Electroencephalograms and Neuro-Rehabilitation. Hsiao-Lung Chan Dept Electrical Engineering Chang Gung University

Transcription

1 Electroencephalograms and Neuro-Rehabilitation Hsiao-Lung Chan Dept Electrical Engineering Chang Gung University

2 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

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

4 Cerebral functional areas 4

5 Neurons & interconnections 5

6 Cerebrum Gray matter refer to cerebral cortex ~ 25 mm thick but contains ~ 100 billion neurons Pyramidal neuron 6

7 Axon ( 軸突 ) to synapse ( 突觸 ) via neurotransmitter 7

8 Electroencephalogram (EEG) M. Bear et al, Neuroscience: exploring the brain, Lippincott Williams & Wilkins,

9 Action potential (Afterhyperpolarization) 9

10 EEG rhythms (8 ~ 13 Hz) Alpha Beta Alpha (>13 ~ 30 Hz) (4 ~ <8 Hz) (<4 Hz) 10

11 EEG changes in sleep 11

12 Original system of electrode placement 12

13 EEG electrode placement 13

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

15 Sleep stages 3 nonrapid eye movement (NREM) (N1, N2, N3) Wakefulness (W) with alpha rhythm and frontal beta rhythm N1 (drowsiness) with irregular slow waves at 3-7 Hz N2 (light sleep) vertex sharp wave slow wave occipital sharp transients sleep spindle

16 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

17 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. 17

18 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) 18

19 Lempel-Ziv complexity 19

20 EEG waveform recorded from one patient under sevoflurane in different states LZ complexity awake state intermediate state asleep state 20

21 Epileptic seizures A seizure results from abnormal discharges of cortical neurons Partial-onset seizures Generalized-onset seizures 21

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

23 Spinal cord Spinal nerve connects the spinal cord to muscles C = cervical T = thoracic L = lumbar S = sacral 23

24 Nerve to muscle 24

25 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. 25

26 Functional electrical stimulation (FES) 26

27 Selective neural activation for motor neural prostheses: functional electrical stimulation (FES) Spinal cord-based activation Nerve-based activation Muscle-based activation 27

28 Strength-duration curves for nerve and muscle For the same 500-μs pulse, 3 ma and 38 ma are required to stimulate the nerve and muscle, respectively. 28

29 Electrode for electrical stimulation Percutaneous electrode Transcutaneous electrode Subcutaneous electrode 29

30 Liberson s method of muscular stimulation in human beings to aid in walking A pressure switch under the heel of one foot activated a stimulator when the heel was raised. The stimulator transmitted current surface electrodes to the peroneus longus muscle, which could raise the foot.

31 Stimulating hand and leg muscles with surface electrodes (Bioness, Inc., Valencia, California) 31

32 Cleveland FES center Standing & transfer Walking 32

33 Cleveland FES upper and lower-extremity systems 33

34 Cortical neuroprothesis 34

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

36 Intracortical sensor types compared with a surface EEG electrode 36

37 The BrainGate neural interface system (Brown University) An implanted microelectrode array 37

38 Neuronal decoding for imaginary movements A subject was asked to imagine movements such as toward left/right. Action potentials recorded from motor cortex for decoding. Each bar indicates a neuronal firing Time 38

39 Control computer cursor by thinking (The BrainGate in 2006) 39

40 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

41 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

42 Prosthetic Control Using Myoelectric Signals A prosthetic arm that "feels" The Center for Bionic Medicine at the Rehabilitation Institute of Chicago 42

43 Arm amputations 43

44 Body-powered prostheses Squish your shoulders It pulls on a bicycle cable The bicycle cable can open or close a hand or a hook or bend an elbow. 44

45 Bionics ( 仿生學 ) The science of replacing part of a living organism with a mechatronic device or a robot. 45

46 Myoelectric control system at University of New Brunswick, Canada 46

47 Myoelectric control system (cont.) 47

48 Myoelectric prostheses Motorized devices controlled by electrical signals from your muscle Several robotic limbs available on the market Open and close of a hand A wrist rotator Vari-grip ability 48

49 Myoelectric prostheses in the Rehab Institute of Chicago Using a biological amplifier (muscles) to amplify nerve signals Take the nerve away from chest muscle and let nerves for arms grow into it.

50 50

51 Targeted reinnervation Now you think, "Close hand," and a little section of your chest contracts. You think, "Bend elbow," a different section contracts. 51

52 Targeted reinnervation patients Jesse Sullivan 1 st targeted reinnervation patient Amanda Kitts, patient and research collaborator 52

53 More degrees of freedom in control a robotic arm Up to 10 different degrees of freedom hand closed and open wrist flexion and extension elbow that goes up and down shoulder joints movable hands. 53

54 Reference G. D. Baura, Medical device technologies, Elsevier Inc., John G. Webster, Bioinstrumentation, John Wiley & Sons, John G. Webster, Medical Instrumentation, application and design, 3 rd Ed., Houghton Mifflin, Joseph J. Carr, John M. Brown, Introduction to Biomedical Equipment Technology, Pearson Education, Wikipedia, the free encyclopedia 54