A Review of Studies Leveraging Multimodal TMS-fMRI Applications in the Pathophysiology and Treatment of Schizophrenia

Abstract

The current review provides an overview of the existing literature on multimodal transcranial magnetic stimulation, and functional magnetic resonance imaging (TMS/fMRI) studies in individuals with schizophrenia and discusses potential future avenues related to the same. Multimodal studies investigating pathophysiology have explored the role of abnormal thalamic reactivity and have provided further evidence supporting the hypothesis of schizophrenia as a disorder of aberrant connectivity and cortical plasticity. Among studies examining treatment, low-frequency rTMS for the management of persistent auditory verbal hallucinations (AVH) was the most studied. While multimodal TMS/fMRI studies have provided evidence of involvement of local speech-related and distal networks on stimulation of the left temporoparietal cortex, current evidence does not suggest the superiority of fMRI based neuronavigation over conventional methods or of active rTMS over sham for treatment of AVH. Apart from these, preliminary findings suggest a role of rTMS in treating deficits in neurocognition, social cognition, and self-agency. However, most of these studies have only examined medication-resistant symptoms and have methodological concerns arising from small sample sizes and short treatment protocols. That being said, combining TMS with fMRI appears to be a promising approach toward elucidating the pathophysiology of schizophrenia and could also open up a possibility toward developing personalized treatment for its persistent and debilitating symptoms.

Neurostimulation for the treatment of functional neurological disorder: A systematic review

“…The most serious concern is the potential risk of inducing an epileptic seizure, which translates into a minimal risk once following proper screening processes (by medical professionals) and TMS guidelines [23] , [94] . In terms of therapeutic applicability, TMS has been approved by the FDA for the treatment of major depressive disorder (2008) [95] , migraine (2013) [96] and most recently OCD (2018) [97] , and will likely continue to expand as TMS continues to show benefit for the treatment of many other disorders including post-traumatic stress disorder (PTSD) [98] substance use disorders [99] , schizophrenia [100] , cognitive abilities in Alzheimer’s Disease (AD) [101] , etc. Transcranial direct current stimulation (tDCS) is a non-invasive technique that uses a low-amplitude direct current (0.5–2 mA) through a pair of saline-soaked electrode pads placed directly over the scalp and connected to a battery device.…”

A novel whole-head RF coil design tailored for concurrent multichannel brain stimulation and imaging at 3T

“…The combination of TMS and fMRI was presented for the first time two decades ago [ 5 , 6 ]. After showing the feasibility of combining non-invasive brain stimulation and functional imaging several groups have performed concurrent TMS/fMRI studies [ 7 – 9 ] yielding important data characterizing effects of TMS on the ongoing neural processes immediately after stimulus delivery.…”