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Patients with Parkinson's disease have great difficulty in performing sequential and bimanual movements. We used H2(15)O PET to study the regional cerebral blood flow associated with performance of sequential finger movements made unimanually and bimanually in a group of Parkinson's disease patients and a group of control volunteers. In controls, sequential finger movements led to activation of the contralateral motor cortex and inferior parietal cortex (Brodmann area 40), the lateral premotor cortex and bilateral supplementary motor area. No prefrontal activation was seen. Sequential finger movements in the Parkinson's disease group were associated with a similar pattern of activation but there was relative impairment of activation in the mesial frontal and prefrontal areas. A novel finding was the presence of relative overactivity in the lateral premotor and inferolateral parietal regions. We conclude that in Parkinson's disease there is a switch from the use of striato-mesial frontal to parietal-lateral premotor circuits in order to facilitate performance of complex finger movements.

Event-related potentials were recorded in 25 abstinent alcoholics, and 25 gender- and age-matched controls during a two-tone discrimination (odd ball) task. All the subjects were free from medication and dextral. MR images were examined in the alcoholics. The amplitudes of N100, N200 and P300 in the alcoholics were reduced compared with those of the controls. In order to identify morphological changes responsible for ERP abnormalities, linear regression analyses were performed between ERP measures and MRI parameters. The amplitude of N100 was inversely correlated with ventricular size. The amplitudes of P300 were inversely correlated with both ventricular size and width of cortical sulci. It was suggested that the N100 abnormality was related to subcortical structure, and P300 alteration was related to both subcortical and cortical structures in the alcoholics.

The authors studied the validity of a low dose (0.5 mg) dexamethasone suppression test (DST) in identifying depression. Nine patients who met the criteria of major depressive episode (MDE) in the Diagnostic and Statistical Manual of Mental Disorders, another nine psychiatric patients and one normal subject underwent the DST. At least one of the two blood samples obtained either at 8 a.m. or at 2 p.m. from each of the nine patients with MDE showed a cortisol concentration of over 5.0 micrograms/dl, while the cortisol concentration in the other 10 subjects was uniformly suppressed under this level. All the patients with MDE could be identified by nonsuppression of the cortisol secretion at 8 a.m. or at 2 p.m. An "early escape" phenomenon in depressed patients reported by Carroll et al. (1976) was absent in a 0.5 mg DST, and the blood samples at 8 p.m. were less useful for identifying the depressive patient. The reason why the one point sampling method used by previous investigators was insufficient to identify the depressed patient was discussed.