Thuật toán mạng nơ ron cho đánh giá hoạt động suy nghĩ dùng kỹ thuật điện não

v


TịMăTT

máy tính  (BCI: Brain Computer Interface ) 
 trong .   không
 cho các  BCI là  (EEG). Trong , 



  
(). Mô hình  Neuron o 
  .  
 3   200    
 các   các 
vi


ABSTRACT

Brain Computer Interface (BCI) has attracted many researchers in recent
years. One of non-invasive techniques for the BCI issue is Electroencephalography
(EEG) which is applied for rehabilitation and diagnosis. In this study, band-pass
filtering, Laplacian filtering and common average reference (CAR) filtering are
used to enhance EEG signal. For feature extraction of the EEG signal, the Common
Spatial Pattern (CSP), Power Spectral Density (PSD), and Principal Component
Analysis (PCA) are employed to find out features of imagery. In addition, an
Artificial Neuron Network (ANN) model is utilized to classify imagery status.
Experiments are performed on 3 subjects with 200 runs per subject to illustrate the
effectiveness of the proposed methods.

vii

MCăLC
CHNGă1:ăTNGăQUAN 1
1.1 TNGăQUAN 1
1.2ăMCăTIểUăĐăTĨI 2
1.3ăGIIăHNăCAăĐăTĨI 3
1.4ăPHNGăPHỄPăNGHIểNăCU 3
1.5ăCUăTRÚCăLUNăVĔN 3
CHNGă2:ăCăSăLÝăTHUYT 5
2.1ăTNGăQUANăVăNĩOăNGIăVĨăCỄCăVỐNGăCHCăNĔNGăCAă
NĩOăNGI 5
2.2ăPHNGăPHỄPăTHUăTHPăTệNăHIUăNĩOăEEG 8
2.2.1ăTngăquanăvăcácăphngăphápăthuăthpătínăhiuănƣo 8
2.2.2ăĐoăTínăHiuăDùngăPhngăPhápăĐinăNƣoăĐăEEG 9
2.3ăCỄCăPHNGăPHỄPăXăLÝăTệNăHIUăSịNGăNĩOăEEG 11
2.3.1 Các phngăphápătinăxălỦ 11
2.3.2ăCácăphngăphápătríchăđcătrngătínăhiuăEEG 12
2.4ăPHỂNăLOIăDăLIUăSịNGăNĩOăBNGăMNGăNRONăNHỂN
TO 17
2.4.1ăMngălanătruynăngc 17
2.4.2ăKhinătrúcămngălanătruynăngc 20
2.5.ăTINăTRỊNHăCỄCăBCăNGHIểNăCU 22
2.6.ăTịMăTT 23
CHNGă3:ăXăLÝăTệNăVĨăPHỂNăLOIăTệNăHIUăNĩOăNGIăDỐNG
KăTHUTăEEG 24
3.1ăTHITăBăĐOăVĨăTINăTRỊNHăTHUăTHPăTệNăHIUăEEG 24

3.1.1ăăThităbăđo 24
3.1.2ăThuăthpătínăhiuăEEGătrongănghiênăcu 25
3.2ăTINăXăLÝăTệNăHIU 28
3.2.1ăăBălcătầnăs 28
3.2.2ăăBălcăkhôngăgian 29
viii

3.3ăTRệCHăĐCăTRNG 33
3.3.1ăăPhng pháp CSP (Common Spatial Pattern ) 33
3.3.2ăăPhngăphápăPSDă(PowerăSpectralăDensity) 39
3.3.3ăăPhngăphápăphơnătíchăthƠnhăphầnăchínhă(PCA) 42
3.4ăPHỂNăLOIăDăLIUăSịNGăNĩOăBNGăMNGăNRON 45
3.4.1.ăPhơnăloiăđiăviăphngăphápătríchăđcătrngăCSP 45
3.4.2.ăPhơnăloiăđiăviăphngăphápătríchăđcătrngăPSD 48
3.4.3.ăPhơnăloiăđiăviăphngăphápătríchăđcătrngăPCA 50
3.5ăTịMăTT 53
CHNGă4:ăKTăLUNăVĨăHNGăPHỄTăTRINăCAăĐăTĨI 55
4.1 KTăLUN 55
4.2ăHNGăPHỄTăTRINăCAăĐăTĨI 55
TĨIăLIUăTHAMăKHO 56


ix

DANHăMCăBNG

 36

 37


 39
 44
 
 47

 47

 48

 49

 49

 50

PCA 50

 51
x


 51

 52
  53

xi



DANHăMC HÌNH

 6
 7
 7


theo: [2]) 9

Hình 2 9
 18
m sigmoid 19

 23
Hình 3.1. Máy Active Two  24
 25
 26
 26
 26

 27
 28
 29
xii

 30
 31
 31
 31
h C3 sau khi qua
 33

SL 33

 33

 35

 35


1

 36

 38

 40
 pháp
 41

 42
 44
xiii

DANHăMC TăVITăTT

AR ậ Autoregresion
ANN  Artificical Neural Network
BCI  Brain Computer Interface
CAR  common average reference
CSP  Common Spatial Pattern
EEG  Electroencephalogram
ECoG  ElectroCorticoGraphy
fMRI  function Magnetic Resonance Imaging
LFPs  Local Field Potentials
MEG  Magnetoencephalography
MLP  Multi - Layer Perceptron
ME  Mocro-Electrode
MEA  Micro-Electrode Array

NIRS  Near - Infrared Spectroscopy
SL  Small Laplacian
PSD  Power Spectral Density
PCA  Principal Component Analysis


1

CHNGă1:ăTNGăQUAN
1.1 TNGăQUAN






s-

-12Hz [1].



              
d




 Và


2,3,25].
, 



2

,  
 [6], . 
 iên
 
1.2ăMCăTIểUăĐăTĨI
 
Khi có các h
 

N
1) Thu thp và x c tín hiu EEG t thit b ca Biosemi.
2) Phân bic g ca mt s hong di chuyn gi
bng các phân tích không trc tuy       
hiu qu ca t lý tín hiu.
Hai 

 
-bass filtering)
SL
  các 
pháp  CSP (Common Spatial Pattern),
  PSD (Power Spectral Density


, 
 .

3

1.3 GIIăHN CAăĐăTĨIă


 

1.4 PHNGăPHỄPăNGHIểNăCU

 u tài liu: thu thp các tài liu, bài báo khoa hc
    c nghiên cu. Nghiên cu lý thuy xây dng
thu tài.
 c nghim: tiu não t máy Active Two.
Áp dng các thu x lý tín hic.
 So sánh kt cc gi
1.5 CUăTRÚCăLUNăVĔN
4 
sau:
 1: Tngăquan: 
  .
CăsălỦăthuyt: Ctrình bày các 

XălỦăvƠăphơnăloi tínăhiu nƣoăngiădùngăkăthută EEG:

Trong c  
trích ra các 
suy ng 



4

4: KtălunăvƠăhngăphátătrinăcaăđătƠi: 



5

CHNGă2:ăCăSăLÝăTHUYT


2.1 TNGă QUANă Vă NĩOă NGIă VĨă CỄCă VỐNGă CHCă NĔNGă CAă
NĩOăNGIăă


Theo [9], b
11



.




 thùy trán (frontal lobe), thùy

trong hình 


6


Hìnhă2.1.ăCácăthùyăcaănƣoă(Ngun:ă[11])
              

 





7


Hìnhă2.2.ăCácăchcănĕngătrongăvùngăthùyăđnhă(Ngun:ă[12])

Hìnhă2.3.ăVătríăcácăchcănĕngătrongăvùngătinăvnăđngă(Ngun:ă[12])

2
.

8

2.2 PHNGăPHỄPăTHU THP TệNăHIU NÃO EEG
2.2.1ăTngăquanăvăcácăphngăpháp thuăthpătínăhiuănƣo
 [2] -
             

       -invasve) thì có MEG

 



          
(Mocro-E    -Electrode Array) và LFPs (Local
      

Hình 2.4 



9

Hình 2. 4. ĐăchínhăxácăvăkhôngăgianăvƠăthiăgianăviăcácăphngăphápăkhácă
nhauătrongăcácănghiênăcuăvăBCIă(Ngun:ăGervenăvƠăcngăsựădnătheo:ă[2])
4 
 () 


2.2.2 ĐoăTínăHiuăDùngăPhngăPhápăĐinăNƣoăĐ EEG
 
5 
 

Hình 2.5. ĐoătínăhiuăđinănƣoădùngăphngăphápăEEG







c tính tn s tín hin
não. Theo [3], tín hic chia làm 5 loi:

10

 Tn s n s thp nht, nm trong khoãng t 1-4 Hz, nó có
 i ln và ch c khi các thanh thiu niên chìm vào gic
ng sâu. Sóng delta xut hin ch yu ti Fp1 và Fp2
 Tn s   m trong khoãng 4-  c quan sát trong tình
tr  c bun ng)  nhi tr tui. Sóng
theta xut hin nhiu ti C3, C4.
 Tn s  nm trong khoãng 8-12 Hz,  vùng sau cu và khi
i thí nghim trong tình trang nhm mt ho
gin. Sóng alpha tp trung nhiu ti O1 và O2.
 Tn s ng nm trong khoãng 8-13 Hz v t
n c trong vùng vng và cm giác vng ca não.
 ca nó s i khi thc hin các c ng.
 Tn s n s sóng não nm trong khoãng 13-30 Hz vi biên
 n 30uV. Nó xut hin trong trng thái tnh táo, nó ch b i khi
có hong di chuyn. Sóng beta xut hin nhiu  nh và thùy trán.
 Tn s n s t hin 
tn s n 80 Hz ho các hong nhn thc
và các chi chuyn.






m c
 Giá thành th

11

 Thit b nh gn, vì vy có th c nhi
ng t, hng ngoi gn có thit b rt to, cng
knh.
 EEG có th c nh n (cng t bt
bung phi c nh cho t
 EEG không t   ng t        i
ng ng t ng cao (máy fMRI
hong vng t ng cao nên có th gây n sc
khi)
m c
  n cc gn trc ti     thu tín hiu EEG. Bi vì s di
chuyn cu, cht sn cc và tín hin
thc tc s cha nhiu.
2.3 CỄCăPHNGăPHỄPăX LÝăTệNăHIUăSÓNG NÃO EEG

 

2.3.1 CácăphngăphápătinăxălỦ




2.3.1.1 Bălc tầnăs

C 



12

. FT
FIR, IIR.
2.3.1.2 Bălcăkhôngăgian


 (common aveSmall Laplacian).
 
kênh, theo [13] ta có 
e
Ne
j
j
i
i
N
V
VV



0
~

(2.1)


i

e
 

 
 
[14] 
4
4
~



i
j
j
ii
V
VV

(2.2)

i

j

 .
2.3.2 Cácăphngăphápătríchăđcătrng tínăhiuăEEG

Theo [2] EEG   
      
 này
                

13

 
lý.

CSP,  trung bình (PSD)
, PCA


 ba g pháp: CSP,



. 
  
2.3.2.1 Phngăpháp CSP (Common Spatial Pattern )
 
  
Theo [15] n
xe

 


)(EE'

EE'
C
trace


(2.3)
C C
tb1
, C
tb2


C
c
= C
tb1
+ C
tb2

(2.4)



14

C
c
= U
c
λ

c
U
c
’

(2.5)
U
c
C
c
và λ
c
C
c

.
P 
'
c
1
UλP



(2.6)

S
1
= PC
tb1

P’ và S
2
= PC
tb2
P’
(2.7)
B u:
S
1
= Bλ
1
B’ và S
2
= Bλ
2
B’
(2.8)



















ch
1


.
.
.
λ
1

(2.9)




















ch
1
1
1
.
.
.
1
λI = λ
2

(2.10)

1
 
2
 
ch
.
W 
P) 
sau:
W = B’P
(2.11)


15

E W 

Z = WE
(2.12)

 
Z.

)
)var(
)var(
log(
2
1



m
i
p
p
Zi
Z
f

(2.13)
f
p


2.3.2.2 Phng pháp PSD (Power Spectral Density)


 .
Theo [2] pPSD 
            




 Theo [17] p
 trên tín 
t 

n


16

2.3.2.3 PhơnătíchăthƠnhăphầnăchính PCA
PPCA (Principal Component Analysis






         




 trích.
--
Theo [18
u:




nTr
i
i
p
nTr
m
1
1

(2.14)

i



T
i
nTr
i
i

mpmp ))((
1



A

(2.15)

Ax=λx
(2.16)
x={e
1
, e
2
,ă…,ăe
d
} là các vector riêng và λ
1

2

d

e 