EN
Brain representations of numbers are spatially represented on so-called mental number line. We investigated the activation patterns related to the number magnitude and its spatial position during fMRI scanning. Each trial started with a fixation point replaced by a cue stimulus – one of four digits (1, 2, 8 or 9) or non-digit symbols (#, %, & or §). The target stimulus consisted of a pair of such digits and/or symbols. Participants responded by indicating the position (left/right) of the cue digit/symbol within the target, which could be either congruent (e.g. 8 on the right) or incongruent (e.g. 9 on the left). The behavioural results showed faster reactions to low than high number magnitude and fMRI results revealed the asymmetry patterns dependent of the digit magnitude, irrespectively of stimuli congruency. In trials with low digit magnitude the right hemisphere as well as left cerebellum preponderance was observed, while in trials with high digit magnitude the opposite pattern was present. However, the analysis of the activation volume calculated in each condition and hemisphere, showed the main effect of digit magnitude, but no significance for congruency and hemisphere. These results suggest that number magnitude processing affects the reaction time and volume of brain activation.