RESUMEN
Behavioral studies contribute largely to a broader understanding of human brain mechanisms and the process of learning and memory. An established method to quantify motor learning is the analysis of thumb activity. In combination with brain stimulation, the effect of various treatments on neural plasticity and motor learning can be assessed. So far, the setups for thumb abduction measurements employed consist of bulky amplifiers and digital-to-analog devices to record the data. We developed a compact hardware setup to measure acceleration data which can be integrated into a wearable, including a sensor board and a microcontroller board which can be connected to a PC via USB. Additionally, we provide two software packages including graphical user interfaces, one to communicate with the hardware and one to evaluate and process the data. This work demonstrates the construction and application of our setup at the example of thumb acceleration measurement with a custom made glove and its use for research. Using integrated circuits, the size of the measurement devices is reduced to this wearable. It is simple to construct and can be operated easily by non-technical staff.
RESUMEN
Peripheral magnetic stimulation is a promising assistive technique for rehabilitation. Today's magnetic stimulation devices, designed for transcranial stimulation, operate at currents of 6 kA and higher. This makes them expensive and bulky. Many motor neurons in peripheral nerves are more accessible, have large diameters, and require significantly lower field strengths for stimulation. In this work, we present a simulation environment to determine the threshold current required to trigger an action potential in phrenic nerve motor neurons for different coil geometries. An anatomical model was used for coil placement and realistic field calculations. The field distribution was calculated using the finite integration technique and then applied to a neuronal model to simulate the axon membrane dynamics. For general applicability, the coil-nerve distance and the axon diameter were varied. We show that the required current was approximately 1.3 kA for a nerve-coil distance of 35 mm, which corresponds to 20% of the available power of a commercial TMS device. By including the nearby vagus nerve in the simulations, we showed that accidental stimulation of this nerve is highly unlikely. Our results pave the way for the development of smaller, less complex, and more affordable stimulators and promise to increase the use of peripheral magnetic stimulators in clinical settings.
