Differential effects of motor coordination context on EEG alpha/mu sub band modulation.
David Watson1, Muhammad Naeem1, Girijesh Prasad1, J. A. Scott Kelso1, 2
1Intelligent Systems Research Centre, School of computing and Intelligent Systems,University of Ulster, Magee Campus, Londonderry BT487JL, Northern Ireland, UK
2Human Brain and Behavior Laboratory, Center for Complex Systems and Brain Sciences, Florida Atlantic University, Boca Raton, FL 3343 1, USA
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Abstract
Mu activity occurs in the alpha band over the sensory motor cortex and has been associated with motor coordination within social contexts. Afunctional dissociation of lower (8-10Hz) and upper (10-12 Hz) mu band activity has been argued to occur dependent on particular characteristics of an interaction. The goal of this research was to investigate sub-band modulations of mu domain in different coordination contexts.
Dyads of subjects performed a finger movement task under three conditions: intrinsic-ignore their partner’s movement; in-phase- synchronise with their partner; and anti-phase- maintain syncopation with their partner. EEG was recorded during task and at baseline (partner’s actions hidden from view). Log power ratios of mu band activity (active against baseline) were used to assess the relative levels of synchronisation/de-synchronization in both the upper and lower bands.
The results show that co-ordination conditions had differential effects in these bands over central-parietal areas. Bilateral suppression was found to increase from intrinsic, through in-phase to the anti-phase conditions in the lower mu band. This non specificity is attributed to general (attentional) processing demandrather than coordination contextspecific effects. In contrast the upper mu band showed itself to be sensitive to properties of the interaction conditions. There was evidence of a specific right sided modulation of activity in this band over the central-parietal region which varied with task instructions.
These results are consistent with previous work suggesting a dissociation of mu band activity and the information processing systems they represent. Further it suggests that activity in the upper mu band may represent specific mechanisms related to value and interpretation of another’s actions in terms of required response or co-ordination of behavior. These mechanisms appear to be specific to the right central-parietal cortex.