Atlas of Intracranial Recordings on Cortical Responses After Functional tACS

Study Overview
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Brief Summary
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By analyzing the SEEG recordings, we explore the range of cortical functional responses to strings of 77.5Hz stimulations delivered by tACS,

Official Title
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An Atlas of Cerebral Responses to the Stimuli of the tACS Recorded by SEEG

Conditions
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Transcranial Alternating Current Stimulation

Intervention / Treatment
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* Device: tACS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All epileptic patients that would receive the implantation of SEEG electrodes, regardless of the seizure locations; There was no metal implantation before; Eligible for MRI examination; No other lesional neurological disorders; Could be well informed by the study protocols. Exclusion Criteria: Suffered from any other mental illnesses prior to the enrollment; Those suffering from the serious or unstable organic diseases; Pregnant or lactation women, and those who have a plan of pregnant; Patients with central nervous system tumors, acute brain injury or infection; Skin injured, or allergic to the exposure of the conductive gel; Those with implanted devices; Those who received modified electrical convulsive therapy, or TMS within the recent one month; The score of item 3 (suicidal item) in HAMD-17 equal or greater than 3; Enrolled in any other on going trials; Other situations evaluated by the researchers as inappropriate to the enrollment

Ages Eligible for Study
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Minimum Age: 14 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: tACS arm<br>The patient would receive strings of tACS stimulations in 77.5 HZ, each string would last for 1 second, followed by an interval of 5 seconds. A total of 600 strings would be sent out to the patients. | Device: tACS<br>* tACS would be performed to epilepsy patients who have already received implantation of the SEEG electrodes<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of intracranial activities | The change of the power in a band of 0-200 HZ according to the intracranial EEG recording. | Within 250 ms immediately after the stimulation. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of the epileptic discharges | To count the numbers of epileptic discharges within the same duration before and when tACS intervention. | 50 minutes during the stimulation and 50 minutes of the interictal baseline before the intervention during the same hour of the day | 
| Event related potential (ERP) | ERP related to cognitive tasks before and immediately after the tACS intervention | Baseline: 24 hours before the tACS intervention; Observation: Immediately after the end of the tACS intervention. |