  Transcranial magnetic stimulation (TMS) is a technique for noninvasively
stimulating a brain area for therapeutic, rehabilitation treatments and
neuroscience research. Despite our understanding of the physical principles and
experimental developments pertaining to TMS, it is difficult to identify the
exact brain target as the generated dosage exhibits a non-uniform distribution
owing to the complicated and subject-dependent brain anatomy and the lack of
biomarkers that can quantify the effects of TMS in most cortical areas.
Computational dosimetry has progressed significantly and enables TMS assessment
by computation of the induced electric field (the primary physical agent known
to activate the brain neurons) in a digital representation of the human head.
In this review, TMS dosimetry studies are summarised, clarifying the importance
of the anatomical and human biophysical parameters and computational methods.
This review shows that there is a high consensus on the importance of a
detailed cortical folding representation and an accurate modelling of the
surrounding cerebrospinal fluid. Recent studies have also enabled the
prediction of individually optimised stimulation based on magnetic resonance
imaging of the patient/subject and have attempted to understand the temporal
effects of TMS at the cellular level by incorporating neural modelling. These
efforts, together with the fast deployment of personalised TMS computations,
will permit the adoption of TMS dosimetry as a standard procedure in clinical
procedures.
