The first case of interest in this study addresses the EEG-SL of real EEG signals performed in a single instant of time every 0.5 s. This part of the study aims to evaluate the methods MLE, MNE, wMNE and sLORETA in the SL of a real brain signals containing motor task information in instants of the signal before the movement started, at the moment when the movement started and after the movement had started. In terms of the selected segment of trial, 9 estimations were performed: at −2 s, at −1.5 s, at −1 s, at −0.5 s, at 0 s, at 0.5 s, at 1 s, at 1.5 s and at 2 s of the averaged trial. In total there were 9 SLs for each arm movement,
thus 18 SLs for each participant, thus 270 SLs for each of the SLMs, thus 1080 SLs in total for case one.
The results for the EEG-SL for participant 1 are shown in table 4.1. The top part shows the BAs where the maximum brain activity was located at each given time when the partic-ipant moved the left arm. The bottom part of the table shows the BAs where the maximum brain activity was located at each given time when the participant moved the right arm. The color yellow was used to indicate that the maximum brain activity was located at the right hemisphere of the brain, which is associated with movements of the left side of the body, given the contralaterality of the brain. In a similar manner, the blue color was used to indi-cate that the maximum brain activity was loindi-cated at the left hemisphere of the brain, which is associated to movements of the right side of the body [4]. From these results, it is important to highlight that sLORETA estimated the source to be in BA 6 at the instant the movement began and in the correct hemisphere for both arms.
Left Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 7 7 9 6 6 22 7 11 42
MLE BA 22 19 21 19 47 21 47 47 22
MNE BA 22 19 21 19 47 21 47 47 22
wMNE BA 21 19 21 21 47 21 45 45 21
Right Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 11 9 9 7 6 7 7 38 7
MLE BA 40 21 22 47 19 21 47 21 39
MNE BA 40 21 22 47 19 21 47 21 39
wMNE BA 47 21 21 45 21 21 45 21 19
Table 4.1: Study two: Case one: Brodmann areas located with source localization for partici-pant 1.
It is highly important to verify the relevance of the other BAs found for participant 1.
Area 7 found with sLORETA is involved in the location of objects in space. Areas 9 and 10 are related to memory. Area 11 is involved in decision making, while area 19 is involved in processing visual information. Areas 21, 22, 40, 45, 47 are involved in accessing word meanings and in contemplating distances. Area 38 is related to emotional responses and area 39 is involved in reading [1] [4] [6]. All estimated maximum brain activity for participant 1 throughout the development of the experiment was estimated to be in a BA whose function is related to the experiment in some way, except for BA 38.
The results for the participant 6 are displayed in table 4.2. For this participant similar BAs were estimated to have the maximum brain activity. In a similar way to the first partic-ipant, the main activity was found with sLORETA in the left hemisphere of the BA 6 when the participant had just begun the movement with the right arm. The other BAs found are similar to the ones found for participant 1, except for BA 8 which is involved in the planning of complex movements and BA 20 which is involved in processing of visual information just like BA 19. Again, except for BA 38, every area estimated to have the maximum brain activity for participant 6 throughout the experiment has a role in its development.
Left Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 38 10 38 4 47 38 38 11 38
MLE BA 8 8 8 47 8 47 8 47 45
MNE BA 8 8 8 47 8 47 8 47 45
wMNE BA 8 8 8 45 8 45 8 47 45
Right Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 38 11 38 38 6 38 38 20 38
MLE BA 8 8 47 21 8 47 8 47 8
MNE BA 8 8 47 21 8 47 8 47 8
wMNE BA 8 8 47 21 8 45 8 45 8
Table 4.2: Study two: Case one: Brodmann areas located with source localization for partici-pant 6.
The results for participant 11 are shown in table 4.3. For this participant the maximum brain activity was estimated to be located in the left hemisphere of the brain and in BAs 9 and 10 solely. Both areas are related to memory and are also involved in cognitive processes [1]
[4] [6]. Even though there were no main sources estimated to be in the motor cortex, the BAs found with the SLMs are still related to the activities of the experiment.
Left Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 9 10 9 10 10 9 10 10 10
MLE BA 9 9 9 9 10 9 9 9 9
MNE BA 9 9 9 9 10 9 9 9 9
wMNE BA 9 9 9 9 10 9 9 9 9
Right Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 10 10 9 10 9 10 10 10 10
MLE BA 9 9 9 9 9 9 9 10 9
MNE BA 9 9 9 9 9 9 9 10 9
wMNE BA 9 9 9 9 9 9 9 10 9
Table 4.3: Study two: Case one: Brodmann areas located with source localization for partici-pant 11.
The results for participant 15 are displayed in table 4.4. This time, the methods that esti-mated the maximum brain activity in the motor cortex were MLE, MNE and wMNE, finding it in the left hemisphere of the BA 6 at the moment the participant started the movement with the right arm. The other areas found through the experiment were BAs 3, 10, 19, 40 and 45.
Area 3 is involved in finding the location of the body in space. Area 10 is related to the mem-ory and in cognitive processes, and BAs 40 and 45 are involved in accessing word meanings and in contemplating distances [1] [4] [6].
Left Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 10 45 10 3 10 10 10 10 10
MLE BA 40 6 40 40 40 6 6 40 40
MNE BA 40 6 40 40 40 6 6 40 40
wMNE BA 40 6 40 40 40 6 6 40 40
Right Arm Movement
Time -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
sLORETA BA 45 6 10 19 45 10 10 19 3
MLE BA 6 6 19 19 6 40 40 6 40
MNE BA 6 6 19 19 6 40 40 6 40
wMNE BA 6 42 6 19 6 40 40 6 40
Table 4.4: Study two: Case one: Brodmann areas located with source localization for partici-pant 15.
The results for the rest of participants can be appreciated in Appendix B, where the tables showing the BAs that were found to have the maximum brain activity throughout the experiment. In table 4.5 are all of the BAs in which the main source of brain activity was estimated to be for all 15 participants [1] [4] [6] for case one. As can be seen, the function in which the BAs in the table are involved are coherent with the activities that were carried out by the participants during the experiment. The only exception seems to be BA 38, which is related with emotions. The most important BAs, given the nature of the experiment, could be BAs 4, 6, 2, 3, 7, 8 and 11 since the entire experiment is focused on moving an arm, choos-ing which arm to move or what action to perform, and plannchoos-ing the movement to perform.
From this first case, it can be concluded that SLMs are a valuable tool in obtaining relevant information from the EEG.
Brodmann Areas (BA)
BA Associated function
2 & 3 Location of own body
4 Primary motor cortex
6 Secondary motor cortex
7 Locating objects in space
8 Planning of complex movements
9 & 10 Related to memory and cognitive processes
11 Decision making
18, 19 & 20 Processing of visual information
21, 22, 40, 44, 45 & 47 Contemplating distances // Accessing words meanings
38 Emotional responses
39 Involve in reading
42 Auditory area
46 Attention, memory
Table 4.5: Brodmann areas located with source localization of the 15 participants.