New Multi-channel Measurement Near IR Light
For Optical Brain Imaging
Jean-Claude Vouakouanitou, Cognitive Neuroscience Lab. Encino, CA 91436
Method
Near Infrared Spectroscopy (NIRS)
is a noninvasive IR imaging to monitor the hemodynamic activity of the brain,
including sensorimotor responses. Various techniques and devices have been
developed to utilize this method for assessing cortical activity during cognitive
tasks. In this paper, a prototype wireless optical recording technology (known as
Neurobek) is described.
Materials
We developed a continuous wave Near Infrared Spectroscopy topography system. It
is a highly sensitive neuroimaging device based on a titanium sapphire (NIR) 8401,100 nm and incorporating frequency-domain technology with quantitative optical
brain imaging of deep tissue (optical fibers are used to illuminate tissue).
Our Optical tomography system has 48 light sources and 6 objective lenses for IR
video camera using advanced real-time signal processing: cut-off wavelength with a
spectral response range of 0.9 to 1.7µm, 14-bit AD conversion.
To have good quality of changes in concentration several wavelengths laser diodes
modulated at 110 MHz were combined between 660 and 980 nm.
The spectral range is 660 – 1,700 nm.
Relationships between Synaptic Activity and Hemodynamic Responses.
A    i ci
We present and evaluate techniques by using an integrated system combining Near
Infrared Spectroscopy (NIRS) and electroencephalographic activity (EEG).
In this study, we evaluated NIRS changes over the four cortical areas (frontal,
parietal, temporal and occipital) in the normal and pathological brain during the
performance of different experimental tasks: attention, verbal working memory and
all other cognitive activities.
Oxygenated (ΔO2Hb) and
deoxygenated hemoglobin (ΔHHb)
Total hemoglobin
(ΔcHb = ΔO2Hb + ΔHHb)
The optical and electrical signals were recorded simultaneously on thirteen patients:
- spastic diplegia (n= 3, one male, two females; mean age 13.2 years)
- stroke (n= 2)
- major depression (n= 4)
- psychotic disorders (n= 2), schizophrenia (n= 2)
and healthy volunteers (n= 7)
Dr   [3 abs r    scat r 
We now measured the cerebral electric activity and NIRS simultaneously during
the same session.
With different-measurement approaches we can cover most of the adult head,
especially collect optical data from prefrontal, sensorimotor and visual cortices in
both hemispheres simultaneously. We also can provide 3D images which offers
high spatial and temporal resolution.
Spatial light modulation
High Resolution spectrometer
Digital Transform Spectroscopy (DTS)
Temporal resolution: 160 ms up to 660
<5.0 nm
660/820 (2)
660/980 (2)
664/848 (2)
664/830 (1)
758/830 (8)
760/840 (3)
779/834 (1)
780/870 (2)
780/960 (2)
782/830 (1)
CBV 
EEG’s were recorded with Neurobek system using standard recording techniques.
QEEG’s were evaluated with Thatcher NeuroGuide database.
6 objective lens were placed approximately at anatomical localizations as
mentioned above.
In spastic patients fNIRS had shown a significant increase of [HbO2], (p = 0.008)
and [Hb sum], (p = 0.0001). Increased oxyhemoglobin [HbO2], total Hb [Hb sum],
and cerebral blood volume (CBV) were found in the right region. With treatment,
most children can significantly improve their abilities. Muscle relaxation was
confirmed and cocontraction’s relation to strength and motor function were
determined.
1
2
3
4
5
6
Multi-channel IR camera: 48 light
sources and six lenses video camera
are placed in a headband to provide
tomographic imaging of the brain.
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In depression and schizophrenia alterations in the left frontal lobe were
examined: [oxy-Hb] and [deoxy-Hb] (average values from 0.07 ± 1.1 to -1.19 ±
0.33 µM, p = 0.007, t test, p = 0.01), [Hb] (average values from -0.27 ± 0.27 to 0.95 ± 0.92 µM, NS, t test ) and [Hb sum] (average values from -0.2 ± 1.13 to -2.1
± 0.23 µM, p = 0.06, t test, p = 0.04).
With CP (3 males, 2 females;
12.6±2.7 yr) and control (3 males, 4
females; 13.7±2.8 yr)
Significant (p<0.05) difference were
noted at 3
CP 15.7 ±6.3 vs
Control 10.6 ±1.5 ml.kg-l. min-1),
% VO2 max
Correlated significantly with
(r=0.61 to 0.86, p≤ 0.001) and
(r= -0.69 to 0.063, p≤ 0.001) and
(r= -0.70 to -0.61, p≤ 0.001) scores
50
rCBV
Neurobek is a whole-head optical system combining Near Infrared
Spectroscopy (NIRS) and electroencephalographic activity (EEG) so, the optical
and electrical signals were recorded simultaneously. This is a very promising
methodology that combines knowledge about the electrical activity of the brain
and its BOLD (blood oxygen level dependent) on the dynamic responses.
30
20
3  DR c 
4    B0  D c 
0
*
2
After the training was done, then QEEG measures were averaged for the following
6 pairs of electrodes : Fp1-F7, Fp2-F8, C3-C4, T3-T4, P3-P4, O1-O2 via Fast
Fourier Transform (FFT) with a spectral resolution of 0.5Hz, and at Cz-C4 and F3F4 at 4-8 Hz, 7-10 Hz and 12-15 Hz.
The results have shown
- various patterns of cerebral blood oxygenation (CBO) changes in the frontal lobe
during cognitive tasks and a correlation of alpha rhythm in QEEG and functional
near infrared spectroscopy (fNIRS) with changes in local cerebral blood
oxygenation.
Measurements demonstrated a positive cross-correlation in occipital cortex
between alpha activity and concentration changes of deoxygenated hemoglobin,
indicating that there exists correlations between cognitive paradigms and
hemodynamic responses.
rCBF
10
0
1
2
3
4
5
6
time (sec)
Sites
1-4 Hz
5-7 Hz
8-12
Hz
13-18
Hz
19-23 Hz
Fp1-F7
15.81
3.56
9.33
3.42
2.26
Fp2-F8
17.29
3.74
11.32
3.16
1.86
C3-C4
15.38
2.06
9.12
3.50
2.49
T3-T4
13.48
0.38
6.92
3.85
3.12
P3-P4
10.82
1.26
6.58
2.73
1.39
O1-O2
8.63
0.19
5.78
1.72
1.361
The opportunity exists to measure the optical properties of tissue and to study
higher cognitive functions such as the neurobiology of language development.
Other projects in optical imaging system have been developed and tested,
including applications for neuropsychologists.
Multiplexed-NIRS system with its noninvasiveness allowed us to examine a
dynamic blood flow and oxygenation in the deep microcirculation. It is a
promising tool for diagnostic and neuroscientific applications.
Literature cited
Results
1
60
These measurements have allowed us to identify changes occurring in deeper
tissues.
40
Mitochondrial enzyme
cytochrome oxidase (or
cytochrome aa3) (ΔCtOx) in µmol
Poisson Equation & Equation diffusion.
1
 k r , t     Dr  k r , t    abs r  k r , t   S t r  sk 
c t
Implementation of Beer’s Law
i
Patients were scheduled for a full evaluation which was completed during a 6-week
period. Having two sessions a week of QEEG and NIRS, patients received from
their doctors regular medical treatment.
How to merge these two technologies? conventional radio-frequency RF
wireless and optical fibers. We have mathematical solutions:
Conclusions
%
Introduction
Group
N
S1µV
S2µV
S1-S2µV
S2/S1 x 100
Spastic
Diplegia
3
3.4±1.5
1.8±1.3
1.6±.2
52±86
Stroke
2
2.6±1.7
1.9±1.1
0.7±.6
73±64
Major
Depression
4
2.7±1.7
1.7±1.5
1±0.2
62±88
Psychotic
disorders /
Schizophrenia
4
1.5±1.2
1.9±1.1
-4±0.1
126±91
Healthy
volunteers
7
2.8±1.3
1.1±1.1
1.7±1.6
41±39
Maria Angela Franceschini, Danny K. Joseph, Theodore J. Huppert, Solomon G. Diamond, David A. Boas
« Diffuse optical imaging of the whole head »
Massachusetts General Hospital Athinoula A. Martinos Center for Biomedical Imaging, Charlestown,
Massachusetts 02129
Gu X. Ren K. Hieischer AH.
Frequency-domain sensitivity analysis for small imaging domains using the equation of radiative transfer.
Appl Opt. 2007 Apr 1;46(10):1624-32.
Graber HL, Xu Y, Barbour RL.
Image correction scheme applied to functional diffuse optical tomography scattering images.
Appl Opt. 2007 Apr 1;46(10):1705-16
Quantitative analysis of [ΔO2Hb] & [ΔHHb]
[O2Hb]0
(M)
[HHb] 0
(M)
D[O2Hb]
(M)
D[HHb]
(M)
DP%
CP
DR%
CR
AP/AR
r2
with R
r2
without R
Spastic
Diplegia
(CP)
00.6
±1.2
-1.17
±0.26
0.007
-0.25
±0.24
0.96
0.94
0.85
0.90
2.41
±1.17
0.785
0.785
Stroke
30.1
±2.6
6.0
±1.7
0.53
0.21
3.47
0.93
0.92
0.95
2.63
±0.36
0.975
0.9373
Bipolar
disorder &
Shizophrenia
0.009
±4.6
6.4
±1.3
0.42
0.24
3.58
0.96
0.58
0.46
2.38
±1.63
0.986
0.8936
Healthy
31.5
±3.4
Subjects
12.6
±1.5
0.36
0.35
3.36
0.83
0.82
-0.27
3.71
±0.87
0.8683
0.8449
Statistics of physiological parameters
Total
Right
Middle
V. Toronov, M. Wolf, A. Michalos, and E. Gratton, "Analysis of cerebral hemodynamic fluctuations measured
simultaneously by magnetic resonance imaging and near-infrared spectroscopy," WA5, Proc. OSA
Technical Digest, Biomedical Topical Meeting (2000)
Vouakouanitou, J. C., Hershel Toomim (1999). Conscience du comportement et biofeedback pondéral,
Editions ihs, Paris.
Acknowledgments
This work would not be possible if Subversion did not exist. I would like to
gratefully acknowledge the support of Pierre & Marie Curie University, PitieSalpetriere School of Medecine*, with funding from ECNR and EucharisticHeart Society (ihs).
Special thanks to Doctor Hershel Toomim and Robert Marsh, Biocomp
Research Institute of Los Angeles.
Left
Scalp
Brain
Scalp
Brain
Scalp
Brain
Scalp
brain
ΔCtOx
(µmol)
61.13
± 3.52
62.47
±4.81
61.79
± 3.14
64.71
± 5.73
60.38
± 3.04
64.28
± 5.92
61.03
± 3.75
65.69
± 5.73
ΔcHb
(M)
46.32
±10.8
73.65
±12.6
58.47
± 8.09
78.86
± 12.14
53.87
± 11.8
75.62
± 14.19
66.71
± 12.54
75.92
± 14.94
ΔO2Hb
(M)
36.27
± 7.81
53.81
±10.3
43.59
± 5.68
58.64
± 9.04
38.62
± 8.13
56.39
± 12.52
38.91
± 9.12
56.38
± 12.65
ΔHHb
(M)
15.48
± 3.15
19.36
±5.74
15.81
± 3.65
19.83
± 5.61
14.79
± 3.43
19.63
± 5.79
15.69
± 3.36
19.70
± 6.92
Jean-Claude Vouakouanitou
ECNR – NeuroImaging Laboratory
5990 Sepulveda Blvd, Suite 200
Van Nuys, CA 91411
Tel.: 818-786-6286
jcv@ecnr.org
DPF
=660 nm
6.08
± 0.72
4.79
±1.36
6.12
± 0.84
4.75
± 1.24
6.12
± 0.65
4.63
± 1.82
5.96
± 0.92
4.73
± 1.25
* Federative Institute of Neuroscience Research, University Hospital – Pitie-Salpêtrière, Paris
(France).
Contact