Apraxia

Limb apraxia is a multi-faceted disorder that emerges primarily after damage to the left hemisphere of the brain and manifests broadly as an impairment in performing skilled movements. Two broad subtypes of apraxia are generally defined: ideational apraxia characterized by deficient knowledge of object function, and ideomotor apraxia characterized by spatiotemporal deficits in the actual execution of an action. Investigations of the neural basis of apraxia suggest that sub-divisions of the classic “dorsal” and “ventral” pathways might underlie the behavioral deficits in apraxia. New research is starting to shed light on the complex connectivity patterns and integration across these different routes during the production of skilled actions. The current chapter lays out some of the foundational aspects of the disorder starting with its definition, moves to some historical perspectives on the underlying mechanisms, and finally delves more deeply into its neural basis.