Apnea-Induced Cortical BOLD-fMRI and Peripheral Sympathoneural Firing Response Patterns of Awake Healthy HumansReport as inadecuate

Apnea-Induced Cortical BOLD-fMRI and Peripheral Sympathoneural Firing Response Patterns of Awake Healthy Humans - Download this document for free, or read online. Document in PDF available to download.

End-expiratory breath-holds BH and Mueller manoeuvres MM elicit large increases in muscle sympathetic nerve activity MSNA. In 16 healthy humans 9♀, 35±4 years we used functional magnetic resonance imaging with blood oxygen level-dependent BOLD contrast to determine the cortical network associated with such sympathoexcitation. We hypothesized that increases in MSNA evoked by these simulated apneas are accompanied by BOLD contrast changes in the insular cortex, thalamus and limbic cortex. A series of 150 whole-brain images were collected during 3 randomly performed 16-second end-expiratory BHs and MMs -30 mmHg. The identical protocol was repeated separately with MSNA recorded from the fibular nerve. The time course of the sympathoexcitatory response to both breathing tasks were correlated with whole-brain BOLD signal changes. Brain sites demonstrating both positive activation and negative deactivation correlations with the MSNA time course were identified. Sympathetic burst incidence increased p<0.001 from 29±6 rest to 49±6 BH and 47±6 bursts-100 heartbeats MM. Increased neural activity Z-scores was identified in the right posterior and anterior insular cortices 3.74, 3.64, dorsal anterior cingulate 3.42, fastigial and dentate cerebellar nuclei 3.02, 3.34. Signal intensity decreased in the left posterior insula 3.28 and ventral anterior cingulate 3.01. Apnea both activates and inhibits elements of a cortical network involved in the generation of sympathetic outflow. These findings identify a neuroanatomical substrate to guide future investigations into central mechanisms contributing to disorders characterized by elevated basal MSNA and exaggerated sympathetic responses to simulated apneas such as sleep apnea and heart failure.

Author: Derek S. Kimmerly , Beverley L. Morris, John S. Floras

Source: http://plos.srce.hr/


Related documents