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.

[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).

Specific features of learning with nociceptive electrical reinforcement in rats of different genetic strains: role of brain neurotransmitter systems.

The interaction between neurotransmitter systems and opioid system in rats of different strains was studied during learning and emotional stress. The interaction between noradrenergic, serotoninergic, and opioid systems in the brain is the main neurochemical mechanism underlying learning reinforced by nociceptive electrical stimulation, which determine individual differences in the rate and type of learning.

HLDF-6 peptide relieves symptoms of abstinence syndrome during experimental opium abuse.

Experiments were performed on rats with opium abuse induced by chronic administration of morphine in increasing doses. We studied the effect of HLDF-6 peptide on symptoms of naloxone abstinence. Repeated administration of HLDF-6 peptide in a dose of 0.2 mg/kg 24 and 0.5 h before naloxone relieved the major symptoms of the abstinence syndrome. A possible neurochemical mechanism underlying the effect of HLDF-6 peptide is inhibition of enkephalinase A in structures of the endogenous antinociceptive system.

Changes in thermonociceptive thresholds and the role of enkephalinase A in homeostasis in morphine-tolerant rat offspring.

The dynamics of thermonociceptive thresholds as a marker of the state of the endogenous opioid system was studied in the offspring of morphine-tolerant rats. Significant, age-dependent increase in thermonociceptive thresholds and higher levels of enkephalinase A in structures of the endogenous antinociceptive system were observed in the offspring compared with the control. These findings attest to disturbances of the opioid system in the progeny of morphine-tolerant rats and confirm the key role of enkephalinase A in the maintenance of homeostasis disturbed by chronic prenatal morphine treatment.

[Dopaminergic mechanisms of the oculomotor behavior of primates]. / Dofaminergicheskie mekhanizmy glazodvigatelnogo povedeniia primatov.

Behavioral changes and eye movements were studied through chronic low-dose MPTP exposure (ten intramuscular injections of 0.2 mg/kg per day) in four monkeys (Macaca rhesus). The monkeys developed the deficit of spontaneous saccades and decreased oculomotor range. The vertical component of saccades were hardly reduced. The examination of vestibuloocular reflex revealed no changes (r = approximately 1.0), but the fast phase of nystagmus was blocked.

Action of beta-endorphin antiserum of different antibody titres on thermal or tail-shock pain in rats.

Intravenous injection of beta-endorphin antiserum (AS) with antibody titres of 1:1,600, 1:3,200, 1:12,800, and 1:20,000 decreased the voltage threshold in the tail-shock test (electrocutaneous nociceptive stimulus) in rats for 2 days, after which time control levels were regained. In the case of AS of titres 1:12,800 and 1:20,000 this threshold then increased to above control levels for about 40 and 100 days, respectively. This effect was abolished by naloxone. In the same rats, an injection of AS of titre 1:1,600 did not alter the latency of the tail-flick test (thermal nociceptive stimulus) but AS of titres 1:3,200, 1:12,800, and 1:20,000 decreased it for 1-4 h, the actual length of time being titre-dependent. After control levels had been regained, there was no further change in latency in the tail-flick test in the subsequent 42 days. Injection with preimmune serum did not change either voltage threshold or latency in the two tail-stimulation tests in control rats. Thus the hyperalgesic short-term effect seen in response to treatment with beta-endorphin AS was more pronounced in response to an electrocutaneous stimulus than to a thermal one, and the long-term selective analgesic effect was present in response to rats given electrocutaneous stimulation but not to thermal stimulation. It is proposed that beta-endorphin AS has a two-stage selective effect: a reduction in beta-endorphin release followed by a 'rebound' increase.