Application of facial Neuromuscular Electrical Stimulation (fNMES) in
psychophysiological research – systematic review and practical
recommendations
Abstract
Facial neuromuscular electrical stimulation (fNMES), which allows for
the non-invasive and physiologically sound activation of facial muscles,
has great potential for investigating fundamental questions in
psychology and neuroscience, such as the role of proprioceptive facial
feedback in emotion induction and emotion recognition, as well as for
clinical applications, such as alleviating depression symptoms. However,
despite illustrious origins in 19th century work of Duchenne de
Boulogne, the practical application of fNMES remains largely unknown to
researchers in psychology and human physiology. In addition, published
studies vary dramatically in use and reporting of parameters, such as
stimulation frequency, amplitude, duration, and electrode size. Because
fNMES parameters impact the comfort and safety of volunteers, as well as
its physiological (and psychological) effects, it is of paramount
importance to establish recommendations of good practice. Here, we
provide an introduction to fNMES, a systematic review of the existing
literature focusing on stimulation parameters used, and we offer
recommendations on how to safely and reliably deliver fNMES. In
addition, we provide a free webpage, allowing to easily verify and
compare the safety of fNMES parameters based on current density. As an
example of a potential application, we focus on the use of fNMES for the
investigation of the facial feedback hypothesis.