CyberSightings

In the Spotlight

A brain–computer interface (BCI) is a particular type of human–computer interaction device that allows a direct communication pathway to be established between a brain (or other functional parts of the central nervous systems) and an external object (i.e., a computing device). In classic BCI systems, also classified as unidirectional, the flow of information originating from the brain is used to operate a computer. In the context of biomedical engineering and neuroengineering, BCI systems have been effectively applied to support individuals with motor disabilities. In these assistive systems, electroencephalogram (EEG) signals are recorded from the user's scalp and translated into actions that allow the disabled individual to actuate several operations, such as selecting a letter from a spelling matrix or driving a wheelchair (www.youtube.com/watch?v=gvR0kHm9fwo/). Further promising applications in the domain of domotic and ambient assisted living are currently under investigation.

An alternative and more challenging implementation is represented by the so-called bidirectional (or recurrent) BCI. Differently from unidirectional BCI, recurrent BCI provides direct feedback to the brain by stimulating sensory neurons, thus closing the loop between the nervous system and the machine. Since a recurrent BCI is based on the acquisition and processing of neural activity, the resulting information can be used not only to operate a remote effector, such as a robotic arm, but also to create a novel interaction channel between the nervous systems of different organisms. The feasibility of this approach has been demonstrated between two rats (www.nature.com/srep/2013/130228/srep01319/full/srep01319.html/) and, more recently, between two humans (http://homes.cs.washington.edu/∼rao/brain2brain/). In the first experiment, a rat performed a forced choice task, while its cortical activity was sampled and transmitted to matching cortical areas of a “decoder” rat using intracortical microstimulation. Results showed that the “decoder” rat was able to learn to make similar behavioral selections, guided solely by the information provided by the “encoder” rat's brain. In the second experiment, human subjects were requested to solve a computer game cooperatively via brain-to-brain communication. Only subject 1 (the “sender”) watched the game: the sender was unable to press the “fire” button, which was only available to subject 2 (the “receiver”). The receiver in turn received information from the sender via transient noninvasive brain stimulation induced by a rapidly changing magnetic field. Researchers carried out four experimental sessions, each including several trials. Results showed that there was a successful transmission of information from the sender to the receiver, and they were able to create a “coupled” system that operated as an “individual” player.

Clearly, although these are preliminary findings obtained on a very simple sensory–motor task, they show the technical feasibility of brain-to-brain interfaces and suggest a number of possible application scenarios, which could go beyond science fiction to create novel opportunities for human-to-human, human-to-animal, or human-to-machine interactions.

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