Physically disabled people must be able to switch on brain-computer interfaces without external help if the futuristic devices are to give them greater freedoms, say researchers beginning to study the little-addressed problem.
Brain computer interfaces (BCI) allow incapacitated people to control robotic limbs, steer wheelchairs, type messages, and even walk through virtual worlds using their brain activity instead of a physical control.
Typically, such machines use an to sense a person鈥檚 brain waves via electrodes in a skullcap.
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But the newfound freedoms offered by these interfaces rely on having someone around to boot up the equipment first. So at Graz University of Technology, Austria, and colleagues have started testing ideas that could solve this problem for EEG-based interfaces.
Ignored problem
Scherer notes that shutting down a BCI is relatively simple since the user can manoeuvre a thought-controlled cursor or operate a keyboard to enter the necessary command. 鈥淚t is switching it on that is not so simple,鈥� he says.
鈥淲e want these interfaces to improve quality of life and give independence,鈥� Scherer continues. 鈥淏ut every time you want to use them you rely on others.鈥�
Researchers have spent little time considering the problem, admits Slawomir Nasuto, who works on BCIs at Reading University in the UK. They have focused on improving the recognition of brain signals, he says, but haven鈥檛 addressed the fact that a BCI cannot be left switched on indefinitely.
鈥淲ithout switching a BCI on and off, its operation may yield quite undesired effects,鈥� Nasuto told 快猫短视频. 鈥淯nintended operation of a device can be tiring and de-motivational for the end user.鈥�
Using brain signals to wake a BCI from a 鈥渟tandby鈥� mode might seem an obvious solution, but it is not practical because it means identifying the correct signal from a stream of normal brain activity. This is too complex for today鈥檚 technology to reliably achieve.
Spike signal
Scherer鈥檚 group believes another biological signal could be the answer. In recent experiments they tested whether volunteers could use voluntary spikes in their heart rate as the 鈥渙n鈥� signal for a BCI.
Subjects in their trials produced the spikes by breathing rapidly for a short period, while software compared their heart rate to one recorded at rest.
The 10 volunteers in their trial used the technique to activate a BCI, perform simple tasks with a prosthetic hand, and switch it off again. Each person was able to repeat the tasks four times.
However, Scherer admits that his group may not have found the perfect solution 鈥� during 30 minutes of testing there were, on average, 2.9 false positive 鈥渙n鈥� signals.
鈥淲hile our results so far show this is not really suitable at the moment, we have shown this is one possible route. This is a problem that needs solving if BCIs are really to give people true independence,鈥� he says.
Journal reference:
The Human Brain 鈥� With one hundred billion nerve cells, the complexity is mind-boggling. Learn more in our cutting edge special report.
