Brain-Machine Interface Flashcards
Define brain-machine interfaces (BMIs).
Medical devices that measure or alter electrophysiological activity at the level of populations of neurons.
What are the four main categories of BMI uses?
Restore lost sensory capabilities.
Restore lost motor capabilities.
Restore lost brain processing capabilities.
Regulate pathological neural activity.
Describe how cochlear implants work.
Sounds are captured by a microphone that resides outside the skin.
Signals are sent to a receiver subcutaneously implanted near the ear.
Signals are encoded to appropriate temporal signal patterns, which electrically stimulate spiral ganglion cells in the cochlear modiolus.
Signals from the activated cochlear cells are transmitted through the auditory nerve to the brainstem and higher auditory areas.
Neural signals are interpreted as the sounds captured by the microphone.
Who can benefit from cochlear implants?
Patients with a peripheral cause of deafness that leaves the cochlear nerve and central auditory pathways intact.
What is the concept behind motor BMIs?
One or more electrode arrays are implanted in motor brain regions.
APs and LFPs from many neurons are recorded.
This is converted by a decoding algorithm into computer commands for controlling a computer interface or prosthetic, OR stimulation patterns for functional electrical stimulation of muscles in a paralysed limb.
What is supervisory software?
Software that monitors overall BMI performance and safety, and that monitors whether the patient wishes to use the prosthesis, e.g. if they are sleeping.
How would a discrete BMI decoder work?
Estimates one of several possible movement goals.
Solves a classification problem in statistics.
Can be applied to a preparation activity or execution activity.
How would a continuous BMI decoder work?
Estimates the moment-by-moment details of a movement trajectory.
Solves a regression problem in statistics.
Usually applied to execution activities.
What are the two phases of neural decoding?
Calibration phase.
Ongoing use phase.
Explain the calibration phase of neural decoding.
Neural activity is recorded while a paralysed person attempts to move, imagines moving, or passively observes movement.
The relationship between neural activity and movement is characterised by a statistical model.
Explain the ongoing use phase of neural decoding.
Once the relationship between neural activity and movement has been defined, the statistical model is used to decode new observed neural activity. The goal is to find the movement that is most consistent with the observed neural activity.
