Yotam Bahat

Postural adjustments as an acquired motor skill: Delayed gains and robust retention after a single training session within a virtual environment

Postural adjustments are essential for voluntary movement as they provide the foundation for motor performance. Yet the time-course of learning postural adjustments, the specificity of learning and the ability to effectively retain this knowledge are not well known. The objective of this research was to study the characteristics of the acquisition of postural control skills in healthy adults within a virtual environment (VE). Seven healthy young adults, aged 20-40 years (mean plusmn SD = 28.6 plusmn 2.7), performed a single training session in a VE in which maintenance of balance on a moving platform according to a given road scenario, as well as a secondary visual target reaching task were required, in repeated runs. Balance performance was assessed during training and additional assessments were performed at 24 hours and 4 weeks post-training. The results showed that the Center of Pressure (CoP) displacement decreased during the training session (P=0.001) and continued to decrease 24 hours post-training (P=0.01) (i.e., a delayed gain in skill). The gains were robustly maintained and increased by 4 (p=0.008) and 12 (p=0.005) weeks post training. New learning occurred when the secondary task was made more demanding but was not required, and when the path traveled was experienced without the secondary task or with eyes closed. Thus, a single balance maintenance training session in a VE setting was sufficient to trigger a learning process of balance control resulting in immediate gains, delayed gains and robust retention. The time-course (including the expression of delayed gains, i.e., a consolidation phase) and magnitude of this learning process appear to be similar to that which takes place during volitional manual task learning.

Can we climb with our eyes? Preliminary report on the effect of conflicting virtual scenery on leveled and inclined gait

We studied the effects of visual scenery modulation related to path inclination on gait performance. So far, seven young healthy adults were tested with an advanced virtual reality (VR) system. While walking on treadmill in a self-paced mode in straight, uphill and downhill inclinations, the subjects were exposed to visual scenery providing visual flow presenting either conflicting or matching visual inclination to the treadmill inclination. When visual scenery changed to uphill or downhill scenery, gait was immediately affected, even when no corresponding treadmill inclination. Further research is required to understand if this effect can be employed to facilitate rehabilitation programs.

Effect of a secondary task on the time course and specificity on learning a balance skill

The objective of this study was to use an advanced VR-based system to explore the extent to which posture control mechanisms in adults can undergo experience-dependent changes when a novel balance task is acquired and retained. Eight healthy young adults practiced a novel complex task with and without a concurrent manual task within a single training session in a virtual environment (VE). The time-course of learning the balance aspects of the task with and without the concurrent secondary visuo-motor task was similar. Thus, the learning process was robust enough to withstand the attention demands of a complex visuo-motor secondary task. The implications of these findings for rehabilitation are discussed.

No transfer of gains after a single training session within a virtual environment to fundamental tests of stability

How specific are postural and balance control skills? An important issue for the establishment of effective training and retraining (rehabilitation) programs is whether skills gained while training in laboratory settings can be transferred to performance gains in somewhat different conditions (including every-day life). While there is much evidence showing that for volitional motor tasks the gains in performance (procedural, implicit, knowledge) accrued in practice may not always be transferable to novel task conditions, it is not clear whether the (implicit) knowledge gained in learning postural adjustments can be transferred to measures of balance (reaction to external perturbations) that have not been trained. The objective of the current study was to elucidate what aspects of a postural skill learned within a virtual environment (VE) by healthy adults may be transferable to the performance of standard tests of postural adjustments. Sixteen healthy young adults, aged 20–40 years (mean α SD = 29.8 α 2.8 years), were pseudo-randomly assigned to either a training group (Group A) or a no-training, control group (Group B). Group A performed a single training session in a VE in which maintenance of stability on a platform, while travelling along a road scenario and reaching for visual targets (secondary task) were required. Each participant underwent 8 consecutive runs of the task (2:48 m per run). A balance assessment with a given set of perturbations was performed before and after training as well as at 24 hours and 4 weeks post-training. Group B underwent the same assessments but without VE training. The results showed that the Center of Pressure (CoP) displacement tended to decrease over successive balance assessments in both groups, however, this decrease was not statistically significant. Moreover, there was no clear advantage for Group A. Thus, the postural adjustment gains were not transferred to the balance assessment tests. Non-volitional balance control gains are, in this respect, similar to gains attained in a volitional manual task learning.

Virtual reality–based cognitive-motor training for middle-aged adults at high Alzheimer's disease risk: A randomized controlled trial

Ubiquity of Alzheimers disease (AD) coupled with relatively ineffectual pharmacologic treatments has spurred interest in nonpharmacologic lifestyle interventions for prevention or risk reduction. However, evidence of neuroplasticity notwithstanding, there are few scientifically rigorous, ecologically relevant brain training studies focused on building cognitive reserve in middle age to protect against cognitive decline. This pilot study will examine the ability of virtual reality (VR) cognitive training to improve cognition and cerebral blood flow (CBF) in middle‐aged individuals at high AD risk due to parental history.

Immersive trail making: Construct validity of an ecological neuropsychological test

Traditional neuropsychological tests of executive function are designed to assess a range of behavioral competencies necessary for the cognitive control of behavior in the real world. Though considered the ‘gold standard’, these pen-and-paper tests have been criticized for questionable relevance to everyday functioning. Immersive virtual reality (VR) technologies may be a viable tool for developing more ecologically valid human performance testing and training environments. The present study provides initial data on the construct validity of a full-body 360-degree VR version of the classic Trail Making Test. Sixteen healthy volunteers completed both pen-and-paper and VR versions of the Color Trails Test (CTT). During Part A of the test, the participant connects circles containing numbers in sequential order, and in Part B, which loads more on executive function, the participant does the same but alternates between two colors. Among the eleven participants who have completed testing to date, for both pen-and-paper and VR versions, Task B completion time was longer than Task A completion time (Pen-and-paper CTT: Trails A 36.6±15.9 seconds, Trails B 64.5±17.9 seconds; VR CTT: Trails A: 137.4±52.0 seconds; Trails B: 219.2±74.4 seconds). Trails B-A completion time delta was 27.8±8.2 seconds for the pen-and-paper CTT, and 81.8±36.6 seconds for the VR CTT. The correlation (Spearmans rho; rs) between Part A completion time on the pen-and-paper CTT and the corresponding Part A completion time on the immersive VR CTT was 0.76 (p=.007). The correlation for Part B completion time was 0.88 (p<.001). For Trails B-A delta, the correlation was 0.59 (p=.056). These findings indicate the convergent construct validity of the novel VR CTT, suggesting that it indeed measures the same cognitive construct (selective attention) as the gold standard pen-and-paper test. The longer completion times may reflect contributions of additional cognitive and motor processes. These results pave the way for larger validation studies, explorations of discriminant validity, and even more ecologically valid applications of neuropsychological test designs as implemented in the VR context.

A multi-dimensional approach to evaluate performance of complex daily activities of older adults in a simulated mall

Age-related decline in physiological, physical and cognitive functions as well as disabilities resulting from pathological conditions may interfere with the ability to adapt to the environmental and social demands. It is important to understand and characterize the ways in which these age-related is to present a multi-dimensional approach to assess performance of a simulated complex daily activity of older adults compared to young adults. Six young adults aged 28.2 ± 4.3 years and seven community dwelling older adults aged 74.3 ±5.8 years were tested during a single session. After training on a self-paced treadmill a non-functional simulation to learn how to navigate within the virtual environment (VE), they perform the Virtual Multiple Errands Test (VMET) in a mall simulation. The young adults performed the VMET significantly better than the older group. In contrast, the older group made significantly more stops while performing the VMET, they walked for a greater distance and wandered about more in the VE. The results of this study provide support for the need to use more realistic virtual environments that truly simulate the challenges experienced by people when engaging in functional tasks.

Virtual Environments for the study of the effect of context on dual tasking

the purpose of this poster is to present the development of functional and non-functional virtual environments for the investigation of dual tasking capabilities after traumatic brain injury.