Influence of vibration on the spontaneous neuronal activity of the neurons of the superior vestibular nucleus

The results of vibration action (5, 10 and 15 daily) on spontaneous neuronal activity of superior vestibular nucleus were studied using software for biological signals. Average histograms and autocorrelograms were drawn up after computerized interspike interval analysis. The results have demonstated that neurons of superior vestibular nucleus have mean frequency 14.0 +/- 1.4 Hz. The results obtained suggest significant reconstruction of spontaneous impulse activity in neurons of the superior vestibular nucleus within postvibration period.     

Dynamics of the background impulse activity of neurons of the lateral vestibular nucleus in the norm and under vibrational influence

The background impulse activity (BIA) generated by neurons of the right lateral vestibular nucleus (LVN) of rats in the norm and under conditions of long-lasting general vibrational stimulation was subjected to computer analysis. Statistically significant changes in intragroup values of the mean BIA frequency were observed after 5 and 10 days with 2-h-long sessions of vibrational stimulation. Significant shifts in the distributions of LVN neurons by the level of regularity and dynamic types of BIA were observed 10 and 15 days with vibrational influences. Trends toward return of the intragroup mean value of the BIA frequency to the initial level were noticeable at the end of the stimulation period (15 days). Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 424–431, September–December, 2005.     

Postvibration changes in the spontaneous activity of neurons in the medial vestibular nucleus

The method of computer analyses was used for the research of the spectral changes of spontaneous neuronal activity of the medial vestibular nucleus ander vibration action (5, 10 and 15 daily). On the basis of neurons activity analyses it is possible to conclude that the majority of investigated units of flow and instability figured on different levels. The findings are discussed in respect to special points of functional meaning.     

Effect of ethanol on base activity of neurons of the lateral vestibular nucleus in the cat

Experiments with cats immobilized with arduane showed that a single intravenous injection of ethanol (1 g/kg) affects 95% of the neurons of the lateral vestibular nucleus. In 56.5% of the neurons that have predominantly high-frequency base activity of the continuously arrhythmic type, injecting ethanol decreased impulse frequency by 84–93%. In 14.5% of the cells, mainly with bundle-group type activity, there was first an increase in average discharge frequency, the duration of the bundles and number of impulses in them, were replaced by a sharp inhibition of base activity, even complete suppression, in 20–30 min after ethanol injection. In 23.6% of the neurons, predominantly with an initial low frequency of base activity, a clear excitation effect developed and was recorded over the whole period of observation. Restoration of base activity to the original level usually did not occur even after 90 min. Repeated injection of the same dose of ethanol had a cumulative effect.Ivano-Frank Medical Institute, Ukrainian Ministry of Public Health. Translated from Neirofiziologiya, Vol. 24, No. 2, pp. 145–151, March–April, 1992.     

Analysis of unit activity in the cat lateral geniculate body

Spontaneous and evoked single unit activity of lateral geniculate body neurons was recorded extracellularly in acute experiments on cats. Eight groups of neurons differing in the durations of the minimal and mean interspike intervals of spontaneous unit activity, and in the latent period and duration of the first volley of spikes of evoked activity, were distinguished by analysis of the data. On the basis of this classification a scheme for interaction between neurons of the lateral geniculate body is suggested.Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 10, No. 1, pp. 30–37, January–February, 1978.     

Analysis of spontaneous unit activity in the cat pyramidal tract

For a statistical analysis of spontaneous activity of cortical pyramidal neurons (PN) of the cat, recordings were obtained from axons of those neurons descending in the lateral pyramidal tract in lumbar segments of the spinal cord. Spontaneous activity of all investigated PN is not random in sequence but has a complex temporal structure. Three types of spontaneous activity were distinguished by the character of distribution of the interspike intervals (ISI); the degree of grouping of the spikes into volleys separated by long intervals increases from type I to type III. Type III is more often found in PN with fast-conducting axons. As a rule the number of volleys in the spontaneous activity differed from that expected by the hypothesis of random spike sequence. In some cases repetition of volleys with an identical, or nearly identical, temporal structure was observed. It is postulated that the type of spontaneous activity is determined by the functional state of the neuron and by its morphological properties. Experiments were carried out on two groups of animals: 1) briefly anesthetized a long time before the recording was obtained, and then immobilized; 2) anesthetized with chloralose and Nembutal. The differences between the character of spontaneous PN activity were mainly in the degree of grouping of the spikes (which was greater in the second group). Significant positive correlation was found between the velocity of conduction along the PN axon and the mean ISI of the spontaneous activity.A. A. Bogomolets' Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 4, No. 1, pp. 3–11, January–February, 1972.     

Effect of epidural spinal cord stimulation on the activity of lateral vestibular nucleus neurons in the cat

The activity of neurons in Deiters' lateral vestibular nucleus was recorded in decerebrate cats before, during and after spinal cord stimulation. An almost equal number of units were inhibited and excited early during stimulation. Later during stimulation the majority of units was inhibited. Early after cessation of stimulation an ever larger number of units were inhibited to an even larger extent (for about 2 imp/s on the average). Later after stimulus cessation the predominant inhibitory effect could still be noted, as well as excitation in some units. The results could support the hypothesis that the inhibition of Deiters' neurons during and for some time after epidural cord stimulation may play a part in the decrease of limb spasticity. The mechanism of inhibitory and excitatory unitary responses, side effects during stimulation and differences between the experimental model and human state are discussed.     

Analysis of spontaneous unit activity of the cat caudate nucleus

Spontaneous unit activity recorded extracellularly from the caudate nucleus in acute experiments on cats was analyzed. A graph of the sliding mean frequency, an interspike interval histogram, correlogram, intensity function, and histogram of correlation between adjacent intervals were plotted for the spontaneous activity of each neuron. The spontaneous activity of neurons of the caudate nucleus showed considerable variability in time and its mean frequency varied for different neurons from 0.5 to 20 spikes/sec. Depending on the temporal pattern of the spikes and also on the statistical indices, spontaneous unit activity in the caudate nucleus was conventionally divided into two types: single and grouped. A switch from one type of activity to the other was observed for the same neuron. On the basis of the data as a whole it is impossible to regard the spontaneous unit activity of the caudate nucleus as a simple random (Poissonian) spike train.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 9, No. 4, pp. 369–376, July–August, 1977.     

The effects of influence of electromagnetic irradiation of millimeter wavelength on background impulse activity of supraoptic nucleus' neurons of rats' hypothalamus

In conditions of acute experiment on white rats anaesthetized by Nembutal (40 mg/kg, intraperitoneally), the registration and analysis of background impulse activity of the supraoptic nucleus neurons of rats' hypothalamus in norm and after electromagnetic irradiation of millimeter wavelength on organism, were carried out. Distributions of neurons by the degree of rhythm regularity, the character of types of dynamics of the following impulse flows, the modality of histograms of interspike intervals, the average discharge frequency, the coefficient of interspike intervals variation, were found out. Changes of the background impulse activity which were related mainly to the changes of the inner structure of registered impulse flows, were revealed. Significant shifts were generally observed in the character of dynamics of neuronal current flows and degree of regularity of the impulse activity. Statistically significant changes of the average frequency of discharges of different frequency range neurons' populations were revealed.     

Randomness of spontaneous activity and information transfer in neurons

The analysis of information coding in neurons requires methods that measure different properties of neuronal signals. In this paper we review the recently proposed measure of randomness and compare it to the coefficient of variation, which is the frequently employed measure of variability of spiking neuronal activity. We focus on the problem of the spontaneous activity of neurons, and we hypothesize that under defined conditions, spontaneous activity is more random than evoked activity. This hypothesis is supported by contrasting variability and randomness obtained from experimental recordings of olfactory receptor neurons in rats.     

Comparative effects of amygdala and central gray matter of the midbrain on lateral hypothalamic unit activity

The effect of stimulation of the stria terminalis, the main afferent component of the amygdalo-hypothalmic system, and of the central gray matter and tegmentum of the midbrain on lateral hypothalamic unit activity was investigated in acute experiments on rats. Five types of unit responses were discovered: phasic excitation and inhibition, tonic activation and inhibition, and a biphasic response. In response to stimulation of the stria terminalis and lateral hypothalamus mainly inhibitory responses (62.7%) were recorded. As a result of stimulation of the central gray matter most lateral hypothalamic neurons (87%) were activated. Convergence of influences from the amygdala and tegmentum was observed on 14.4% of responding neurons. The structures had an antagonistic action on most (84.6%) of the lateral hypothalamic neurons tested.Institute of Physiology, Siberian Branch, Academy of Medical Sciences of the USSR, Novosibirsk. Translated from Neirofiziologiya, Vol. 9, No. 1, pp. 25–32, January–February, 1977.     

The presence of phosphatidylcholine in neurons isolated from the lateral vestibular nucleus of ox brain

1. Lipid was extracted from neurons isolated from the lateral vestibular nucleus of ox brain and examined by two-dimensional thin-layer chromatography. 2. The major lipids found were phosphatidylethanolamine and its plasmalogen, phosphatidylcholine, phosphatidylserine and cholesterol.     

Effect of vestibular,somatic, and autonomic afferent impulsation on vestibular nuclear unit activity in cats

Single unit responses in nuclei of the vestibular complex to stimulation of the labyrinths and of proprioceptive and autonomic afferents were investigated. Different types of unit responses were obtained to stimulation, including evoked activity consisting of a group of action potentials followed by inhibition of the spike discharge. Unit activity in the vestibular nuclei was shown to depend on extralabyrinthine stimulation. In response to adequate stimulation of the labyrinths by tilting the head, the role of receptors of muscles and joints in the neck was distinguished. The question of the somatotopic organization of the vestibular nuclei and convergence of various afferent flows on neurons giving rise to the vestibulospinal tract is discussed.Institute of Medico-Biological Problems, Ministry of Health of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 8, No. 5, pp. 507–513, September–October, 1976.     

The effects of hypergravity and substrate vibration on vestibular function in developing chickens

We used linear vestibular evoked potentials (VsEPs) to characterize peripheral and central vestibular function in birds following embryogenesis at 2G centrifugation or at elevated levels of vibration (+20dB re: background levels). Additionally, we characterized peripheral and central vestibular adaptation to 2G centrifugation in early post-hatch birds. Linear VsEP response peak latencies, amplitudes, thresholds and input/output functions were quantified and compared between experimental and control animals. Birds vibrated throughout embryogenesis and up to one-week post-hatch revealed no changes in linear VsEP response components compared to control siblings. Birds centrifuged at 2G throughout embryogenesis also evidenced no changes in the linear VsEP measured at hatch (P0). Significant changes were seen, however, for linear VsEPs of post-hatch birds placed at 2G for 7 days beginning on post-hatch day 5. Linear VsEPs for these animals displayed significant reductions in response amplitudes associated with peaks P2, N2 and P3, response peaks generated by central neural relays of gravity receptors. The earliest response components, generated by the peripheral vestibular nerve (i.e., P1, N1), were not significantly altered with the 7-day exposure to 2G. Thus, there was no evidence of generalized changes in peripheral gravity receptor excitability or in the rate of maturation in developing animals under increased levels of gravity or vibration. If gravity level plays a critical role in shaping peripheral vestibular ontogeny at magnitudes between 1 and 2G, then it may serve to stabilize function under changing G-fields or it may operate on physiological features that can not be resolved by the VsEP. In contrast, exposure to elevated gravity during post-hatch periods does alter central vestibular function thus providing direct evidence for central vestibular adaptation to the gravitational environment. The fact that central functional change was observed in hatchlings and not embryos, raises the possibility that the first 2-weeks post-hatch may be a critical period of "heightened developmental sensitivity" to hypergravity.