Posterior hypothalamic theta rhythm: Electrophysiological basis and involvement of glutamatergic receptors

The posterior hypothalamic area (PHa), including the supramammillary nucleus (SuM) and posterior hypothalamic nuclei, forms a crucial part of the ascending brainstem hippocampal synchronizing pathway, that is involved in the frequency programming and modulation of rhythmic theta activity generated i...

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Published in:Hippocampus 2023-07, Vol.33 (7), p.844-861
Main Authors: Kowalczyk, Tomasz, Staszelis, Agata, Bocian, Renata, Siwiec, Marcin, Sowa, Joanna E., Tokarski, Krzysztof, Kaźmierska‐Grębowska, Paulina, Caban, Bartosz
Format: Article
Language:English
Subjects:
Animals
Brain stem
Electroencephalography
Electrophysiology
glutamate receptors
Glutamatergic transmission
Hippocampus
Hypothalamus
Hypothalamus, Posterior - physiology
Kainic acid
Membrane potential
membrane potential oscillations
Neurons
Neurons - physiology
posterior hypothalamic nuclei
Rats
Rats, Wistar
supramammillary nucleus
theta rhythm
Theta Rhythm - physiology
Theta rhythms
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Summary:The posterior hypothalamic area (PHa), including the supramammillary nucleus (SuM) and posterior hypothalamic nuclei, forms a crucial part of the ascending brainstem hippocampal synchronizing pathway, that is involved in the frequency programming and modulation of rhythmic theta activity generated in limbic structures. Recent investigations show that in addition to being a modulator of limbic theta activity, the PHa is capable of producing well‐synchronized local theta field potentials by itself. The purpose of this study was to examine the ability of the PHa to generate theta field potentials and accompanying cell discharges in response to glutamatergic stimulation under both in vitro and in vivo conditions. The second objective was to examine the electrophysiological properties of neurons located in the SuM and posterior hypothalamic nuclei. Extracellular in vivo and in vitro as well as intracellular in vitro experiments revealed that glutamatergic stimulation of PHa with kainic acid induces well‐synchronized local theta field oscillations in both the supramammillary and posterior hypothalamic nuclei. Furthermore, the glutamatergic PHa theta rhythm recorded extracellularly was accompanied by the activity of specific subtypes of theta‐related neurons. We identify, for the first time, a subpopulation of supramammillary and posterior hypothalamic neurons that express clear subthreshold membrane potential oscillations in the theta frequency range.
ISSN:1050-9631
1098-1063
1098-1063
DOI:10.1002/hipo.23500