The disconnection apraxias.

Limb apraxia is the loss of the ability to perform voluntary skilled movements, when this loss cannot be attributed to elemental sensorimotor deficits. Successful manual interactions with the objects in the environment require the storage of information about movement parameters. This information is stored in specific cortical modules and the correct performance of a skilled act requires interactions between these modules. Thus, apraxia can occur with degradation of these critical representations or a disconnection between modules. The goal of this paper is to define the different forms of limb apraxia and discuss how apraxia can be induced by both a deterioration of these modules as well as disconnections between these modules that form an anatomically distributed system.