Electronic Thesis and Dissertation Repository


Master of Science




Dr. Kevin Shoemaker


Functional imaging reveals overlapping forebrain and basal ganglia regions associated with heart rate (HR) and heart rate variability (HRV) regulation. Somatosensory stimulation (STIM) and isometric handgrip (HG) were used to test the hypotheses that a) STIM would modulate HG-induced changes to HR and HRV, and b) HG+STIM would produce different cortical activation relative to HG alone (n=12). During STIM, high-frequency (HF)-HRV increased (p<0.05), whereas HR did not change. During HG, HF-HRV decreased (p<0.01) while HR increased (p<0.001). HG+STIM reversed the HG-induced change in HF-HRV (p<0.01). However, the HR response to HG remained unaffected. HG increased insular activation, while ventral medial prefrontal cortex (vMPFC) activity decreased. HG+STIM produced similar vMPFC deactivation. However, insular activation was no longer evident. These data indicate that somatosensory inputs through STIM can modulate HG-induced changes to HF-HRV. Different insular activations during HG versus HG+STIM suggest afferent signals to the insula may inhibit descending motor signals affecting HF-HRV.