[Functional coupling of the frontal and parietal lobes in action]

Apraxia is the inability to perform actions or move different parts of the body in the intended manner, despite normal physical capability of movement. Based on his studies, Liepmann divided apraxia into three types: ideational apraxia, ideomotor apraxia, and limb-kinetic apraxia. Clinical findings such as ideomotor apraxia in Broca's area and apraxia in patients with Parkinson's disease (PD) and parietal ataxia suggest sensorimotor integration and action control in the parietofrontal circuits. Based on studies of the mirror neuron system, disorders in gesture production could be associated with disorders of gesture understanding. We recently reported ideomotor apraxia in association with lesions in Broca's area. Broca's area is the center of speech production, and also mediates action production. Although apraxia is not a typical clinical feature of PD, varying degrees of apraxia have been reported. The dysfunction of the motor and premotor areas, which send projections to the basal ganglia, causes this apraxia. Parietal ataxia is caused by lesions in the parietal lobe, which are thought to be caused by disconnection between the cerebellum and Brodmann area 5 in the parietal lobe.