Alterations of Functional Brain Connectivity After Long-Duration Spaceflight as Revealed by fMRI.

The present study reports alterations of task-based functional brain connectivity in a group of 11 cosmonauts after a long-duration spaceflight, compared to a healthy control group not involved in the space program. To elicit the postural and locomotor sensorimotor mechanisms that are usually most significantly impaired when space travelers return to Earth, a plantar stimulation paradigm was used in a block design fMRI study. The motor control system activated by the plantar stimulation involved the pre-central and post-central gyri, SMA, SII/operculum, and, to a lesser degree, the insular cortex and cerebellum. While no post-flight alterations were observed in terms of activation, the network-based statistics approach revealed task-specific functional connectivity modifications within a broader set of regions involving the activation sites along with other parts of the sensorimotor neural network and the visual, proprioceptive, and vestibular systems. The most notable findings included a post-flight increase in the stimulation-specific connectivity of the right posterior supramarginal gyrus with the rest of the brain; a strengthening of connections between the left and right insulae; decreased connectivity of the vestibular nuclei, right inferior parietal cortex (BA40) and cerebellum with areas associated with motor, visual, vestibular, and proprioception functions; and decreased coupling of the cerebellum with the visual cortex and the right inferior parietal cortex. The severity of space motion sickness symptoms was found to correlate with a post- to pre-flight difference in connectivity between the right supramarginal gyrus and the left anterior insula. Due to the complex nature and rapid dynamics of adaptation to gravity alterations, the post-flight findings might be attributed to both the long-term microgravity exposure and to the readaptation to Earth's gravity that took place between the landing and post-flight MRI session. Nevertheless, the results have implications for the multisensory reweighting and gravitational motor system theories, generating hypotheses to be tested in future research.

Effects of Navigated Repetitive Transcranial Magnetic Stimulation After Stroke.

PURPOSE: The purpose of this study was to test the effects of navigated repetitive transcranial magnetic stimulation, delivered in different modes, on motor impairments and functional limitations after stroke. METHODS: The study sample included 42 patients (58.5 ± 10.7 years; 26 males) who experienced a single unilateral stroke (1-12 months previously) in the area of the middle cerebral artery. Patients completed a course of conventional rehabilitation, together with 10 sessions of navigated repetitive transcranial magnetic stimulation or sham stimulation. Stimulation was scheduled five times a week over two consecutive weeks in an inpatient clinical setting. Patients were randomly assigned to one of four groups and received sham stimulation (n = 10), low-frequency (1-Hz) stimulation of the nonaffected hemisphere (n = 11), high-frequency (10-Hz) stimulation of the affected hemisphere (n = 13), or sequential combination of low- and high-frequency stimulations (n = 8). Participants were evaluated before and after stimulation with clinical tests, including the arm and hand section of the Fugl-Meyer Assessment Scale, modified Ashworth Scale of Muscle Spasticity, and Barthel Index of Activities of Daily Living. RESULTS: Participants in the three groups receiving navigated repetitive transcranial magnetic stimulation showed improvements in arm and hand functions on the Fugl-Meyer Stroke Assessment Scale. Ashworth Scale of Muscle Spasticity and Barthel Index scores were significantly reduced in groups receiving low- or high-frequency stimulation alone. CONCLUSIONS: Including navigated repetitive transcranial magnetic stimulation in a conventional rehabilitation program positively influenced motor and functional recovery in study participants, demonstrating the clinical potential of the method. The results of this study will be used for designing a large-scale clinical trial.

Physical therapy for correcting postural and coordination deficits in patients with mild-to-moderate traumatic brain injury.

The purpose of this study was to test the effects of a conventional exercise program designed for correcting postural and coordination abnormalities in patients with mild-to-moderate traumatic brain injury (TBI). Using principles of motor learning applied to functional exercise training, exercises were performed while lying, sitting, standing and walking, with the goal of improving intra- and inter-limb coordination in the upper and lower extremities, postural stability and gait pattern. Twenty-two participants with TBI-related deficits received therapy in a supervised outpatient clinic. Therapy included 20 sessions, each approximately 55 to 60 min in duration, scheduled four to five times a week over four consecutive weeks. Each participant was evaluated with a battery of clinical tests at baseline and immediately after therapy. Upon completion of the therapy, participants improved static and dynamic postural stability and gait, evaluated with the Berg Balance Scale (from 45.2 ± 5.9 to 49.2 ± 4.2 points) and the Functional Gait Assessment (from 22.8 ± 4.1 to 26.9 ± 3.4 points). They also reduced truncal, upper and lower extremity ataxia, evaluated with the Ataxia Scale (from 7.3 ± 4.5 to 5.9 ± 4.2 points). Results will be used to refine the current version of the exercise therapy, which focused on whole body coordination and balance, and to design a large-scale clinical trial establishing effectiveness of this intervention and for comparison with other forms of therapy.

A comparative kinematic analysis of cyclical bending in patients with early stages of Parkinson's disease and in patients with essential tremor.

Early stage Parkinson's disease (PD) shares certain symptoms with essential tremor (ET), which makes it difficult to differentiate between the two. We analyzed cyclical body bends to find kinematic parameters that are capable of differentiating among PD, ET and normal control (NC) subjects. A linear discriminant analysis of the joint angles showed a reliable distinction between NC and the two groups of patients, while differentiating reasonably well between PD and ET. PD patients showed difficulty performing hip segment rotation around the vertical axis, whereas ET patients demonstrated enlarged torso sway in the frontal plane. These findings suggest that kinematic parameters of body movement in the standing position are sensitive enough to serve as subclinical marks in the early diagnosis of PD and ET.

Effect of robotic locomotor training in an individual with Parkinson's disease: a case report.

PURPOSE: The purpose was to test the effect of robot-assisted gait therapy with the Lokomat system in one representative individual with Parkinson's disease (PD). METHODS: The patient was a 67-year-old female with more than an 8-year history of PD. The manifestations of the disease included depressive mood with lack of motivation, moderate bradykinesia, rigidity and resting tremor, both involving more the right side of the body, slow and shuffling gait with episodes of freezing and risk of falling. The patient underwent six sessions of robot-assisted gait training. The practice included treadmill walking at variable speed for 25-40 min with a partial body weight support and assistance from the Lokomat orthosis. RESULTS: After the therapy, the patient increased the gait speed, stride length and foot clearance during over ground walking. She reduced the time required to complete a 180° turn and the latency of gait initiation. Improvements were observed in some items of the Unified Parkinson's Disease Rating Scale including motivation, bradykinesia, rigidity, freezing, leg agility, gait and posture. CONCLUSIONS: Although the results supported the feasibility of using robot-assisted gait therapy in the rehabilitation an individual with PD, further studies are needed to assess a potential advantage of the Lokomat system over conventional locomotor training for this population.

Learning postural tasks in hemiparetic patients with lesions of left versus right hemisphere.

There are a number of studies concerning difference of postural control following left or right hemisphere lesions. Few studies, however, compare the role of the right and left hemisphere in learning new postural tasks. This study aimed to address this question. Twenty patients with hemiparesis after ischemic stroke in the middle cerebral artery territory (11 with a right and 9 with a left hemispheric lesion) were investigated. All subjects were trained using two different tasks during ten training sessions. In both tasks, the subjects stood on a force platform and were taught to change the position of the center of pressure (COP) presented as a cursor on a monitor screen in front of the patient. The subjects were instructed to align the COP with the target and then move the target by shifting the COP in the indicated direction. In the "Balls" task, the position of the target (a ball) varied randomly, so the subject had to learn a general strategy of voluntary COP control. In "Bricks", the subject always had to move the target in a single direction (downward) from the top to the bottom of the screen, so that a precise postural coordination had to be learned. The number of correctly performed trials for a session was scored. The task performance and its rate were analyzed and compared with respect to the lesion lateralization between two patient groups. The voluntary control of the COP position and learning course were initially impaired in all groups of patients in both tasks. In "Balls", there were no differences between the two groups of patients. In contrast, in "Bricks", there was a greater initial deficit in patients with right hemisphere lesions, while the rate of postural learning and the final performance level did not differ between the groups. With a lower initial deficit and similar rate of learning, the maximal level of the task performance was reached earlier (on the 5th day of training) in patients with left hemisphere lesions. This group stopped improving its performance during follow-up training. The results suggest that the motor structures of the right hemisphere are more involved in the precise control of COP trajectory, but not in learning. There is no difference between hemispheres in the initial performance and learning of the general strategy of voluntary COP control. Possibly, the control of specific COP trajectory needs more sensory feedback that is associated with greater involvement of the right hemisphere. This might be a reason for the greater initial impairment of this task after lesions in the right hemisphere.