Healthy
Conditions
Brief summary
An increasing number of studies have used the intermittent theta-burst stimulation (iTBS) protocol to investigate neural plasticity non-invasively in the prefontal cortex in healthy humans and in patients with psychiatric disorders. However, the variability in the neurophysiological response to iTBS stimulation is high. The cause of this variability is multifactorial and to some degree still unknown. Therefore, the current study explores inter- and intra-individual factors that are potentially moderating iTBS-induced excitability changes. A greater understanding of these determinants would be highly valuable for optimizing the therapeutic application of iTBS.
Detailed description
The investigators will measure the cortical excitability induced by iTBS with concurrent TBS/fNIRS technique in the same healthy individuals on multiple testing days. Meanwhile, several potential inter- (age, gender, etc.) and intra-individual factors (daily mood, daily physical activity levels, etc.) recently identified in non-invasive transcranial brain stimulation studies will be assessed before applying iTBS to the same individual on each testing day.
Interventions
DEVICEIntermittent theta burst stimulation (iTBS)
The iTBS protocol consists of 20 trains of stimulation. Each train comprises ten 3-pulse bursts, delivered at an intra-burst frequency of 50 Hz, with a 5 Hz overall frequency, followed by 8 seconds of rest. A total of 600 pulses (10\*3\*20) will be administered in this 3-minute iTBS protocol. Concurrent TBS/fNIRS stimulation will be applied over the left DLPFC at an intensity of 90% of the resting motor threshold (RMT), which is considered appropriate to ensure compliance and elicit robust DLPFC activation. Considering that the fNIRS optode beneath the coil increases the distance between the TMS coil and the skull by 10 mm, we will use the equation AdjMT% = MT + 2.8 \* (Dsitex - Dm1). Therefore, 2.8 \* 10 = 28% will be added to the normal intensity. The stimulation site over the DLPFC will be determined by the MNI coordinate (x-38, y+44, z+26) reported in previous studies.
Sponsors
The Hong Kong Polytechnic University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
* healthiness based on history and psychiatric assessment * being able to hear and understand the verbal instructions * completed at least 6 years of formal education
Exclusion criteria
* a current or past diagnosis of psychiatric, neurological disorders, or severe internal illness * any conditions that will contraindicate to iTBS or fNIRS * psychiatric disorders in their first-degree relatives * pregnancy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Oxygenated hemoglobin (HbO) change compared to baseline | During and post TBS-fNIRS measurement, up to 3 months | iTBS-induced HbO change in the DLPFC before, during and after stimulation |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Deoxygenated hemoglobin (HbR) change compared to baseline | During and post TBS-fNIRS measurement, up to 3 months | iTBS-induced HbR change in the DLPFC before, during and after stimulation |
| Oxygen saturation change compared to baseline | During and post TBS-fNIRS measurement, up to 3 months | iTBS-induced oxygen saturation change in the DLPFC before, during and after stimulation |
Countries
Hong Kong
Contacts
PRINCIPAL_INVESTIGATORGeorg Kranz, PhD
The Hong Kong Polytechnic University
Outcome results
None listed