Dual-task motor performance with a tongue-operated assistive technology compared with hand operations

<p>Abstract</p> <p>Background</p> <p>To provide an alternative motor modality for control, navigation, and communication in individuals suffering from impairment or disability in hand functions, a Tongue Drive System (TDS) has been developed that allows for real time tracking of tongue motion in an unobtrusive, wireless, and wearable device that utilizes the magnetic field generated by a miniature disk shaped magnetic tracer attached to the tip of the tongue. The purpose of the study was to compare the influence of a concurrent motor or cognitive task on various aspects of simple movement control between hand and tongue using the TDS technology.</p> <p>Methods</p> <p>Thirteen young able-bodied adults performed rapid and slow goal-directed movements of hand and tongue (with TDS) with and without a concurrent motor (hand or tongue) or cognitive (arithmetic and memory) task. Changes in reaction time, completion time, speed, correctness, accuracy, variability of displacement, and variability of time due to the addition of a concurrent task were compared between hand and tongue.</p> <p>Results</p> <p>The influence of an additional concurrent task on motor performance was similar between the hand and tongue for slow movement in controlling their displacement. In rapid movement with a concurrent motor task, most aspects of motor performance were degraded in hand, while tongue speed during rapid continuous task was maintained. With a concurrent cognitive task, most aspects of motor performance were degraded in tongue, while hand accuracy during the rapid discrete task and hand speed during the rapid continuous task were maintained.</p> <p>Conclusion</p> <p>Rapid goal-directed hand and tongue movements were more consistently susceptible to interference from concurrent motor and cognitive tasks, respectively, compared with the other movement.</p

Source Separation for Target Enhancement of Food Intake Acoustics from Noisy Recordings

International audienceAutomatic food intake monitoring can be significantly beneficial in the fight against obesity and weight management in our society today. Different sensing modalities have been used in several research efforts to accomplish automatic food intake monitoring with acoustic sensors being the most common. In this study, we explore the ability to learn spectral patterns of food intake acoustics from a clean signal and use this learned patterns for extracting the signal of interest from a noisy recording. Using standard metrics for evaluation of blind source separation, namely signal to distortion ratio and signal to interference ratio, we observed up to 20dB improvement of separation quality in very low signal to noise ratio conditions. For more practical performance evaluation of food intake monitoring, we compared the detection accuracy for chew events on the mixed/noisy signal versus on the estimated/separated target signal. We observed up to 60% improvement in chew event detection accuracy for low signal to noise ratio conditions when using the estimated target signal compared to when using the mixed/noisy signal. – Index Terms—food intake monitoring, audio source separation , nonnegative matrix factorization, harmonizable processe

An Implantable Peripheral Nerve Recording and Stimulation System for Experiments on Freely Moving Animal Subjects

A new study with rat sciatic nerve model for peripheral nerve interfacing is presented using a fully-implanted inductively-powered recording and stimulation system in a wirelessly-powered standard homecage that allows animal subjects move freely within the homecage. The Wireless Implantable Neural Recording and Stimulation (WINeRS) system offers 32-channel peripheral nerve recording and 4-channel current-controlled stimulation capabilities in a 3 × 1.5 × 0.5 cm3 package. A bi-directional data link is established by on-off keying pulse-position modulation (OOK-PPM) in near field for narrow-band downlink and 433 MHz OOK for wideband uplink. An external wideband receiver is designed by adopting a commercial software defined radio (SDR) for a robust wideband data acquisition on a PC. The WINeRS-8 prototypes in two forms of battery-powered headstage and wirelessly-powered implant are validated in vivo, and compared with a commercial system. In the animal study, evoked compound action potentials were recorded to verify the stimulation and recording capabilities of the WINeRS-8 system with 32-ch penetrating and 4-ch cuff electrodes on the sciatic nerve of awake freely-behaving rats. Compared to the conventional battery-powered system, WINeRS can be used in closed-loop recording and stimulation experiments over extended periods without adding the burden of carrying batteries on the animal subject or interrupting the experiment

Qualitative assessment of Tongue Drive System by people with high-level spinal cord injury

The Tongue Drive System (TDS) is a minimally invasive, wireless, and wearable assistive technology (AT) that enables people with severe disabilities to control their environments using tongue motion. TDS translates specific tongue gestures into commands by sensing the magnetic field created by a small magnetic tracer applied to the user’s tongue. We have previously quantitatively evaluated the TDS for accessing computers and powered wheelchairs, demonstrating its usability. In this study, we focused on its qualitative evaluation by people with high-level spinal cord injury who each received a magnetic tongue piercing and used the TDS for 6 wk. We used two questionnaires, an after-scenario and a poststudy, designed to evaluate the tongue-piercing experience and the TDS usability compared with that of the sip-and-puff and the users’ current ATs. After study completion, 73% of the participants were positive about keeping the magnetic tongue-barbell in order to use the TDS. All were satisfied with the TDS performance and most said that they were able to do more things using TDS than their current ATs (4.22/5)

A wireless microsystem for neural stimulating microprobes.

This project seeks to develop wireless circuit interface and associated electronics for an implantable neural stimulating microsystem with a large number of stimulating sites for use in neural prostheses. The implantable microsystem should be inductively powered, button-sized, with 1024 sites, arranged in a 3-D configuration, with 128 simultaneous channels, each capable of sourcing +/-100muA. The major challenges towards this goal are the implant size, microassembly method, large number of sites, effective and safe stimulation, low power consumption, and wideband wireless link between the implant and the external world. Three approaches were followed in design of this microsystem: (1) Interestim-1, a telemetry interface chip for operating the existing micromachined hardwired active stimulating probes by providing regulated power, serial data bit-stream, clock, and synchronization pulses. (2) Interestim-2, a modular, wireless, microstimulating chip for any kind of microelectrodes, including the passive micromachined silicon probes. (3) Interestim-3, a modular, wireless, active silicon microstimulating probe with all the wireless, stimulation, and site selection circuitry integrated on the probe backend to reduce the total number of interconnects to only 2 per probe. Research on different blocks of this microsystem resulted in several state-of-the-art circuit designs, which can be used in similar applications such as radio-frequency identification (RFID) and smartcards. Many of these blocks are brought together in Interestim-2B, a 4.6mm x 4.6mm, modular, 32-site, wireless microstimulating SoC (2 modules/chip), fabricated in a 1.5-mum, 2M/2P standard-CMOS foundry process, which can receive power and stimulation data at 2.5Mbps, using a 5/10MHz FSK carrier. An on-chip full-wave rectifier, followed by a series regulator, can supply the chip with up to 50 mW. Eight current drivers per module can generate up to 65,800 stimulus pulses/sec at +/-270muA full-scale, with 5 bits of resolution, &sim;100MO of output impedance, and a wide voltage compliance range that extends within 150mV and 250mV of the 5V and ground supply rails for sinking and sourcing currents, respectively. The modular architecture of Interestim-2B allows the operation of up to 64 modules in parallel, while sharing a single receiver LC-tank circuit, in order to support a total of 2048 stimulating sites. Interestim-2B was combined with 1--4, 16-site, passive, chronic, intracortical microelectrode arrays in several prototype implants, and successfully used in various in vitro and acute in vivo experiments.Ph.D.Applied SciencesBiomedical engineeringElectrical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124675/2/3150204.pd