Open AccessThe effects of individualised intermittent theta burst stimulation in the prefrontal cortex: A TMS‐EEG study
Author(s) -
Chung Sung Wook,
Sullivan Caley M.,
Rogasch Nigel C.,
Hoy Kate E.,
Bailey Neil W.,
Cash Robin F. H.,
Fitzgerald Paul B.
Publication year - 2019
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.24398
Subject(s) - transcranial magnetic stimulation , psychology , electroencephalography , neuroscience , stimulation , n100 , prefrontal cortex , neurophysiology , brain stimulation , mood , audiology , medicine , cognition , event related potential , psychiatry
Recent studies have highlighted variability in response to theta burst stimulation (TBS) in humans. TBS paradigm was originally developed in rodents to mimic gamma bursts coupled with theta rhythms, and was shown to elicit long‐term potentiation. The protocol was subsequently adapted for humans using standardised frequencies of stimulation. However, each individual has different rhythmic firing pattern. The present study sought to explore whether individualised intermittent TBS (Ind iTBS) could outperform the effects of two other iTBS variants. Twenty healthy volunteers received iTBS over left prefrontal cortex using 30 Hz at 6 Hz, 50 Hz at 5 Hz, or individualised frequency in separate sessions. Ind iTBS was determined using theta‐gamma coupling during the 3‐back task. Concurrent use of transcranial magnetic stimulation and electroencephalography (TMS‐EEG) was used to track changes in cortical plasticity. We also utilised mood ratings using a visual analogue scale and assessed working memory via the 3‐back task before and after stimulation. No group‐level effect was observed following either 30 or 50 Hz iTBS in TMS‐EEG. Ind iTBS significantly increased the amplitude of the TMS‐evoked P60, and decreased N100 and P200 amplitudes. A significant positive correlation between neurophysiological change and change in mood rating was also observed. Improved accuracy in the 3‐back task was observed following both 50 Hz and Ind iTBS conditions. These findings highlight the critical importance of frequency in the parameter space of iTBS. Tailored stimulation parameters appear more efficacious than standard paradigms in neurophysiological and mood changes. This novel approach presents a promising option and benefits may extend to clinical applications.