**3.1.6 Results and discussions**

140 Infrared Spectroscopy – Life and Biomedical Sciences

60秒 20秒

**Imaginary Walking**

30秒

**Rest**

**Rest**

According to previous studies, oxy-Hb is more useful for analysis of cortical activation than deoxy-Hb because of its higher reproducibility (Plichta 2006; Sato 2005), lower inter-subject variability (Sato 2006), and higher correlation with fMRI signals. Therefore, in the present study, oxy-Hb was measured as an indicator of changes in blood volume. The measurements of the subjects were checked visually for artifacts due to body movements. Obtained data were analyzed using the "integral mode" in the ETG-7100 software. We defined a 48 s measurement block made up of a 9 s pretask baseline period before task period (20 s), a 12s recovery period and a 7 s posttask baseline period (Fig. 9). Linear fitting

> ( 9 s ) ( 20 s) ( 7 s ) Pre Task Rec Pos

Fig. 9. Parameters of the integral mode in the ETG-7100 analysis software

Total Period

( 48 s )

Statistical Period ( 32 s )

( 12 s )

Procedure 1 Procedure 2

Fig. 7. Walking video shown to the subjects during WO task

Fig. 8. Walking video shown to the subjects during WO task

**Real Walking**

30秒 20秒

**Rest**

**3.1.5 Data analysis** 

Fig. 10. Results of procedure 1

Fig. 11. Results of procedure 2

The average oxy-Hb of subject SL and ZJ during the statistical period of procedure 1 and 2 are shown in Fig. 10 and Fig. 11, respectively. In Fig. 10 and Fig. 11, the horizontal axis is the time shown in Fig. 9. Both oxy-Hb and deoxy-Hb, and their sum total-Hb are shown. It can be seen from the experiment results that both in procedure 1 and procedure 2, oxy-Hb increased significantly no matter the subject really walked or just imagined walking. The experiment results suggest that the cortical areas related to walking is activated by both RW and WO. The possibility of brain exercise for walking rehabilitation by mental imagery of walking was implied.

Comparison of Cortical Activation During Real Walking and Mental Imagery of

video eyewear

probe

Fig. 12. Experiment scene

Walking – The Possibility of Quickening Walking Rehabilitation by Mental Imaginary of Walking 143

optical fiber

treadmill

**1 2 3**

**456 7**

**8 9 10**

**15 16 17**

**18 19 20 21**

**11 12 13 14**

**Cz**

**22 23 24**

**Detectors**

Fig. 13 shows the positions of optodes on the head of the subjects. The optodes were fixed with a plastic shell and placed on the subject's head according to the international 10-20 system. The numbers between the emitters and detectors were channel numbers. Channels were labelled from front to back as CH1-CH24. The midpoint between CH12 and CH13 was placed on Cz of the International 10-20 system. According to the correlation between the international 10–20 system and cortical region, the areas measured by CH4, 5, 8, 11, 12 and

Fig. 13. Schematic placement of the emitter and detector optodes on the subject's head

**Emitters**

fNIRS system

The average oxy-Hb of subject SL and ZJ during the statistical period are listed in Table 1.We can conclude from Table 1 that although individual difference was significant, the oxy-Hb during the imaginary walking task was higher than that during the real walking task, regardless of the order of the tasks.


\*\*oxy-Hbs are given in mM·mm

Table 1. Average oxy-Hb during RW and WO tasks

fNIRS measures cerebral blood volume. When we walk along a straight line on a level road without any obstacles, the primary somatosensory cortex and the primary motor cortex do not involve much, with the cerebellum controlling the movement of the legs. On the other hand, during the imaginary walking task of the experiment, the subjects have to conceive their movement to match their gaits with those in the video. Although the subjects did not move, they have to plan their walking in their brain. This might be the reason why the oxy-Hb during the WO task was higher than that during the RW task. However, at present since fNIRS can only measure cerebral blood flow in cortex, not in deeper structures, how the other neural systems, such as cerebellum, the spinal cord and the peripheral nervous system, involve in mental imagery of walking is still not clear.

#### **3.2 Experiment 2**

In the second experiment, we compared the activation in the primary motor area and the primary somatosensory area of the brain during RW, VW and WO by means of fNIRS, in order to find an effective way to activate the motor area in mental imagery. The difference between VW and WO is that VW is first-person perspective, imaging oneself is walking following the visual scene in the video, while WO is third-person perspective, imaging oneself is following the gait of the person in the video. We quantitatively compared their brain activation effect based on the experiment results.

#### **3.2.1 Subjects**

Four students (YJ, RL, QQ and LS) of Kochi University of Technology participated in the experiment. Their ages were 28 to 31 years. All were right-handed and had no medical history of neurological or psychiatric disorders.

#### **3.2.2 fNIRS measurement**

As shown in Fig. 12, the concentrations of oxy-Hb and deoxy-Hb were measured by ETG-7100 system. The subject stood on a treadmill throughout the experiment. Data were measured with a sampling rate of 10 Hz.

Fig. 12. Experiment scene

The average oxy-Hb of subject SL and ZJ during the statistical period are listed in Table 1.We can conclude from Table 1 that although individual difference was significant, the oxy-Hb during the imaginary walking task was higher than that during the real walking

Subject SL 0.027 0.147 0.056 0.114 Subject ZJ 0.043 0.135 -0.087 -0.062

fNIRS measures cerebral blood volume. When we walk along a straight line on a level road without any obstacles, the primary somatosensory cortex and the primary motor cortex do not involve much, with the cerebellum controlling the movement of the legs. On the other hand, during the imaginary walking task of the experiment, the subjects have to conceive their movement to match their gaits with those in the video. Although the subjects did not move, they have to plan their walking in their brain. This might be the reason why the oxy-Hb during the WO task was higher than that during the RW task. However, at present since fNIRS can only measure cerebral blood flow in cortex, not in deeper structures, how the other neural systems, such as cerebellum, the spinal cord and the peripheral nervous

In the second experiment, we compared the activation in the primary motor area and the primary somatosensory area of the brain during RW, VW and WO by means of fNIRS, in order to find an effective way to activate the motor area in mental imagery. The difference between VW and WO is that VW is first-person perspective, imaging oneself is walking following the visual scene in the video, while WO is third-person perspective, imaging oneself is following the gait of the person in the video. We quantitatively compared their

Four students (YJ, RL, QQ and LS) of Kochi University of Technology participated in the experiment. Their ages were 28 to 31 years. All were right-handed and had no medical

As shown in Fig. 12, the concentrations of oxy-Hb and deoxy-Hb were measured by ETG-7100 system. The subject stood on a treadmill throughout the experiment. Data were

Procedure 1 Procedure 2 RW WO RW WO

task, regardless of the order of the tasks.

Table 1. Average oxy-Hb during RW and WO tasks

system, involve in mental imagery of walking is still not clear.

brain activation effect based on the experiment results.

history of neurological or psychiatric disorders.

measured with a sampling rate of 10 Hz.

\*\*oxy-Hbs are given in mM·mm

**3.2 Experiment 2** 

**3.2.1 Subjects** 

**3.2.2 fNIRS measurement** 

Fig. 13. Schematic placement of the emitter and detector optodes on the subject's head

Fig. 13 shows the positions of optodes on the head of the subjects. The optodes were fixed with a plastic shell and placed on the subject's head according to the international 10-20 system. The numbers between the emitters and detectors were channel numbers. Channels were labelled from front to back as CH1-CH24. The midpoint between CH12 and CH13 was placed on Cz of the International 10-20 system. According to the correlation between the international 10–20 system and cortical region, the areas measured by CH4, 5, 8, 11, 12 and

Comparison of Cortical Activation During Real Walking and Mental Imagery of

Procedure 2 was performed in the following order.

(40s) →Rest (30s)

(40s) →Rest (30s)

walking.

**3.2.5 Data analysis** 

**3.2.6 Results and discussions** 

Walking – The Possibility of Quickening Walking Rehabilitation by Mental Imaginary of Walking 145

Rest (30s) →VW (40s) →Rest (30s) →RW (40s) → Rest (30s) →WO (40s) →Rest (30s) →RW

Rest (30s) →RW (40s) →Rest (30s) →VW (40s)→ Rest (30s) →RW (40s)→Rest (30s) →WO

Oxy-Hb was considered as an indicator of changes in blood volume. The measurements of the subjects were checked visually for artifacts due to body movements. Obtained data were analyzed by calculating the average oxy-Hb level during RW, VW and WO. In the analysis we compared the average oxy-Hb of CH4, 5, 6, 7, 8, 10, 11, 12, 13, 14 which covered PM, SMA and M1 involved in planning and execution of movements related to

In Fig.15 and Fig.16, the color maps of typical activation pattern of oxy-Hb were extracted. These maps were created by interpolation to the measurement data of 24 measure points. It

RW VW RW WO

oxy-Hb -0.50 0.50 mM·mm oxy-Hb

oxy-Hb -0.50 0.50 mM·mm oxy-Hb

VW RW WO RW

Fig. 15. Color maps of typical activation pattern in procedure 1

Fig. 16. Color maps of typical activation pattern in procedure 2

CH6, 7, 10, 13, 14 covered PM, SMA and the primary motor cortex (M1) which plans and executes movements related to walking.
