Possible Mechanisms of the Influence of the Supramillary Nucleus on the Functioning of the Dentate Gyrus and the CA2 Fie
- PDF / 621,791 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 40 Downloads / 174 Views
RETICAL ARTICLES
Possible Mechanisms of the Influence of the Supramillary Nucleus on the Functioning of the Dentate Gyrus and the CA2 Field of the Hippocamsus (Role of Disinhibition) I. G. Silkisa, * and V. A. Markevicha aInstitute
of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia Received March 11, 2020; revised April 28, 2020; accepted April 30, 2020
Abstract—We analyzed possible mechanisms of the influence of the supramammillary nucleus of the hypothalamus (SMN) on the activity of granule cells of the dentate gyrus and pyramidal neurons of the CA2 field of the hippocampus. We used known data on the functional organization of excitatory and inhibitory interactions in the neural network, which includes the SMN, hippocampus, septum, and entorhinal cortex. We propose that the induction of long-term potentiation in the perforant path inputs to granule cells and pyramidal neurons of the CA2 field during simultaneous stimulation of the SMN and the entorhinal cortex is promoted by disinhibition, which involves interconnected inhibitory neurons located in different fields of the hippocampus, the septum, and the SMN. In the waking state, the glutamatergic input from the SMN to the CA2 field promotes the potentiation of inputs from the entorhinal cortex and from the CA3 field to the pyramidal neurons of the CA2 field, which facilitates the propagation of signals through the trisynaptic hippocampal pathway. Taking into account the known data on the increased activity of the SMN during paradoxical sleep, data on the participation of the SMN in an increase in the activity of granule cells and pyramidal neurons of the CA2 field, and data on the high efficiency of input from the CA2 field into the CA1 field, we hypothesized that during paradoxical sleep, when the transmission of information through the classical trisynaptic pathway is suppressed, it is transferred to the CA1 field through the dentate gyrus and CA2 field. Our analysis suggests that the SMN-induced facilitation of signal transmission through different hippocampal fields as well as an increase in the activity of SMN and granule cells during paradoxical sleep, which promotes neurogenesis, may underlie the participation of SMN in memory processes. Keywords: supramammillary nucleus, hippocampus, disinhibition, synaptic plasticity DOI: 10.1134/S181971242004011X
INTRODUCTION Previously, it was proposed that the mammillary bodies are involved in memory processes, since they facilitate the transmission of information from the hippocampus through the subiculum to the anterior thalamus, and from there to the cingulate cortex. However, the potential significance of other connections of the mammillary bodies was ignored. For example, the supramamillary nucleus (SMN) of the hypothalamus is associated not only with the dentate gyrus (DG) and CA2 field of the hippocampus but also with the entorhinal cortex (EC), medial septum (MS), and lateral septum [1–4]. It was hypothesized that, due to these connections, the SMN is one of the Abbr
Data Loading...
