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M P Granstrem

Publications and source records attributed to M P Granstrem.

14 recordsLinked to original sources
PubMed2003

[Self-controlled artificial respiration].

We compared respiratory parameters during natural and self-controlled mechanical breathing to investigate mechanisms of respiratory control in alert humans. The self-control of mechanical breathing is realised manually: duration and velocity of air flow are controlled by left and right hands, resp. In this case, the respiratory afferent information is used to control activity of hand muscles but not of breathing muscles. The findings show that lung ventilation during self-controlled mechanical breathing increases by 7.5 l/min. at resting, by 6.3 l/min. during an exercise, as compared with the natural breathing. The increase in the lung ventilation occurs on account of an increase in the tidal volume but the frequency of the self-controlled mechanical breathing tends to be lesser at resting and was statistically significantly lower in exercise that at natural breathing. The exercise increases the lung ventilation by 13.0 l/min. at natural breathing and by 11.8 l/min. during self-controlled mechanical breathing. The findings suggest that the increased lung ventilation during self-controlled mechanical breathing is connected with creation of a new movement skill, and the modified pattern of self-controlled mechanical breathing is caused by a process of cortical transformation of respiratory afferents signals to efferent signals towards the hand muscles.

Adolescent↗
PubMed2000

Changes in reactivity of rat arteries subjected to dynamic stretch.

The effect of dynamic stretch on the reactivity of the rat tail and mesenteric artery segments was studied. Segments mounted on a myograph were stretched by a computer-controlled motorized micromanipulator. Dynamic stretch (1, 5 or 7 Hz) inhibited the artery constriction induced by noradrenaline (10 microM), 5-hydroxytryptamine (0.7 microM), or electrical field stimulation of intramural nerves. In contrast, dynamic stretch enhanced the tetrodotoxin-insensitive dilation induced by electrical field stimulation of noradrenaline-contracted arteries. Maximal increase of dilation evoked by electrical field stimulation (24.5 +/- 5.0% in mesenteric and 50.3 +/- 15.6% in the tail artery) was observed at a dynamic stretch-frequency of 5 Hz. An inhibitor of nitric oxide synthesis, NG-nitro-L-arginine (100 microM), abolished the difference in reactivity between static and dynamic conditions. The results indicate that dynamic stretch of the arteries activates nitric oxide synthesis/secretion, thus reducing constrictor and increasing dilator responses to the stimuli used.

Acetylcholine↗
PubMed2000

[Sensitivity of the cat lateral geniculate body neurons to orientation of the brightness gradient vector].

A new property of visual neurons: their sensitivity to orientation and the vector brightness gradient, was revealed and described. Receptive fields of the lateral geniculate body neurons in the cat have preferred orientation maximum reaction (average mean of orientation sensitivity coefficient--0.55 +/- 0.20). The preferred orientation mainly has a radial or tangential trend in the visual field. Temporal characteristics of the neuronal responses were analysed. A role of inhibition processes in the orientation sensitivity is discussed.

Animals↗
PubMed1995

[A quantitative assessment of the process of the reflection of the spatial-brightness properties of a stimulus by the neuronal structures in the lateral geniculate body of the cat].

Correlation between spatial brightness distribution in the test image and the spatial response distribution was estimated for the cat LGB. The correlation was found to be quite high. The data obtained corroborate the hypothesis by Podvigin and Kuperman of the topological correspondence of isophote structure family to the pattern of activity reflecting the test image.

Animals↗
PubMed1983

[Responses of neurons of the medial geniculate body in the cat to positive and negative intensity increments in noise signals].

73% of the cat internal geniculate body neurons responded with a phasic on-response to positive intensity increments of the white noise signal. 35% of the neurons responded with a phasic off-response to negative increments of the signal. At a constant rate of increment (6 dB), the amplitude and latency of the responses were found to depend on the level of the basis intensity. The amplitude dependence was rather irregular whereas the latency dependence was different in different neurons. Neurons were found which had the latencies of their on-responses augmenting with increase of the basis. The on- and off-responses revealed the ability of most neurons to single out the moment of intensity increment of a wide-band signal.

Animals↗
PubMed1980

[Perception of voiceless plosive consonants in syllables of the "vowel--consonant" type].

Bursts were the determining cue for perception of stops in VC syllables in Russian material under conditions of partial exclusion of information and in conflict combinations; the transitional part of vowels also contained certain information. If the information was reduced, /p/--answers predominated, but in conflict combination /p/ was suppressed by competing cues. The distribution of answers for a conflict combination cannot be described as a sum of distributions of answers for its parts.

Computers↗
PubMedDate not supplied

The sensitivity of neurons in the lateral geniculate body of the cat to the orientation vectors of brightness gradients.

We describe here a new property of visual neurons: sensitivity to the magnitude and orientation of the brightness gradient vector in a test stimulus presented in the receptive field of the neuron. The brightness gradient test image was a spot (diameter 4 degrees) on the dark background of the slide. Brightness changed linearly within the spot. The absolute value of the brightness gradient varied over the range 0.4-2.7 cd/m2 /degrees in the direction of the brightness gradient. The integral brightness in the test spot containing the gradient image was identical for different values of the brightness gradient. The numbers of spikes in the on- and off-responses of on and off neurons in the lateral geniculate body of cats depended on the orientation of the brightness gradient vector in the test stimulus. The sensitivity of neurons to the orientation of the brightness gradient vector, K (the coefficient of sensitivity), was assessed as the normalized difference between the number of spikes in neuron responses in the preferred and non-preferred orientations of the brightness gradient vector in the neuron's receptive field. The mean sensitivity coefficient for 53 cells was 0.55 +/- 0.20. A 6.7-fold decrease in the brightness gradient resulted in a 3.7-fold decrease in the coefficient of sensitivity (for the preferred direction of the orientation of the gradient vector); there was no change in the latent period of responses. The preferred orientation of the brightness gradient vector in the receptive fields of neurons coincided (to within +/-22.5 degrees) with the radial direction on the map of the field of vision in 45% of cases, and with the tangential direction in 26% of cells.

Animals↗