Neurophysiological Impact of a Fronto-temporal Transcranial Direct Current Stimulation (tDCS) in Healthy Subjects: a Multimodal Imaging Approach
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 37
- 试验地点
- 2
- 主要终点
- Change in dopamine transmission induced by 1 session of 30min tDCS
研究概览
简要总结
tDCS is a technique emerging as a prospective therapy for neurologic, psychiatric and addictive disorders. Specifically, fronto-temporal tDCS, with anodal stimulation over the left dorsolateral prefrontal cortex (DLPFC) and cathodal stimulation over the left temporo-parietal junction (TPJ), has been reported to reduce treatment-resistant auditory hallucinations (AH), negative symptoms and insight of the illness in schizophrenia. However, despite an increasing use in clinical settings, tDCS suffers from limitations, especially regarding the strength and the duration of therapeutic effects.
Some imaging reports suggest that tDCS effects are not restricted to the brain areas located under the electrodes, but spread through distributed cortical networks functionally connected with the targets and reach subcortical areas. Overall, these studies suggest that tDCS modulates functional connectivity within and across resting-state networks and brain activity. However, these effects are currently described at different levels depending on the imaging technique used. Moreover, the majority of studies have focused on motor cortex stimulation, while the specific effects of fronto-temporal tDCS are scarce. Finally, effects of the stimulation applied online are rarely inspected.
According to the therapeutic effects of fronto-temporal tDCS on schizophrenia and the dopaminergic pathophysiological hypothesis of schizophrenia, the effect of fronto-temporal tDCS on dopaminergic transmission is of major interest. As the cortex is densely connected with basal ganglia areas, tDCS effects are probably capable to reach subcortical dopaminergic areas. Indeed, recent fMRI studies highlighted subcortical effects of tDCS applied at the cortical level including modulations of cortico-striatal and thalamo-cortical functional connectivity. In addition, some studies suggest that cortical stimulation by other approaches, such as transcranial magnetic stimulation (rTMS) modulates dopaminergic transmission. However, tDCS effects on dopaminergic transmission have been investigated only indirectly.
Finally, information about biological effects of tDCS is scattered and creating a coherent ensemble is a mandatory and critical step to understand the mechanisms of action of tDCS.
According to the hypothesis that fronto-temporal tDCS modulates brain activity, connectivity and dopaminergic transmission, the aim of this project is to reveal the combined neurobiological impact of an online single session of fronto-temporal tDCS in a unique experiment by developing a simultaneous multimodal imaging approach (PET-MRI). The online implementation of the stimulation will allow deciphering changes induced during and after stimulation. As a first step before investigating patients with schizophrenia, healthy subjects will be involved in the present study.
The distributed changes will be explored at rest through:
- Spontaneous functional connectivity assessed by functional magnetic resonance imagery (fMRI).
- Brain activity assessed by cerebral blood flow quantitatively and directly measured by arterial spin labelling (ASL).
- Connectivity assessed by diffusion tensor imaging (DTI).
- Specific and localized dopaminergic transmission evaluated by positron emission tomography (PET) using dopaminergic D2 subtype receptor availability via [11C]raclopride binding.
The pioneering aspects of the project are to use an innovative simultaneous multimodal imaging system, adopt the tDCS montage used in our validated therapeutic context and apply tDCS online. We expect that our unique approach will provide an imaging biomarker essential to improve our understanding of:
- the "normal brain" and further deficient mechanisms underlying schizophrenia as well as neurological disorders.
- neurobiological effects of tDCS in order to:
- Bring key element of the proof of concept of tDCS
- Optimize tDCS in a therapeutic context
- Suggest a marker of the therapeutic response
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Basic Science
- 盲法
- Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
盲法说明
Double blind
入排标准
- 年龄范围
- 18 Years 至 45 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •non smoker
- •right handed
- •non psychotropic consumption
- •no medical treatment except oral contraception
- •no psychiatric or somatic (neurological, endocrine, cardiac, renal) disorders
- •affiliated to the French social security
排除标准
- •No Consent formed signed
- •For female participants : pregnancy
- •contraindications to stimulation by tDCS or to an MRI exam
- •being in an exclusion period or over the annual compensation threshold
- •participation in another study using ionizing radiation in less than a year
结局指标
主要结局
Change in dopamine transmission induced by 1 session of 30min tDCS
时间窗: Continuous measure during 110min of PET scan
Measure of the Binding Ratio of the radiomarker defined as the ratio of : region of interest / cerebellum activities
次要结局
- Change in spontaneous functional connectivity (using rs fMRI) during and after 1 session of 30min tDCS(- Before stimulation : t+15 to t+28min - During stimulation : t+45 to t+58min - After stimulation : t+76 to t+89min)
- Change in cerebral blood flow (using ASL) during and after 1 session of 30min tDCS(- Before stimulation : t+30 to t+36min - During stimulation : t+60 to t+66min - After stimulation : t+91 to t+97min)
- Change in structural connectivity (using DTI) after 1 session of 30min tDCS(- Before stimulation : t+0 to t+10min - After stimulation : t+100 to t+110min)