Combined action observation and motor imagery facilitates visuomotor adaptation in children with developmental coordination disorder.

The internal modelling deficit (IMD) hypothesis suggests that motor control issues associated with Developmental Coordination Disorder (DCD) are the result of impaired predictive motor control. In this study, we examined the benefits of a combined action observation and motor imagery (AO + MI) intervention designed to alleviate deficits in internal modelling and improve eye-hand coordination during a visuomotor rotation task. Twenty children with DCD were randomly assigned to either an AO + MI group (who watched a video of a performer completing the task whilst simultaneously imagining the kinaesthetic sensations associated with action execution) or a control group (who watched unrelated videos involving no motor content). Each group then attempted to learn a 90° visuomotor rotation while measurements of completion time, eye-movement behaviour and movement kinematics were recorded. As predicted, after training, the AO + MI group exhibited quicker completion times, more target-focused eye-movement behaviour and smoother movement kinematics compared to the control group. No significant after-effects were present. These results offer further support for the IMD hypothesis and suggest that AO + MI interventions may help to alleviate such deficits and improve motor performance in children with DCD.

Pre-shot EEG alpha-power reactivity during expert air-pistol shooting: a comparison of best and worst shots.

The aim of this study was to examine the proposal that pre-shot occipital electroencephalogram (EEG) alpha-power reactivity would not only associate with, but also have a causal role in, the relative success of performance outcome in expert air-pistol shooting. Six expert air-pistol shooters performed a sixty-shot match, individually, while electroencephalograms were captured from occipital and anterior-temporal electrode sites during the aiming period (3 x 2 s epochs) before shot release. The five best shots and five worst shots were selected for each shooter on the basis of four shot quality indicators, and pre-shot EEG alpha power for best shots was compared with that of worst shots. Occipital EEG alpha power was found to increase during epochs 1-3 before best shots, but to decrease before worst shots; it was significantly greater during the final pre-shot epoch of best shots. This finding suggests that visual attention to the pistol and target was gradually suppressed during the pre-shot period of best shots, whereas it gradually increased before worst shots. In addition, significantly greater EEG alpha power was found at the left than at the right anterior-temporal site, lending support to the robust findings of previous target-sport studies. We conclude that the participants were able to shoot at the target with greatest success when not having maximal visual attention on where the pistol was aimed and that suppression of visual attention during the final seconds of the pre-shot period is a necessary prerequisite for automatic shot execution, as controlled by mechanisms of intention.

Pneumomediastinum associated with inhalation of white smoke.

Hexachloroethane (HC) smoke, also known as white smoke, is an obscurant used in numerous military situations. Many adverse health effects are associated with the use of white smoke, some of which are potentially life threatening. Inhalation is the most frequent route of injury. Two deaths among U.S. Army personnel resulted from HC smoke exposure in 1988. As recently as 1997, a United Nations soldier in Bosnia died after an HC smoke canister was discharged in his tent. Injuries are predominantly pulmonary and range from cough and dyspnea to chemical pneumonitis, pulmonary edema, and adult respiratory distress syndrome. In the case presented, a soldier developed pneumomediastinum after exposure to HC smoke. This is the first case reported in the literature of pneumomediastinum associated with HC smoke inhalation.