Effect of articulatory and mental tasks on postural control.

The present study sought to determine whether the increased postural instability produced by a spoken mental task was due to competing demands for attentional resources or perturbation of posture by articulation. Postural sway was measured in 36 normal subjects under the following conditions: repeating a number aloud (articulation), counting backwards aloud in multiples of seven (articulation and attention), counting backwards silently (attention), and no mental task (neither articulation nor attention). Articulation resulted in a significant increase in sway, whereas no effect of attention was observed. We conclude that in order to accurately assess the effect of attentional demands on postural control, it is important to eliminate or control the effects of articulation.

Bacteriuria and bacteraemia in patients with long-term indwelling catheters--a domiciliary study.

Men with indwelling catheters and men and women with suprapubic catheters were studied in their homes. Urine and blood were cultured and body temperature recorded after every catheter change. Nearly all patients had infected urine after 4 weeks of catheterisation, and all had bacteriuria after longer periods, usually with a mixture of organisms. Culture on selective media revealed a wider range of organisms than was detected on routine C.L.E.D. and blood agar with antibiotic sensitivity disks, but routine culture gave adequate information for clinical purposes. Bacteraemia was demonstrated after 20 of 197 changes of urethral catheter and after one of 19 changes of suprapubic catheter; but no patient had pyrexia or other symptoms. However, two had rigors on other occasions. When assessing "risk factors" for blood-stream infection in catheterised patients, it is important to record the total incidence of bacteraemia, asymptomatic as well as symptomatic.

Relationship between postural control and motion sickness in healthy subjects.

This study examined the relationship between reported susceptibility to motion sickness, anxious personality and postural control. Postural stability was assessed in 34 healthy subjects standing with eyes open, eyes closed and viewing a disorienting virtual reality display. These measures were repeated with vibration of the calf muscles to distort the somatosensory feedback from the legs. Susceptibility to motion sickness and anxious personality were evaluated by questionnaire. Greater postural instability was correlated with susceptibility to motion sickness. Motion sickness susceptibility correlated most strongly with increased sway when the visual and somatosensory feedback was absent or distorted. Anxiety was correlated with reported susceptibility to motion sickness but not with postural stability. These findings suggest that deficient perceptual-motor responses to disorienting conditions may contribute to motion sickness susceptibility.

A preliminary investigation into the use of virtual environments in memory retraining after vascular brain injury: indications for future strategy?

PURPOSE: In a preliminary investigation of the use of Virtual Environments (VEs) in neurorehabilitation, this study compares the effects of active and passive experience of a VE on two types of memory in vascular brain injury patients and controls. METHOD: Forty-eight patients with vascular brain injury and 48 non-impaired control participants were randomly assigned to active and passive VE conditions. The active participants explored a virtual bungalow seeking a particular object; the passive participants observed, but did not control movement through the VE, also seeking the object. Afterwards, both active and passive participants completed spatial recognition and object recognition tests. RESULTS: Expectedly, the patients were impaired relative to the controls but were able to perform the virtual tasks. Active participation in the VE enhanced memory for its spatial layout in both patients and controls. On object recognition, active and passive patients performed similarly, but passive controls performed better than active controls. CONCLUSIONS: The findings are discussed in relation to their implications for memory rehabilitation strategies.

Clostridium sordelli infection.

A case of human Clostridium sordelli soft tissue infection is presented. Analysis of this patient's course led to the use of a mouse experimental model for examination of this organism's potential for toxin production. Data thus obtained correlated with that seen in this instance of human infection, indicates that the lethal effects of this organism may be related to the ability to Clostridium sordelli to produce a widespread "toxin-mediated" edema with subsequent marked "third-space" sequestration of fluid.

The specificity of memory enhancement during interaction with a virtual environment.

Two experiments investigated differences between active and passive participation in a computer-generated virtual environment in terms of spatial memory, object memory, and object location memory. It was found that active participants, who controlled their movements in the virtual environment using a joystick, recalled the spatial layout of the virtual environment better than passive participants, who merely watched the active participants' progress. Conversely, there were no significant differences between the active and passive participants' recall or recognition of the virtual objects, nor in their recall of the correct locations of objects in the virtual environment. These findings are discussed in terms of subject-performed task research and the specificity of memory enhancement in virtual environments.