A method that allows disabled people to overcome - by sniffing - different movement limitations, to write and steer a wheelchair.

A new invention by Weizmann Institute of Science scientists * The next step: a "third hand" for pilots and surgeons

Sniffing - gentle inhalations and exhalations through the nose - allows paralyzed people to overcome various movement limitations, write and steer a wheelchair. The system developed by Prof. Noam Sobel, electronics engineers Dr. Anton Plotkin and Aharon Weisbrod, and research student Lee Sela from the Department of Neurobiology at the Weizmann Institute of Science, together with Prof. Nahum Soroker from Levinstein Hospital, detects changes in the air pressure in the nasal cavity, and translates them into electrical signals. A test of the device on healthy and paralyzed volunteers showed that its control is extremely fast, and that it allows a wheelchair to be moved along a complex track and to play a computer game with speed and accuracy similar to those achieved using a computer mouse or joystick.

Prof. Sobel: "It is exciting to prove that severely injured people, who suffer from 'entrapment syndrome' - that is, people whose cognitive function is normal but are 'imprisoned inside their body' due to complete paralysis - can, using the new system, communicate with their family members, answer questions, and even initiate communication with the environment. The disabled who used the device wrote moving messages to their family members, sharing their thoughts and feelings with them for the first time." Four sniff writing systems were given to four patients who participated in their examination. These days, the "Knowledge Research and Development" company - which promotes industrial applications based on the inventions of Weizmann Institute of Science scientists - is examining possibilities for the commercialization and distribution of the technology.

The act of sniffing is a precise motor skill, which is controlled, among other things, by the position of the soft palate - a flexible partition whose movement directs the passage of air through the mouth (inhaling) or through the nose (sniffing). The control of the soft palate is done by several nerves that come directly from the brain (without leaving the cranial cavity). This fact led the team of scientists, led by Prof. Sobel, to hypothesize that the ability to sniff, that is, to control the movement of the soft palate, is preserved even in cases of severe nerve damage, which causes paralysis. An examination using functional magnetic resonance imaging (fMRI) strengthened their hypothesis, showing that the control of the movement of the soft palate is done in a large number of brain areas. They also discovered that the areas that control the movement of the soft palate largely overlap brain areas associated with language. The scientists hoped that this natural connection would allow an intuitive use of the sniffing device to create communication, and would contribute to the speed of its use.

To test this, the scientists created a device that measures the changes in air pressure in the nasal cavity (using a non-invasive sensor installed in the nasal opening), and translates them into electrical signals. For breathing patients, a tolerable (passive) version of the device was created, which flows air into the nasal cavity. In this case, the user of the device must learn to move the soft palate - an ability achieved by about 75% of the population. A preliminary test of the device made by healthy volunteers who played a computer game with it, showed that the efficiency of the sniffing mechanism is similar to that of a hand controlling a computer mouse or a joystick. Replacing the computer game with software for writing text, allowed the volunteers to write at a rate of about nine letters per minute. In the next step, which was done in collaboration with Prof. Nachum Soroker from Levinstein Hospital, patients suffering from paralysis of the four limbs and "locked-in syndrome" participated. One of the patients, who was confined for seven months following a stroke, learned to operate the device within a few days, and delivered the first message to her family members. Another patient, imprisoned for 18 years following a car accident, wrote to the researchers that the new device is more convenient and simpler than the one based on eye blinks. Ten other patients, suffering from paralysis in all four limbs, were able to write and operate a computer by sniffing.

In addition to being an effective means of communication, the new interface is also a means of transportation. The scientists created a "motion controller" based on a simple "sniff code", in which two sniffs in (two inhalations through the nose) signal "forward", two sniffs out signal "back", a sniff out followed by an in signal "left", and a sniff in followed by an out Mark "right", and connect him to an electric wheelchair. A patient suffering from paralysis from the neck down was able to navigate the chair along a complex route - which includes several sharp turns - after 15 minutes of training, with a level of accuracy similar to that achieved by a healthy person.

The "sniffing language" - based on direction (in-out), varying intensity and duration - creates versatility that allows the creation of complex codes that will increase the safety, accuracy and range of operation of the devices operated with it. The new system is cheap to manufacture, simple, and fast to operate, compared to other brain-machine interfaces. Prof. Sobel believes that the new development does not only bring hope to paralyzed people, and that it will be used in a variety of other fields, as a kind of "third hand" that will serve surgeons, pilots, and the like.