Effects of the Transcranial Alternative Electric Stimulation on the Consciousness Access in Healthy Subjects
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 67
- 试验地点
- 2
- 主要终点
- Change in subjective performance on the behavioral task (% of seen masked target) between before and after stimulation.
研究概览
简要总结
The aim of this study is to investigate the effect of transcranial Alternating Current Stimulation (tACS) at theta frequency and the the effect of transcranial Direct Current Stimulation (tDCS) on the conscious access to visual stimuli. tACS and tDCS are non-invasive stimulation techniques that are used to induce brain oscillations at certain frequency or to increase the brain activity in applied region. Healthy participants will perform a behavioral task measuring conscious access (visual backward metacontrast masking task) before, during and after fronto-parietal tACS or tDCS stimulation which will increase neural activity in the two sites. This will allow us to examine online and remaining effects of the stimulation and the causal role of fronto-parietal activity on conscious access.
详细描述
Behavioral task
The behavioral task consists in presentation of a para-foveal numerical target on a screen for 16 ms either right or left of a central fixation point, followed by a visual mask, made of letters surrounding the target, presented for 250 ms. The delay between the target and the mask (Stimulus Onset Asynchrony - SOA) will be variable (16 ms, 33 ms, 50 ms, 66 ms or 83 ms). Participants will then be asked to perform two tasks. First (objective task), participants will be asked to indicate as quickly as possible whether the target was bigger or smaller than the digit "5". Second (subjective task), they will be requested to judge the visibility of the presented target by indicating whether they had seen the target or not.
tACS
Study design
The study design is composed of three experimental sessions. In these sessions, participants will first complete the behavioral paradigm as presented above while having their brain activity recorded with EEG. Afterwards, they will re-perform the task during and after tACS stimulation. tACS stimulation type will differ in each session : in-phase, anti-phase or sham (see below for further details). Stimulation sessions will occur in a double-blind randomized crossover design (neither the participant nor the experimenter knows which session includes which stimulation type), with at least 2 days of interval between them.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Double (Participant, Investigator)
盲法说明
Study will be double-blind : neither participant nor the investigator will know which stimulation type (in-phase active, anti-phase active or sham) is on.
入排标准
- 年龄范围
- 18 Years 至 60 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •French social security affiliation
- •Absence of neurological and psychiatric disorders
- •Absence of antiepileptic treatment
- •Normal vision (with or without correction)
- •Age between 18 and 60 years
- •Right-handedness
- •Signed informed consent to participate
排除标准
- •Person under legal protection (legal guardian, tutor, curator)
- •Past medical history of epilepsy
- •Past medical history of neurological or psychiatric disorders
- •Electrical stimulation contraindication (metallic intra-cranial implants, pacemaker or implantable cardioverter-defibrillator, cranial prosthesis)
- •Antiepileptic and other psychotropes treatment
- •Pregnant, parturient or breastfeeding women
- •Left-handedness
研究组 & 干预措施
In-phase tACS
6 Hz stimulation (1000 μA) will be applied simultaneously over the left prefrontal dorso-lateral cortex (F3 of the 10-20 international scalp EEG system) and the left parietal cortex (P3) for 20 minutes using an 8-channels stimulator. The phase difference between the two stimulation sites will be 0°.
干预措施: tACS (Device)
Anti-phase tACS
6 Hz stimulation (1000 μA) will be applied simultaneously over the left prefrontal dorso-lateral cortex (F3 of the 10-20 international scalp EEG system) and the left parietal cortex (P3) for 20 minutes using an 8-channels stimulator. The phase difference will be 180°,
干预措施: tACS (Device)
Sham tACS
The stimulation (anti-phase) will start with a current intensity of 1000 μA lasting for 30 seconds. Afterwards, the intensity will progressively decrease over 20 seconds until cessation.
干预措施: tACS (Device)
Active tDCS
1000 μA tDCS stimulation will be applied simultaneously over the left prefrontal dorso-lateral cortex (F3 of the 10-20 international scalp EEG system) and the left parietal cortex (P3) for 20 minutes using an 8-channels stimulator
干预措施: tDCS (Device)
Sham tDCS
The stimulation will start with a current intensity of 1000 μA lasting for 30 seconds. Afterwards, the intensity will progressively decrease over 20 seconds until cessation.
干预措施: tDCS (Device)
结局指标
主要结局
Change in subjective performance on the behavioral task (% of seen masked target) between before and after stimulation.
时间窗: Measured at each stimulation sessions (three sessions in a randomized cross-over order) for each participant. The three sessions will span in an average of two weeks.
Change in the percentage of the correct responses on the subjective evaluation, that is the percentage of seen masked target at each SOA over all masked target presented, between before and after stimulation, for each stimulation modality (inphase theta, antiphase theta, sham).
次要结局
- Change in visual evoked potentials between before and after stimulation.(Measured at each stimulation sessions (three sessions in a randomized cross-over order) for each participant. The three sessions will span in an average of two weeks.)
- Change in quantitative EEG measures between before and after stimulation.(Measured at each stimulation sessions (three sessions in a randomized cross-over order) for each participant. The three sessions will span in an average of two weeks.)
- Change in objective performance on the behavioral task (% of correct response on the number comparison task for masked target) between before and after stimulation.(Measured at each stimulation sessions (three sessions in a randomized cross-over order) for each participant. The three sessions will span in an average of two weeks.)