Neuronal response produced in the human thalamic nucleus reticularis by significant and non-significant verbal and sensory stimuli

Response recorded by microelectrode techniques during the course of 46 stereotaxic operations on dyskinesia patients was investigated in 340 units of the nucleus reticularis (rt) of the human thalamus. Differences were found between the multistage response of three types of rt neurons (A, B, and C) to verbal (or acousticcum-sensory) functionally significant stimuli (FSS) at both the stage of stimulus presentation and during the performance of goal-directed motion. Phasic activation produced by FSS presentation (as well as onset and execution of movement) in 102 out of 183 type A cells (or 55.7%) was characteristic of these cells, combined with inhibition of B type neurons in 82 out of a 139 sample (or 59.0%) produced by FSS and at the preparatory as well as the execution stage of movement. Activity of type C neurons remained unchanged. A correlation was revealed between response in A and B cells and "excitatory" trigger stimuli, but no specificity with respect to physical or semantic parameters of verbal signals. A correlation occurred during the course of movement performance with somatosensory afferents without any specific relationship to type and somatotopic aspects of movement. The time-related dynamics of A and B cell response is thought to illustrate the interaction of two neuronal subsystems within the rt participating in the performance of goal-directed motor performance triggered by speech.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Institute of Neurosurgery, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 4, pp. 441–451, June–July, 1990.     

Selectivity in the response of human cerebral neurons to visual stimuli at different angles of alignment

The neuronal activity of different nuclei of the thalamus and striopallidar complex was investigated in Parkinsonian patients with intracerebral electrodes chronically implanted in these structures for diagnostic and therapeutic purposes. Neuronal populations were discovered responding differently to the presentation of stimuli identical in all but angle of presentation, some of which responded solely to a single orientation and might therefore be thought of as displaying directional sensitivity. It is suggested that when motor and visual information converge within the above systems, a matching process takes place, together with an interaction relating to stability of visual perception.Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad; Institute of Information and Automotive Sciences, Academy of Sciences of the USSR, Leningrad. Translated from Neirofizologiya, Vol. 19, No. 1, pp. 3–11, January–February, 1987.     

Principal component analysis of evoked neuronal firing pattern in the human brain

Evoked firing activity (EFA) in neurons of the human thalamic reticular nucleus (Rt) was recorded by microelectrodes using extracellular recording techniques in the course of stereotaxic surgery for dyskinesia. Activity was induced by functionally significant verbal and sensory stimuli together with performance of goal-directed behavioral actions (BA). Use of the principal component method and construction of peristimulus covariance matrices are suggested in view of the presumably convergent nature of EFA in Rt neurons, taking the form of superposing independent components of response and variability in these in the course of BA testing and performance for the purpose of analyzing EFA and interneuronal correlations. The multivariate pattern of Rt EFA time courses during the action of functionally significant stimuli was revealed; this reflects different stages in performance of BA. The dynamics of components of response are revealed and occurrence of rapidly developing interneuronal correlations in functionally significant stages of goal-directed BA are described. Findings point to the efficacy of the suggested approach applied to analysis of EFA neurons.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 6, pp. 811–818, November–December, 1990.     

Neuronal interaction in the cat cerebellar cortex: A cross correlation analysis

Neuronal interaction in the cat cerebellum was investigated by cross correlation analysis techniques. Excitatory connections of varying effectiveness were found between neurons of 13 out of 90 pairs investigated (or 14%). Inhibitory interaction was observed in 38 pairs, or 42%. Neurons of 26 pairs (40%) had shared inputs. Effectiveness of connections between cerebellar cortex neurons was demonstrated by changing stimulus parameters. Findings obtained agree with existing data on the functional organization of the cerebellar cortex. Possible reasons for the large numbers of inhibitory connections discovered are discussed.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow, Institute of Experimental Biology, Polish Academy of Sciences, Warsaw. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 672–678, September–October, 1987.     

Sites of action potential generation in Helix pomatia neurons

The site of action potential generation in unipolar snail neurons was identified by stimulating neurons isolated together with the initial portion of the process from the neuropile. Stimulation consisted of a sinusoidal from electrical current passed along the soma-axonal axis in saline solution. No low threshold sites of action potential generation were found in 80% of test neurons using this technique. Spontaneous activity was determined by the operation of one dominant site on the neuronal process. Antidromic activation of the soma by axonal action potentials (even with simultaneous hyperpolarization of the soma) induced somatic potentials more successfully than direct somatic depolarization by the current flowing through the solution.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 90–98, January–February, 1988.     

Model of interaction at chemical synapses

A simple, quasi-static model for convergence between afferent flows of influences at the neuronal membrane is presented. Interaction between afferent flows reaching chemical synapses of different types is examined. It was found that the pattern of this interaction diverges from algebraic summation of separate effects. The mechanism underlying action between internal negative feedbacks constitutes the basis for this phenomenon.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 20, No. 4, pp. 503–509, July–August, 1988.     

Programmed type movement in patients with lesion to different cerebellar systems

The contribution of the lateral and intermediate cerebellar systems to fast voluntary movement control was investigated in man. The trial consisted of executing a series of dorsal or plantar flexions of increasing amplitude with minimal difference from that of other local movements. A close connection was found between the intermediate cerebellar system and information processing and proprioception. The lateral cerebellar system was shown to make a direct contribution to programming movements, tailoring these to the requirements of a given task. Lesioning of the pyramidal tract is accompanied by severe impairment in the execution of programmed mechanisms (or of the system of carrying out the programs): it is impossible to execute programmed movements when the pyramidal system is damaged.Institute for Disorders of Information Transmission, Academy of Sciences of the USSR, Moscow. Institute of Neurology, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 233–241, March–April, 1986.     

Coordination of arm movement during locomotion in ophiurans

During movement of the ophiuranAmphipholis kochii Lutken, any one of its arms can point forward and, consequently, any arm can perform different functions. The arm, when separated from the ophiuran together with the adjacent part of the nerve ring, is capable of complex motor acts, including locomotion. Division of the nerve ring in the ophiuran disturbs coordination of the arms. The results of experiments in which one or more arms were amputated showed that the choice of leading arm and of method of locomotion depends mainly on afferent impulses received from the arms. The results indicate that the neural centers of individual arms possess relative autonomy. Coordinated working of the centers is achieved through their interaction. This interaction ensures the distribution of functions between the arms in accordance with the motor task to be undertaken and coordinates the activity of the arms in time. The dominant role in the distribution of functions between the arms is played by the center of the leading arm, which controls the activity of at least the adjacent centers.Institute of Oceanology, Academy of Sciences of the USSR, Moscow. Institute of Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Moscow State University. Translated from Neriofiziologiya, Vol. 8, No. 5, pp. 529–537, September–October, 1976.     

Investigation of a monosynaptic excitatory connection by means of a biomathematical model of neuronal interaction

A biomathematical model of neuronal interaction, including real mollusk neurons and mathematical models of functioning of deficient synaptic connections between these neurons and synaptic endings of other neurons, was created on the basis of a computer and an experimental arrangement for investigating molluscan ganglia. The effect of the properties of a monosynaptic excitatory connection of the statistical characteristics of spike trains of interacting pacemaker neurons was investigated.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 12, No. 4, pp. 413–420, July–August, 1980.     

Changes in reactivity of visual cortical neurons after local photic stimulation of their receptive fields in cats

Recovery cycles of unit responses in the primary visual cortex to local photic stimulation of their receptive fields were studied in unanesthetized, immobilized cats by the paired stimulus method. In most cases the process of recovery of neuronal reactivity did not follow a steady course. Recovery from depression evoked by the first stimulus took place more suddenly in neurons in the central part of the visual field, and initial recovery of activity was more complete than in peripheral neurons. Differences in the synchronization of inhibitory and excitatory inputs to neurons responsible for central and peripheral vision are discussed.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 13, No. 3, pp. 233–240, May–June, 1981.     

Frequency characteristics of skate electroreceptive central neurons responding to electrical and magnetic stimulation

Responses of single neurons in the lateral lobes of the medulla to stimulation of the electroreceptive system by homogeneous sinusoidal electrical and magnetic fields were investigated in acute experiments on the skateRaja radiata. Thresholds of neuronal responses to electrical stimulation varied from 0.03 to 10 µV/cm. The optimal frequency ranges for electrical and magnetic reception were in the regions of 0.05–5 and 2–3 Hz respectively. The possible mechanisms and functional significance of frequency characteristics of central neurons are discussed.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 16, No. 4, pp. 464–470, July–August, 1984.     

Cortical and subcortical spreading depression in rats produced by focused ultrasound

Steady potential shifts produced by focused ultrasond were recorded in the cerebral cortex, hippocampus, thalamus, and caudate nucleus. Impulses of 50–100 msec duration were presented at a frequency of 5 and 10 Hz. Negative steady potential shifts were produced in each of the structures investigated, which gradually increased during rhythmic electrical reaction to reach –3 to –7 mV within 10–30 sec, often succeeded by a wave of spreading depression (SD). In each structure analyzed amplitude of SD waves measured 20–30 mV, lasting 30–40 sec in the cortex, the caudate nucleus and the thalamus, and 80–120 sec in the hippocampus. In unanesthetized and lightly anesthetized animals SD waves were on occasions the precursors of convulsive discharges forming under the action of focused ultrasound. Ultrasound at threshold doses proved ineffective for 5–7 min after the occurrence of an SD wave, but again evoked repeated SD waves once the refractory period had ended. Accordingly, local effects produced by focused ultrasound can result in functional blockage of the brain structures due to cortical and subcortical spreading depression.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Institute of Brain Research, All-Union Research Center of Mental Health, Academy of Medical Sciences of the USSR, Moscow. N. N. Andreev Acoustic Institute, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 1, pp. 55–61, January–February, 1986.     

Modular organization of callosal neurons in the rabbit sensomotor cortex

The density of distribution of callosal neurons in the rabbit sensomotor cortex was studied by injecting horseradish peroxidase into the symmetrical region of the cortex. The degree of inequality of distribution of labeled neurons was determined visually and by statistical analysis. Stained callosal neurons were mainly small and medium-sized pyramidal cells, located chiefly in layer III–IV, and substantially less frequently in layers V and VI. Different forms of grouping of labeled neurons were observed in layer III–IV: two cells at a time, five to eight cells arranged vertically, or in concentrations, whose width was usually 120–200µ, and separated by areas with reduced density. The results are regarded as confirmation of those drawn previously from results of electrophysiological investigations on the modular organization of callosal connections in the rabbit sensomotor cortex.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Brain Institute, Academy of Medical Sciences of the USSR, Moscow. I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 16, No. 4, pp. 451–457, July–August, 1984.     

Characteristics of background unit activity in the nucleus reticularis of the human thalamus

Background firing activity was examined in 240 neurons belonging to the thalamic nucleus reticularis (Rt) in the unanesthetized human brain by extracellular microelectrode recording techniques during stereotaxic surgery for dyskinesia. The cellular organization of Rt was shown to be nonuniform, and distinguished by the presence of three types of neuron: one with arrhythmic single discharge (A-type, 40%), another with rhythmic (2–5 Hz) generation of short high-frequency (of up to 500/sec) burster discharges (B-type, 49%) and a third with aperiodic protracted high-frequency (of up to 500/sec) bursting discharges separated by "silent" intervals of a constant duration of 80–150 msec (i.e., C-type, 11%). Differences between the background activity pattern of these cell types during loss of consciousness under anesthesia are described. Tonic regulation of neuronal type was not pronounced but a tendency was noticed in the cells towards a consistent rise in firing rate, rhythmic frequency and variability, etc. in both A and B units, especially in the latter. Findings pointing to the absence of a direct relationship between rhythmic activity in the Rt and parkinsonian tremor were confirmed. Background activity in B-type cells was found to increase and then stabilize with a rise in the degree of tremor. The nature of regular bursting activity patterns in B and C neurons is discussed in the light of our findings.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Institute of Neurosurgery, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 19, No. 4, pp. 456–466, July–August, 1987.     

Distribution of neurons responding to sensory stimuli and organization of topic projections in the cat caudate nucleus

The distribution of neurons responding to presentation of different sensory stimuli was investigated during chronic experiments on cats. These showed that cells responding to somatic and visual stimulation were unevenly distributed and that areas with differing levels of activity within the same nucleus alternated. No single topic projection was identified within the structure reaching the entire nucleus. The findings were compared with those found during morphological research indicating heterogeneity in caudate nucleus structure, implying the existence of neuronal groupings (or striosomes) belonging to a topically organized projection from the animal's body.Institute for Research into Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 2, pp. 156–162, March–April, 1990.     

Serotonin-induced changes in the action of functionally distinct neurons in Helix pomatia

The effects of serotonin on the amplitude of summated EPSP in interneurons and on the duration of action potentials in sensory neurons, interneurons, and motoneurons involved in avoidance behavior were investigated in functionally distinct neurons isolated from theHelix pomatia nervous system. The duration of action potentials in sensory neurons was found to increase under the effects of serotonin (and this could underly the rise in EPSP amplitude), although that of interneuron and motoneuron spikes did not change. The functional significance of selective neuronal response to a rise in serotonin concentration is discussed, together with the mechanics underlying such effects.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 316–322, May–June, 1987.     

Visual cortical detector neurons in the Siberian chipmunkEutamias sibiricus

Three functional classes of neurons are described in the visual cortex of the Siberian chipmunk: neurons not selective for direction of movement and orientation, neurons selective for movement in a particular direction, and neurons selective for orientation. Unselective and directionally-selective neurons were activated maximally at speeds of movement of 100–500 deg/sec or more, most orientation-selective neurons at speeds of 10–50 deg/sec. For all three classes of neurons clear correlation was observed between selectivity for velocity of movement and character of responses to presentation of stimuli stationary in the receptive field. With reference to this sign the neurons were divided into two groups: phasic (fast) and tonic (slow). Phasic (fast) neurons predominate in the visual cortex ofEutamias sibiricus.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 16, No. 6, pp. 807–814, November–December, 1984.     

Parameters of photic stimulation and characteristics of thermal response in the white rat cerebral cortex

The dynamics of the localized thermal response produced in the cerebral cortex when a retinal photic stimulation pattern is established were studied through the unopened skull during acute experiments on white rats using techniques of thermovision and digital image processing. The relationship was evaluated between amplitude, time course, and spatial characteristics of response on the one hand and stimulus size, position on the retina, focus, duration, quantity, and frequency of presentation on the other. A discussion follows of the properties, significance, and underlying mechanisms of the thermal effects discovered.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 3, pp. 332–340, May–June, 1985.     

Two types of binocular convergence of visual information in the cat superior colliculus

During binocular stimulation of different sectors of the retina the amplitude of the two first postsynaptic components of the evoked potential in the superior colliculus to the second stimulus varies with the time delay between the testing and conditioning stimuli. Correlation is shown between the form of the evoked potential arising in response to the conditioning stimulus and the character of convergence of visual impluses in the superior colliculus. Qualitative differences are found in binocular interaction between sensory impulses depending on the way in which the conditioning impulses reach the region of the superior colliculus tested. An attempt is made to assess interaction between sensory volleys in the superior colliculus quantitatively.Institute of the Brain, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 5, No. 2, pp. 133–137, March–April, 1973.     

Dynamic thermal mapping of rat brain during sensory stimulation and spreading depression

Using both techniques of thermovision and statistical analysis of thermal imaging, dynamics of temperature distribution over the dorsal surface of the brain were investigated through the intact skull during acute experiments on white rats. Both diffuse and regionally specific cerebral thermal reactions were observed during visual, acoustic, and somatosensory stimulation, together with multiple local thermal response, often following a specific pattern. These outline thermal effects differing from the compartment of the brain to another in degree, stability, and point of onset. Temperature waves developed together with spreading depression, produced in the cortex by injecting KC1. Once investigations had been performed this response could be divided into diffuse and spatially ordered components. The possible mechanisms of this thermal imaging of brain processes are discussed, together with how they are linked with changes in cerebral blood flow and neuronal metabolic thermal production.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Institute of Radio Engineering and Electronics, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 1, pp. 26–35, January–February, 1986.