The Effect of Surgical Procedure in the Nasal Cavity on the Passive Avoidance Conditioning and the Hypothalamic Level of Monoamines in Rats.

A rat biological model of septoplasty was used to study the effect of surgery on passive avoidance conditioning (PAC). Septoplasty was shown to increase anxiety and to reduce exploratory activity in rodents during PAC. A neurochemical analysis of the hypothalamus was carried out immediately after the end of the experiment and showed an increase in norepinephrine (NE) metabolism after septoplasty. The finding was tentatively associated with activation of the hypothalamic-pituitary-adrenal axis.

[Network analysis of cognitive, oculomotor and speech parameters in schizophrenia]. / Setevoi analiz kognitivnykh, glazodvigatel'nykh i rechevykh pokazatelei pri shizofrenii.

OBJECTIVE: To determine the network connections between clinical, cognitive, speech and oculographic parameters in patients with schizophrenia. MATERIAL AND METHODS: The study included 104 patients with schizophrenia and schizophrenia spectrum disorders and 70 healthy subjects. Clinical assessment of the patients was performed using a number of scales: PANSS, CDSS, YMRS, SAS and BAS. Basic cognitive functions were assessed by BACS. Eye movements were recorded using the SMI RED-500 non-invasive eye tracking system. Several experimental paradigms were used - free viewing of animal images with subsequent description of these images, performing progressive saccades in the experimental Go/NoGo scheme, and performing anti-saccades. RESULTS: The severity of clinical symptoms, cognitive impairments, oculomotor parameters and characteristics of speech structure of written speech are largely independent, although not completely isolated from each other. Cognitive and oculomotor parameters have the largest number of connections. In this case, the results of cognitive tests are the central element of the «network¼ that connects other groups. CONCLUSION: Further development of the approach should be aimed at studying the influence of node changes on the structure of the network that would potentially allows the identification of the most effective points of application of therapeutic and rehabilitation programs.

Influence of Cranial Irradiation with High-Energy Protons on the Visuomotor Behavior in Monkeys.

The visually driven instrumental conditioning of a single monkey (Macaca mulatta) was conducted after single-dose cranial irradiation with high-energy protons. The monkey executed saccades toward the visual stimuli and then responded by manually pressing right or left lever for stimuli in right or left half-field, respectively. The percentage of correct responses with dominant right hand exceeded the percentage of such responses with left hand and temporarily decreased two months after irradiation. A month later, the percentage of correct right-hand responses returned to the level before irradiation. No significant dynamic was found for changes in percentage of correct left-hand responses. The proton irradiation effect on right-hand responses suggests possible short-term disturbances in the eye-hand coordination for right handedness while the visual perception remains unaffected.

[Eye movement parameters in reading the sentences with syntactic ambiguity in Russian language].

We studied the eye movement parameters during reading of syntactically ambiguous sentences with feminine relative clause in Russian language. A priori difficulties of sentence structural analysis results in increase of time spent on reading as opposed to reading control sentences (unambiguous). Such a delay is caused by an increase of frequency of regressions (backward saccades) which are executed for rereading an ambiguous fragment ofsentence. This fact in turn leads to an increase in number of fixations and their duration. The total reading time for particular words composing the ambiguous fragment of sentence depended on disambiguation result (relative clause attachment, early/late closure). In case of early closure (when the subject attached relative clause to first noun) the total reading time for this noun exceeded one for second noun. In case of late closure (when the subject attached relative clause to second noun) the total reading time for both nouns didn't differ. Our results indicate that early closure domination in Russian language determines the greater total reading time for first noun of nominal group associated with relative clause.

[Functional asymmetry of monkeys' hand movements (Macaca mulatta)].

Three Macaca mulatta were tested in two different tasks. In the naturalistic behavioral experiment, a monkey had to grasp a piece of food from a hollow cube with an asymmetric position of an aperture. The preferable hand was determined. In the second experiment, a monkey performed a more difficult instrumental task: it pulled the lever by the right or by the left hand depending on the position of a trigger stimulus in a corresponding visual hemifield. It was shown that, in the second task, the preferable hand to some extent is characterized by the following: 1) it was mainly used if the trigger stimulus was presented in the contralateral midline region of the visual field, 2) shorter latencies, 3) higher maximum speed of the movement. On the basis of the results obtained a hand preference criterion can be developed in monkey laboratory experiments.

[Integration of videooculography and encephalography for investigation of visual selective attention in humans].

An original method of EEG recording in combination with eye tracking was developed. Due to the precise synchronization (which can include any amount of various recording devices), it is now possible to record short-time electrophysiological patterns evoked by some visual stimulus. The key feature of the method is the possibility to study not only single effects of a stimulus but to extract electrophysiological records corresponding to some part of complex image scanning.

[Alpha ERD and human visual selective attention].

We compared the alpha band EEG depression (event-related desynchnization, ERD) level in two tasks, involving activation of different attentional processes: visual search for a deviant relevant stimulus among many similar ones and visual oddball. Control data for the visual search task consisted of simple viewing of several stimuli being of the same shape as the relevant stimulus in the search trials. Gaze position was verified by eye tracking method. We interpreted alpha band ERD as a correlate of activation of attentional processes. Fixating the target in visual search task caused a significantly larger ERD than fixating the same stimuli in control trials over all leads. We suppose this to be related with task and visual environment complexities. The frontal ERD domination may indicate attentional control over voluntary movements execution (top-down attention). The caudal ERD may be related with updating of visual information as a result of search process (bottom-up attention). Both relevant and irrelevant stimuli in the oddball task also induced alpha band ERD, but it was larger in response to relevant one and reached maximum level over occipital leads. Domination of caudal ERD in oddball task is supposed to indicate bottom-up attention processes.

Effects of visual environment complexity on saccade performance in humans with different functional asymmetry profiles.

Studies in 47 right-handed subjects with right and left leading eyes addressed the latent periods of visually-evoked saccades in the horizontal, vertical, and diagonal directions within the field of vision. Visual environments with three levels of temporospatial complexity and two standard time protocols of visual stimulation, with "gap" and "overlap," were used. In subjects with left leading eyes, saccades were more often performed with shorter latent periods in the direction ipsilateral to the leading eye than in the contralateral direction (53% versus 20%); among subjects with right leading eyes, the proportions with decreases in the latent periods in the ipsi- and contralateral directions were different (25% and 22%, respectively). Thus, there was a relationship between eye dominance and the spatial asymmetry of the latent periods of saccades.

[Saccadic latency in human with different profiles of functional asymmetry depending on visual space complicity].

The latencies of visually-guided saccades of 47 right-handed subjects (32 with right leading and 15 with left leading eyes) were studied. Stimulation paradigm was spatially bidimentional, and stimuli were presented along horizontal, vertical and oblique axes. Three levels of visual space complicity and two traditional single-step GAP and OVERLAP temporal paradigms were used. A half of the left-leading-eye subjects had shorter latencies of the saccades directed towards the left (ipsilateral) hemifield, whereas only one fifth of the subjects demonstrated shorter latencies ofsaccades towards the right (contralateral) hemifield (53% vs 20%). Only one fourth of right-leading-eye subjects had shorter latencies of saccades towards the inpsilateral hemifield and one fifth of these subjects had shorter latencies of the saccades towards the contralateral hemifield (20% vs 25%). The interrelation between eye dominance and spatial asymmetry of saccadic latencies is revealed.

[Groups of passive and active control state in longitudinal experiments: an electrophysiological study].

Long-term electrophysiological experiments were carried out with rats with chronically implanted electrodes into dopaminergic brain structures. Within 4 weeks after surgery, the relative spectral power of electrical activity in the delta1 and delta2 frequency bands decreased, while the relative spectral power in the alpha, beta1 and beta2 bands increased. A delayed (to the 4-5th week after surgery) increase in the total amount of sleep and REM sleep percent was observed in the sleep architecture of these animals. Multiple (during 2 weeks daily) intraperitoneal saline injections altered the dynamic of electrophysiological indices on the 2nd-3rd postsurgery weeks. The total sleep amount being not increased, the total and mean REM sleep durations increased, and the dynamic of the relative spectral power of electrical activity in the dopaminergic brain structures in the delta1, alpha and beta2 bands was found to be changed.

[Effect of dopamine deficiency on the preparation of visually guided saccadic eye movements].

Parameters of saccadic eye movements were studied in patients with Parkinson's disease and control subjects. In parkinsonian patients, the number of slow regular saccades was shown to be increased, and the number of express saccades was shown to be decreased. As a result the mean of saccade latency in patients was longer than in the control group. Moreover, the percentage of multistep saccades in patients with Parkinson's disease. In this case, not one but two or three saccades were performed with smaller amplitude to the target. We point, that the multistep saccades occurred mainly among the express saccades. Obviously, the dopamine deficiency distinguishing parkinsonian patients takes the primary part in the development of saccadic disorders. Degeneration of the nigrostriatal dopamine pathway results in imbalance in activity of the direct and indirect output pathways of the striatum. We suppose that this leads to inhibition of neurons activity in the superior colliculus during the saccade performance, which results in the early saccade interruption. In support of this reasoning, the mean of saccade latency and the percentage of the multistep saccades decreased in patients with Parkinson's disease after dopamine D2/D3 agonist (piribedil) treatment, due to activity restoration of the indirect pathway.

Asymmetry of the amplitude-time properties of directed saccades in monkeys depending on the complexity of the spatial scheme of visual stimulation.

Three Macaca rhesus monkeys were used for studies of the performance of visually evoked saccades in single-step changes in the position of a stimulus using standard schemes for presentation of GAP-OVERLAP stimuli. Two spatial schemes were used: presentation of stimuli along the horizontal meridian (one-dimensional) and presentation of stimuli within a rectangular area of the visual field (two-dimensional). Asymmetrical foci of short-and long-latency saccades were found in the visual field. Dispersion factor analysis demonstrated that the dimensionality factor (one-dimensional versus two-dimensional stimulation schemes) had greater effects on the latent period of saccades than the lateralization factor (presentation on the left or right sides of the gaze point). The precision of the performance of visually evoked saccades decreased with increases in its eccentricity in both spatial stimulation schemes.

[Asymmetry of the latent periods of saccades in human depending on visual space complicity].

Saccadic latencies of visually-guided saccades of 10 right-handed subjects with right-leading eyes were studied. Stimulation paradigm was spatially bidimentional, and stimuli were shown along horizontal and vertical meridians. Three traditional single step GAP - NO DELAY - OVERLAP temporal paradigms were used. In the first experiment, each paradigm was applied separately (simple visual space). In the second experiment, all the three paradigms were varied pseudo-random order and equiprobably, which complicated the time parameters of visual stimulation (complicated visual space). Asymmetry of visually-guided saccades along the vertical and horizontal meridians was revealed. The character of this asymmetry varied between subjects. MANOVA showed that the factor of visual space complicity (simple or complicated visual space) affected the latent period of saccades to a greater extent than the factor of stimulus lateralization (stimulus presentation in the left/right or upper/lower visual hemifields).

[Asymmetry of the amplitude-temporal properties of visually-guided saccades in monkeys depending on the complexity of the spatial scheme of the visual stimulation].

The properties of visually-guided saccades were studied in three monkeys (Macaca rhesus). Traditional single-step GAP-OVERLAP temporal paradigms were used. Target stimuli were presented in accordance with two spatial stimulation schemes: (i) along the horizontal meridian (one-dimensional scheme) and (ii) within rectangle part of the visual field (two-dimensional scheme). We revealed asymmetric focuses of short- and long-latency saccades in the two-dimensional scheme of stimulation. The MANOVA revealed that the factor of dimensionality influenced saccadic latency to a greater extent than the factor of lateralization of stimuli (presenting in the right or left visual hemifields). Accuracy of saccades decreased with increasing in their eccentricity in both spatial schemes of stimulation.

Disturbances of saccadic eye movements in monkeys during development of MPTP-induced syndrome.

Changes in the amplitude and dynamic parameters of purposive saccades were studied in monkeys with MPTP-induced Parkinson-like syndrome. Lengthening of saccade latency, decreased maximum velocity of eye movements, and impaired saccade accuracy were observed at the early stages MPTP-syndrome. Different disturbances of large- and small-scale saccades were found.

[A method for the chronic electromagnetic recording of eye and head movements in monkeys]. / Metodika khronicheskoi élektromagnitnoi registratsii dvizhenii glaz i golovy u obez'ian.

A search-coil method for two-dimensional chronic registration of eye and head movements is described. The method is based on the analysis of the electromotive force induced by a magnetic field in a search coil. The output parameters of the original dual system were measured using both the standard search coil and that implanted into monkey's eye. The precision of eye movement recording was evaluated in real time. Standard deviation of spontaneous noise level for both channels was equal to 0.16 degrees (deg). The same parameters representing eye movement error during gaze fixation in the horizontal (in the range of -20/+20 deg) and vertical (in the range of -13/+13 deg) directions were equal to 0.27-0.38 and 0.23-0.31 deg, respectively. The obtained errors were comparable with the angular size of the peripheral target stimuli (0.20 deg), which had to be traced by an animal with saccadic movements.

[Changes in the behavior and EEG of rats administered penicillin and a physiological solution into the amygdalar basal nuclei]. / Izmeneniia povedeniia i EEG krys pri vvedenii v bazal'nye iadra mindalevidnogo kompleksa penitsillina i fiziologicheskogo rastvora.

Three weeks after implantation of the electrodes for EEG recording, hyperactivation of the basal nucleus of rat's amygdala was produced by a local injection of penicillin (0.5 mcl, 1% solution). Saline injection of the same volume served as control. The hyperactivation of the amygdala resulted in a long-lasting (at least for 3 weeks) increase in the locomotor activity against the background and deficit in exploratory behavior and rise of the level of anxiety and fear. The behavioral changes were accompanied by a long-term disruption of the hippocampal theta rhythm, appearance and slowing of the immobility-related high-voltage spindles, and increase in the EEG dominant frequency in the state of emotional tension. Saline injection led to a short-time (up to 1 week) decrease in locomotor and exploratory activity and increase in anxiety. These phenomena were accompanied by a short-time disruption of the theta rhythm and appearance of the 10-13-Hz oscillations characteristic for the state of emotional tension.

[The behavioral changes and the EEG of the rat brain induced by hyperactivation of the amygdaloid body under noradrenergic deficiency]. / Izmeneniia povedeniia i EEG mozga krys, vyzvannye giperaktivatsii mindalevidnogo kompleksa v usloviiakh noradrenergicheskoi nedostatochnosti.

The brain NA deficit was produced by bilateral injection of 6-OHDA into the locus coeruleus. Three weeks later amygdala hyperactivation was initiated by local penicillin injection (1% solution, 0.5 mcl). Saline in the same volume was used in control groups in both cases. It was shown that the decrease in NA level facilitated the development of epileptiform activity in rat brain and appearance of immobility-related high-voltage spindles during waking. The amygdala hyperactivation after NA deprivation resulted in a decrease in exploratory activity and disruption of the reaction to novelty. The delta component of the EEG power spectrum increased. The alterations appeared 1-2 weeks after the experimental procedure and became more pronounced towards the end of the third week.

Brightness perceptive space in monkeys (rhesus macaques).

Operant differentiation was used to study black/white stimulus intensity discrimination (over the range 1-37 cd/m2; CIE-31 coordinates X = 0.340, Y = 0.304) in two monkeys (rhesus macaques). Confusion matrices were constructed from the probabilities that animals would make operant responses when required to select from pairs (a conditioned stimulus and one of 9 differentiation stimuli) of stimuli in 10 series of experiments with conditioned stimuli of 10 intensities. Correlation matrices for vectors consisting of stimuli in the confusion matrices were assessed by factor analysis for identification of their intrinsic vectors. A perceptive space of two-dimensional structure was obtained for the brightness of black/white stimuli, and the main characteristics of this were similar to those of the analogous perceptive spaces for humans, fish (carp), and rabbits. The coordinate axes of this space can be interpreted in terms of excitation of two intensity-encoding channels: light and dark.