The relationship between blood flow and neuronal activity in the rodent olfactory bulb.
Journal of Neuroscience. 2007-06-13; 27(24): 6452-6460
DOI: 10.1523/jneurosci.3141-06.2007
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1. J Neurosci. 2007 Jun 13;27(24):6452-60.
The relationship between blood flow and neuronal activity in the rodent olfactory
bulb.
Chaigneau E(1), Tiret P, Lecoq J, Ducros M, Knöpfel T, Charpak S.
Author information:
(1)Institut National de la Santé et de la Recherche Médicale U603, Laboratory of
Neurophysiology, Université Paris Descartes, 75006 Paris, France.
In the brain, neuronal activation triggers an increase in cerebral blood flow
(CBF). Here, we use two animal models and several techniques (two-photon imaging
of CBF and neuronal calcium dynamics, intracellular and extracellular recordings,
local pharmacology) to analyze the relationship between neuronal activity and
local CBF during odor stimulation in the rodent olfactory bulb. Application of
glutamate receptor antagonists or tetrodotoxin directly into single rat olfactory
glomeruli blocked postsynaptic responses but did not affect the local odor-evoked
CBF increases. This suggests that in our experimental conditions, odor always
activates more than one glomerulus and that silencing one of a few clustered
glomeruli does not affect the vascular response. To block synaptic transmission
more widely, we then superfused glutamate antagonists over the surface of the
olfactory bulb in transgenic G-CaMP2 mice. This was for two reasons: (1) mice
have a thin olfactory nerve layer compared to rats and this will favor drug
access to the glomerular layer, and (2) transgenic G-CaMP2 mice express the
fluorescent calcium sensor protein G-CaMP2 in mitral cells. In G-CaMP2 mice,
odor-evoked, odor-specific, and concentration-dependent calcium increases in
glomeruli. Superfusion of glutamate receptor antagonists blocked odor-evoked
postsynaptic calcium signals and CBF responses. We conclude that activation of
postsynaptic glutamate receptors and rises in dendritic calcium are major steps
for neurovascular coupling in olfactory bulb glomeruli.
DOI: 10.1523/JNEUROSCI.3141-06.2007
PMID: 17567806 [Indexed for MEDLINE]