Effects of Functional Electrical Stimulation on Attention and Brain Activity in Healthy Participants Using Near-Infrared Spectroscopy: An Interventional Study.

Background Involuntary limb activation using functional electrical stimulation (FES) can improve unilateral spatial neglect. However, the impact of FES on brain activity related to spatial attention remains unclear. Thus, in this study, we aimed to examine the effects of FES on spatial attention. Methodology In this interventional study, 13 healthy right-handed participants were asked to perform the Posner task for six minutes both before and after either FES or sham stimulation during each set, resulting in a total of two sets. FES was applied to the left forearm extensor muscles, with a frequency of 25 Hz, a pulse width of 100 µs, and the intensity adjusted to reach the motor threshold. Both the energization and pause times were set to five seconds. The Posner task was used to measure reaction time to a target appearing on a computer screen. Brain activity, indicated by oxygenated hemoglobin values, was measured using near-infrared spectroscopy with 24 probes according to the International 10-20 system method. Results In the left hemisphere, oxygenated hemoglobin values in the premotor and supplementary motor areas, primary somatosensory cortex, and somatosensory association areas were significantly higher after FES than after sham stimulation. In the right hemisphere, oxygenated hemoglobin values were significantly increased in the premotor, primary, and supplementary motor areas; in the supramarginal gyrus; and in the somatosensory association areas after FES. Reaction times in the Posner task did not differ significantly between the FES and sham conditions. Conclusions Collectively, these results suggest that FES of the upper limbs can activate the ventral pathway of the visual attention network and improve stimulus-driven attention. Activation of stimulus-driven attentional function could potentially contribute to symptom improvement in patients with unilateral spatial neglect.

Effect of stimulation-driven attention in virtual reality balloon search training of patients with left unilateral spatial neglect after stroke: A randomized crossover study.

Patients with unilateral spatial neglect (USN) commonly experiences stimulus-driven attention deficit characterized by unexpected stimuli detection. We investigated whether virtual reality (VR) balloon search training with the screen background shifted to left space could improve stimulus-driven attention in patients with USN. The participants were divided into two groups: immediate VR group (n = 14) and delayed VR group (n = 14). The immediate VR group first received VR balloon search training, followed by control training, for two weeks each. Delayed VR group received the same training in reverse order. Outcomes were changes in scores on Catherine Bergego Scale (CBS) and reaction time on the modified Posner task (MPT). There was significant improvement in CBS score change after VR balloon retrieval training (all F > 2.71; P < 0.002). In the invalid condition of MPT, significant improvements were shown after VR balloon search training in left-sided reaction time (improvement of stimulation-driven attention). This study shows that VR balloon search training can improve neglect symptoms by using an intensive intervention lasting 2 weeks.

Effects of visual-motor illusions with different visual stimuli on the sit-to-stand of people with hemiplegia following stroke: A randomized crossover controlled trial.

BACKGROUND: The objective of this study was to determine the effects of different visual stimuli during visual-motor illusion on sit-to-stand in people with hemiplegia following stroke. METHODS: This was a randomized crossover controlled trial. Twenty people with hemiplegia following stroke were randomly divided into groups. The video images used for visual-motor illusion were ankle dorsiflexion without resistance (standard visual-motor illusion [standard illusion]) and maximum effort dorsiflexion with resistance (power visual-motor illusion [power illusion]). People with hemiplegia following stroke underwent both illusion interventions with a 1-week washout period in between; group A started with the standard illusion intervention and group B started with the power illusion intervention. Outcomes included the sit-to-stand duration, maximum weight-bearing value, trunk movement during sit-to-stand, ankle joint movement during sit-to-stand, and active ankle dorsiflexion movement on the paralyzed side. RESULTS: The angular velocity of the trunk and ankle joints increased significantly during sit-to-stand, and sit-to-stand duration decreased significantly in response only to power illusion. In addition, the change in angular velocity of active ankle dorsiflexion was significantly greater in response to power illusion than was the change in response to standard illusion. CONCLUSION: Power illusion induces a greater improvement in paralyzed ankle dorsiflexion function than standard illusion, resulting in shorter sit-to-stand duration.

Effects of visual-motor illusion in stroke hemiplegic patients with left-side personal neglect: A report of two cases.

Personal neglect is the neglect of self-body space, which often occurs in patients with unilateral spatial neglect (USN), but lacks a dedicated rehabilitation. The purpose of this study was to investigate the effects of visual-motor illusion (VMI) on two-stroke hemiplegic patients with left-side personal neglect. Case 1 was a 53-year-old man diagnosed with a right lenticulostriate artery infarction. Case 2 was a 76-year-old woman diagnosed with a right middle cerebral artery infarction. USN symptoms were not observed in either patient in the desk USN assessment, but personal neglect and USN symptoms in daily life were observed in both patients. Intervention effects were verified using an ABA design, comprising a 5-day three-phase (A1, B, A2). In phase B, VMI was performed on the paralyzed upper limb for 10 min in addition to conventional physical therapy. Outcomes measures were the Fluff test, Catherine Bergego Scale (CBS), Fugl-Meyer Assessment (FMA), and Functional Independence Measure (FIM). In both patients, no improvements were noted in FMA, but improvements were observed in the Fluff test, CBS, and FIM in phase B; these effects were retained in phase A2. Therefore, VMI may have contributed to improvements in Personal neglect and USN symptoms in daily life.

Functional Connectivity Pattern Using Resting-state fMRI as an Assessment Tool for Spatial Neglect during the Recovery Stage of Stroke: A Pilot Study.

PURPOSE: To determine if functional connectivity measured with resting-state functional MRI could be used as a tool to assess unilateral spatial neglect during stroke recovery. METHODS: Resting-state functional MRI was performed on 13 stroke patients with lesions in the right cerebral hemisphere and 31 healthy subjects. The functional connectivity score was defined as a correlation of a target region with the right inferior parietal lobule. Spatial neglect was measured with a behavioral inattention test. RESULTS: First, the functional connectivity scores between the right inferior parietal lobule and right inferior frontal gyrus, including the opercular and triangular parts, were significantly decreased in stroke patients with unilateral spatial neglect compared with patients without unilateral spatial neglect and were significantly correlated with the behavioral inattention test score. Second, the functional connectivity scores between the bilateral inferior parietal lobules were also significantly decreased in patients with unilateral spatial neglect compared with patients without unilateral spatial neglect and were significantly correlated with the behavioral inattention test score. Third, negative functional connectivity scores between the right inferior parietal lobule and bilateral medial orbitofrontal cortexes, which are related to the default mode network, were detected in patients without unilateral spatial neglect in contrast to a reduction of this negative tendency in patients with unilateral spatial neglect. The functional connectivity scores between these regions were significantly different between patients with and without unilateral spatial neglect and were negatively correlated with the behavioral inattention test score. CONCLUSION: Though still in the pilot research stage and using a small number of cases, our findings are consistent with the hypothesis that functional connectivity maps generated with resting-state functional MRI may be used as a tool to evaluate unilateral spatial neglect during stroke recovery.

The Effect of Trunk Position on Attentional Disengagement in Unilateral Spatial Neglect.

Unilateral spatial neglect (USN) causes difficulties in disengaging attention from the right side to unexpected targets on the left. However, the relationship between egocentric spatial position and attentional disengagement remains unclear. Therefore, this study aimed to clarify the relationship between trunk position and attentional disengagement. Thirty-eight patients with early stroke onset were classified as follows: USN (n = 18), right brain damage without USN (n = 10), and left brain damage (n = 10). The primary outcome was reaction time (RT) in the modified Posner task (MPT). The MPT comprised a condition in which the preceding cue and target direction were the same (valid condition) and a condition in which the directions were opposite (invalid condition). RT to the target was calculated. The MPT was performed in three different trunk positions (trunk midline, left, and right). In each group, the RT was compared on the basis of the stimulus conditions and trunk position. The RT was delayed in the valid and invalid left conditions, especially in the invalid left condition. The RT of the trunk right condition was significantly reduced compared with that of trunk midline and left conditions in the invalid left condition. Thus, trunk position influences attentional disengagement. This study contributes to the rehabilitation of patients with neglect symptoms.

Effects and Adaptation of Visual-Motor Illusion Using Different Visual Stimuli on Improving Ankle Joint Paralysis of Stroke Survivors-A Randomized Crossover Controlled Trial.

Visual-motor illusion (VMI) is an intervention to induce kinesthetic sensation from visual stimuli. We aimed to compare the effects of VMI of different visual stimuli on the paralyzed side ankle joint of stroke hemiplegic patients (hemiplegic patients) and to clarify their indication. We applied two types of VMI images of ankle dorsiflexion: ankle dorsiflexion without resistance (standard VMI (S-VMI)) and maximum effort dorsiflexion with resistance (power VMI (P-VMI)). Twenty-two hemiplegic patients were divided into two groups: Group A, which received S-VMI first and P-VMI one week later (n = 11), and Group B, which received P-VMI first and S-VMI one week later (n = 11). Immediate effects were evaluated. Outcomes were the dorsiflexion angle and angular velocity, degree of sense of agency (SoA), and sense of ownership. Patient's characteristics of cognitive flexibility were assessed using the Trail making test-B (TMT-B). Fugl-Meyer assessment and the Composite-Spasticity-Scale were also assessed. P-VMI was significantly higher than S-VMI in SoA and dorsiflexion angular velocity. Additionally, the degree of improvement in dorsiflexion function with P-VMI was related to TMT-B and degree of muscle tone. Therefore, P-VMI improves ankle function in hemiplegic patients more than S-VMI but should be performed with cognitive flexibility and degree of muscle tone in mind.

Reaction time analysis in patients with mild left unilateral spatial neglect employing the modified Posner task: vertical and horizontal dimensions.

Unilateral spatial neglect (USN) is a common neurological syndrome that develops after a right hemisphere lesion. By examining the performance of the modified Posner task added to the vertical dimensions of the left and right visual fields, we studied whether the lower left area had different neglect symptoms than the other locations. 41 patients with right hemisphere damage were classified into those with mild USN (USN+ ; n = 20) and without USN (USN- ; n = 21). Twenty older participants made up the healthy control (HC; n = 20) group. All participants recorded deficits in the paper-and-pencil tests established for neglect and reaction times in the modified Posner task. In the paper-and-pencil tests, there was no difference in deficit between the upper and lower left visual fields in any of the groups. According to the modified Posner task, the USN+ group exhibited delays in reaction time in the lower left visual field rather than the upper left visual field. Importantly, reaction times were delayed, and USN symptoms persisted, particularly for the lower left quadrant. Our findings imply that the modified Posner task can accurately uncover neglect symptoms in the case of mild USN.

Effects of kinesthetic illusion induced by visual stimulation on the ankle joint for sit-to-stand in a hemiparesis stroke patient: ABA' single-case design.

[Purpose] The purpose of this study was to investigate the effect of kinesthetic illusion induced by visual stimulation to the paralyzed side ankle joint on the sit-to-stand of a hemiparesis stroke patient. [Participant and Methods] A 33-year-old male with left hemiparesis due to a right putamen hemorrhage participated. This study used the ABA' single-case design. Phase A and A' conducted only conventional physiotherapy. Phase B conducted kinesthetic illusion induced by visual stimulation and conventional physiotherapy. To create a kinesthetic illusion, a video image of the patient's ankle joint dorsiflexion movement on the non-paralyzed side was inverted and placed on the patient's paralyzed ankle. The patient observed this display for 5 min. We evaluated weight-bearing symmetry values during sit-to-stand, duration of sit-to-stand, trunk and ankle joint movement on the paralyzed side during sit-to-stand, active ankle dorsiflexion angle on the paralyzed side, and the composite spasticity score. [Results] The weight-bearing symmetry values, movement of the ankle dorsiflexion during sit-to-stand, active ankle dorsiflexion angle, and composite spasticity score were significantly improved in phase B as compared with phase A and the effect was sustained in phase A'. [Conclusion] Kinesthetic illusion induced by visual stimulation for a hemiparesis stroke patient affected the ankle dorsiflexion function, resulting in an improved asymmetry during sit-to-stand as assessed by weight-bearing symmetry values.

Effects of standing and walking training using a laser pointer based on stimulus-driven attention for behavioural outcome in spatial neglect: A single-case study.

The therapy for unilateral spatial neglect (USN) is unclear. This case report investigated the effect of standing and walking training using a laser pointer based on stimulus-driven attention for USN. The patient was a right-handed 79-year-old man with cardiogenic cerebral embolism in the right middle and posterior cerebral arteries. Initially, we evaluated the absence of hemiparalysis in the lower limb and sensory disorder; almost all daily activities were performed independently. Intervention effects were verified using the BABA method. The course of the four phases (B1, A1, B2, A2) was conducted for 5 days. In the B1 and B2 phases, standing and walking training using a laser pointer was performed additionally to conventional physical therapy. Outcomes were measured using the Behavioural Inattention Test conventional subtest (BIT-c), Catherine Bergego Scale (CBS), and modified Posner task (MPT). The BIT-c remained unchanged in each phase. CBS scores improved after B1 and B2. In the MPT, the reaction time in the left space reduced after B1 and B2 compared with those in the A1 and A2 control phases. In this case, training may have contributed to the improvement in the response to the neglected space and behavioural assessment of USN.

Investigating the Characteristics of Covert Unilateral Spatial Neglect Using the Modified Posner Task: A Single-subject Design Study.

OBJECTIVES: Patients identified as asymptomatic for unilateral spatial neglect (USN) based on paper-and-pen tests nonetheless often collide with objects to their left while walking. This study aimed to investigate chronic USN in subjects who experienced collisions while walking. METHODS: Two patients with chronic USN who experienced collisions while walking were evaluated using the Behavioral Inattention Test-conventional (BIT-c). Additionally, the modified Posner task (MPT) was used to evaluate the left and right reaction times. MPT targets randomly appeared either on the side indicated by the cue (valid condition) or on the opposite side (invalid condition). This study used an alternating treatments single-case design. The valid and invalid conditions of the MPT alternated rapidly and randomly to determine differences in reaction time. Statistical analysis compared left and right reaction times using a one-tailed randomization test to study valid and invalid conditions. RESULTS: The total BIT-c score was in the normal range for both subjects, whereas MPT reaction times were higher on the left side than on the right side for the invalid condition. However, for the valid condition, only Case B had increased reaction times on the left side. CONCLUSIONS: The MPT valid condition evaluates voluntary attention, whereas the invalid condition evaluates the reorientation of attention. Consequently, for Case A, a left reorientation of attention deficit was observed, whereas, for Case B, left voluntary attention and left reorientation of attention deficits were observed. The MPT results revealed the characteristics of covert neglect signs. USN evaluation would benefit from additional research using MPT.