Trial: Improved sense of touch and control in prosthetic hand

In the ongoing effort to improve the dexterity of prosthetics, a recent trial showed an improved sense of touch and control over a prosthetic hand.  EPFL professor Silvestro Micera and colleagues surgically attached electrodes from a robotic hand to a volunteer’s median and ulnar nerves. Those nerves carry sensations that correspond with the volunteer’s index finger and thumb, and with his pinky finger and the edge of his hand, respectively. The volunteer controlled the prosthetic with small muscle movements detected by sEMG, a non-invasive method that measures electrical signals through the skin.

Over seven days, the volunteer was asked to grasp something with a light grip, a medium grip, and a hard grip, and to evaluate the shape and stiffness of three kinds of objects. During 710 tests, he wore a blindfold and earphones so that he could not use his vision or sound to guide the prosthetic. The researchers also sometimes turned off the sensory feedback to test whether he was using time to modulate his grip.

The subject was able to complete the requested tasks with his prosthetic thumb and index finger 67 percent of the time the first day and 93 percent of the time by the seventh day of the experiment. His pinky finger was harder to control: he was only able to accomplish the requested grip 83 percent of the time. In both the grip strength tests and in detecting the stiffness of objects, the volunteer made mistakes with the medium setting and object, but he never confused the softest and hardest objects. The ability to modulate his grip strength is this study’s main progress over previous work by the same group.

Nobel-worthy stem cell discovery

Haruko Obokata and colleagues at the RIKEN Center for Developmental Biology have created embryonic stem cells from a single blood cell by putting white blood cells from a baby mouse in a mild acid solution. Eventually a few stem cells emerge that can turn into any other cell in the body including skin, heart, liver or neurons.

Scientists have long searched for ways to make human embryonic stem cells that did not destroy human embryos. These cells hold great potential for treating Alzheimer’s, Parkinson’s, heart disease and diabetes.

Obokata put the blood cells in a mild acid for about 30 minutes. The pH of the solution was about 5.7. A few days later, the cells stopped acting like blood and started behaving like stem cells.  When the researchers injected the cells into a mouse embryo, the cells acted just like other stem cells: They created all the organs needed for an adult mouse. The team named the cells stimulus-triggered acquisition of pluripotency, or STAP.

This breakthrough could enable scientists to create stem cells from any person, thus controlling genetic similarity, and use them to repair nerve injuries.