Age and dementia related differences in spatial navigation within an immersive virtual environment.

BACKGROUND: Immersive virtual reality (VR) is an innovative tool that can allow study of human spatial navigation in a realistic but controlled environment. The purpose of this study was to examine age- and Alzheimer's disease-related differences in route learning and memory using VR. MATERIAL/METHODS: The spatial memory task took place in a VR environment set up on a Computer Workstation. Participants were immersed by putting video unit goggles over their eyes using a Head Mounted. Participants were shown a path within a virtual city, and then had to navigate it as quickly and accurately as possible. They were granted four learning trials on this path. An interference path was then presented before asking participants to re-navigate the first route at short and long delays. Finally, participants were tested for recognition of the city's buildings and objects. RESULTS: Young adults were consistently quicker and more accurate in their path navigation than older participants whilst those patients with Alzheimer's Disease made more mistakes on the recognition task in particular, being more likely to mistakenly affirm having seen an element in the city when it was in fact a foil. CONCLUSIONS: Our study would suggest that spatial navigation is susceptible to the effects of aging and Alzheimer's Disease. The potential applications of VR to the study of spatial navigation is seemingly important in that it may help place the science of neuropsychology on firmer scientific grounds in terms of its validity to real world function and dysfunction.

Utilizing virtual reality to improve the ecological validity of clinical neuropsychology: an FMRI case study elucidating the neural basis of planning by comparing the Tower of London with a three-dimensional navigation task.

Virtual reality (VR) was used to create an ecologically valid spatial-navigation task in hand with functional magnetic resonance imaging (fMRI) to articulate the neural basis of planning behavior. A virtual version of a traditional planning measure, the Tower of London, was also developed to ascertain convergent and divergent validity in terms of planning behavior and functional neuroanatomy. This VR-fMRI case study experiment was performed at 3.0 Tesla on a young healthy male subject. The obtained image data suggest both convergent and divergent specificity between the two conditions in terms of location and overall intensity of activation. Overall, the present case study provides supportive evidence that the activity of various brain regions associated with planning tasks is largely modulated by the ecological validity of the measure being used. This finding may extend to all domains of inquiry in neuropsychological research and assessment when deductive conclusions are formulated on the results of neuropsychological test measures that could be considered contrived in nature.

Electrodermal recording and fMRI to inform sensorimotor recovery in stroke patients.

BACKGROUND: Functional magnetic resonance imaging (fMRI) appears to be useful for investigating motor recovery after stroke. Some of the potential confounders of brain activation studies, however, could be mitigated through complementary physiological monitoring. OBJECTIVE: To investigate a sensorimotor fMRI battery that included simultaneous measurement of electrodermal activity in subjects with hemiparetic stroke to provide a measure related to the sense of effort during motor performance. METHODS: Bilateral hand and ankle tasks were performed by 6 patients with stroke (2 subacute, 4 chronic) during imaging with blood oxygen level-dependent (BOLD) fMRI using an event-related design. BOLD percent changes, peak activation, and laterality index values were calculated in the sensorimotor cortex. Electrodermal recordings were made concurrently and used as a regressor. RESULTS: Sensorimotor BOLD time series and percent change values provided evidence of an intact motor network in each of these well-recovered patients. During tasks involving the hemiparetic limb, electrodermal activity changes were variable in amplitude, and electrodermal activity time-series data showed significant correlations with fMRI in 3 of 6 patients. No such correlations were observed for control tasks involving the unaffected lower limb. CONCLUSIONS: Electrodermal activity activation maps implicated the contralesional over the ipsilesional hemisphere, supporting the notion that stroke patients may require higher order motor processing to perform simple tasks. Electrodermal activity recordings may be useful as a physiological marker of differences in effort required during movements of a subject's hemiparetic compared with the unaffected limb during fMRI studies.

Demonstrating the BlackBerry as a clinical communication tool: a pilot study conducted through the Centre for Innovation in Complex Care.

Canadians are living longer with chronic medical conditions, which have led to an increasing complexity and volume of care for hospitalized patients. Effective in-patient care depends on the effective coordination of care through rapid and efficient communication between various care providers. A delay in coordinating this care has downstream effects on other parts of the system, ultimately contributing to increased emergency department wait times. To address this system-wide issue, the Centre for Innovation in Complex Care at the University Health Network collaborated with Sunnybrook Health Sciences Centre to pilot the use of BlackBerry devices on the general internal medicine wards to improve clinical communication. We describe the implementation process, impact on clinical care and lessons learned from this experience. We observed that residents quickly adopted this new technology and felt that it improved their workflow efficiency and productivity.

Shared and differential neural substrates of copying versus drawing: a functional magnetic resonance imaging study.

Copying and drawing-from-memory tasks are popular clinical tests to assess visuo-motor skills in neurological patients. The tasks share some motor and visual processes; however, they differ substantially in their cognitive demands. We used functional magnetic resonance imaging to identify brain regions underlying processes involved in these tasks while avoiding confounds related to basic motor requirements, through use of a specially developed functional magnetic resonance imaging-compatible computer tablet. For the copying task, activation was observed in brain regions subserving visual processing and crossmodal attention (e.g. left lingual gyrus, cuneus). Drawing activated the anterior cingulate, an area associated with motor control and linking intention with action. These findings suggest distinct neural networks subserving copying and drawing.

A haptic force feedback device for virtual reality-fMRI experiments.

Simulation of real-world tasks using virtual reality (VR) and measurement of associated neural activity by functional magnetic resonance imaging (fMRI) have potential utility in research and clinical stroke applications. However, development of fMRI-compatible sensory feedback technology is required. Presented here is the development of a prototype force feedback device for VR-fMRI. Experiments validated device performance in terms of force output, interaction bandwidth, transmission delay, and fMRI-compatibility. A subsequent VR-fMRI experiment involved six participants touching a virtual object and verified modulation of brain activity with force feedback versus no force feedback. This device may facilitate further experiments to clarify the effect of haptics in VR, and may be adapted for characterizing brain function and behaviour associated with stroke-related hand paresis.

An fMRI study of the Trail Making Test.

This study investigated the cerebral correlates of the Trail Making Test (TMT), used commonly as a measure of frontal lobe function. Such work sheds additional light on the known shortcomings of the TMT as a localizing instrument, as indicated, for example, by studies of patients with focal brain lesions. Functional magnetic resonance imaging (fMRI) was used to record brain activity while participants performed the TMT using a custom-built, fiber-optic fMRI-compatible writing device, the "virtual stylus". Unlike in a previous fMRI study that used a verbal adaptation of the TMT, the virtual stylus enabled a closer depiction of the brain regions engaged by the actual paper-and-pencil task. Twelve, right-handed healthy young adults participated. In Part A of the task, participants were required to link in ascending order numbers (1-2-3 ...) that were randomly distributed on a computer screen. In Part B, participants were required to link alternately between numbers and letters (1-A-2-B ...). Although behavioral performance was somewhat less than typically obtained with the TMT due to use of the virtual stylus, distinct left-sided dorsolateral and medial frontal activity was revealed when comparing Part B versus Part A. These findings agree with existing literature showing sensitivity of the TMT to frontal regions in the left hemisphere. However, other activity was also observed (left middle and superior temporal gyrus) reinforcing that the brain-behavior correlations for the TMT are multifaceted and not restricted to the frontal lobe.

A data glove with tactile feedback for FMRI of virtual reality experiments.

Virtual reality (VR) technology is increasingly recognized as a useful tool for the assessment and rehabilitation of neurologic and psychiatric disorders. The hope that VR can accurately mimic real-life events is also of great interest in basic neuroscience, to identify the brain activity that underlies complex behavior by combining VR with techniques such as functional magnetic resonance imaging (fMRI). Toward these applications, in this study we designed and validated an fMRI-compatible data glove with a built-in vibratory stimulus device for tactile feedback during VR experiments. A simple VR-fMRI experiment was performed at 3.0 Tesla on four young healthy adults involving touching a virtual object with and without tactile feedback. The usefulness of the data glove was subsequently assessed using a series of questionnaires, behavioral performance, and the resulting activation images. Questionnaire scores indicated positive opinions with respect to the data glove, the tactile feedback, and the experimental paradigm. All subjects felt comfortable in the scanner during the VR experiment and were able to perform all aspects of the tasks successfully and with reasonable accuracy. In addition, activation maps showed the anticipated modulations in motor, somatosensory, and parietal cortex. These results support that tactile feedback enhances the realism of virtual hand-object interactions, and that the tactile data glove is suitable for use in other VR-fMRI research applications (e.g., VR physical therapy for stroke recovery).

A platform for combining virtual reality experiments with functional magnetic resonance imaging.

How the brain functions during behavioural tasks conducted in virtual reality (VR) remains largely unresolved. This issue is extremely important both in terms of establishing the benefits of VR through basic science, as well as for future optimization of tasks conducted in VR environments. Here, the authors describe their current work to develop a testing platform for conducting VR experiments that can be probed by functional magnetic resonance imaging (fMRI) to measure brain activity. Examples involving human spatial navigation and data glove operation illustrate the technical feasibility of the approach and introduce thought-provoking observations of brain activation patterns. Future research directions for combined use of VR and fMRI are also discussed.

Real-time automated paging and decision support for critical laboratory abnormalities.

BACKGROUND: For patients with critical laboratory abnormalities, timely clinical alerts with decision support could improve management and reduce adverse events. METHODS: The authors developed a real-time clinical alerting system for critical laboratory abnormalities. The system sent alerts to physicians as text messages to a smartphone or alphanumeric pager. Decision support was available via smartphone or hospital intranet. The authors evaluated the system in a prospective controlled stepped-wedge study with blinded outcome assessment in general internal medicine units at two academic hospitals. The outcomes were the proportion of potential clinical actions that were actually completed in response to the alert, and adverse events (worsening of condition or complications related to treatment of the condition). RESULTS: The authors evaluated 498 laboratory conditions on 271 patients. Overall, only 50% of potential clinical actions were carried out, and there were adverse clinical events within 48 h for 36% of the laboratory conditions. The median (IQR) proportion of potential clinical actions that were actually completed was 50% (33-75%) with alerting system on and 50% (33-100%) with alerting system off (p=0.94, Wilcoxon rank sum test). When the alerting system was on (n=164 alerts) there were 67 adverse events within 48 h of the alerts (42%). When the alerting system was off (n=334 alerts), there were 112 adverse events within 48 h (33%; difference: 9% higher with alerting system on, p=0.06). CONCLUSIONS: The provision of real-time clinical alerts and decision support for critical laboratory abnormalities did not improve clinical management or decrease adverse events.

Visually navigating a virtual world with real-world impairments: a study of visually and spatially guided performance in individuals with mild cognitive impairments.

In recent years, computer technology has evolved such that highly realistic virtual environments (VEs) can be used within a lab setting. Such VEs provide controlled ability to examine behavioral performance across different populations. The primary goal of this investigation was to examine the ability of mild cognitive impaired (MCI) participants to navigate effectively through a realistic, fictional virtual city. A total of 26 healthy control participants (age: 69 +/- 7.7 years; Mini-Mental State Examination, MMSE >or= 29) and 8 MCI patients (age: 72 +/- 7 years, MMSE >or= 26) were recruited. Both groups exhibited similar spatial-navigation ability. However, the MCI groups' ability to use effective visually guided navigation to traverse the VE was significantly compromised compared to healthy controls; a similar performance reduction was also observed when selecting appropriate paths. Though initially groups appear practically indistinguishable in regard to spatially navigating their way through the VE, these data indicate that careful evaluations of behavior in VEs may provide novel ways to differentiate between populations that have historically displayed relatively subtle differences.

Convergent validity and sex differences in healthy elderly adults for performance on 3D virtual reality navigation learning and 2D hidden maze tasks.

This study assessed the convergent validity of a virtual environment (VE) navigation learning task, the Groton Maze Learning Test (GMLT), and selected traditional neuropsychological tests performed in a group of healthy elderly adults (n = 24). The cohort was divided equally between males and females to explore performance variability due to sex differences, which were subsequently characterized and reported as part of the analysis. To facilitate performance comparisons, specific "efficiency" scores were created for both the VE navigation task and the GMLT. Men reached peak performance more rapidly than women during VE navigation and on the GMLT and significantly outperformed women on the first learning trial in the VE. Results suggest reasonable convergent validity across the VE task, GMLT, and selected neuropsychological tests for assessment of spatial memory.

Brain activity during a motor learning task: an fMRI and skin conductance study.

Measuring electrodermal activity (EDA) during fMRI is an effective means of studying the influence of task-related arousal, inferred from autonomic nervous system activity, on brain activation patterns. The goals of this study were: (1) to measure reliable EDA from healthy individuals during fMRI involving an effortful unilateral motor task, (2) to explore how EDA recordings can be used to augment fMRI data analysis. In addition to conventional hemodynamic modeling, skin conductance time series data were used as model waveforms to generate activation images from fMRI data. Activations from the EDA model produced significantly different brain regions from those obtained with a standard hemodynamic model, primarily in the insula and cingulate cortices. Onsets of the EDA changes were synchronous with the hemodynamic model, but EDA data showed additional transient features, such as a decrease in amplitude with time, and helped to provide behavioral evidence suggesting task difficulty decreased with movement repetition. Univariate statistics also confirmed that several brain regions showed early versus late session effects. Partial least squares (PLS) multivariate analysis of EDA and fMRI data provided complimentary, additional insight on how the motor network varied over the course of a single fMRI session. Brain regions identified in this manner included the insula, cingulate gyrus, pre- and postcentral gyri, putamen and parietal cortices. These results suggest that recording EDA during motor fMRI experiments provides complementary information that can be used to improve the fMRI analysis, particularly when behavioral or task effects are difficult to model a priori.

Improving functional magnetic resonance imaging motor studies through simultaneous electromyography recordings.

Specially designed optoelectronic and data postprocessing methods are described that permit electromyography (EMG) of muscle activity simultaneous with functional MRI (fMRI). Hardware characterization and validation included simultaneous EMG and event-related fMRI in 17 healthy participants during either ankle (n = 12), index finger (n = 3), or wrist (n = 2) contractions cued by visual stimuli. Principal component analysis (PCA) and independent component analysis (ICA) were evaluated for their ability to remove residual fMRI gradient-induced signal contamination in EMG data. Contractions of ankle tibialis anterior and index finger abductor were clearly distinguishable, although observing contractions from the wrist flexors proved more challenging. To demonstrate the potential utility of simultaneous EMG and fMRI, data from the ankle experiments were analyzed using two approaches: 1) assuming contractions coincided precisely with visual cues, and 2) using EMG to time the onset and offset of muscle contraction precisely for each participant. Both methods produced complementary activation maps, although the EMG-guided approach recovered more active brain voxels and revealed activity better in the basal ganglia and cerebellum. Furthermore, numerical simulations confirmed that precise knowledge of behavioral responses, such as those provided by EMG, are much more important for event-related experimental designs compared to block designs. This simultaneous EMG and fMRI methodology has important applications where the amplitude or timing of motor output is impaired, such as after stroke.

Optimizing the experimental design for ankle dorsiflexion fMRI.

Compared to motor studies of the upper limb, few experiments have sought a relationship between blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) sensorimotor signals and the resulting lower limb output. In Experiment 1, using an fMRI simulator system, we determined the optimized experimental protocol based on two design types and four behavioral movement types during ankle dorsiflexion. Experiment 2 involved testing the BOLD sensitivity at 1.5 T during ankle movements. Subjects performed large- and small-amplitude dorsiflexion movement types using an event-related design, with the intent of contrasting spatial and temporal features of the BOLD signal. In both experiments, the subject's behavior was guided by visual biofeedback of their ankle flexion angle, using an MR-compatible fiberoptic tape. From Experiment 1, we found electromyography (EMG) difference voltage ratio of approximately 2:1 for large (40 degrees ) and small (15 degrees ) dorsiflexion, 0.13 mV and 0.07 mV, respectively. In Experimental 2, we found the peak BOLD % signal changes of 1.04% and 0.89%, for large (40 degrees ) and small (15 degrees ) dorsiflexion, respectively. In addition, graded dorsiflexion produced graded BOLD signals in the primary sensorimotor and supplementary motor areas in 10 of 12 healthy young subjects, attesting to the feasibility of lower-limb fMRI at 1.5 T. This study provides insight into the cortical network involved in dorsiflexion using an experimental paradigm that is likely to translate effectively to hemiparetic stroke subjects.