Investigation of the autonomic nervous system control of cardiovascular variables using fMRI and carotid stimulation

Noninvasive neuroimaging using fMRI has the potential to identify the brain regions involved in the processing of autonomic signals. An event-related design was employed to randomly administer 50 efficacious (-60 mmHg) and 30 non-efficacious (-10 mmHg) neck-suction stimuli, with a duration of 8 s each. Six-hundred echo-planar imaging volumes (TR=2.08 ms) with BOLD contrast, covering the whole brain, were collected in each experiment (total duration 20 min). A stimulus-response curve was obtained by averaging the uniformly resampled RR intervals following each stimulation. Fifteen informed volunteers underwent fMRI at 3T during neck suction stimulation. Nine subjects responded to the stimulation, whereas in six subjects the heart period did not show a significant increase during the suction. Efficacious versus nonefficacious stimuli induced a significantly cluster-level increased activation (p<0.005), in the right superior temporal lobe (p-corrected<0.004) and within limbic circuits, involving left amygdala and putamen (pcorrected< 0.01).