A study of kinematics and kinetics in time-constrained arm movements

Several studies such as the equilibrium point hypothesis (EPH) purport that the motor signals that descend from the brain instead of encoding muscle torques, influence an existing relationship between muscle torque and body configuration. In the present study, the possibility of torque depending explicitly on position was tested using a task in which subjects (N=5) moved a simulated weightless frictionless mass through a small (\u3c8 degree) elbow extension in order to move a cursor on a screen to a target location. Each subject completed 720 trials. On ~10% of trials the simulated mass was increased unknown to the subject. The relationship between the cursor’s position and the torque applied to the system was held constant even when the simulated mass was increased. Thus, any change in torque produced was neither due the subjects’ perception of the mass nor due to their perception of the cursor. The time at which the subjects torque changed direction was seen to be significantly different (p\u3c0.005) during trials which the mass changed. This change in torque is concluded to be position-dependent. However the possibility of this being a merely mechanical effect could not be ruled out by due to poor EMG collection. A post-hoc analysis of different position-dependent motor control models, was done. Particularly, an exponential spring model, a linear spring model, and a linear spring with relative damping model were each tested to see how well they could predict a change in produced output torque from a change in position. Only the linear spring and relative damping models were able to do so. This experiment is not enough to prove that descending torque produced is systematically position-dependent but the methodology for testing models is promising and additional studies should be done along similar lines

MODELLING THE MORBIDITY PATTERN OF TUBERCULOSIS AND ITS ASSOCIATED FACTORS IN OYO STATE, NIGERIA

Background: With the advent of HIV, the risk of Tuberculosis (TB) has increased. The trend in the number of cases of TB in Oyo state over the past five years has not been documented. Hence, this study reviewed the number of cases of TB and determined some of its associated factors. Materials and Methods: A retrospective analysis was conducted on TB surveillance data reported between January 1st 2011 and December 31st 2014. Data were obtained from the integrated disease surveillance and response (IDSR) of Oyo state ministry of health, Nigeria. Number of TB cases, age, local government areas (LGA), month and year of reporting was extracted. Data were analysed using descriptive statistics, negative binomial and the Poisson regression models. Model fit was assessed using the AIC and the -2LogL. Results: The incidence of TB was highest in 2013 (23 per 10000 population) in Ibarapa East LGA. The risk of Tuberculosis was 62.8% higher in 2014 (IRR=1.628; 95%CI=1.281, 2.068) and also 17% higher in 2012 (IRR=1.170; 95%CI=1.010, 1.356). Also, the risk of TB was highest in Ibarapa East LGA (IRR=2.576; 95%CI=1.945, 3.412) and lowest in Ogbomoso South LGA (IRR=0.229; 95%CI=0.069, 0.764). Adolescents and adults also had higher risk of TB compared to children. Conclusion: The frequency of Tuberculosis declined overtime and older adults had a higher risk. The low frequency of TB in the state may be an indication and good evidence of concerted control measures. Efforts should be put in place to further bring down the number of cases especially in the identified hotspots

The Role of Premotor Areas in Dual Tasking in Healthy Controls and Persons With Multiple Sclerosis: An fNIRS Imaging Study

Persons with multiple sclerosis (pwMS) experience declines in physical and cognitive abilities and are challenged by dual-tasks. Dual-tasking causes a drop in performance, or what is known as dual-task cost (DTC). This study examined DTC of walking speed (WS) and cognitive performance (CP) in pwMS and healthy controls (HCs) and the effect of dual-tasking on cortical activation of bilateral premotor cortices (PMC) and bilateral supplementary motor area (SMA). Fourteen pwMS and 14 HCs performed three experimental tasks: (1) single cognitive task while standing (SingCog); (2) single walking task (SingWalk); and (3) dual-task (DualT) that included concurrent performance of the SingCog and SingWalk. Six trials were collected for each condition and included measures of cortical activation, WS and CP. WS of pwMS was significantly lower than HC, but neuropsychological (NP) measures were not significantly different. pwMS and HC groups had similar DTC of WS, while DTC of CP was only significant in the MS group; processing speed and visual memory predicted 55% of this DTC. DualT vs. SingWalk recruited more right-PMC activation only in HCs and was associated with better processing speed. DualT vs. SingCog recruited more right-PMC activation and bilateral-SMA activation in both HC and pwMS. Lower baseline WS and worse processing speed measures in pwMS predicted higher recruitment of right-SMA (rSMA) activation suggesting maladaptive recruitment. Lack of significant difference in NP measures between groups does not rule out the influence of cognitive factors on dual-tasking performance and cortical activations in pwMS, which might have a negative impact on quality of life