4.4: BCI Technologies and Basic Principles of Brain Data Acquisition

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The BCI system is based on translating neurophysiological signals to commands and control external devices (Sellers & Donchin, 2006). There are two main techniques to implement such processes: Non-invasive BCI and Invasive BCI. Non-invasive BCI does not require any surgical procedures, instead, the brain activity is recorded from the skull with a channel cap. However, invasive BCI requires neurosurgery. A set of electrodes are attached to a specific region of the brain and signals are directly recorded from gray matter of the brain (Lebedev & Nicolelis, 2006). Both techniques have drawbacks and benefits. Non-invasive BCI is the easiest, safest, and most practical method to elicit signals. However, it only provides a basic communication tool because of its low-resolution signals, since the skull and skin prevent it to acquire high-resolution signals (Lebedev & Nicolelis, 2006). Since the usage of non-invasive methods is limited, Lebedev and Nicolelis (2006) suggested using invasive techniques for important goals such as controlling artificial limbs.

Invasive BCI provides pretty accurate and more specific signals. Nonetheless, this approach has many problems as well. It requires invasive surgery to implant the microelectrodes. Due to the surgical procedure, infection or scar tissue is likely to occur over time. The scar tissue and/or infection prevents the acquiring of signals or decreases the quality of acquired signals over the course of time (Lebedev & Nicolelis, 2006). However, they emphasized that reaching important goals, such as controlling leg prosthesis, are only possible with an ideal recording device that deals with possible consequences of long-term use of microelectrodes. This is because recording simultaneously from several areas of the brain will provide high-resolution signals.

Partially-invasive BCI is another technique to measure and record the electrical activity. In this technique, electrodes are implanted on the surface of the cortex (Levine et al., 1999). Electrocorticography (ECoGs) serves as a partially-invasive recording method.

To summarize, neither invasive BCI nor non-invasive BCI techniques for recording brain activity have an edge over one another. The utility of signal acquisition techniques should depend on the aim of the study. If researchers come up with new solutions for the limitations of the BCI system, both disabled and physically capable people will benefit from it accordingly.