Aims: 

EEG coherence is a measure of synchronization between corresponding frequency components of two signals. The aim of this study was to consider activity and functional coupling of distributed neuronal assemblies in the brain during mental rotation – a visuo-spatial cognitive function based on imaginary manipulation with the object.

Methods: 

EEG was recorded during a mental rotation of 2D alphanumeric characters in 14 healthy undergraduates. EEG coherence was computed in the interval 500 ms before subject's response and compared for stimulus angular displacement 120° (mental rotation) and 0° (control task without mental rotation). Pearson's correlation coefficients were used to investigate the relationship between EEG coherence and reaction time.

Results: 

During mental rotation a widespread increase in EEG coherence was observed in the delta and beta 2 frequency bands. Fronto-temporal coherence in the delta band was negatively correlated with reaction time – the increase in coherence was higher in subjects who solved the task more quickly. In contrast, correlation in the beta 2 band was positive – higher parieto-temporal coherence was associated with longer reaction time. In other frequency bands the changes were less pronounced and less consistent.

Conclusions: 

Our results indicate that synchronization of neuronal activity in the delta band could be specifically related to mental rotation process. Synchronization in the beta band, on the other hand, seems to be related to effort exerted to solve the task.

This work was partially supported by VEGA grant No. 2/5049/27