P300 brain-computer interface spellers allow patients who are severely disabled to communicate. The system consists of electroencephalography acquisition connected to real-time processing software. With little training, a person can “spell” words into a computer by focusing on the desired letters. The process is slow but makes a big difference for someone who can’t communicate any other way.
Steady-State Visual Evoked Potential (SSVEP) BCI can infer an individual’s intent by measuring EEG activity at specific frequencies when viewing one or more oscillating visual stimuli, such as flashing LED lights. When a user focuses attention on one such stimulus, the BCI can trigger a command, such as “move forward”, thus controlling a robot or an online avatar.
In a person that is awake, primary sensorimotor cortical areas show 8-12 hertz of "idling activity" in the thalamus, known as μ rhythms, when the person is not engaged in processing sensory input or producing motor output. Using μ rhythms frequencies, users can employ some form of motor imagery, such as imagining hand movements, to control computer cursors with their mind.
Clinical Application of BCI systems include:
• Hearing Screening
• Vision Screening, e.g. Glaucoma
• Epilepsy Screening
• Brain Functionality
• Mental Disorders
Auditory and Visual Stimulus
BCI Experimental Setup:
Electrode Placement: Know the generators.
• Visual evoked potential→ Occipital lobe.
• Auditory evoked potential → Temporal lobe.
• Somatosensory evoked potential → Centroparietal (Post-central gyrus)
• Motor control → Pre-central gyrus
Montage: How you represent the biopotential values.
Shielding: Shielding is important because it eliminates electromagnetic interference and it increases the signal to noise ratio by reducing noise.
Once you start your recording you should first check with known artifacts. The three basic checks are eye movements, eye blinks, and clenching of jaws.
Check the functionality of your equipment.
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