Wednesday December 29 2021 BCI 1 Brain computer

Wednesday, December 29, 2021 BCI 1

Brain computer interface ØBasic Idea ØGeneric BCI system ØTypes of BCI system ØEEG technique ØApplications ØAdvantages ØDisadvantages ØBCI Innovators ØFuture developments Wednesday, December 29, 2021 BCI 2

MAN AND THE WORLD Man interacts with the world using his five senses and limb movements Wednesday, December 29, 2021 BCI 3

THOUGHTS faster than ACTIONS Ø Actions are mechanical movements while thoughts are electrical impulses. Ø Thoughts are faster than actions Ø So direct interaction with the world through thoughts would be faster. Wednesday, December 29, 2021 BCI 4

Brain Computer Interface Brain-computer interface (BCI) is a fast-growing emergent technology in which researchers aim to build a direct channel between the human brain and the computer. BCI- The Ultimate in Human Computer Interfacing Wednesday, December 29, 2021 BCI 5

What is it good for? Neurofeedback ◦ treating attention deficit hyperactivity disorder (ADHD), poor concentration Brain Computer Interfaces ◦ People with little muscle control (i. e. not enough control for EMG or gaze tracking) ◦ People with ALS, spinal injuries ◦ High Precision ◦ Low bandwidth (bit rate)

Components of BCI ØGeneration of signals from brain ØPreprocessing, ØFeature extraction, ØClassification, ØDevice control. Wednesday, December 29, 2021 BCI 6

Generic BCI System Wednesday, December 29, 2021 BCI 8

signal extraction techniques Different neuroimaging methods are used to derive meaningful interpretations from the brain signals which are captured by microelectrodes: ØEEG ØECo. G ØMEG ØBOLD ØMRI - Electro encephalography - Electro cortico graphy - Magneto encephalo graphy - Blood-Oxygen-Level-Dependent (signal) - Magnetic Resonance Imaging Wednesday, December 29, 2021 BCI 9

What is an EEG? An electroencephalogram is a measure of the brain's voltage fluctuations as detected from scalp electrodes. It is an approximation of the cumulative electrical activity of neurons.

EEG Background 1875 - Richard Caton discovered electrical properties of exposed cerebral hemispheres of rabbits and monkeys. 1924 - German Psychiatrist Hans Berger discovered alpha waves in humans and invented the term “electroencephalogram” 1950 s - Walter Grey Walter developed “EEG topography” - mapping electrical activity of the brain.

Types of BCI Invasiveinside grey matter of brain Partially Invasiveinside the skull but outside the grey matter Non Invasiveoutside the skull, on the scalp Wednesday, December 29, 2021 BCI 12

Invasive BCI S ØElectrode inserted directly into grey matter ØHighest quality signal can obtain ØBut are prone to scartissue build-up Wednesday, December 29, 2021 BCI 13

Partially Invasive BCIs Ø Implanted inside the skull but rest outside the grey matter of the brain Ø Produce better resolution signals than non-invasive BCIs where the bone tissue of the cranium deflects and deforms signals Ø Carry lower risk of forming scar-tissue in the brain than fully-invasive BCIs. Wednesday, December 29, 2021 BCI 14

Non-Invasive BCIs Ø low signal quality due to electrodes are not directly interact with neurons Ø It is safest as no surgery required. Ø EEG is widely used for this technique Wednesday, December 29, 2021 BCI 15

EEG Technique for BCI Ø Electrodes attached to the scalp Ø Electric signals of the brain are amplified. Ø Transmitted to the computer Ø Software converts them into technical control signals ( computer commands) Ø These computer commands Wednesday, December 29, 2021 controls the devices. BCI 16

Physical Mechanisms EEGs require electrodes attached to the scalp with sticky gel Require physical connection to the machine

Cerebral Cortex Parietal Lobe - involved in the reception and processing of sensory information from the body. Frontal Lobe - involved with decision-making, problem solving, and planning. Occipital Lobe - involved with vision. Temporal Lobe - involved with memory, emotion, hearing, and language.

EEG WAVES There are 5 major types of EEG waves 1. Delta Waves 2. Theta Waves 3. Alpha Waves 4. Beta Waves 5. Gamma Waves Wednesday, December 29, 2021 BCI 19

Continuous Brain Waves Ø Generally grouped by frequency: (amplitudes are about 100µV max) Type Frequency Location Use Delta <4 Hz everywhere occur during sleep, coma Theta 4 -7 Hz temporal and parietal correlated with emotional stress (frustration & disappointment) Alpha 8 -12 Hz occipital and parietal reduce amplitude with sensory stimulation or mental imagery Beta 12 -36 Hz parietal and frontal can increase amplitude during intense mental activity Mu 9 -11 Hz frontal (motor cortex) diminishes with movement or intention of movement Lambda sharp, jagged occipital Vertex Wednesday, December 29, 2021 correlated with visual attention higher incidence in patients with epilepsy or encephalopathy BCI 20

Electrode Placement Standard “ 10 -20 System” Ø Spaced apart 10 -20% Ø Letter for region • F - Frontal Lobe • T - Temporal Lobe • C - Center • O - Occipital Lobe Ø Number for exact position • Odd numbers - left • Even numbers - right Ø Wednesday, December 29, 2021 BCI 21

Electrode Placement ØA more detailed view: Wednesday, December 29, 2021 BCI 22

Alpha and Beta Waves Studied since 1920 s Found in Parietal and Frontal Cortex Relaxed - Alpha has high amplitude Excited - Beta has high amplitude So, Relaxed -> Excited means Alpha -> Beta

Mu Waves Studied since 1930 s Found in Motor Cortex Amplitude suppressed by Physical Movements, or intent to move physically (Wolpaw, et al 1991) trained subjects to control the mu rhythm by visualizing motor tasks to move a cursor up and down (1 D)

Mu and Beta Waves (Wolpaw and Mc. Farland 2004) used a linear combination of Mu and Beta waves to control a 2 D cursor. Weights were learned from the users in real time. Cursor moved every 50 ms (20 Hz) 92% “hit rate” in average 1. 9 sec

BCI Examples - Prostheses (Wolpaw and Mc. Farland 2004) allowed a user to move a cursor around a 2 dimensional screen (Millán, et al. 2004) allowed a user to move a robot around the room.

BCI Examples - Music 1987 - Lusted and Knapp demonstrated an EEG controlling a music synthesizer in real time.

In Review… Brain Computer Interfaces ◦ Allow those with poor muscle control to communicate and control physical devices ◦ High Precision (can be used reliably) ◦ Requires somewhat invasive sensors ◦ Requires extensive training (poor generalization) ◦ Low bandwidth (today 24 bits/minute, or at most 5 characters/minute)

Area of implementation v. Medical science Ø Enabling disabled people o Vision and hearing o Paralysis treatment o Prosthetic devices (legs, hands etc) o Provide a means of communication to completely paralyzed patients o Surgically implanted devices used as replacement for paralyzed. Wednesday, patients December 29, 2021 BCI 29

v. General application ØControl a robot ØPlaying games ØFor physically weak persons to handle the computer ØCursor control Allow those with poor muscle control to o communicate and control physical devices o Wednesday, December 29, 2021 BCI 30

Example of BCI application A phsically handicapped man operates a BCI wheelchair Wednesday, December 29, 2021 BCI 31

More examples A single handed man interfaced with BCI Japanese student walking in the virtual world with the character controlled by his brain waves. Wednesday, December 29, 2021 BCI 32

ADVANTAGES • BCIs will help creating a Direct communication between a human or animal brain and computers. • Also it provides better living, more features, more advancement in technologies etc. • High Precision (can be used reliably) • Low bandwidth Wednesday, December 29, 2021 BCI 33

Difficulty in Implementation of BCI: Ø COST require for BCI is very high. Ø It is RISKy, because it operates with brain. Ø Effective BCI technique requires invasive method. Ø Requires magnetically shielded room and special kind of helmet. Ø It is SLOW Wednesday, December 29, 2021 BCI 34

Future Work Improving physical methods for gathering EEGs Improving generalization knowledge of how to interpret waves

Future developments Ø Better signal detection Ø Shortening training time Ø Improving learning (neurobiological and psychological basis) Ø New recording methods (NIRS, ECo. G) Ø Broader range of applications (interface to commercially available assistive devices; treatment of diseases) Wednesday, December 29, 2021 BCI 36

Conclusion Ø BCI is highly promising. Ø Provide high standard of living. Ø Extend our limits. Ø Impart a new level to the popular quote“I think therefore I am!” Wednesday, December 29, 2021 BCI 37

ANY……? ? ? Thank u… Wednesday, December 29, 2021 BCI 38