Prefrontal mechanisms of Neurovisceral Integration: Insights from repetitive transcranial magnetic stimulation

This dissertation aimed to test the causal role of the prefrontal cortex in linking cardiac
vagal activity with cognitive and emotional processing. Combining Neurovisceral Integration
Model and the Vagal Tank Theory, this research project aimed to address the following
research questions: First, is transcranial magnetic stimulation a feasible method to study the
prefrontal regulation of cardiac vagal activity? Second, do tonic and phasic cardiac vagal
activity interactively predict cognitive-affective processing rather than independently? Third,
does transcranial magnetic stimulation of the prefrontal cortex induce interrelated alterations
in both cardiac vagal activity and cognitive-affective processing. To answer these question
three studies were conducted. The first involved a meta-analysis and systematic review to
quantify the effects of non-invasive brain stimulation on heart rate and heart rate variability
(Article #1). The second study investigated the interactive effects of tonic and phasic cardiac
vagal activity on cognitive-affective processing (Article #2). The last study investigated the
effects of transcranial magnetic stimulation over the left dorsolateral prefrontal cortex on both
cardiac vagal activity and cognitive-affective processing (Article #3). The primary findings
were as follows: First, transcranial magnetic stimulation over different cortical regions leads
to changes in heart rate and heart rate variability. Second, tonic and phasic cardiac vagal
activity interactively predict cognitive-affective processing. Third, transcranial magnetic
stimulation over the left dorsolateral prefrontal cortex induced independent changes in tonic
cardiac vagal activity and cognitive-affective processing but not in phasic cardiac vagal
activity. In conclusion, this dissertation offers novel insights into neurovisceral integration,
revealing interactive effects between tonic and phasic cardiac vagal control and distinct
contributions of the dorsolateral prefrontal cortex to tonic and phasic cardiac vagal activity.
These results carry direct theoretical and methodological implications.