Neural origin of spontaneous hemodynamic fluctuations in rats under burst-suppression anesthesia condition

Cereb Cortex. 2011 Feb;21(2):374-84. doi: 10.1093/cercor/bhq105. Epub 2010 Jun 7.

Abstract

Spontaneous hemodynamic signals fluctuate coherently within many resting-brain functional networks not only in awake humans and lightly anesthetized primates but also in animals under deep anesthesia characterized by burst-suppression electroencephalogram (EEG) activity and unconsciousness. To understand the neural origin of spontaneous hemodynamic fluctuations under such a deep anesthesia state, epidural EEG and cerebral blood flow (CBF) were simultaneously recorded from the bilateral somatosensory cortical regions of rats with isoflurane-induced burst-suppression EEG activity. Strong neurovascular coupling was observed between spontaneous EEG "bursts" and CBF "bumps," both of which were also highly synchronized across the 2 hemispheres. Functional magnetic resonance imaging (fMRI) was used to image spontaneous blood oxygen level-dependent (BOLD) signals under the same anesthesia conditions and showed similar BOLD "bumps" and dependence on anesthesia depth as the CBF signals. The spatiotemporal BOLD correlations indicate a strong but less-specific coherent network covering a wide range of cortical regions. The overall findings reveal that the spontaneous CBF/BOLD fluctuations under unconscious burst-suppression anesthesia conditions originate mainly from underlying neural activity. They provide insights into the neurophysiological basis for the use of BOLD- and CBF-based fMRI signals for noninvasively imaging spontaneous and synchronous brain activity under various brain states.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anesthetics, Inhalation / pharmacology*
  • Animals
  • Brain Mapping*
  • Brain Waves / drug effects*
  • Cerebrovascular Circulation / drug effects*
  • Cerebrovascular Circulation / physiology
  • Dose-Response Relationship, Drug
  • Electroencephalography / methods
  • Image Processing, Computer-Assisted / methods
  • Isoflurane / pharmacology*
  • Magnetic Resonance Imaging / methods
  • Male
  • Neural Inhibition / drug effects
  • Nonlinear Dynamics
  • Oxygen / blood
  • Rats
  • Rats, Sprague-Dawley
  • Somatosensory Cortex* / blood supply
  • Somatosensory Cortex* / drug effects
  • Somatosensory Cortex* / physiology
  • Statistics as Topic

Substances

  • Anesthetics, Inhalation
  • Isoflurane
  • Oxygen