Differences in the parameters of memory-guided saccades and saccades to visual stimuli were demonstrated. Increases in the latent periods of memory-guided saccades as compared with saccades to visual stimuli provided evidence of slowing of saccade programming based on the extraction of information from working memory. Differently directed lateral differences were seen in the latent periods and durations of saccades to visual targets and memory-guided saccades, reflecting the leading role of the left hemisphere in the programming of saccades to visual stimuli and the right hemisphere in the programming of memory- guided saccades. Comparison of parameters of the temporospatial dynamics of initiation potentials P -1 and N -1, which develop in the last 100 msec of the latent periods of saccades, suggest that there are different mechanisms for the final step of programming saccades to visual stimuli and memory-guided saccades. Decreases in the latent period of the P -1 and N -1 peak potentials before memory-guided saccades may be evidence showing acceleration of the initiation processes for memory-guided saccades as compared with visually evoked saccades. This provides grounds for suggesting that the slowing of the programming of memory-guided saccades occurs at steps preceding saccade initiation.

Longer latency and duration of memory-guided saccades and their lower amplitude compared with visually-guided saccades testify to the slower programming of the former. Lateral distinctions in the latencies and durations of memory-guided and visually-guided saccades can reflect leading role of the right hemisphere in programming memory-guided saccades and leading role of the left hemisphere in programming visually-guided saccades. Topography and spatiotemporal dynamics of presaccadic potentials P-1 and N-1 within the last 100 ms of latent period suggest that the mechanisms of final stage of the programming of memory-guided and visually-guided saccades are different. Shorter latencies of the presaccadic P-1 and N-1 prior to memory-guided saccades testify to acceleration of the initiation of the memory-guided saccades. The acceleration of the initiation period of memory-guided saccades suggest that deceleration of memory-guided saccade programming occurs at the stages preceding saccade initiation.

Heart rate variability (HRV) in individuals with autism spectrum disorders (ASD) has been investigated in some studies but the procedures and results vary. We conducted a systematic review and meta-analysis to compare HRV in individuals with and without ASD; the influence of different conditions and HRV indices is considered. Baseline HRV and HRV reactivity were analyzed in several ways: parasympathetic indices in hierarchical order (main analysis), total variability, specific parasympathetic indices and respiratory sinus arrhythmia (RSA), etc. The review covered 34 studies for quantitative analysis. Individuals with ASD had a significantly lower baseline HRV for parasympathetic indices in hierarchical order (Hedges’g=-0.5168, p < 0.0001) and RSA (g=-0.5860, p=0.0010). The reactivity of HRV in situations of social stress (g=-0.4647, p = 0.0033) and social debriefing (g=-0.5001, p = 0.0007) was also significantly lower in subjects with ASD. RSA reactivity was significantly lower in ASD group for all situations, with the largest effect size for social stress (g=-0.7246, p < 0.0001). The results support low HRV to be a potential biomarker of ASD, especially RSA reactivity under social stress.

The perception of time by humans was studied by the method of time reproduction. The EEG was recorded in Os, Od, Cs, Cd, Fs and Fd derivations. The relative EEG spectral power was determined in the delta-1, delta-2, theta, alpha, beta-1, and beta-2 ranges. All the subjects were divided in two groups: I--those who reproduced time-intervals with a delay, and II--those who were ahead in their reproduction. The spectral power of the delta-rhythm was significantly lower and that of the beta-rhythm higher in the subjects of the I than of the II group. In subjects of the II group total power of the beta range (beta-1 + beta-2) was significantly less than that in the delta-range (delta-1 + delta-2). This ratio was inverse in subjects of the I group. The described relationships were expressed both in the background EEG and during functional loads in all the studied derivations.

Dependence of the dominant alpha frequency on the processes of perception and subsequent reproduction of time intervals by rhythmic hand pressing was analysed. Two groups of subjects were separated, which demonstrated either an increase (I) or a decrease (II) in the dominant alpha frequency after the transition from perception to reproduction. In the I group 83% of the subjects reproduced time intervals with a delay. In the II group reproduction in advance was observed in 75% of the subjects. The dynamics of the dominant alpha frequency probably reflects formation of the optimal functional state underlying the individual level of activation and properties of the higher nervous activity in the subjects from both groups.

Present research is devoted to psychophysiological study of the mechanisms of functional state control in normal and educationally disabled children using EEG, neuropsychological, and heart rate data obtained during different types of mental activity, including performance of arithmetic, verbal, spatial, and time-perception tests. Attention index and one-minute time interval production in the group of educationally disabled patients were found to be statistically lower than in the normal children. Heart rate level in this group was also lower than in the normal children of the same age. Increase of heart rate indices during perception of instruction and transition to its realization was statistically higher in the group of normal children. The differences between the groups can be explained by disfunction of the functional state regulation mechanisms, deficit of sympathetic influence and prevalence of parasympathetic ones, as well as by the weakness of the functions of the nervous system which causes disadaptation in educationally disabled children.

Some characteristics of electroencephalographic reaction (alpha frequency, whole alpha range power spectrum and alpha index) have been studied. In the first series the indifferent single, rhythmic and complex stimuli were presented to the test subjects, in another series a conditioned motor reflex was elaborated, in the third series the test subjects rhythmically reproduced fixed temporal interval. It has been shown that the functional loads lead to higher alpha frequency. The alpha rhythm frequency was higher in subjects verbally underestimating and reproducing intervals with some delay than in ones overestimating intervals and reproducing them in advance. It has been suggested that alpha rhythm instability is due to reorganization processes in neuronal complexes of different lability.

An important role of time factor in adaptive process of organisms is shown on the basis of great literary material. The time perception is a result of the interrelationship of the so-called "biological clock" and learning during the whole ontogenesis. The hypothetical mechanisms of time perception are discussed. In own experiments the authors revealed more distinct expressiveness of high-frequency components in electroencephalogram spectrum and less expressiveness of low-frequency components in subjects underestimating time intervals compared with subjects overestimating them. A conception on the role of individual characteristics of nervous system in time perception is developed.