The auditory startle response in parkinsonism may reveal the extent but not type of pathology.

Objectives: We measured the acoustic startle response (ASR) and blink reflex (ABR) in patients with clinically diagnosed Parkinson's disease (PD) and progressive supranuclear palsy (PSP) and determined the specificity of an abnormal result for the diagnosis of PSP.

Methods: Thirty patients (11 PD, 19 PSP) and 12 age matched controls were studied. The PSP group was separated into clinical subgroups.

Anticipatory changes in beta synchrony in the human corticospinal system and associated improvements in task performance.

Synchronized oscillatory activity in the beta frequency band (13-30 Hz) can be detected in the cerebral motor cortex of healthy humans in the form of corticomuscular coherence. Elevated beta activity is associated with impaired processing of new movements and with more efficient postural or tonic contraction. Accordingly, beta activity is suppressed prior to voluntary movements, rebounding thereafter in the face of peripheral afferance.

Corrective movements in response to displacements in visual feedback are more effective during periods of 13-35 Hz oscillatory synchrony in the human corticospinal system.

Oscillatory synchronization in the beta (approximately 20 Hz) band is a common feature of human motor control, manifest at cortical and muscular levels during tonic contraction. Here we test the hypothesis that the influence of visual feedback on performance in a positional hold task is increased during bursts of beta-band synchrony in the corticospinal motor system. Healthy subjects were instructed to extend their forefinger while receiving high-gain visual feedback of finger position on a PC screen.

Lateralization of event-related beta desynchronization in the EEG during pre-cued reaction time tasks.

Objective: Here, we investigate whether the event-related desynchronization (ERD) of spectral components of the cortical EEG in the beta (13-30 Hz) frequency range may, in part, index motor selection processes. Specifically, we sought evidence for a contralaterally dominant component of the beta ERD that is limited to trials in which motor selection is possible prior to any imperative cue to move, with attendant behavioural advantage.

Methods: We measured reaction time and assessed the lateralization of beta ERD in 12 healthy volunteers as they performed pre-cued choice reaction time tasks, in which warning S1 cues were either fully predictive about the laterality of a subsequent imperative S2 signal or provided no laterality information.

NMDA receptor blockade retards axonal growth in the transected spinal cord.

The spinal cord of the eel, Anguilla, recovers function rapidly after it has been completely transected. At transection, the excitability of central pattern generating circuits in the distal denervated segments increases to such a level that undulatory movements can occur spontaneously. When this elevated neuronal activity was reduced locally, just caudal to the transection, by chronic blockade of the NMDA receptor, the normally rapid behavioural recovery was retarded.