Transcranial magnetic stimulation alters multivoxel patterns in the absence of overall activity changes

Farshad Rafiei; Martin Safrin; Martijn E Wokke; Hakwan Lau; Dobromir Rahnev

doi:10.1002/hbm.25466

Transcranial magnetic stimulation alters multivoxel patterns in the absence of overall activity changes

Hum Brain Mapp. 2021 Aug 15;42(12):3804-3820. doi: 10.1002/hbm.25466. Epub 2021 May 15.

Authors

Farshad Rafiei¹, Martin Safrin², Martijn E Wokke³, Hakwan Lau^{4

5}, Dobromir Rahnev¹

Affiliations

¹ School of Psychology, Georgia Institute of Technology, Atlanta, Georgia, USA.
² School of Medicine, University of California Los Angeles, Los Angeles, California, USA.
³ Programs in Psychology and Biology, The Graduate Center of the City University of New York, New York, New York, USA.
⁴ Department of Psychology, University of California Los Angeles, Los Angeles, California, USA.
⁵ The Brain Research Institute, University of California, Los Angeles, Los Angeles, California, USA.

Abstract

Transcranial magnetic stimulation (TMS) has become one of the major tools for establishing the causal role of specific brain regions in perceptual, motor, and cognitive processes. Nevertheless, a persistent limitation of the technique is the lack of clarity regarding its precise effects on neural activity. Here, we examined the effects of TMS intensity and frequency on concurrently recorded blood-oxygen-level-dependent (BOLD) signals at the site of stimulation. In two experiments, we delivered TMS to the dorsolateral prefrontal cortex in human subjects of both sexes. In Experiment 1, we delivered a series of pulses at high (100% of motor threshold) or low (50% of motor threshold) intensity, whereas, in Experiment 2, we always used high intensity but delivered stimulation at four different frequencies (5, 8.33, 12.5, and 25 Hz). We found that the TMS intensity and frequency could be reliably decoded using multivariate analysis techniques even though TMS had no effect on the overall BOLD activity at the site of stimulation in either experiment. These results provide important insight into the mechanisms through which TMS influences neural activity.

Keywords: BOLD; MVPA; PFC; TMS; concurrent TMS-fMRI.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Adult
Dorsolateral Prefrontal Cortex / physiology*
Female
Humans
Image Processing, Computer-Assisted* / methods
Male
Multivariate Analysis
Transcranial Magnetic Stimulation* / methods
Young Adult

Abstract

Publication types

MeSH terms

Grants and funding