In vitro activation of the medial septum—Diagonal band complex generates atropine-sensitive and atropine-resistant hippocampal theta rhythm: An investigation using a complete septohippocampal preparation

Abstract : The medial septum and diagonal band complex (MS-DB) is believed to play a key role in generating theta oscillations in the hippocampus, a phenomenon critical for learning and memory. Although the importance of the MS-DB in hippocampal theta rhythm generation is generally accepted, it remains to be determined whether the MS-DB alone can generate hippocampal oscillations or is only a transducer of rhythmic activity from other brain areas. Secondly, it is known that hippocampal theta rhythm can be separated into an atropine-sensitive and insensitive component. However, it remains to be established if the MS-DB can generate both types of rhythm. To answer these questions, we used a new in vitro rat septohippocampal preparation placed in a hermetically separated two side recording chamber. We showed that carbachol activation of the MS-DB generated large theta oscillations in the CA1 and CA3 regions of the hippocampus. These oscillations were blocked by applying either the GABA(A) receptor antagonist bicuculline or the AMPA/kainate antagonist DNQX to the hippocampus. Interestingly, the application of the muscarinic receptor antagonist atropine produced only a partial decrease in the amplitude, without modification of the frequency, of theta. These results show for the first time, that upon optimal excitation, the MS-DB alone is able to generate hippocampal oscillations in the theta frequency band. Moreover, these MS-DB generated theta oscillations are mediated by muscarinic and nonmuscarinic receptors and have a pharmacological profile similar to theta rhythm observed in awake animals.
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https://hal.archives-ouvertes.fr/hal-02349376
Contributor : Romain Goutagny <>
Submitted on : Tuesday, November 5, 2019 - 4:15:08 PM
Last modification on : Wednesday, November 6, 2019 - 1:36:27 AM

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Romain Goutagny, Frédéric Manseau, Jesse Jackson, Marc Danik, Sylvain Williams. In vitro activation of the medial septum—Diagonal band complex generates atropine-sensitive and atropine-resistant hippocampal theta rhythm: An investigation using a complete septohippocampal preparation. Hippocampus, Wiley, 2008, 18 (6), pp.531-535. ⟨10.1002/hipo.20418⟩. ⟨hal-02349376⟩

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