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V A Velling

Publications and source records attributed to V A Velling.

10 recordsLinked to original sources
PubMed1987

[Modulation of the functional state of the brain using focused ultrasound].

The effects of focused ultrasonic action (SUA) on the brain functional state was found to depend on the intensity: there was no effect at 0.1 mWt/cm2 whereas an activation of the brain activity occurred at 1-100 mWt/cm2. The SUA 1-100 Wt/cm2 suppressed the ECoG. The mechanism of the SUA effect is supposed to be based on a change in permeability of neuronal membrane leading through a chain of intracellular molecular reactions to general de- or hyperpolarization of membranes of the neuronal populations and to a change in the brain activity.

Animals↗
PubMed1982

[Changes in neocortex function in the direct action of optical radiation].

Direct action of ultraviolet radiation with wavelength of 280, 310 and 365 nm increased the amplitude of neocortex EEG and enhanced the epileptiform activity in the penicillin--induced epileptic focus, whereas action of superthreshold radiation with wavelength of 580 and 630 nm decreased the EEG amplitude and suppressed the epileptiform activity. The mechanism of ultraviolet radiation effect on the neocortical electrical activity seems to be based on changes in permeability of neuronal membranes for Na and K ions and on following depolarization of the membranes, whereas the action of visible radiation leads to the heat injuring of neurons in the irradiated area which evokes irreversible suppression of their activity and reducing of their EEG amplitude.

Animals↗
PubMed1977

[Slowly-adapting mechanoreceptor units of the guinea pig mammary nipple].

Slowly--adapting mechanoreceptor units of areola and nipple (MAI and MAII) at rest exhibited spontaneous 1--2/sec firing in 6% only. At constant mechanical displacement of the skin surface. MAI had an irregular firing while MAII--regular one. Mean frequency of MAI and MAII APs linearly depended on the amplitude of mechanical stimulus. trepeated stimulation of MAI and MAII reduced number of APs for each successive stimulus. At sinusoidal mechanical stimulation, the smallest AP threshold for MAI and MAII was about 10--15 Hz.

Adaptation, Physiological↗
PubMed1976

[Properties of the mechanoreceptors of the nipple of the guinea pig mammary gland. (Rapidly adapting mechanoreceptor units)].

Two types of rapidly adapting mechanosensitive units have been found in skin of the teat of guinea--pig mammary gland (RA1 and RA2). They wee not both spontaneously active. RA1 and RA2 have no position response. The relation between average frequency of discharge and displacement velocity at a constant displacement amplitude was linear for RA1. With constant velocity displacements, frequency versus displacement curves assume a horizontal orientation of relatively low discharge frequencies and are then displaced upward as velocity increases for RA1. The number and frequency of afferent impulses of RA1 decreased during repeated ramp mechanical stimulation. Vibratory tuning points were in the range of 10--25 Hz for RA1. 20% of mechanosensitive units were RA2, which have a high velocity threshold and rarely produce more than 2--3 impulses to high velocity. The fatigue of RA2 is not prominent. RA1 were classed as the velocity detectors and RA2 as "transient" detectors.

Action Potentials↗
PubMed1976

[Functional characteristics of rapidly adapting mechanoreceptor units of the rat mammary gland nipple].

Two types of rapidly adapting mechanosensitive units were found in the teat of the rat mammary gland (RAI and RAII). Neither was spontaneously active. 10% of the units were RAII and had the functional characteristics of "transient" receptors. The relation between the average frequency of discharge and the velocity of displacement at a constant displacement amplitude was linear for RAI. The latency of the first spike decreased when indentation velocity increased. The number and frequency of afferent impulses decreased at a repeated mechanical stimulation. Vibratory tuning points were in the range 10--25 Hz for RAI. RAI units were not directionally sensitive to the teat displacement.

Action Potentials↗
PubMed1975

[Electrical activity of mechanoreceptor neurons in rat mammary gland nipple skin].

Three types of the mechanosensitive units were found in the skin of the rat mammary gland nipple: receptors detecting: 1) transients, 2) velocity, 3) position and velocity. The 1st and the 2nd types were spontaneously inactive and both adapted rapidly to mechanical stimuli. The 3rd type had a spontaneous activity 1-4/sec and adapted slowly to mechanical stimuli.

Action Potentials↗
PubMedDate not supplied

Changes in neocortical function in response to the direct action of optical radiation.

The action of optical radiation on neocortical bioelectrical activity and on a penicillin-induced epileptic focus was investigated. The direct action of ultraviolet (UV) radiation with wavelengths 280, 310, and 365 nm was shown to increase the amplitude of the spontaneous EEG and to potentiate epileptiform activity, whereas the action of subthreshold radiation with wavelengths of 580 and 630 nm caused a reduction of EEG amplitude and inhibition of epileptiform activity. On the basis of the writers' own results and data in the literature it is postulated that the mechanism of action of UV radiation on neocortical electrical activity is based on changes in permeability of neuronal membranes to Na and K ions and subsequent membrane depolarization, whereas the action of visible radiation leads to thermal injury to the neurons in the irradiated zone, inducing irreversible suppression of their activity and a decrease in amplitude of the EEG.

Animals↗
PubMedDate not supplied

Modulation of the functional state of the brain with the aid of focused ultrasonic action.

We investigated the possibility of modifying the functional state of the brain with the aid of focused ultrasound and studied various regimes of its action. A specific pattern in the effect of focused ultrasonic action was discovered with regard to its intensity: the effect is absent at low (less than 0.1 mW/cm2) intensities; activation of bioelectrical activity in the brain takes place at intensities from 1 to 100 mW/cm2; and suppression of the ECoG takes place at intensities from 1 to 100 W/cm2. On the basis of our own data and the data in the literature, we suggest that the mechanism of ultrasound action is based upon changes in the permeability of neuronal membranes leading, after a chain of intracellular molecular reactions, to a subsequent general de- or hyperpolarization of the membranes of neuronal populations and to a change in the bioelectrical activity of the brain.

Animals↗