[Computer method for fusional reserves evaluation with objective control of fusion break].

A method of assessing fusional reserves using an interactive computer program, which allows to monitor the subjects report on the moment of fusion break with artificial increase of convergence or divergence of the vii sual axes in the measurement process was developed and tested. Control is achieved through the use of a purely binocular stimuli--random-dot stereograms, as well as dynamic markers, which are added to the main test object in a random order in the course of the measurement procedure to change the type of test-object. Test-object with a marker, encoded in the stereogram, is seen only at the expense of binocular mechanisms, and in violation ofifusion is no longer visible. Its disappearance helps the subject to determine when failure of fu-sion occurred, and the type of object with a marker before this point allows the experimenter to check the subject. Statistical analysis of primary and repeated measurements of fusion reserves in 72 subjects confimed the sufficient reliability of the method.

[Computer treatment of strabismus and amblyopia using random-dot stereograms]. / Komp'iuternoe lechenie kosoglaziia i ambliopii s primeneniem sluchaino-tochechnykh stereogramm.

Application interactive CLASS software for stimulating productive binocular cooperation based on random-dot patterns and stereograms was used for treating strabismus and amblyopia in 105 children during a standard course of treatment. The children were divided into 3 groups treated by the CLASS alone (1), Class + two other application programs (2), and CLASS + traditional methods. General positive changes (improvement of visual acuity, decrease of eye deviation, etc.) were similar in these 3 groups. Positive effect of CLASS exercises on binocular visual mechanisms was significant. Due to precise evaluation of binocular interaction provided by CLASS, positive changes in binocular cooperation and stereovision were attained in 93% of children.

[Model of the bicercal mechanism of constant direction perception of a mechano-acoustic signal in the insect]. / Model bitserkal'nogo mekhanizma konstantnogo vospriiatiia napravleniia mekhanoakusticheskogo signala u nasekomykh.

Model of signal processing in mechano-acoustical cercal system of insects is described in which the invariance of the perceived signal direction with respect to the positions of sense organs (cerci) is achieved due to connections of four central neurons with certain receptor groups on both cerci. The data published earlier suggest that the monocercal constancy mechanism for invariant estimation of signal direction is based on a proper change in the weights of receptoral inputs to the central neurons in accordance with the position of each cercus. In contrast with it the bicercal constancy mechanism discussed in this paper does not imply either any regulation of receptoral inputs to the central neurons or some other utilization of information about the position of sense organs at the moment of signal perception. The model is based on two properties of the cercal system: on each cercus there are receptors with optimal directions of stimulation which are parallel and perpendicular to the cercus axis; two cerci usually occupy symmetrical positions relative to the insect body. Signal processing in the proposed neural circuit is equivalent to the signal direction estimation by projecting the vector of velocity on the two stable basic directions whose orientations do not change when symmetrical changes in cercus positions occur.

Perception of stabilized retinal stimuli in dichoptic viewing conditions.

Perception of stabilized retinal stimuli was studied both in monocular and dichoptic viewing conditions. When identical stabilized stimuli of large size and high luminance were presented to both eyes, the phenomena characteristic of monocular perception (rapid fading of perceived images within a few seconds or their episodic disappearance and regeneration) failed to be observed: the visual images were perceived as decaying only gradually and slowly within several minutes. The results suggest that rapid changes and fluctuations of visual images perceived monocularly may be due to the effects of binocular interaction (cooperation/rivalry), episodic darkenings of the visual field seeming to be caused by temporary predominance of the occluded eye.

[Directional sensitivity of neurons of the cercal system of crickets in different body positions in a gravitational field]. / Direktsional'naia chuvstvitel'nost' neironov tserkal'noi sistemy sverchka pri razlichnykh polozheniiakh tela v gravitatsionnom pole.

The giant interneurons in the terminal abdominal ganglion of cricket (Acheta domesticus) were studied using sound signals with special interest to the effect of the body tilt on the directional sensitivity diagrams. The neurons under study receive their inputs from the cerci which have receptors sensitive to mechanic and acoustic stimulation and receptors sensitive to the cricket orientation in the gravity field. Directional sensitivity diagrams of the neurons were estimated by counting the numbers of impulses in their responses to sound signals of various directions for various body tilt. A detailed experimental investigation and corresponding calculation have demonstrated that the sound directional sensitivity diagrams of the neurons always turn as being fixed to the body when the cricket is tilted. This result indicates that cercal gravity receptors do not exert any specific influence on directional sensitivity of the abdominal ganglion neurons.

[Optimal air flow directions for activating the giant neurons of the cercal system in the cricket, Gryllus domesticus]. / Optimal'nye napravleniia vozdushnykh potokov dlia aktivatsii gigantskikh neironov tserkal'noi sistemy sverchka Gryllus domesticus.

Studies have been made of the directional sensitivity of the giant neurons in the abdominal nervous chain of the cricket during the effect of air flows and sound stimuli on the cercal system. It was found that the axis of sonic and air flow diagrams of the directional sensitivity for a given neuron are practically identical. On the basis of flow diagrams, in each of the connectives at the edge of terminal abdominal ganglion 4 giant neurons were identified which may form a system accounting for the reception of air flows of any directions approximating horizontal plane. It was found that 3 neurons from this system receive the main bulk of excitatory impulsation from the ipsilateral cercus, and only 1 of them--from the contralateral one. The data obtained are discussed in relation to morphological and physiological characteristics of the investigated group of giant neurons.

[Mechanism of the constant representation of the position of a sound signal source by the cricket cercal system neurons]. / Issledovanie mekhanizma konstantnogo otobrazheniia polozheniia istochnika zvukovogo signala neironami tserkal'noi sistemy sverchka

Previously it has been shown that some abdominal giant neurones of the cricket have constant preffered directions of sound stimulation in relation not to the cerci (the organs bearing sound receptors) but to the insect body (fig. 1) [1]. Now it is found that the independence of directional sensitivity of giant neurones on the cerci position disappears after cutting all structures connecting the cerci to the body (except cercal nerves) (fig 2). Therefore the constancy of directional sensitivity of the giant nerones is provided by proprioceptive signals about cerci position.

[Constant representation of signal spatial location in the cricket cercal system]. / Konstantnoe otobrazhenie polozheniia istochnika signala v prostranstve v tserkal'noi sisteme sverchka

Directional sensitivity of the abdominal giant fibers of the cricket to auditory stimulation has been investigated with special interest to the effect of the cerci position on the directional sensitivity of the giant neurons of the terminal abdominal ganglion. It has been shown that at least for some giant neurons the preferred directions of stimulation are practically independent of cerci position. (Fig. 2, 3). By other words these neurons have constant preferred directions in relation to the insect body, but not to the cerci. This property of giant neurons can be accounted for their changeable connections with many receptors having different directional selectivity. If innervation of the giant neuron is artificially restricted to one group of receptors with identical directional selectivity the described constancy of preferred directions in relation to the body disappears (Fig. 4).