The neural basis of functional brain imaging signals

Trends Neurosci. 2002 Dec;25(12):621-5. doi: 10.1016/s0166-2236(02)02264-6.


The haemodynamic responses to neural activity that underlie the blood-oxygen-level-dependent (BOLD) signal used in functional magnetic resonance imaging (fMRI) of the brain are often assumed to be driven by energy use, particularly in presynaptic terminals or glia. However, recent work has suggested that most brain energy is used to power postsynaptic currents and action potentials rather than presynaptic or glial activity and, furthermore, that haemodynamic responses are driven by neurotransmitter-related signalling and not directly by the local energy needs of the brain. A firm understanding of the BOLD response will require investigation to be focussed on the neural signalling mechanisms controlling blood flow rather than on the locus of energy use.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Action Potentials / physiology
  • Astrocytes / physiology
  • Brain / blood supply*
  • Brain / physiology
  • Brain Mapping
  • Cerebrovascular Circulation / physiology*
  • Energy Metabolism / physiology*
  • Humans
  • Magnetic Resonance Imaging
  • Neural Inhibition / physiology
  • Presynaptic Terminals / physiology