The investigators use paired associative stimulation (PAS) protocols to target cortico-cortical and cortico-subcortical networks to study cognitive deficits in methamphetamine addiction.
Paired associative stimulation (PAS) is a form of transcranial magnetic stimulation in which paired pulses can induce plasticity at cortical synapses, producing long-term potentiation (LTP) or long-term depression (LTD) effect. The investigators use paired associative stimulation (PAS) protocols to target cortico-cortical and cortico-subcortical networks (frontoparietal control pathway) by using different intervals between the paired pulses to explore the mechanism of cognitive deficits in methamphetamine addiction. The investigators hypothesize that different temporal sequences of cortical stimulation could produce facilitation or inhibition effect.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
90
Each cPAS experimental session contained 100 pairs of stimuli at 0.2 Hz. The experimental conditions differed in the interstimulus interval of the paired pulses. DLPFC stimulation precedes IPL/MPFC stimulation by 10 ms (DLPFC+10) or by 4 ms (DLPFC+4), and IPL/MPFC stimulation precedes DLPFC stimulation by 4 ms (IPL/MPFC+4) or by 10 ms (IPL+10).
Haifeng Jiang
Shanghai, Shanghai Municipality, China
Change of working memory
The N-Back is a working memory task where the subject is presented with a sequence of stimuli (letters). The task consists of indicating when the current stimulus matches the one from n steps earlier in the sequence.
Time frame: 30 minutes
Change of response inhibition
Response inhibition was assessed with the SST (Cambridge Cognition, Cambridge, UK). The subject responded to an arrow (go signal), pointing either right or left, by pressing one of two buttons with the right or left index finger. If an audio tone (stop signal) was present, the subject needed to withhold the response.
Time frame: 30 minutes
Change of attention bias
During the dot-probe task, participants are situated in front of a computer screen with their chin securely placed on a chin rest. Participants are asked to stare at a fixation cross on the center of the screen. Two stimuli, one of which is neutral and one of which is threatening, appear randomly on either side of the screen. The stimuli are presented for a predetermined length of time (most commonly 500ms), before a dot is presented in the location of one former stimulus. Participants are instructed to indicate the location of this dot as quickly as possible, either via keyboard or response box.
Time frame: 30 minutes
Change of risk decision
The Balloon Analogue Risk Task (BART) is a computerized measure of risk taking behavior. In the task, the participant is presented with a balloon and offered the chance to earn money by pumping the balloon up by clicking a button. Each click causes the balloon to incrementally inflate and money to be added to a counter up until some threshold, at which point the balloon is over inflated and explodes.
Time frame: 30 minutes
Change of eeg oscillatory (Alpha, Beta, Theta and Delta)
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EEG was recorded to evaluate the changes in the oscillatory domain before and after the stimulation.
Time frame: 30 minutes
Change of eeg functional connectivity (Alpha, Beta, Theta and Delta)
EEG was recorded to evaluate the changes of functional connectivity before and after the stimulation.
Time frame: 30 minutes
Change of motor evoked potential
Single-pulse TMS will be used to evoke a motor response that is recorded using electromyography (EMG). The peak-to-peak amplitude of the EMG response will be measured.
Time frame: 30 minutes
Change of resting motor threshold
Single-pulse TMS will be used to evoke a motor response that is recorded using electromyography (EMG). The lowest stimulator output needed to elicit a consistent response will be recorded.
Time frame: 30 minutes