1. The reproduction of movements sequence organized by simple rule by left and right hand Lyakhovetskii V.A., Bobrova E.B., Bogacheva I.A. Pavlov Institute of Physiology, Movement Physiology Laboratory e-mail: v_la2002@mail.ruv_la2002@mail.ru

2. Introduction It is well known that the information in brain hemispheres is represented by different manner. Left hemisphere operates with the categorical information and right hemisphere operates with the precise coordinate information (Kosslyn et al., 1995). The control of sequence acquisition is realized by the structures of left hemisphere for the right hand, by both hemispheres for the left one (Grafton et al., 2002). What happened if subject had to memorize very simple movement sequence by the right or the left hand?

3. Method: procedure The hand of the blindfolded volunteer was moved by experimenter from center through 6 different positions at a sheet of paper A4 located under touch screen. The volunteer had to remember and immediately after that to reproduce by hand the sequence of positions. 40 right-handed volunteers (divided onto 2 groups). 2 groups: carried out the task by the right hand, and then by the left one (group A), and carried out the task by the left hand, and then by the right one (group B).

4. Method: stimuli (sequence structure) 1: random positions 264 1 35 2: ordered positions, ordered way (diagonal locations with one trajectory change to 90°) 4 35 26 1

5. Method: stimuli examples Random positions Ordered positions

6. Method: data analysis Positional errors Movement errors 1 1 2 1 11 1 2

7. Results: Positional errors (random versus ordered)

8. Results: Movement errors (random versus ordered)

9. Results: Positional errors (group A versus group B) The values of the positional and orientation errors of reproduced hand movements were low compared with the errors in a case of random order of the stimuli proving the person applies his abstract knowledge about sequence’ structure.

10. Results: Movement errors (group A versus group B) Both the positional and movement errors of the both hands are significantly lower for group B than for group A (2.9 cm versus 2.6 cm / 13º versus 9º for first sequences; 3.2 cm versus 2.7 cm / 17º versus 10º for second sequences).

11. Results: mean errors for ordered sequences

12. Conclusions We suppose the improvement in the case when the left hand begins to perform the task connected with the activation of the right-hemisphere mechanism controlling the precise coordinates of touch screen points. Thus, the prehistory of performance may activate different brain areas and force to choose different control strategies embodying conceptual knowledge about sequence’ structure even in a case of the simple motor tasks.