Deep brain stimulation in the subthalamic nucleus for Parkinson's disease can restore dynamics of striatal networks

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is highly effective in alleviating movement disability in patients with Parkinson's disease (PD). However, its therapeutic mechanism of action is unknown. The healthy striatum exhibits rich dynamics resulting from an interaction of beta, gamma and theta oscillations. These rhythms are at the heart of selection, initiation and execution of motor programs, and their loss or exaggeration due to dopamine (DA) depletion in PD is a major source of the behavioral deficits observed in PD patients. Interrupting abnormal rhythms and restoring the interaction of rhythms as observed in the healthy striatum may then be instrumental in the therapeutic action of DBS. We develop a biophysical networked model of a BG pathway to study how abnormal beta oscillations can emerge throughout the BG in PD, and how DBS can restore normal beta, gamma and theta striatal rhythms. Our model incorporates STN projections to the striatum, long known but understudied, that were recently shown to preferentially target fast spiking interneurons (FSI) in the striatum. We find that DBS in STN is able to normalize striatal medium spiny neuron (MSN) activity by recruiting FSI dynamics, and restoring the inhibitory potency of FSIs observed in normal condition. We also find that DBS allows the re-expression of gamma and theta rhythms, thought to be dependent on high DA levels and thus lost in PD, through cortical noise control. Our study shows how BG connectivity can amplify beta oscillations, and delineates the role of DBS in disrupting beta oscillations and providing corrective input to STN efferents to restore healthy striatal dynamics. It also suggests how gamma oscillations can be leveraged to enhance or supplement DBS treatment and improve its effectiveness.

The Time-varying Networks of the Wrist Extension in Post-stroke Hemiplegic Patients

Background: Hemiplegia is a common dysfunction caused by a stroke and leads to movement disability. Although the movement-related oscillation, the lateralization of the movement-related potential, and the event-related desynchronization have been investigated, the dynamic network modalities related to the movements in post-stroke hemiplegic patients are still left unveiled. Methods: In our present study, we designed the motor execution task of the wrist extension, collected the movement-related electroencephalograms, and adopted the adaptive directed transfer function to investigate the dynamic motor networks in post-stroke hemiplegic patients. The corresponding time-varying networks of the wrist extension in post-stroke hemiplegic patients were constructed and then statistically explored. Results: The results demonstrated that the effective connectivity between the stroked motor area and other areas decreased. In contrast, connectivity between non-stroked motor area and other areas was enhanced, especially the frontal and parietal-occipital lobes, to compensate for the dysfunction of the motor behaviors of the stroked patients.Conclusions: These findings help us better understand the time-varying networks underlying the implementation of the motor behaviors of the patients with post-stroke hemiplegia and might provide a reliable biomarker to predict their future rehabilitation.

A COMMUNICATION AID SYSTEM BY FEATURE EXTRACTION OF ELECTROOCULOGRAPHIC SIGNALS

People with serious movement disabilities due to neurodegenerative diseases have problems in their communication with others. Considerable numbers of communication aid systems have been developed in the past. Especially, some of the systems driven by eye movements are thought to be effective for such people. Electrooculographic (EOG) signal reflects the eye movement and the specific pattern of eye movement can be seen in EOG signals. This paper proposes a communication aid system by extracting the features of EOG. The system consists of a computer, analog-to-digital converter, biological amplifier and two monitors. Two monitors, one for a system user and the other for other people, display the same information. Five items are presented in the monitor, and a user selects those items according to the situation in the communication. Selection of the items is done by combining three eye movements: gaze at left, gaze at right and successive blinks. Basic concept of the communication aid system was designed by taking into account the current state of a subject’s movement disability. Then, the design of a screen and the algorithm for detecting eye movement pattern from EOG were determined by using the data of normal healthy subjects. The system worked almost perfectly for normal healthy subjects. Then, the developed system was operated by a subject with serious movement disability. Parts of the system operation were regarded as satisfactory level, and some miss-operation were also seen.

Safety Needs of People With Disabilities During Earthquakes

ObjectiveThe needs of people with disabilities are not taken into account during disasters, and there is no or little preparation for them. Hence, such people are very anxious about their personal safety during disasters. The aim of this study was to explain the safety needs of people with disabilities during earthquakes.MethodsThis qualitative study was conducted with purposive sampling. A total of 12 people with movement disability, aged between 18 and 60 years, and with an experience of facing earthquakes, participated in semi-structured interviews. Thematic analysis was used.ResultsThe safety needs of people with disabilities were categorized into three phases: those before an earthquake were considering building codes and resistant construction, building safe and resistant-to-climate-change shelters, and securing the room at the home and workplace; that during an earthquake was the existence of personal protection facilities; and those after an earthquake were adaptation of bathrooms in secure areas, prioritizing conex containers instead of tents, and sheltering in a safe and vermin-free area.ConclusionsThe sudden death of people with disabilities during disasters is preventable through proper planning and preparedness of emergency personnel. Hence, identifying the safety needs of these people and inclusion of such plans in disasters management systems can assure safety for people with disabilities during disasters. (Disaster Med Public Health Preparedness. 2018;12:615–621)

Striatal cholinergic receptor activation causes a rapid, selective, & state-dependent rise in corticostriatal β activity

Cortico-basal ganglia-thalamic (CBT) β oscillations (15–30 Hz) are elevated in Parkinson’s disease and correlated with movement disability. To date, no experimental paradigm outside of loss of dopamine has been able to specifically elevate β oscillations in the CBT loop. Here, we show that activation of striatal cholinergic receptors selectively increased β oscillations in mouse striatum and motor cortex. In individuals showing simultaneous β increases in both striatum and M1, β partial directed coherence (PDC) increased from striatum to M1 (but not in the reverse direction). In individuals that did not show simultaneous β increases, β PDC increased from M1 to striatum (but not in the reverse direction), and M1 was characterized by persistent β-HFO phase-amplitude coupling. Finally, the direction of β PDC distinguished between β subbands. This suggests: (1) striatal cholinergic tone exerts state-dependent and frequency-selective control over CBT β power and coordination; (2) ongoing rhythmic dynamics can determine whether elevated β oscillations are expressed in striatum and M1; (3) altered striatal cholinergic tone differentially modulates distinct β subbands.

Movement Disability: Situations and Factors Influencing Access to Health Services in the Northeast of Thailand

Background Persons with movement disability (PWMDs) are the biggest group of persons with disabilities (PWDs) with needs helps especially on health. There has been no evident to show health services accessibility situation of PWMDs in the Northeast of Thailand, the biggest region.Objective This study aimed to explore the current situation of accessibility to health services among PWMDs, and factors influencing such access.Method This cross-sectional study used a multistage stratified random sampling to select 462 subjects from the national registered PWMDs poll to response to a structured questionnaire. This study complies with the principles of the Declaration of Helsinki and was approved by the Khon Kaen University Ethics Committee for Human Research prior to the data collection.Result We found that most of PWMDs (66%) had overall health service accessibility at medium level. Factors influencing the access to health services were living in rural area (adj. mean diff.= -24.01; 95 % CI: -45.88 to-2.31; p-value=0.032), high income (adj. mean diff.=0.002; 95 % CI: 0.001 to 0.005; p-value = 0.044), and having offspring or spouse as care givers (adj. mean diff.=40.44; 95% CI: 7.69 to 73.19; p-value=0.044; and adj. mean diff.=48.99; 95%CI: 15.01-82.98; p-value=0.016, respectively). PWMDs who lived in rural areas had better access to health services especially to the sub-district health promoting hospital than those in the urban area.Conclusion Accessibly to health services of PWMDs still limited. Income, care givers and residential areas had influences on their access.Kathmandu University Medical Journal Vol.12(3) 2014; 168-174