EP 71. The effect of intermittent theta burst stimulation over the dorsolateral prefrontal cortex on cortico-striatal connectivity

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• 作者：I. Effnert^a ; ; K. Sakreida^a ; ^b ; F. Binkofski^a ; F. Mottaghy^b
• 刊名：Clinical Neurophysiology
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：127
• 期：9
• 页码：e268-e269
• 全文大小：46 K

文摘

Fronto-striatal loops play an important role in various cognitive and emotional processes. Intermittent theta burst transcranial magnetic stimulation has been shown to increase regional excitability as well as functional connectivity of connected areas (Huang et al., 2005). The issue of choosing an optimal TMS intensity, which is interlinked with ethical and practical issues such as pain and muscle twitches, has not been explored in detail yet. Furthermore, the role of purely anatomical white matter tracts on functional connectivity has often not been taken into account when studying TMS effects. We therefore applied intermittent theta burst stimulation (iTBS) with different intensities and methods of determining the exact stimulation sites to systematically test optimal parameters combining strong fronto-striatal activity with minimal adverse effects.

Methods

Healthy subjects underwent iTBS at different intensities (90% and 120% of individual resting motor threshold). The excitatory iTBS protocol consisted of 600 pulses (2 s trains and 8 s pauses for 3.33 min) and was applied over the left dorsolateral prefrontal cortex (lDLPFC). Directly before and 7 min after stimulation a task-free resting state functional magnetic resonance imaging scan was conducted. The exact stimulation site was either determined using a lDLPFC standard coordinate or by extracting an individual lDLPFC coordinate from diffusion tensor imaging (DTI) data. The latter was done by analysing DTI data with FSL (Smith et al., 2004) and finding individual tracts connecting the left caudate with the lDLPFC. Resting state data was analysed using the Data Processing Assistant for Resting-State fMRI (DPARSF; Chao-Gan, 2012) SPM toolbox, with the caudate and the stimulation sites as seed regions.

Results and conclusion

Our preliminary findings suggest that a sub-threshold stimulation intensity of 90% is sufficient to induce changes in functional connectivity of the fronto-striatal network when stimulation is applied over the lDLPFC. Furthermore, stimulation effects might be increased by determining an individual stimulation site based on DTI tracts, rather than using a standardised mean coordinate for all participants. By using sub-threshold intensities adverse effects such as pain and head movements due to muscle twitches can be reduced or avoided.