Information transfer and cortical interactions in a visuomotor tracking task

The human brain undertakes highly sophisticated information processing facilitated by the interaction between its sub-regions. We present a method of identifying directed inter-regional information structure (using extensions to the transfer entropy), and the changes in this structure with respect to some variable (e.g. time). This method is distinguished in using asymmetric, multivariate, information-theoretical analysis, which captures not only non-linear relationships, but also collective interactions and the direction of these relationships. The method is used to analyse blood oxygen level-dependent time series to establish the directed information structure between regions involved in a visuomotor tracking task. Importantly, this is a tiered structure, with known movement planning regions driving visual and motor control regions. Also, we examine the changes in this structure as the difficulty of the tracking task is increased, and find greater coupling between regions involved in movement planning (left SMA and left PMd) and execution (right cerebellum for right hand and right SC for eye movements) with task difficulty. It is likely these methods will find utility in identifying inter-regional structure (and structural changes) in other cognitive tasks.