Conectividad funcional en estado de reposo como predictor de efectos de TDCS en adolescentes con trastorno del espectro autista

For cathodal tDCS condition, participants will receive cathodal stimulation on the dorsolateral prefrontal cortex with ramp up and ramp down mode for 10 seconds, eliciting a tingling sensation on the scalp that fades over seconds. Following that, a twenty-minute executive functional task will be initiated five minutes subsequent to the stimulation mode, and the stimulation will be terminated when the task ends.

Participant will receive three stimulation conditions: cathodal tDCS of the left DLPFC, anodal tDCS of the left DLPFC and sham-tDCS. The order of the conditions will be randomized and counterbalanced across participants, and the three stimulation conditions will be administered at least a week apart to avoid carry-over effects. The tDCS session will last for 20 minutes.

For anodal tDCS condition, participants will receive anodal stimulation on the dorsolateral prefrontal cortex with ramp up and ramp down mode for 10 seconds, eliciting a tingling sensation on the scalp that fades over seconds. Following that, a twenty-minute executive functional task will be initiated five minutes subsequent to the stimulation mode, and the stimulation will be terminated when the task ends.

Participant will receive three stimulation conditions: cathodal tDCS of the left DLPFC, anodal tDCS of the left DLPFC and sham-tDCS. The order of the conditions will be randomized and counterbalanced across participants, and the three stimulation conditions will be administered at least a week apart to avoid carry-over effects. The tDCS session will last for 20 minutes.

For sham-tDCS condition, participants will receive initial stimulation with ramp up and ramp down mode for 30 seconds, eliciting a tingling sensation on the scalp then it will be discontinued. Participant will also receive the twenty-minute executive functional task five minutes subsequent to the stimulation mode.

Participant will receive three stimulation conditions: cathodal tDCS of the left DLPFC, anodal tDCS of the left DLPFC and sham-tDCS. The order of the conditions will be randomized and counterbalanced across participants, and the three stimulation conditions will be administered at least a week apart to avoid carry-over effects. The tDCS session will last for 20 minutes.

RTI assesses motor and mental response speeds, reaction time, response accuracy and impulsivity. It consists of 30 trials with five potential targets and requires participants to make flexible responses as fast as possible to the target stimulus (shown in yellow). Specifically, movement and reaction time will be measured, where shorter duration reflects faster processing speed.

SWM assesses retention and manipulation of visuospatial information. The participant should find one yellow "token" in each of a number of boxes and use them to fill up an empty column on the right of the screen by selecting the boxes and using a process of elimination. Error selecting boxes that have already been found to be empty and revisiting boxes which have already been found to contain a token will be measured.

MTT assesses the ability to resolve the interference of task-irrelevant information (stroop-like effect). The test displays an arrow which can appear on either the left or right side of the screen and can point to either the left or right side. In each trial, participants are presented with a cue that indicates which button to press according to two different rules. And the rules that participants have to follow may change from trial to trial in a randomized order. Participant's response latencies will be measured.

MTT assesses the ability to resolve the interference of task-irrelevant information (stroop-like effect). The test displays an arrow which can appear on either the left or right side of the screen and can point to either the left or right side. In each trial, participants are presented with a cue that indicates which button to press according to two different rules. And the rules that participants have to follow may change from trial to trial in a randomized order. Participant's error scores will be measured.

Each participant will be tested individually to collect EEG data. The participants' eyes-open resting condition will be assessed by EEG for 5 minutes, before and after the tDCS to evaluate the tDCS-induced alteration in their neural activity and functional connectivity. Raw data will be processed with the EEGLAB Toolbox using MATLAB® R2019a. Data from 19 electrodes will be used for analysis.