Abstract

The functional interplay between the parietal and the frontal lobe is based on the operations of a continuum of cortical areas linked by association connections, that in most instances are reciprocal. As a general rule, any given parietal area is linked to a discrete number of frontal areas (and vice versa) through long oligosynaptic pathways, thus creating in the brain different parieto­frontal information processing streams with varying degrees of segregation and overlap. The axons origination from each area have different diameters and conduction speeds, hence they generate slow and temporally ­dispersed conduction delays, which can determine different oscillatory regimes at post­synaptic level. Among other consequences, this mechanism can be a substrate for the representation of information in different reference frames. These pathways are the edges of a distributed system necessary for the composition of commands for different daily actions, such as reaching, grasping, constructing objects, using tools, perceiving heading direction, avoiding obstacles etc. Such functions are represented in a distributed and redundant fashion, and their command emerges from the area/s (node) within the network possessing the functional repertoire more appropriate to current task demands in the action space. These ideas will be illustrated trough the analysis of parietal neural activity during action tasks requiring different forms of eye­-hand coordination and in relation to the dramatic consequences of posterior parietal lesions on higher­order motor behavior.