Electroencephalogram (EEG) Hsiao-Lung Chan Dept Electrical Engineering Chang Gung University

Transcription

1 Electroencephalogram (EEG) Hsiao-Lung Chan Dept Electrical Engineering Chang Gung University

2 Cerebral function examination Electroencephalography (EEG) Near infrared ray spectroscopy (NIRS) Magnetoencephalography (MEG) Magnetic resonance image (MRI)

3 EEG recording M. Bear et al, Neuroscience: exploring the brain, Lippincott Williams & Wilkins, EEG 3

4 Neurons & interconnections EEG 4

5 Axon ( 軸突 ) to synapse ( 突觸 ) via neurotransmitter EEG 5

6 Origin of biopotentials Na + Cl - Extracellular domain Phospholipid bilayer Intracellular domain K + EEG 6

7 Action potential Na Outside cell Plasma membrane Inside cell Na Resting phase K + 3 Repolarizing phase K + Na + Na Depolarizing phase K + 4 Undershoot phase K + Membrane potential (mv) t EEG 7

8 Action potential EEG 8

9 Simplified synapse in biologocal neuron EEG 9

10 Active channel: sodium-potassium pump Remove 3 Na + for every 2 k + outside K+ Na+ inside K+ Na+ M. Bear et al, Neuroscience: exploring the brain, Lippincott Williams & Wilkins, EEG 10

11 Brain Cerebrum ( 大腦 ) Receives and processes conscious sensation Generates thought, and controls conscious activity Hypothalamus ( 丘腦下部 ) controls most vegetative and endocrine functions, including body temperature Medulla ( 延腦 ) Vital centers that regulates heart rate, respiratory rate, blood pressure, blood vessel, etc. Cerebellum ( 小腦 ) Controls motor activities and muscle contractions EEG 11

12 Cerebral functional areas EEG 12

13 Cerebrum Gray matter refer to cerebral cortex ~ 25 mm thick but contains ~ 100 billion neurons Pyramidal neuron EEG 13

14 EEG rhythms (8 ~ 13 Hz) Alpha Beta Alpha (>13 ~ 30 Hz) (4 ~ <8 Hz) (<4 Hz) EEG 14

15 EEG changes in sleep EEG 15

16 Sleep stages EEG 16

17 Sleep spindle EEG 17

18 K-complex, fusion of vertical wave and sleep spindle EEG 18

19 Sleep stages 3 nonrapid eye movement (REM) (N1, N2, N3) Wakefulness (W) with alpha rhythm and frontal beta rhythm N1 (drowsiness) with irregular slow waves at 37 Hz N2 (light sleep) vertex sharp wave slow wave occipital sharp transients sleep spindle

20 Sleep stages (cont.) N2 (light sleep) N3 (deep sleep) R (REM sleep) sleep spindle rapid eye movement K complex slow wave slow wave occipital sharp transients

21 Bispectral index monitor (BIS) A high bispectrum value indicates a phase coupling among the triplet of frequencies, f 1, f 2, and (f 1 +f 2 ) The BIS was shown to reduce the incidence of anesthesia awareness (Myles et al., 2004) BIS ranges from 0 to 100, a BIS value below 60 has been shown to prevent anesthesia awareness (Baura, 2008) EEG 21

22 Sleep monitoring using wearable brain wave device Z.Q. score Not only helps you with quantifying your sleep, but also tells others you re awake. EEG 22

23 Lempel-Ziv complexity EEG 23

24 EEG waveform recorded from one patient under sevoflurane in different states LZ complexity awake state intermediate state asleep state EEG 24

25 Original system of electrode placement EEG 25

26 EEG electrode placement EEG 26

27 Referential montage: reference is based on the average of the A1 and A2 channels (ears) EEG 27

28 Epileptic seizures A seizure results from abnormal discharges of cortical neurons Partial-onset seizures Generalized-onset seizures EEG 28

29 EEG spikes or abnormal waveform in epilepsy John G. Webster, Medical Instrumentation, application and design, 3rd Ed., Houghton Mifflin, EEG 29

30 Vaga nerve stimulation for preventing seizure EEG 30

31 Brain-computer interface EEG 31

32 Control robotic arms using braincomputer interface Belle, a monkey in Brain Machine Interface study Articles from Scientific American, Nature, EEG 32

33 Tetraplegia (Quadiplegia) Cervical (neck) injuries usually result in four limb paralysis. Injuries above the C4 level may require a ventilator or electrical implant for the person to breathe.

34 Cortical neuroprothesis EEG 34

35 From primates to humans Miguel Nicolelis et al, Duke University Scientific American 2002, Nature Review Neuroscience BrainGate Collaboration Brown University, Nature 2012 EEG 35

36 The BrainGate neural interface system (Brown University) An implanted microelectrode array EEG 36

37 Raster plot Action potentials recorded from motor cortex Each bar indicates neuronal firing at a given moment Time EEG 37

38 Control computer cursor by thinking (The BrainGate in 2006) EEG 38

39 Reach for and grasp objects using robotic arms controlled by brain activity A 58-year-old woman, paralyzed by a stroke for almost 15 years uses her thoughts to control a robotic arm, grasp a bottle of coffee, serve herself a drink, and return the bottle to the table. BrainGate Collaboration Brown University, Nature 2012 EEG 39

40 A vision of future A neurochip would amplify arrays of microwires implanted in motor cortex, convert the thoughts into a train of radio-frequency signals, and send them to a backpack computer. The computer would convert the signals into motor commands for stimulating muscle nerves to move arm controlling a wheelchair or a robotic arm Control Robots with the Mind Scientific American 2002 EEG 40

41 Reference Leif Sörnmo, Pablo Laguna, Bioelectrical Signal Processing in Cardiac and Neurological Applications, Academic Press, 2005, John Enderle, Susan Blanchard, Joseph Bronzino, Introduction to Biomedical Engineering, Academic Press, John G. Webster, Bioinstrumentation, John Wiley & Sons, John G. Webster, Medical Instrumentation, application and design, 3 rd Ed., Houghton Mifflin, F.M. Ham, I. Kostanic, Principle of Neurocomputing for Science & Engineering, McGraw Hill, G. D. Baura, Medical device technologies, Elsevier Inc., EEG 41