The lateral PMC is preferentially active during externally cued movements, as opposed to non-cued movements,43 and PMC and parietal overactivity has been reported in PD patients during the performance of sensory-cued motor tasks.44 Hanakawa et al showed enhanced activation in the right lateral PMC in PD patients while walking on a treadmill. They concluded that a brain circuit including posterior parietal lifescience cortex, cerebellum, and lateral PMC plays a key role in the development of the paradoxically Inhibitors,research,lifescience,medical enhanced gait

induced by external stimuli in PD patients. The authors suggested that, utilization of nonaffected brain areas is a compensatory mechanism for basal ganglia dysfunction in movement activation.45 In our study, we also observed a compensation for the impairment of stride-length regulation under external stimulation via treadmill walking in all Inhibitors,research,lifescience,medical patient groups. As in PD, external stimuli could enable the PMC and SMA to better compensate for deficiencies in thalamo-cortical output, caused either by antidopaminergic effects of antipsychotic treatment or by a primary pathophysiological condition of schizophrenia. In contrast to the effects of

external sensory stimuli on gait, we Inhibitors,research,lifescience,medical could not demonstrate a normalization of diadochokinetic movements under the use of an attentional strategy. This contrasts with the findings in PD patients. The reason for the different enhancing effects of sensory stimuli and attentional strategies in Inhibitors,research,lifescience,medical schizophrenic patients is unclear. One possible explanation for the variation of the enhancing effects of treadmill walking at the various velocities could be found in the varying degrees of gait, automation at the three tested gait velocities.

Slow and very slow gaits are poorly automated-especially when performed on the treadmill-and Inhibitors,research,lifescience,medical require marked cognitive processes, whereas gait, at, normal velocity is highly automated. Thus, cognitive deficits in schizophrenic patients could lead to additional deficits in the generation of optimal gait, patterns. These cognitive deficits could also be the reason for the failure of attentional strategies Rutecarpine to normalize disturbed motor parameters in schizophrenic patients, as has been observed in our study on diadochokinetic movements. This suggests that, the pathophysiological processes underlying motor disturbances in schizophrenic patients arc much more widespread than in PD patients, and also involve-in addition to the basal ganglia-cerebellar, frontal, and prefrontal structures. In conclusion, the studies show that quantitative analyses of motor disturbances can provide objective data on primary motor disturbances in schizophrenic patients, as well as on motor side effects of various antipsychotic treatment options. Thus, they can provide further insight in the pathophysiological conditions of schizophrenia and of adverse effects of antipsychotic treatment.