Cortical asymmetry: catching an object in free fall.

The main goal of the present study was to analyze theta asymmetry through quantitative electroencephalography (qEEG) when individuals were exposed to a sequential motor task, i.e. catching a ball. The sample was composed of 23 healthy subjects, male and female, between 25 and 40 years of age. A two-way factor Anova was applied to compare pre and post moments related to the balls' drop and scalp regions (i.e., frontal and parieto-occipital cortices). The first analysis of the frontal region compared electrodes in the left, right and left/right hemispheres combined, with the frontal midline electrode (FZ) included in the analysis. The results showed moment and region main effects. The second analysis compared left versus right hemisphere without the FZ site. The findings demonstrated an interaction effect between moment and region. The first parieto-occipital analysis, comparing left, right and central regions, with PZ included in all regions, showed main effects of moment and region. The second analysis, comparing left, right (without Pz) and central regions strictly demonstrated a region main effect. Thus, we observed an asymmetric pattern in the frontal cortex (i.e., planning and response selection) when the subjects were waiting for the balls' drop. Moreover, the left hemisphere seems to engage differently from the other regions when the central nervous system needs to prepare for a motor action. On the other hand, the parieto-occipital cortex, which is related to attentive processes, demonstrated a more asymmetric activity towards the right region which implies a participation of this area in cognitive strategies in this particular task. Taken together, we concluded that the adopted experimental approach can be useful to explore several others directions combining sensorimotor integration tasks with different pathologies, such as depression, Alzheimer's and Parkinson's diseases.