In general preferred firing rates ranged from 6 to 13imp/sec and the optimal frequency was near 100cps.3. These parameters of vibrator responsiveness were measured before and after post-tetanic potentiation. They were also measured before and during concomitant stretch of a synergist and stimulation of antagonistic afferents. The facilitatory effect of post-tetanic potentiation and stretch of the synergistic muscle resulted in a broadening and downward shift of the Δ-f curve to the right. This indicated an increase in response area and shift in optimal frequency to a higher value. Reverse inhibitory effects were noted during stimulation of antagonist afferents.4. Similar parameters were generated for Ia afferents by studying their vibrator responsiveness at arbitrarily fixed rates of 20 and 10imp/sec. The optimal frequency of vibration was quite similar for afferents (20imp/sec) and efferent, as were the ΔL values associated with this frequency. The further vibration frequency was removed from the optimal frequency the more pronounced became the difference in ΔL requirements, far less amplitude of stretch being necessary to maintain the selected Ia firing rate. There is a discussion of mechanisms underlying the difference in profile of ΔL-f curves for Ia afferents and motoneurons.

Systematic measurements of the maintained discharge to stretch at time 4–5 sec from onset have been carried out with 69 muscle spindles in ankle extensors and flexors of anaesthetized rabbits. Three main types of spindles can be separated on the basis of rate of discharge, slow, medium and fast spindles. The number of fast spindles is greater in fast muscle. Slow and medium spindles only are found in slow muscle.

1. A skin polarization curve was induced by a minute electrode using rectangular voltage pulses.2. A higher polarizability exsists in sweat pores. The polarization curve led by a large electrode hitherto came from the sweat pores.3. When a large current is charged on the sweat pores which are units of skin polarizability with the minute cathode, a large depolarization occurs which seems as an expression of excitation of the tissue under sweat pore. On the other hand a repolarization occurs when the minute electrode is anode.

1) The skin plays an important role in interfering with the measurement of threshold value of electric stimulation of nerves and muscles in the human body.2) It is possible to measure the threshold of the nerve or muscle by balancing the polarization in the skin. This is called a Balancing Network Method3) Explanations were given on a simple arrangement used for measuring the threshold clinically.4) The true V-t curve was obtained by eliminating the influence of the skin by the B.N.M. The values of chronaxie and rheobase were calculated theoretically. The values of four kinds of nerves and muscles were compared with each other.5) Explanations were given on the measurement of the constant concerning the slope factor.6) Explanations were given on the measurement of threshold for AnOC.