[Learning of reproduction of random sequences by the right and the left hand movements: coding of positions or movements].

Positional and movement errors during reproduction of memorized sequences of six random hand movements were analyzed. The task was performed by two groups of subjects: during six days by one hand (right/left) and during next six days by another hand (left/right). Mean values of accuracy errors decreases during learning only in a group which begins to work by the right hand. The quantity of transposition errors depends on type of error: positional or movement one. Subjects transpose the positions of the right hand more often when it begins to perform the task. Subjects transpose the movements of the left hand more often when it begins to perform the task. The results are evident in favor of the hypothesis about two type of movement coding: positional and vector coding (coding of positions or of changing of positions) specific in the right and the left hemispheres and suggest that learning of reproduction of movement sequences is provided by vector coding.

[Transposition errors during learning to reproduce a sequence by the right- and the left-hand movements: simulation of positional and movement coding].

Transposition errors during the reproduction of a hand movement sequence make it possible to receive important information on the internal representation of this sequence in the motor working memory. Analysis of such errors showed that learning to reproduce sequences of the left-hand movements improves the system of positional coding (coding ofpositions), while learning of the right-hand movements improves the system of vector coding (coding of movements). Learning of the right-hand movements after the left-hand performance involved the system of positional coding "imposed" by the left hand. Learning of the left-hand movements after the right-hand performance activated the system of vector coding. Transposition errors during learning to reproduce movement sequences can be explained by neural network using either vector coding or both vector and positional coding.

[Influence of "prehistory" of sequential movements of the right and the left hand on reproduction: coding of positions, movements and sequence structure].

The dependence of errors during reproduction of a sequence of hand movements without visual feedback on the previous right- and left-hand performance ("prehistory") and on positions in space of sequence elements (random or ordered by the explicit rule) was analyzed. It was shown that the preceding information about the ordered positions of the sequence elements was used during right-hand movements, whereas left-hand movements were performed with involvement of the information about the random sequence. The data testify to a central mechanism of the analysis of spatial structure of sequence elements. This mechanism activates movement coding specific for the left hemisphere (vector coding) in case of an ordered sequence structure and positional coding specific for the right hemisphere in case of a random sequence structure.

[Characteristics of short time interval perception].

Some characteristics of the human perception of short time intervals (less than 3 s) were analyzed. We studied a range of short durations using quite a large number of stimuli (50 time intervals) with a small difference between each other (0.06 s) and were the first to determine the structure of short time interval rating scales. The analysis of the distribution of SD values of the interval durations showed that these scales are discontinuous (quantified) and may include about eight gradations. This result was confirmed in an additional experimental series.

[Storing of spatial order of targets during reproduction of movement sequence: the role of the right hand].

Acquisition of sequences of movements performed with the right and the left hands was studied for three types of positions of their elementary targets: 1) random position; 2) simple rule--diagonal sequence of targets with a single trajectory change by 90 deg.; 3) complicated rule--with the sequence of targets as for simple rule, but randomized order of presentation of targets. It is shown that the information about the location of targets according to the complicated rule is used during movements performed with the right but not left hand. It is suggested that the observed phenomenon is connected with the localization of the spatial sequence acquisition mechanisms in the left brain hemisphere. This type of information coding may underlie the mechanisms of gesture and speech control.

[Sequence acquisition by the right and the left hands: positional and vector coding].

Sequence acquisition by the right and the left hands were studied in 47 blindfold right-handed subjects. The errors of positional or vector coding were estimated as a distance between positions of the hand moved by the experimenter and by a subject on his/her own or as an angle between vectors connecting the successive positions of the hand moved by the experimenter and the subject. The percentages of errors in performance with the right and the left hands did not differ, but the values of positional errors were lower for the right hand. The higher was the amplitude of the movement, the lower were vector errors and higher positional error. The vector coding was predominant in case of the right-hand movements, but prevalence of positional or vector coding was non-significant for the left hand. The results were simulated by the model on the basis of the heteroassociative network.

[Orderly structural organization of intrahemispheric interzonal connections in the cat visual cortex]. / Uporiadochennaia strukturnaia organizatsiia vnutripolusharnykh mezhzonal'nykh sviazei v zritel'noi kore koshki.

The study was aimed at morphometric analysis of cluster organization of neurons, forming interzonal cortico-cortical connections within the visual cortex. The study employed the technique based on horseradish peroxidase retrograde transport and methods of mathematical analysis of spatial distribution of labeled cells. The quantitative characteristics of cell distribution were obtained including cluster volume and linear dimensions, distances between their centers of gravity, periodicity and distribution along cortical surface. Age-related peculiarities in the distribution of initial cells of cortical interzonal connections were found. It was demonstrated that adult cluster organization pattern was established by the end of the second postnatal month. Quantitative differences in the spatial distribution of neuronal groups in the visual cortical areas 17 and 18 were determined.

[The structure of internal intraneuronal connections in the area 17 of the cat cerebral cortex]. / Struktura vnutrennikh mezhneironnykh sviazei polia 17 kory bol'shogo mozga koshki.

Spatial distribution of horizontal intrinsic neuronal connections in area 17 of cat cerebral cortex was studied following HRP microion tophoretic injections into the single cortical columns. Cluster analysis of labelled cell distribution in superficial layers was performed in the tangential cortical plane. Area 17 was found to contain 7 +/- 1 clusters each consisting of 1-5 cells. Clusters were arranged in two rows, separated by a distance of 1.2 +/- 0.3 mm. The distance between the centers of the clusters that form the rows was equal to 0.8 +/- 0.3 mm. The spatial characteristics of cell clusters sending axons to cortical column, found in this study, were compared with the known data on the optical imaging of the activity of neurons of orientation and ocular dominance columns of visual cortex. It is suggested that area 17 cortical column receives inputs from cells of 6-8 hypercolumns that have similar ocular dominance and orientation preference.