Intracellular manganese enhanced MRI signals reflect the frequency of action potentials in Aplysia neurons
Journal of Neuroscience Methods. 2018-02-01; 295: 121-128
DOI: 10.1016/j.jneumeth.2017.12.008
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Svehla P(1), Bédécarrats A(2), Jahn C(3), Nargeot R(2), Ciobanu L(4).
Author information:
(1)NeuroSpin, CEA Saclay, 91191 Gif-sur-Yvette, France; University Paris-Sud, XI,
91450 Orsay, France.
(2)University of Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France.
(3)NeuroSpin, CEA Saclay, 91191 Gif-sur-Yvette, France.
(4)NeuroSpin, CEA Saclay, 91191 Gif-sur-Yvette, France. Electronic address:
.
BACKGROUND: Manganese-enhanced magnetic resonance imaging (MEMRI) is an
increasingly popular alternative to standard functional MRI methods in animal
studies. The contrast in MEMRI images is based on the accumulation of Mn2+ ions
inside neurons, and, since manganese can serve as calcium analogue, this
accumulation reflects calcium dynamics providing versatile information about
brain neuroarchitecture and functionality. However, despite its use as a
functional imaging tool, the exact relationship between the MEMRI signal and
neuronal activity remains elusive.
NEW METHOD: In order to better understand the mechanisms underlying Mn2+
accumulation resulting in MEMRI signal enhancement we investigated single neuron
responses of isolated Aplysia buccal ganglia subjected to chemical (dopamine) or
electrical stimulation of an input nerve (oesophageal nerve). The elicited
electrical activity that represents a fictive feeding was recorded with
electrophysiological methods and the Mn2+ uptake in individual neurons was
evaluated with MEMRI at 17.2T.
RESULTS & COMPARISON WITH EXISTING METHOD(S): We show a positive correlation
between bursts of electrical activity and MEMRI signal intensity in identified
neurons and demonstrate that the MEMRI signal reflects mainly fast and high
membrane depolarization processes such as action potentials, and it is not
sensitive to slow and small membrane depolarizations, such as post-synaptic
potentials.
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