Our last week of this course contains of an exercise lab for EEG measurements in Aalto Behavioural Laboratory. Therefore the course was split into two groups with around 20 people. For the measurements of brain activities one volunteer was needed.
Like the CBRU, the Laboratory of Aalto also consists of 2 rooms. One shielded room for the measurements and another room with the displays for monitoring. The EEG cap contains in total of 34 electrodes, which includes one ground electrode and another one for reference.
The first step was the preparation of the subject. For the right choice of the EEG cap size, the circumference of the head and the distance from the forehead to the beginning of the neck was measured. After the EEG cap was placed on the subject’s head, the hair at the contact spots of the electrodes was pushed aside. Therefore a syringe filled with conductive gel was used and the conductive gel applied afterwards. This procedure was repeated until all the electrodes lit up green. However, the gel should be used carefully. If too much gel is added, a connection between electrodes can be generated. The brain activity was measured while the subject looked on a screen. If the display showed a green square he/she had to press a button, also when he/she heard a sound. The measurements took about 15 minutes. Afterwards the measured data for all electrodes for the two different conditions can be analysed.