The effect of pharmacological inactivation of the mammillary body and anterior thalamic nuclei on hippocampal theta rhythm in urethane-anesthetized rats

Witold Żakowski , Piotr Zawistowski , Łukasz Braszka , Edyta Jurkowlaniec

Abstract

The mammillary body (MB) and the anterior thalamic nuclei (ATN) are closely related structures, which take part in learning and memory processes. However, the exact role of these structures has remained unclear. In both structures neurons firing according to hippocampal theta rhythm have been found, mainly in the medial mammillary nucleus (MM) and anteroventral thalamic nucleus (AV). These neurons are driven by descending projections from the hippocampal formation and are thought to convey theta rhythm back to the hippocampus (HP). We argue that the MB–ATN axis not only relays theta signal, but may also modulate it. To examine it, we performed a pharmacological inactivation of the MM and AV by local infusion of procaine, and measured changes in theta activity in selected structures of the extended hippocampal system in urethane-anesthetized rats. The inactivation of the MM resulted in decrease in EEG power in the HP and AV, the most evidently in the lower theta frequency bands, i.e. 3–5 Hz in the HP (down to 9.2% in 3- to 4-Hz band and 37.6% in 4- to 5-Hz band, in comparison to the power in the control conditions) and 3–4 Hz in the AV (down to 24.9%). After the AV inactivation, hippocampal EEG power decreased in theta frequency bands of 3–8 Hz (down to 61.6% in 6- to 7-Hz band and 69.4% in 7- to 8-Hz band). Our results suggest that the role of the MB–ATN axis in regulating theta rhythm signaling may be much more important than has been speculated so far.
Author Witold Żakowski (FB / DAHP)
Witold Żakowski,,
- Department of Animal and Human Physiology
, Piotr Zawistowski (FB / DAHP)
Piotr Zawistowski,,
- Department of Animal and Human Physiology
, Łukasz Braszka (FB / DAHP)
Łukasz Braszka,,
- Department of Animal and Human Physiology
, Edyta Jurkowlaniec (FB / DAHP)
Edyta Jurkowlaniec,,
- Department of Animal and Human Physiology
Other language title versions
Journal seriesNeuroscience, ISSN 0306-4522, (A 25 pkt)
Issue year2017
Vol362
Pages196-205
Publication size in sheets0.5
Keywords in Englishanteroventral thalamic nucleus, hippocampus, local field potential, medial mammillary nucleus, procaine
DOIDOI:10.1016/j.neuroscience.2017.08.043
URL https://doi.org/10.1016/j.neuroscience.2017.08.043
Languageen angielski
Score (nominal)25
ScoreMinisterial score = 25.0, 20-12-2017, ArticleFromJournal
Ministerial score (2013-2016) = 25.0, 20-12-2017, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 3.277 (2) - 2016=3.318 (5)
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