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Abstract
The present systematic review explores the relationship between left versus right cortical activity or damage and vagal nerve activity. To better understand those pathways we identified various studies that presented results which tested hemispheric asymmetry and vagal nerve index of heart rate variability (HRV). Considering a probable lateralization difference in our brainheart communication, we speculated that HRV would be associated with greater left hemisphere activity. We selected studies that measure HRV and either electrical brain stimulation, brain tissue concentration (voxel-based morphometry) and brain damage. We found a total of 9 studies that fits our criteria of selection. A positive mean effect size of 0.381 was found and evidences a medium effect of the left brain hemisphere on HRV parameters. Of the selected studies, 6 supports the conclusion that the left hemisphere is responsible for the increase in vagal tone and parasympathetic activity, 1 observed that it’s the right hemisphere responsible for the same increase on vagus, and 2 studies consider the effect bilateral. In conclusion, our review presents evidence of a stronger role of the left hemisphere in vagal activity, using measures of HRV.
