Brain computer interfaces Flashcards
What is a BCI
a computer-based system that acquired brain signals, analyses them and translates them into commands that are relayed to an output device that carries out desired actions without using normal biological neuromuscular output pathways
whats the aim of a BCI
estore, replace or enhance brain function by information transmission between external electronic devices
name the three usual action of a BCI
- signal acquisition
- signal processing
- BCI application
does the system always act on the brain?
no, it can act on the spinal cord, peripheral nerves as well
name two basic types of BCI
- electroencephalogram [EEG]
- cochlear implant
list the 5 current examples of applications of BCI
- control of electronic devices
- restoring vision
- restoring speech
- targeted drug delivery
- modulating brain activity via deep brain stimulation
what is electrically controlled drug release
[Feedback systems for real time drug delivery on demand only when needed]
how do electrically controlled drug release work and name the types
they collect the electrical signal from the brain and delivery stimulation
1. non-invasive 2. invasive
give some examples of the questions the FDA will ask
- does it cause harm to surrounding tissue
- does it form scars
- does it move around after insertion causing tissue damage
- how quickly does it degrade over time
- is it robust
what is the tissue response to electrode insertion
injury
name and describe the three nervous tissue response to injuries
- microglia - inactivated is branched morphology that samples the environement, activated results in proliferation and secretion of proteolytic enzymes and phagoctyose debris
- astrocytes - after injury they become reactive and upregulate glial fibrillary acidic protein
- oligodendrocytes - at injury they interface with the myelin sheath which compromises nerve conduction
what is the electrode encapsulation response soon after electrode insertion
- physical damage to all tissues it passes through
- at injury site the microglia become activated rapidly and send long projections
- > 12h microglia migrate toward the implant
- 24 x greater density of microglia adjacent to the implant
whats the long term response to electrode encapsulation
- astrocytes have slower and more varied response
- astrocytea activated by release of blood plasma contents due to disruption of blood vessels damaged during insertion
- astrocytes upregulate GFAP larger and proliferate
- high density of activated microglia and reactive astrocytes near implant is sustained
== is called glial encapsulation
whats a key result of long term electrode performance
continual presence is a sustained immune reaction and neuron death occurs adjacent to electrode, glial encapsulation reduces effectiveness by impeding electrical properties
electrode corrodes
what is brain gate and what are its components
its a mind-to-movement system allowing computer control using through through a BCI
1. electrode
2. connector
3. converter
4. computer
what is signal processing
Signal processing: a neural network decoder was trained to predict the probability that a specific phoneme would be spoken during an 80ms interval
what were the results of the braingate 2 clinical trial
ALS patient retained orofacial movement and can vocalize w no inteligible speech. 2 electrode arrays were placed in ventral premotor cortex and two in Broca’s area
how well did signal processing work
trained with 125,000 and had a 9% error rate, 24% for the 125,000 vocab. 62 word per min vs 18 word per min for the old system
describe the development of mind control of 2 joysticks
JAN 2024, quadriplegic, BCI permitted laterality and was able to distinguish between left and right hand movements
1. no bone or brain infections but 1 removal and 1 impossible removal. 3 patients had seizures but were controllable with medication
describe neuralink and why its controversial
intended to allow wireless mind control of computerized devices in real time with the signal then being sent via bluetooth:
controversial bc elon is not approved by the FDA, animal studies resulted in death, ethics for data collected and impartial scientific scrutiny difficult
what are the components of neuralink
- sealed unit
- battery
- electronics
- threads
what were the results of the prime study of the neuralink
NOLAND ARBAUGH;
- could control cursoe
- lost 85% of threads
- functionality restored but not as well
ALEX:
400 / 1024 threads retained and could use the cursor, this time threads were implanted deeper
Describe synchron
its a thought to action BCI that aims to help people with paralysis perform tasks expandable mesh supporting multiple electrodes inserted into brain blood vessels like a stent
pros for synchron
- synchron uses a minimally-invasive endovascular procedure
- avoids open brain surgery for insertion
- inserting stents is common so medical expertise exists
