Behavioral and EEG results of emotional discrimination task (high-altitude and low-altitude)

Participants were all college undergraduates with normal or corrected vision, right-handed, no history of neurological or psychiatric disorders or other chronic physical conditions, no use of drugs (psychiatric or otherwise) in the last 2 days, and no irregular lifestyle. The high-altitude group consisted of 25 subjects from Tibet University (3658m above sea level), all of whom grew up in the plain, entered the plateau for the first time and lived there for more than 2 years after adulthood. Excluding 1 subjects with missing EEG data and 2 subjects with damaged data, 22 subjects were enrolled ultimately (12 males and 10 females, age ranged between 20 and 24 years, average age as 21.91±0.97 years). The 30 members of the low-altitude group are from universities in Beijing (52m above sea level), who have never been to the plateau. 6 subjects were excluded for excessive disturbance of EEG data, and 24 subjects were finally enrolled (11 males and 13 females, age ranged between 19 and 24 years, average age as 21.43±1.24 years).Emotional face recognition task was adopted. Stimulations were selected from Chinese Affective Face Picture System (Gong et al., 2011), including 3 males and 3 females, each with 3 expressions (angry, happy, neutral), a total of 18 emotional face pictures. A white cross (0.82°×0.82°) was presented in the center of the black background as the fixation point, with the presentation time random between 1200-1600ms. Then, the facial picture appears until subjects press the key and enter the next trial. Subjects are demanded to judge the gender of faces accurately as fast as possible. The position of the buttons was balanced between the subjects, with half of the subjects pressing the left button for a male face, the right button for a female face, and the other half doing the opposite. The experiment is consisted of practice and formal test. During the practice, each picture was presented once in a random order, with a total of 18 trials. The formal experiment was divided into 2 phases, with a short rest in between, 144 trials in each phase, a total of 288 trials, and each picture was repeated 16 times.Electroencephalography (EEG) was collected using the Neuroscan recording and analysis system and the elastic cap with 64 Ag/AgCl electrodes cap of International 10-20 standard system (Neuroscan Inc., USA). The referenced electrode was the left mastoid and the grounding electrode was located at the midpoint of the Fz and FPz. The vertical electrooculogram (VEOG) was recorded with a pair of electrodes placed above and below the left eye, while the horizontal electrooculogram (HEOG) was recorded with another pair of electrodes, located 1 cm from the outer canthus of each eye. The resistance of scalp was kept under 5kΩ. Signals were amplified with a Neuroscan SynamPs-2 amplifier (Neuroscan Inc., USA) which included a 0.05-100 Hz bandpass filter with the sampling frequency as 500Hz.Behavioral results could be opened with E-prime3 and EEG results could be opened with EEGLAB.