BRAIN COMPUTER INTERFACE A SEMINAR REPORT

[seminar class]

presented by:
P . Rajeswari

---

[attachment=10461]
BRAIN –COMPUTER INTERFACE
Introduction to BCI
A brain–computer interface (BCI) is a direct communication pathway between a brain and an external device sometimes called a direct neural interface or a brain–machine interface.
BCIs are often aimed at: assisting, augmenting or repairing
human cognitive or sensory-motor functions
Signal Acquisition
Brain signals can be collected in different ways, one of these methods is EEG (Electroencephalography)
Mu Rhythms
In awake people, even when they are notproducing motor output, motor cortical areas
often display 8–12 Hz EEG activity (Mu Rhythm)
Movement or preparation for movement typicallycauses a decrease in mu rhythms .
• Output Device
• Any controllable machines
• For answering yes/no questions
• For word processing at slow
• Wheelchair
• Virtual Reality
• Usually, Computer screen and the output is the selection of targets or cursor movement
• Need for BCI
Developing technologies for people with disabilities:
• Assist paralyzed people to operate external devices
• Assist blind people to visualize external images without physical movement
• Decode information stored on human brain (as memory)
• Decode information from brain to display human thinking or dream on a screen
• Human BCI
Human BCI Types:
 Invasive
 Partially invasive
 Non Invasive
• Invasive BCI
• Implanted directly into the grey matter of the brain during neurosurgery
• Targeted repairing damaged sight
• Providing new functionality to persons with paralysis
• Produce the highest quality signals
Disadvantage:
• Prone to Scalar tissue build up
• Causes signal to become weaker or even lost as the body reacts to a foreign object
• Partial Invasive BCI
• Implanted inside the skull but rest outside the brain
• Produce better resolution signals than non-invasive BCIs having a lower risk of forming scar-tissue in the brain than fully-invasive BCIs
Examples:
1.Electrocorticography (ECoG)
2.Light Reactive Imaging BCI
• Partial Invasive BCI (Continues)
Electrocorticography (ECoG)
• Measures the electrical activity of the brain taken from beneath the skull
• Electrodes are embedded in a thin plastic pad that is placed above the cortex
• First trialed in humans in 2004 by Eric Leuthardt and Daniel Moran
• Enabled a teenage boy to play Space Invaders using ECoG implant
• Controls are rapid, and requires minimal training
• Partial Invasive BCI (Continues)
Light Reactive Imaging BCI
• Involve implanting a laser inside the skull
• Laser is trained on a single neuron and the neuron's
reflectance measured by a separate sensor
• When the neuron fires, the laser light pattern and wavelengths would change
Advantages of Partial Invasive BCI
• Better signal to noise ratio
• Higher spatial ratio
• Better Frequency Range
• Non-Invasive BCI
• Recorded signal have been used to power muscle implants and
restore partial movement
• Signals are weaken as skull dampens the signal
• Although the waves are still detectable, it is hard to determine the area of the brain or the neuron that created the signal
Examples:
Electroencephalography (EEG)
Magneto encephalography (MEG)
Magnetic resonance imaging (MRI)
• Non-Invasive BCI (Continues)
Electroencephalography (EEG)
 Most studied potential non-invasive interface
 Fine temporal resolution
 EEG in Mid1990s:
• EEG signal was used as a binary signal to
control a computer cursor
• Patients can use computer cursors by
controlling their brainwaves
• Slow – required an hour to write 100
characters
• Non-Invasive BCI (Continues)
This procedure is the first non-invasive neuroimaging technique discovered. It measures the electrical activity of the brain. Due to its ease of use, cost and high temporal resolution this method is the most widely used one in BCIs nowadays
• Non-Invasive BCI (Continues)
Magneto encephalography (MEG)
MEG is a technique for mapping brain activity byrecording magnetic fields produced by electricalcurrents occurring naturally in the brain
• By using Arrays of SQUIDs (superconducting quantum interference devices)
Application :
• Localizing the regions affected by pathology, before surgical removal
• Determining the function of various parts of the brain
• Non-Invasive BCI (Continues)
Magnetic resonance imaging (MRI)
MRI is a technique used in radiology to visualize detailed internal structures.
Functional MRI or FMRI is a type of MRI scan that measures the hemodynamic response (change in blood flow) related to neural activity in the brain or spinal cord.
Recent research in ATR (Advanced Telecommunications Research, in Kyoto, Japan) on FMRI allowed the scientists to reconstruct images directly from the brain and display them on a computer.
Advantages of BCI
1. Induced disability
2. Ease of use in hardware &software
3. Speed
4. Novelty
5. Potentially high impact technology
Conclusions
BCI field is out of the demonstrations phase and is ready for clinical applications .Any new BCI technology should be focused on improving the quality of life of the end user.
This technology enables a disabled person to carry on his work overcoming his inability.