Sensory-Evoked Intrinsic Imaging Signals in the Olfactory Bulb Are Independent of Neurovascular Coupling

Cell Rep. 2015 Jul 14;12(2):313-25. doi: 10.1016/j.celrep.2015.06.016. Epub 2015 Jul 2.

Abstract

Functional brain-imaging techniques used in humans and animals, such as functional MRI and intrinsic optical signal (IOS) imaging, are thought to largely rely on neurovascular coupling and hemodynamic responses. Here, taking advantage of the well-described micro-architecture of the mouse olfactory bulb, we dissected the nature of odor-evoked IOSs. Using in vivo pharmacology in transgenic mouse lines reporting activity in different cell types, we show that parenchymal IOSs are largely independent of neurotransmitter release and neurovascular coupling. Furthermore, our results suggest that odor-evoked parenchymal IOSs originate from changes in light scattering of olfactory sensory neuron axons, mostly due to water movement following action potential propagation. Our study sheds light on a direct correlate of neuronal activity, which may be used for large-scale functional brain imaging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / metabolism
  • Dynamic Light Scattering
  • Evoked Potentials, Somatosensory / physiology*
  • Female
  • Hemodynamics
  • Magnetic Resonance Imaging
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microscopy, Fluorescence
  • Neurotransmitter Agents / metabolism
  • Neurovascular Coupling / physiology*
  • Olfactory Bulb / physiology*
  • Olfactory Marker Protein / genetics
  • Olfactory Marker Protein / metabolism
  • Olfactory Receptor Neurons / metabolism
  • Osmolar Concentration

Substances

  • Neurotransmitter Agents
  • Olfactory Marker Protein
  • Omp protein, mouse