The transmission of coded information over neuronal systems exemplified by the motor rhythmic dominant

Functional organization of neurons in rabbit's sensorimotor cortex was studied before and within several days after formation of the rhythmical dominant focus. Functional reorganization of neurons in cortical microareas took place during actualization of the dominant. The number of functional interneuronal relations within neuronal pairs of a certain type could be increased in comparison with the control values and decreased within pairs of another type. As a result, the total percent of the interneuronal correlations in cortical microareas in the control animals and rabbits with the acting dominant was approximately equal. The total percent of correlations between neurons of the adjacent cortical areas during the actualization of the dominant was significantly higher than in the control due to increased number of correlations with participation of small and medium-sized neurons. A possibility of information circulation about the "stimulus image" in the closed chain of neurons was exemplified by the real micronetwork. The data suggest the reverberation of encoded information between adjacent microareas of the sensorimotor cortex within several days after application of the stimulus, which has formed the excitation focus.     

Effect of a dominant focus created in the center of the wink reflex on the local defense reflex in the rabbit

The paper deals with conjugated inhibition of rabbit's defensive limb reflex at formation of a dominant focus in the center of the eye-lid reflex. In the initial period of dominant focus formation, when the dominant comes through the stage of summation reflex, electrocutaneous limb stimulation induced, along with successive summation, temporary inhibition of the forming dominant focus. The dominant focus formed in the eye-lid center did not induce conjugated inhibition of the limb defensive reflex. In the study of the influence of the eye-lid reflex on the motor defensive one it was found that formation of temporary connection of summation reflex type, led to circulatory interaction between the centers.     

Conjugate inhibition in the presence of an eyelid reflex dominant in the rabbit

Conjugated inhibition was studied of the swallowing reflex during formation of dominant focus in the centre of the eye-lid reflex. In the initial period of the dominant focus formation when the dominant passed through the stage of summating reflex, the swallowing reflex was not inhibited. When the dominant turned to optimal stage, i. e. when it was reinforced by stimuli of various modalities, the swallowing reflex was conjugately inhibited. When the dominant turned to pessimal state, summation was not observed in the dominant focus, and conjugated inhibition went on. In the study of the influence of the eye-lid reflex on the swallowing one, it was found that during formation of temporary connection of the type of summating reflex a circular interaction between the centres took place.     

Intercellular (mis)communication in neurodegenerative disease

Neurodegenerative diseases have been intensively studied, but a comprehensive understanding of their pathogenesis remains elusive. An increasing body of evidence suggests that non-cell-autonomous processes play critical roles during the initiation and spatiotemporal progression or propagation of the dominant pathology. Here, we review findings highlighting the importance of pathological cell-cell communication in neurodegenerative disease. We focus primarily on the accumulating evidence suggesting dysfunctional crosstalk between neurons and astroglia, neurons and innate immune system cells, as well as cellular processes leading to transmission of pathogenic proteins between cells. Insights into the complex intercellular perturbations underlying neurodegeneration will enhance our efforts to develop effective therapeutic approaches for preventing or reversing symptomatic progression in this devastating class of human diseases.     

Interaction between two excitation foci in the central nervous system capable for summation

The interaction between two dominant foci was carried out on different models of dominant. It was shown that the following pairs: latent motor and blinking excitation foci; hunger and hypnotic dominants, decaying polarization dominant (related with functioning of the left-hemisphere) and hypnotic dominant can function simultaneously. After repeated formation of a new dominant focus against the background of the existing stable dominant created earlier, a replacement of dominants takes place. This process passes through the stage of formation of the latent dominant not yet apparent at the behavioral level but with the electrical activity typical for the dominant focus. Actually, two dominants exist at this stage: the previous active and latent foci. The latter determines further behavior of the animal.     

Converging levels of analysis in the cognitive neuroscience of visual attention.

Experiments using behavioural, lesion, functional imaging and single neuron methods are considered in the context of a neuropsychological model of visual attention. According to this model, inputs compete for representation in multiple visually responsive brain systems, sensory and motor, cortical and subcortical. Competition is biased by advance priming of neurons responsive to current behavioural targets. Across systems competition is integrated such that the same, selected object tends to become dominant throughout. The behavioural studies reviewed concern divided attention within and between modalities. They implicate within-modality competition as one main restriction on concurrent stimulus identification. In contrast to the conventional association of lateral attentional focus with parietal lobe function, the lesion studies show attentional bias to be a widespread consequence of unilateral cortical damage. Although the clinical syndrome of unilateral neglect may indeed be associated with parietal lesions, this probably reflects an assortment of further deficits accompanying a simple attentional imbalance. The functional imaging studies show joint involvement of lateral prefrontal and occipital cortex in lateral attentional focus and competition. The single unit studies suggest how competition in several regions of extrastriate cortex is biased by advance priming of neurons responsive to current behavioural targets. Together, the concepts of competition, priming and integration allow a unified theoretical approach to findings from behavioural to single neuron levels.     

Firing responses of bursting neurons with delayed feedback

Thalamic neurons, which play important roles in the genesis of rhythmic activities of the brain, show various bursting behaviors, particularly modulated by complex thalamocortical feedback via cortical neurons. As a first step to explore this complex neural system and focus on the effects of the feedback on the bursting behavior, a simple loop structure delayed in time and scaled by a coupling strength is added to a recent mean-field model of bursting neurons. Depending on the coupling strength and delay time, the modeled neurons show two distinct response patterns: one entrained to the unperturbed bursting frequency of the neurons and one entrained to the resonant frequency of the loop structure. Transitions between these two patterns are explored in the model’s parameter space via extensive numerical simulations. It is found that at a fixed loop delay, there is a critical coupling strength at which the dominant response frequency switches from the unperturbed bursting frequency to the loop-induced one. Furthermore, alternating occurrence of these two response frequencies is observed when the delay varies at fixed coupling strength. The results demonstrate that bursting is coupled with feedback to yield new dynamics, which will provide insights into such effects in more complex neural systems.     

Responses of sensorimotor and visual cortical neurons to light in rabbits with a hidden focus of excitation in the CNS (defensive dominanta)

In the sensorimotor cortex of rabbits with a hidden focus of excitation in the CNS, the firing rate of neurons that responded to light was significantly lower (p = 0.01) than the firing rate of neurons that did not respond to light. The same phenomenon was observed in the visual cortex of intact rabbits. Both in intact rabbits and animals with the hidden focus of excitation, 36% of neurons in the sensorimotor responded to a nonspecific for them light stimulation. In the sensorimotor cortex of rabbits with the hidden focus of excitation, more (p = 0.01) neurons responded to light with the latency lower that 100 ms and less (p = 0.02) neurons responded to light with the latency from 200 to 300 ms as compared to intact animals. In the visual cortex of rabbits with the hidden excitation focus, less (p = 0.01) neurons responded to light stimulation with the latency from 50 to 100 ms as compared to intact rabbits.     

A model for the neuronal implementation of selective visual attention based on temporal correlation among neurons

We propose a model for the neuronal implementation of selective visual attention based on temporal correlation among groups of neurons. Neurons in primary visual cortex respond to visual stimuli with a Poisson distributed spike train with an appropriate, stimulus-dependent mean firing rate. The spike trains of neurons whose receptive fields donot overlap with the focus of attention are distributed according to homogeneous (time-independent) Poisson process with no correlation between action potentials of different neurons. In contrast, spike trains of neurons with receptive fields within the focus of attention are distributed according to non-homogeneous (time-dependent) Poisson processes. Since the short-term average spike rates of all neurons with receptive fields in the focus of attention covary, correlations between these spike trains are introduced which are detected by inhibitory interneurons in V4. These cells, modeled as modified integrate-and-fire neurons, function as coincidence detectors and suppress the response of V4 cells associated with non-attended visual stimuli. The model reproduces quantitatively experimental data obtained in cortical area V4 of monkey by Moran and Desimone (1985).     

Correlation between activities of neurons of sensorimotor and visual cortices after forming a hidden focus of excitation (defensive dominanta) in cortical representation of a forelimb in rabbits

The interaction between neurons of sensorimotor and visual cortices was investigated by cross-correlation analysis. In this interaction, we examined the role of sensorimotor neurons responding to light. In rabbits with a hidden focus of excitation, neurons of the sensorimotor cortex responding to light significantly more often formed correlation joints with cells of the visual cortex than neurons not responding to light. On the other hand, neurons of the visual cortex significantly more often formed correlation joints with neurons of the sensorimotor cortex not responding to light.     

The dominant motivation in the mechanisms of the conditioned reflex

It is substantiated that the mechanisms of dominant motivations play an essential role in conditioning. It is shown that motivations change convergent and chemical characteristics of single neurons of different brain structures and, especially, their sensitivity to corresponding reinforcing stimuli. As a result, motivation plays a role of an initial "canvas", against the background of which molecular "engrams of reinforcement" are built. The processes of interaction between the dominant motivation and reinforcement are mainly addressed to the apparatus of the action result acceptor. It is shown that dominant motivations participate not only in construction of molecular reinforcement engrams but also in their forestalling retrieval.     

Electrophysiologic study of the cerebral control of swallowing

Swallowing dominant, created by serial pouring of water into rabbit's mouth cavity was tested in after-action from water supply. As a result of summation in the dominant focus of excitations elicited by stimuli of various modalities, swallowing took place. The study of swallowing dominant revealed by its stimulus which elicits its own unconditioned reflex (blinking), has shown that temporary feedback is characteristic for the dominant as well as for the conditioned reflex. Summation in the swallowing center during dominant testing by stimulation of the eye cornea takes place without conjugated inhibition of the blinking center. During discrete pouring of water into the animal's mouth, evoked potentials appear in the cortical-subcortical structures of the swallowing center. Identical potentials appear in corresponding structures before the summation swallowing. Appearance of these potentials in the electric activity of the dominant focus testifies to its readiness for summation.     

Comparative analysis of vestibulospinal neuron sizes in the guinea pig

A comparison was made between dimensions of vestibular neurons labeled with horseradish peroxidase projecting to the spinal cord and cells stained with neutral red not differentiated into vestibulospinal and not forming descending projections. The cells in nondifferentiated areas of descending, medial and lateral vestibular nuclei include neurons of all sizes. In the caudorostral direction of the vestibular complex, the number of small and average neurons decreased and the number of large and gigantic neurons increased. The vestibulospinal populations included cells of average, large and gigantic size, and large and gigantic neurons were dominant. In the caudorostral direction, neurons of various sizes were distributed relatively evenly without forming differentiated groups.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 616–624, September–October, 1991.     

Intercentral relations of the electrical processes of the rabbit brain with a polarization dominant

The dynamics of changes in intercentral relations of electrical activity of the sensorimotor and premotor zones of both hemispheres and the ventroposterolateral (VPL) nucleus of the left and right thalamus at formation of motor dominant under the action of the DC anode in the rabbit sensorimotor cortex was studied by the method of spectral-correlation analysis. It is shown that in the much less than dominant much greater than motor analyzer (the sensorimotor cortex and VPL) highly coherent connections of electrical processes are formed in the delta-range with conjugated lowering of biopotential connections between the structures of the motor analyzer of the much less than nondominant much greater than part of the brain. At the same time differently directed connections of electrical processes are formed between the structures of the motor analyzer, and between the premotor cortex and focus area. Thus, during formation of the much less than polarization much greater than dominant, a new structure of the intercentral relations of electrical processes is established not only in the much less than dominant much greater than but also in the other half of the brain.     

普氏蹄蝠下丘谐波主频神经元的时程选择性

为探讨下丘(Inferior colliculus,IC)回声定位信号主频范围内的神经元的时程选择性,在自由声场刺激条件下,我们在4 只普氏蹄蝠的IC 采用不同时程的声刺激,研究了神经元的时程选择性。通过在体细胞外记录,共获得56 个声敏感下丘神经元,其记录深度、最佳频率和最小阈值的范围分别为1547 - 3967 (2878. 9 ±629.1)μm,20 -68 (49.0 ± 11. 1)kHz 和36.5 -95. 5 (59. 8 ±13. 0)dB SPL。根据所记录到的下丘神经元对不同时程的声刺激的反应,即对不同时程的选择性(Duration selectivity),将其分为6 种类型:短通型(Short-pass,SP,n = 11/56)、带通型(Band-pass,BP,n = 1/56)、长通型(Long-pass,LP,n = 5 /56)、反带通型(Band-reject,BR,n = 3 /56)、多峰型(Multi-peak,MP,n =6 /56)和全通型(All-pass,AP,n =30 /56)或非时程选择型(Nonduration-selective,NDS)。通过比较普氏蹄蝠下丘谐波主频内和主频外神经元的时程选择性,我们发现处于回声定位信号主频范围内神经元(n =32)比主频外神经元(n = 24)具有更短的最佳时程和更高的时程选择性。结果提示,在普氏蹄蝠回声定位过程中谐波主频内神经元较谐波主频外神经元发挥了更为重要的作用。     

The intercentral relations of the biopotentials in the rabbit brain during the creation of a blinking dominant]

On rabbits in chronic experiment intercentral relations were studied of biopotentials of the sensorimotor cortical zone (blinking presentation in the cortex), VPM of the thalamus and motor nucleus of the oculomotor nerve at formation of blinking dominant created by serial stimulation of one eye by air jet. By the method of spectral-correlation analysis an increase was revealed of spectrum power and increase of COG of the potentials in delta-range in the structures connected with blinking function of the stimulated eye. At transition of the dominant focus to the inhibitory state and activation of the symmetrical centre of the other eye, in centers constellation of this induced focus a reconstruction of the electrical processes took place typical for the dominant.     

Evoked potentials in the reticular formation of the rabbit midbrain during formation of a dominant focus in it

During creation of a dominant focus in the midbrain reticular formation (RF) by its multiple stimulation with a high-frequency current (stimulation frequency 200 Hz, pulse duration 0.1-0.5 ms, voltage 1-3 V, duration 5 s) a statistically significant increase of the amplitude of the evoked potential (EP) in RF to light flashes was revealed in comparison with background data. Significant increase of EP amplitude was also observed in RF in response to the same stimuli applied in successive experiments without RF stimulation, which pointed to the existence of a latent dominant focus in the CNS.     

Sociality and oxytocin and vasopressin in the brain of male and female dominant and subordinate mandarin voles

The dominant–subordinate hierarchy in animals often needs to be established via agonistic encounters and consequently affects reproduction and survival. Differences in brain neuropeptides and sociality among dominant and subordinate males and females remain poorly understood. Here we explore neuropeptide levels and sociality during agonistic encounter tests in mandarin voles. We found that dominant mandarin voles engaged in higher levels of approaching, investigating, self-grooming and exploring behavior than subordinates. Dominant males habituated better to a stimulus vole than dominant females. Dominant males displayed significantly less oxytocin-immunoreactive neurons in the paraventricular nuclei and more vasopressin-immunoreactive neurons in the paraventricular nuclei, supraoptic nuclei, and the lateral and anterior hypothalamus than subordinates. Dominant females displayed significantly more vasopressin-immunoreactive neurons in the lateral hypothalamus and anterior hypothalamus than subordinates. Sex differences were found in the level of oxytocin and vasopressin. These results indicate that distinct parameters related to central nervous oxytocin and vasopressin are associated with behaviors during agonistic encounters in a sex-specific manner in mandarin voles.     

Interhemispheric relationships of electrical activity in the blinking dominant in rabbits

The study of intercentral and interhemispheric relations of the electrical activity of the cerebral cortex during formation and functioning of winking dominant, by the method of spectral-correlation analysis, has shown that the dominant focus is characterized by an increase of spectrum power in the range of delta-frequencies and a raise of coherence level of potentials in the same range that leads to the appearance of interhemispheric asymmetry according to these parameters. Appearance of the dominant state in the opposite hemisphere is accompanied by a reconstruction of the electrical activity characteristic of dominant focus.     

Total protein content and concentration in the neurons of the "mirror" epileptiform focus in the rat brain at the late stages of its existence]

The experimental lesion in rat brain was produced by the implantation of cobaltogelatin rod into the right parietalis anterior area. A quantitative measurement of total protein was made by microdensitometer in neurons controlateral to cobalt lesion at 112-115 days after cobalt implantation. In the experimental animals, protein content decreased in neurons of lamina III and V area parietalis anterior and the nucleus lateralis thalami by 6, 60 and 53%, resp. It has been concluded that different type neurons have different protein changes in response to paroxyzmal activity at late stages of epileptogenic mirror focus.