Role of propriospinal neurons in inhibition of the afferent flow

The effects of stimulation of the dorsal funiculus on dorsal surface potentials (DSPs) of the spinal cord evoked by stimulation of a peripheral nerve and on antidromic action potentials (AAPs) evoked by stimulation of terminal branches of primary afferent fibers and recorded from the afferent nerve or dorsal root, were investigated in acute experiments on spinal cats and on cats anesthetized with pentobarbital and chloralose. Stimulation of the dorsal funiculus led to biphasic inhibition of the N₁-component of the DSP with maxima at the 15th–30th and 60th–80th milliseconds between the conditioning and testing stimuli. Maximal reinforcement of the AAP was found with these intervals. Bilateral division of the dorsal funiculi between the point of application of the conditioning stimuli and the point of recording the DSP abolished the first wave of inhibition of the DSP and the reinforcement of the AAP. After total transection of the cord above the site of conditioning stimulation the picture was unchanged. It is concluded that the initial changes in DSP and AAP are due to activation of the presynaptic inhibition mechanism by antidromic impulses traveling along nerve fibers running in the dorsal funiculus. Repeated inhibition of the DSP, like reinforcement of the AAP, can possibly be attributed to activation of similar inhibitory mechanisms through the propriospinal neurons of the spinal cord.Dnepropetrovsk State University. Translated from Neirofiziologiya, Vol. 5, No. 4, pp. 401–405, July–August, 1973.     

Activity of propriospinal neurons in segments C3 and C4 during fictitious locomotion in cats

Activity of propriospinal neurons in segments C3 and C4 was recorded in immobilized decerebrate cats, whose spinal cord was divided at the lower thoracic level, during locomotor activity of neuronal mechanisms controlling the forelimbs (fictitious locomotion of the forelimbs). Neurons were identified according to antidromic responses to stimulation of the lateral column of the spinal cord at level C6. Antidromic responses also appeared in 70% of these neurons to stimulation of the medullary lateral reticular nucleus. During fictitious locomotion, i.e., in the absence of afferent signals from the limb receptors, rhythmic modulation of the discharge of most neurons was observed, correlating with activity of motoneurons. If the rostral region of the cervical enlargement of the spinal cord was cooled, causing generation of the locomotor rhythm to cease, rhythmic activity of propriospinal neurons in segments C3 and C4 also ceased. The main source of modulation of activity of propriospinal neurons in segments C3 and C4 is thus the central spinal mechanisms controlling activity of the forelimbs.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. M. V. Lomonosov Moscow University. Translated from Neirofiziologiya, Vol. 17, No. 3, pp. 320–326, May–June, 1985.     

Effect of preliminary mechanical and antidromic influences on orthodromic activity in C fibers from mechanoreceptors of the cat skin

Analysis of afferent activity in unmyelinated fibers of a cutaneous nerve was carried out by the colliding impulses method in cats. The effect of antidromic excitation of the nerve and mechanical stimulation of the receptors on subsequent orthodromic activity during stretching of the skin was investigated. Both these factors were shown to reduce subsequent orthodromic activity evoked by testing stimulation. The reduction in activity was greatest 10–15 sec after stimulation. The duration of the inhibitory effect was greater after mechanical than after antidromic stimulation. Combined mechanical stimulation and antidromic excitation resulted in a greater decrease of afferent activity and an increase in the time of its recovery. An increase in the frequency of antidromic excitation potentiated the inhibitory effect of preliminary stimulation on orthodromic activity in C fibers.Research Institute of Applied Mathematics and Cybernetics, N. I. Lobachevskii Gor'kii State University. Translated from Neirofiziologiya, Vol. 9, No. 3, pp. 307–312, May–June, 1977.     

Activity of lumbar interneurons during fictitious locomotion in thalamic cats

Unit activity of the lumbar interneurons was recorded in thalamic cats during fictitious locomotion. Neurons whose activity was modulated in the rhythm of fictitious locomotion were found in the lateral parts of the intermediate zone of gray matter and ventral horn. Of these neurons, 41.2% were activated mainly in the phase of "flexion," 48.5% in the phase of extension, and 10.3% in both phases. Neurons with tonically increasing or decreasing activity during rhythmic discharges and neurons whose activity was unchanged during fictitious locomotion also were observed. During later discharges all these neurons were similarly activated, although a depth of modulation of unit activity was lower than during fictitious locomotion. Afferent inputs to the recorded interneurons also were studied. The neuronal organization of the spinal locomotor generator is discussed on the basis of these results.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 11, No. 4, pp. 329–338, July–August, 1979.     

Limb movement,intensity of integral afferent impulses from limb receptors,and level of primary afferent terminal polarization during locomotion in cats decerebrated at high level

The relationship between parameters of electrical muscle activity, changes at hindlimb joint angles, intensity of integral afferent flow, and dorsal root potential during real-life locomotion was investigated in cats decerebrated at high level. Characteristics of rear limb movements before and after deafferentation were described. It was found that afferent activity during locomotion motion consists, of two components — a tonic and a periodic phasic stage. Three main waves may be distinguished in the latter, each of which gives rise to associated changes in the level of primary afferent terminal polarization. These changes in turn are summated with the effects produced by the central generator. Correlations, between the parameters of these processes were investigated and the mechanisms underlying afferent control of locomotion generator function discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 119–127, January–February, 1988.     

QTLs and epistasis underlying activity of acid phosphatase under phosphorus sufficient and deficient condition in rice (Oryza sativa L.)

Eighty-four selected lines from a recombinant inbred (RI) line population of 284 lines derived from a cross between the indica varieties IR20 and IR55178-3B-9-3 were used in a hydroponic culture experiment with sufficient P supply (10 mg P L^–1) and P-deficient stress (0.05 mg P L^–1). After 2 weeks, the activity of acid phosphatase (AAP) in roots of each parent and each line from both normal culture and P-deficient stress was determined. QTLs for AAP, P-deficiency stress induced AAP (Psi-AAP) and relative AAP (RAAP) were detected using 178 molecular markers mapped on all 12 chromosomes based on single marker analysis and interval mapping. One QTL for AAP and three QTLs for Psi-AAP were detected on chromosome 1, 6 and 12, respectively. Two QTLs for RAAP were identical with these for Psi-AAP on chromosome 6 and 12. The results in this case indicated that the genetic system for Psi-AAP was different with that for AAP under normal culture. The AAP was mainly influenced by interaction among muti-factors, while Psi-AAP was controlled by a Psi genetic system.     

Neuronal firing activity in the lateral vestibular nucleus during locomotion in the guinea pig

The effects of spontaneous locomotor activity on neuronal background firing in the lateral vestibular nucleus was investigated during experiments on decerebrate guinea pigs. The onset of rhythmic muscular activity in the extramities was found to produce a rise in the rate of such discharges, which increased from 10–15 to 100 spikes/sec in most neurons. A higher rate occurred as activity began in the ipsilateral forelimb extensor muscles (the stage corresponding to the end of the swing phase and start of the stance phase in the locomotor cycle). The alterations noted in vestibular neuronal activity during locomotion are thought to ensure the background of high anti-graveity muscle tonus against which rhythmic limb movements take place.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 536–541, September–October, 1991.     

Heart and circulatory functions in a spider (Eurypelma californicum): the effects of hydraulic force generation

Summary In the tarantulaEurypelma californicum, the relationships between heart activity, circulation and the generation of hydraulic pressure for locomotion were studied. Several new techniques were employed.Mean resting heart rate was 21 beats min^–1 rising to 90 beats min^–1 after burst activity. Decay time to resting rates was related to the increase of heart rate. Post-recovery resting rates were usually elevated in comparison with rates after very long resting periods.A relative measure of heart amplitude was obtained. Four distinct patterns could be distinguished: (i) regular beats; (ii) short-term fluctuations of amplitude within a few heart beats; (iii) a slow rhythmic change of heart/pericardium filling, and (iv) non-periodic, stronger amplitude changes during periods of activity.During locomotion, heart rate rises with maximum rates often reached only minutes after the onset of activity. The rising phase is often characterized by irregularities and a reduction of heart amplitude.Prosomal hemolymph pressure in resting, restrained animals was 41±19 Torr, rising to ca. 90, and 217±48 Torr during walking and fast sprints, respectively. Values in unrestrained spiders were similar. Opisthosomal hemolymph pressures were ca. 20 Torr in resting animals, rising to 40–60 Torr during locomotion.Opisthosomal volume changes were measured. A small volume of hemolymph moved from the prosoma to the opisthosoma at the onset of locomotion, but following activity this volume quickly returned to the prosoma.The simultaneous measurement of carapace depression, opisthosomal volume changes and hemolymph pressures, and heart activity revealed the relationship between circulation and hydraulic force generation. The direction of hemolymph flow was also studied. In non-active animals, the heart occasionally changes its main pumping direction. During locomotion, hemolymph flow from the heart to the prosoma is often reduced or stopped. With a slight delay, hemolymph flow to the opisthosoma is increased. The critical pressure at which prosomal perfusion from the heart is halted is 50–70 Torr.It is concluded that anterior and posterior circulations are separate: hemolymph returning from the prosoma passes only through the anterior lungs, while hemolymph returning from the opisthosoma passes through the posterior lungs.Dedicated to Dr. Rosemarie John, in recognition of her unflagging enthusiasm and support for zoological researchProf. B. Linzen unexpectedly died on August 5, 1988     

Unit responses of the first and second somatosensory areas to stimulation of the ventroposterior thalamic nucleus

Single unit responses of the first (SI) and second (SII) somatosensory areas to stimulation of the ventroposterior thalamic nucleus (VP) were investigated in cats immobilized with D-tubocurarine. In response to VP stimulation 12.0% of reacting SI neurons and 9.5% of SII neurons generated an antidromic spike. In most antidromic responses of both SI and SII neurons the latent period did not exceed 1.0 msec. The minimal latent period of spike potentials during orthodromic excitation was 1.5 msec in SI and 1.7 msec in SII. Neurons with an orthodromic spike latency of not more than 3.0 msec were more numerous in SI than those with a latency of 3.1–4.5 msec. The ratio between the numbers of neurons of these two groups in SII was the opposite. In SII there were many more neurons with a latency of 5.6–8.0 msec than in SI. EPSPs appeared after a latent period of 1.1–9.0 msec in SI and of 1.4–6.6 msec in SII. The latent period of IPSPs was 1.5–6.8 msec in SI and 2.2–9.4 msec in SII. The relative importance of different pathways for excitatory and inhibitory influences of VP on SI and SII neurons is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 8, No. 2, pp. 115–121, March–April, 1976.     

Phase-dependent changes in dorsal root potential during actual locomotion in rats

Fluctuations in dorsal root potential (DRP) were investigated in trials on white rats during two types of locomotion, differing in the intensity of afferent flow (swimming and walking). Two negative waves of DRP were observed corresponding to the stance (or propulsive) phase and the swing (or transfer) phase within a single locomotor cycle. Whereas DRP had risen primarily during the stroke phase with increased intensity during swimming, it increased during the standing phase in walking. A relationship was revealed between the amplitude of DRP and the intensity of afferent flow apparent during passive displacement of the limb, as well as locomotion. It is concluded that DRP waves are mainly due to influences from peripheral afferents during actual locomotion.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 3, pp. 333–340, May–June, 1988.     

Responses of medial geniculate body neurons to auditory cortical stimulation

Extracellular and intracellular unit responses of thepars principalis of the medial geniculate body to stimulation of the first (AI), second (AII), and third (AIII) auditory cortical areas were studied in cats immobilized with D-tubocurarine. In response to auditory cortical stimulation both antidromic (45–50%) and orthodromic (50–55%) responses occurred in the geniculate neurons. The latent period of the antidromic responses was 0.3–2.5 msec and of the orthodromic 2.0–18.0 msec. Late responses had a latent period of 30–200 msec. Of all neurons responding antidromically to stimulation of AII, 63% responded antidromically to stimulation of AI also, confirming the hypothesis that many of the same neurons of the medial geniculate body have projections into both auditory areas. Orthodromic responses of geniculate neurons consisted either of 1 or 2 spikes or of volleys of 8–12 spikes with a frequency of 300–600/sec. It is suggested that the volleys of spikes were discharges of inhibitory neurons. Intracellular responses were recorded in the form of antidromic spikes, EPSPs, EPSP-spike, EPSP-spike-IPSP, EPSP-IPSP, and primary IPSP. Over 50% of primary IPSP had a latent period of 2.0–4.0 msec. It is suggested that they arose through the participation of inhibitory interneurons located in the medial geniculate body.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 8, No. 1, pp. 5–12, January–February, 1976.     

Comparative analysis of the kinematics of hind limb movements in rats during different kinds of locomotion

A comparative analysis of phases of the locomotor cycle and the dynamics of changes in hind limb joint angles during swimming and stepping movements (on a treadmill), involving the fore- and hind limbs to different degrees, were undertaken in rats. Differences in the sequence and degree of changes in joint angles during locomotion of the types investigated were participation of the forelimbs in locomotion was found to be accompanied by more marked forward carrying of the hind limb. Dependence of the swing phase on duration of the cycle was observed and differences were found in the period of protraction of the limb (F period) during swimming and stepping. The role of central spinal processes and influences of peripheral afferents in the formation of different types of locomotion is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 17, No. 2, pp. 189–198, March–April, 1985.     

Antidromic indentification of hypothalamic neurosecretory cells in rats

Characteristics of antidromic action potentials of neurons of the paraventricular and supraoptic nuclei of the rat hypothalamus were studied during stimulation of the hypothalamo-hypophyseal tract by stimuli of varied amplitude and frequency. Step-like changes were found in spike latency in response to an increase in strength (up to 1.5–2.5 thresholds) or frequency (over 100 Hz) of stimulation, as well as cases with variation of the degree of division of the peak into A and B components. Injection of leu-enkephalin analog into the third ventricle or intravenous injection of NaCl solution (1 M) caused reversible changes in the level of excitability of antidromically activated neurons: leu-enkephalin mainly increased the latent period and threshold of action potential generation and reduced the reproducible frequency of stimulation to 10 Hz, whereas NaCl had the opposite effect. The results indicate that when the adopted criteria of antidromic identification of neurosecretory cells are used the level of their excitability must be taken into account.A. A. Ukhtomskii Physiological Research Institute, A. A. Zhdanov Leningrad State University. Translated from Neirofiziologiya, Vol. 14, No. 6, pp. 585–591, November–December, 1982.     

Active selection of afferent information as the basic principle of peripheral correction of the activity of spinal rhythmic movement generators

This paper summarizes information obtained in the experimental study of the dynamics of polarization of central primary afferent endings and modifications of segmental responses to afferent stimuli during fictitious locomotion and fictitious scratching in immobilized, decorticated, decerebrate, and spinal cats. Fictitious locomotion was accompanied by tonic hyperpolarization, fictitious scratching by tonic depolarization of central primary afferent endings. Against the background of these long-lasting changes in primary afferent depolarization, it exhibited periodic changes in the rhythm of efferent activity. Periodic changes of depolarization were virtually in phase in different ipsilateral segments of the lumbosacral enlargement. Data on groups of afferent fibers in whose central endings tonic and phasic changes of polarization took place. The appearance of fictitious locomotion was accompanied by a tonic increase, and of fictitious scratching by tonic inhibition of several evoked segmental responses. These tonic changes were a background against which segmental responses were modulated in step with the working rhythm of the locomotion and scratching generators. Many of the changes in evoked segmental responses were shown to be based on modulation of polarization of central endings of primary afferents by locomotion and scratching generators. It is concluded that active tonic and phase-dependent selection of incoming afferent information is effected through modulation of presynaptic inhibition of the generator. The role of this selection in peripheral collection of activity of locomotion and scratching generators is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 16, No. 3, pp. 343–353, May–June, 1984.     

Polarization of primary afferent terminals in the lumbar spinal cord during fictitious locomotion

Changes in electrical polarization of primary afferent terminals in the lumbosacral portion of the spinal cord were investigated during fictitious locomotion in immobilized decorticated and spinal cats. Fictitious locomotion was accompanied by stable hyperpolarization of the afferent terminals, against the background of which they were periodically depolarized in rhythm with efferent activity. These tonic and phasic changes were observed in terminals of all groups of afferent fibers tested: cutaneous and muscular (Ia and Ib). Periodic in-phase depolarization was carried out in different ipsilateral segments of the lumbosacral enlargement. During ficitious galloping changes in depolarization of the primary efferents were in phase on different sides; during fictitious walking, these periodic changes were out of phase. On the basis of these results the physiological importance of changes in electrical polarization of primary afferent terminals of the spinal locomotor generator is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 5, pp. 481–489, September–October, 1980.     

Changes in antidromic discharges in peripheral nerves during polarization of the cat spinal cord by a steady current

The effect of a steady current passed through the spinal cord on antidromic discharges in primary afferent groups of Agb cutaneous nerves of the hind limb, evoked by single and paired stimulation of the terminals of these fibers, was investigated by Wall's technique in acute experiments on spinal and anesthetized cats. A current of up to 50–100 µA, flowing in the dorso-ventral direction, led to an increase in amplitude of antidromic dischanges evoked by single stimulation of afferent terminals; if the current flowed in the opposite direction, the opposite effect was observed. The relative degree of facilitation of antidromic discharges caused by conditioning stimulation of these same fibers was reduced by a polarizing current in either direction. It is suggested that the effects of the action of a steady current flowing through the spinal cord observed in these experiments are due mainly to shifts of membrane potential in primary afferent terminals.Dnepropetrovskii State University. Translated from Neirofiziologiya, Vol. 14, No. 4, pp. 386–391, July–August, 1982.     

Kinematics of different types of locomotor movements in the deafferented rat

The kinematics of rat hindlimb movements were assessed and compared pre- and post-deafferentation during swimming, forelimb treadmill locomotion plus hindlimb swimming motion, and walking using all four limbs. All types of locomotion were characterized by an increase in the frequency of locomotor rhythm and reduced amplitude of motion at the hindlimb joints following deafferentation. The reduced change observed in the angle of the coxofemoral joint, indicative of a horizontal component in locomotor motion, was mainly brought about by less marked extension. This would confirm evidence indicating that increased load on the extremities, with its ensuing naturally-occurring afferent outflow, is accompanied by a reduced locomotor motion rate and a rise in the amplitude of the latter due to intensified extension of the limb. The increased forward carriage of the hind limb seen during the transition to four-legged locomotion persisted after deafferentation; this may be considered a sign of coordination amongst the limbs. Deafferentation led to a reduction in the MEG of muscle activity, which was found to be lowest in swimming and highest during walking. The role of the afferent inflow in shaping different types of locomotor motion is evaluated.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 4, pp. 520–525, July–August, 1987.     

Classification of lumbosacral neurons by their discharge pattern during evoked locomotion

Unit activity was recorded in the lumbosacral division of the spinal cord during evoked locomotion in mesencephalic cats with the afferent fibers from their hind limbs intact or divided. If the afferent fibers were intact, all neurons recorded showed modulation of activity during locomotion in the rhythm of stepping movements. In experiments on cats with afferent fibers from the hind limbs divided modulation was absent in 30% of neurons, while in the modulated neurons, the frequencies in the excitation phase were approximately the same as when the limb innervation was intact. Modulation of activity in some neurons occurred in response to stimulation of the locomotor region even before stepping movements began. The tuning of the spinal generator of stepping movements is discussed.M. V. Lomonosov Moscow State University. Institute of Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 4, No. 4, pp. 410–417, July–August, 1972.     

Single unit responses of the reticular and ventral anterior nuclei of the thalamus to electrical stimulation of the centrum medianum

In acute experiments on cats anesthetized with thiopental (30–40 mg/kg, intraperitoneally) and immobilized with D-tubocurarine (1 mg/kg) responses of 145 neurons of the reticular and 158 neurons of the ventral anterior nuclei of the thalamus to electrical stimulation of the centrum medianum were investigated. An antidromic action potential appeared after a latent period of 0.3–2.0 msec in 4.1% of cells of the reticular nucleus and 4.4% of neurons of the ventral anterior nucleus tested in response to stimulation. The conduction velocity of antidromic excitation along axons of these neurons was 1.7–7.6 m/sec. Neurons responding with an antidromic action potential to stimulation both of the centrum medianum and of other formations were discovered, electrophysiological evidence of the ramification of such an axon. Altogether 53.8% of neurons of the reticular nucleus and 46.9% of neurons of the ventral anterior nucleus responded to stimulation of the centrum medianum by orthodromic excitation. Among neurons excited orthodromically two groups of cells were distinguished: The first group generated a discharge consisting of 6–12 action potentials with a frequency of 130–640 Hz (the duration of discharge did not exceed 60 msec), whereas the second responded with a single action potential. Inhibitory responses were observed in only 0.7% of neurons of the reticular nucleus and 4.4% of the ventral anterior nucleus tested. Afferent influences from the relay nuclei of the thalamus, lateral posterior nucleus, and motor cortex were shown to converge on neurons responding to stimulation of the centrum medianum.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 36–45, January–February, 1980.     

Effects of stimulation of peripheral nerves,the lateral reticular nucleus,and the inferior olive on fastigial neurons of the cat cerebellum

Activity of fastigial neurons was investigated during stimulation of peripheral nerves of the fore- and hind limbs and also of brain-stem nuclei — the lateral reticular nucleus and inferior olive, transmitting indirect peripheral impulses to the cerebellum, in cats under superficial pentobarbital anesthesia. Stimulation of the nerves was accompanied by excitation of most neurons tested, reflected in repeated discharges to a single stimulus. Three main groups of responses latencies were distinguished: Those corresponding to conduction of peripheral impulses along slow and (partly) fast spinocerebellar tracts were predominant. Stimulation of the lateral reticular nucleus and inferior olive was accompanied by mono- and polysynaptic, and also by antidromic activation of fastigial neurons. Monosynaptic and antidromic activation of neurons are regarded as evidence of the presence of direct reticulo-and olivofastigial projections and of feedback in the system of these inputs into the nucleus fastigius respectively.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 13, No. 2, pp. 168–178, March–April, 1981.