Background: Mixed reality (MR) technology, which combines the best features of augmented reality and virtual reality, has recently emerged as a promising tool in cognitive rehabilitation therapy. Objective: To investigate the effectiveness of an MR-based cognitive training system for individuals with mild cognitive impairment (MCI). Methods: Twenty-one individuals aged 65 years and older who had been diagnosed with MCI were recruited for this study and were divided into two groups. Participants in the MR group (n=10, aged 70.5±4.2 years) received 30 minutes of training 3 times a week for 6 weeks using a newly developed MR-based cognitive training system. Participants in the control group (n=11, aged 72.6±5.3 years) received the same amount of training using a conventional computer-assisted cognitive training system. Both groups took the Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD-K) both before and after intervention. To determine the effect of the intervention on cognitive function, we compared the difference in each group’s CERAD-K scores. Results: There was a statistically significant interaction between intervention (MR group vs control group) and time (before vs after intervention) as assessed by the Constructional Recall Test. The individuals with MCI who participated in the MR training showed significantly improved performance in visuospatial working memory compared with the individuals with MCI who participated in the conventional training. Conclusion: An MR-based cognitive training system can be used as a cognitive training tool to improve visuospatial working memory in individuals with MCI.

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Motor and sensory deficits after spinal cord injury (SCI) result in functional reorganization of the sensorimotor network. While several task-evoked functional magnetic resonance imaging (fMRI) studies demonstrated functional alteration of the sensorimotor network in SCI, there has been no study of the possible alteration of resting-state functional connectivity using resting-state fMRI. The aim of this study was to investigate the changes of brain functional connectivity in the sensorimotor cortex of patients with SCI. We evaluated the functional connectivity scores between brain areas within the sensorimotor network in 18 patients with SCI and 18 controls. Our findings demonstrated that, compared with control subjects, patients with SCI showed increased functional connectivity between primary motor cortex and other motor areas, such as the supplementary motor area and basal ganglia. However, decreased functional connectivity between primary somatosensory cortex and secondary somatosensory cortex also was found in patients with SCI, compared with controls. These findings therefore demonstrated alteration of the resting-state sensorimotor network in patients with SCI, who showed increased connectivity between motor components, and decreased connectivity between sensory components, within the sensorimotor network, suggesting that motor components within the motor network increased in functional connectivity in order to compensate for motor deficits, whereas the sensory network did not show any such increases or compensation for sensory deficits.

The purpose of the study was to investigate the influence of the chin-tuck maneuver on the movements of swallowing-related structures in healthy subjects and formulate standard instructions for the maneuver. A total of 40 healthy volunteers (20 men and 20 women) swallowed 10 mL of diluted barium solution in a “normal and comfortable” position (NEUT), a comfortable chin-down position (DOWN), and a strict chin-tuck position (TUCK). Resting state anatomy and kinematic changes were analyzed and compared between postures. Although angles of anterior cervical flexion were comparable between DOWN (46.65 ± 9.69 degrees) and TUCK (43.27 ± 12.20), the chin-to-spine distance was significantly shorter in TUCK than in other positions. Only TUCK showed a significantly shorter anteroposterior diameter of the laryngeal inlet (TUCK vs. NEUT, 14.0 ± 4.3 vs. 16.3 ± 5.0 mm) and the oropharynx (18.8 ± 3.1 vs. 20.5 ± 2.8 mm) at rest. The maximal horizontal displacement of the hyoid bone was significantly less in TUCK (9.6 ± 3.0 mm) than in NEUT (12.6 ± 2.6 mm; p < 0.01) or DOWN (12.1 ± 3.0 mm; p < 0.01). TUCK facilitated movement of the epiglottic base upward (TUCK vs. NEUT, 15.8 ± 4.7 vs. 13.3 ± 4.5 mm; p < 0.01). In contrast, DOWN increased the horizontal excursion of the epiglottic base and reduced movement of the vocal cords. These results quantitatively elucidated the biomechanical influences of the chin-tuck maneuver including reduced horizontal movement of the hyoid bone, facilitation of vertical movement of the epiglottic base, and narrowing of the airway entrance. Comparing DOWN and TUCK, only TUCK induced significant changes in the airway entrance, hyoid movement, and epiglottic base retraction.