Postural stability of canoeing and kayaking young male athletes during quiet stance.

We studied the postural stability of 23 canoeing and kayaking young athletes and 15 healthy untrained age matched subjects during quiet and sensory conflicted stance (standing on stable and foam support with open and closed eyes). We measured with a force platform the center of pressure excursions and applied mean sway amplitude (MA), mean sway velocity (SV) and their Romberg ratios, and sway dispersion index to evaluate standing balance. During standing with eyes open, the athletes in comparison to non-athletes showed in sagittal and frontal plane greater MA and SV when the support was stable and smaller MA and SV when it was unstable.

Interactions between cortical rhythms and spiking activity of single basal ganglia neurons in the normal and parkinsonian state.

In order to evaluate the specific interactions between cortical oscillations and basal ganglia-spiking activity under normal and parkinsonian conditions, we examined the relationship between frontal cortex electroencephalographic (EEG) signals and simultaneously recorded neuronal activity in the internal and external segments of the pallidum or the subthalamic nucleus (STN) in 3 rhesus monkeys. After we made recordings in the normal state, hemiparkinsonism was induced with intracarotid injections of the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in one animal, followed by additional recordings. Spiking activity in the pallidum and STN was associated with significant shifts in the level of EEG synchronization.

Oscillations in the basal ganglia under normal conditions and in movement disorders.

A substantial body of work within the last decade has demonstrated that there is a variety of oscillatory phenomena that occur in the basal ganglia and in associated regions of the thalamus and cortex. Most of the earlier studies focused on recordings in rodents and primates. More recently, significant advances have been made in this field of research through the analysis of basal ganglia field potentials recorded from implanted deep brain stimulation electrodes in the basal ganglia of human patients with Parkinson's disease and other disorders.

Changes in plantar pressures during bipedal stance with different stance width.

We studied the influence of stance width and vision on the plantar pressures for the left and right foot during bipedal quiet standing on the pressure-sensitive insoles. The support widening shifted the left and right centers-of-foot-pressure (CFPs) laterally and forward (right foot), diminished SDs of: the left and right mean plantar pressures (MPPs), the anteroposterior and mediolateral displacements of left and right CFPs. It also decreased negative correlations between left and right MPPs and between mediolateral displacements of left and right CFP and increased positive correlation between anteroposterior displacements of left and right CFPs, more expressive with eyes-open.

Effects of maturity and training on bimanual ballistic isometric handgrip.

We studied maturity and training effects on maximal force and accuracy of force targeting during ballistic handgrips. Male right-handed nontrained adolescents (16-20 yrs.), trained adolescents (oarsmen--16-18 yrs.