scholarly journals The Theta Rhythm of the Hippocampus: From Neuronal and Circuit Mechanisms to Behavior

2021 ◽  
Vol 15 ◽  
Author(s):  
Angel Nuñez ◽  
Washington Buño
Keyword(s):  
Rem Sleep ◽  
Hippocampal Neurons ◽  
Theta Rhythm ◽  
Spatial Navigation ◽  
Medial Septum ◽  
Memory Encoding ◽  
Intrinsic Properties ◽  
Θ Rhythm ◽  
Diagonal Band ◽  
Diagonal Band Of Broca

This review focuses on the neuronal and circuit mechanisms involved in the generation of the theta (θ) rhythm and of its participation in behavior. Data have accumulated indicating that θ arises from interactions between medial septum-diagonal band of Broca (MS-DbB) and intra-hippocampal circuits. The intrinsic properties of MS-DbB and hippocampal neurons have also been shown to play a key role in θ generation. A growing number of studies suggest that θ may represent a timing mechanism to temporally organize movement sequences, memory encoding, or planned trajectories for spatial navigation. To accomplish those functions, θ and gamma (γ) oscillations interact during the awake state and REM sleep, which are considered to be critical for learning and memory processes. Further, we discuss that the loss of this interaction is at the base of various neurophatological conditions.

scholarly journals Interconnection and synchronization of neuronal populations in the mouse medial septum/diagonal band of Broca

2015 ◽  
Vol 113 (3) ◽  
pp. 971-980 ◽  
Author(s):  
Richardson N. Leão ◽  
Zé H. Targino ◽  
Luis V. Colom ◽  
André Fisahn
Keyword(s):  
Action Potentials ◽  
Theta Rhythm ◽  
Medial Septum ◽  
Gabaergic Neurons ◽  
Action Potential Firing ◽  
Neuronal Populations ◽  
Diagonal Band ◽  
Potential Firing ◽  
Diagonal Band Of Broca ◽  
Hippocampal Theta

The medial septum/diagonal band of Broca (MS/DBB) is crucial for hippocampal theta rhythm generation (4–12 Hz). However, the mechanisms behind theta rhythmogenesis are still under debate. The MS/DBB consists, in its majority, of three neuronal populations that use acetylcholine, GABA, or glutamate as neurotransmitter. While the firing patterns of septal neurons enable the MS/DBB to generate rhythmic output critical for the generation of the hippocampal theta rhythm, the ability to synchronize these action potentials is dependent on the interconnectivity between the three major MS/DBB neuronal populations, yet little is known about intraseptal connections. Here we assessed the connectivity between pairs of MS/DBB neurons with paired patch-clamp recordings. We found that glutamatergic and GABAergic neurons provide intraseptal connections and produce sizable currents in MS/DBB postsynaptic cells. We also analyzed linear and nonlinear relationships between the action potentials fired by pairs of neurons belonging to various MS/DBB neuronal populations. Our results show that while the synchrony index for action potential firing was significantly higher in pairs of GABAergic neurons, coherence of action potential firing in the theta range was similarly low in all pairs analyzed. Recurrence analysis demonstrated that individual action potentials were more recurrent in cholinergic neurons than in other cell types. Implementing sparse connectivity in a computer model of the MS/DBB network reproduced our experimental data. We conclude that the interplay between the intrinsic membrane properties of different MS/DBB neuronal populations and the connectivity among these populations underlie the ability of the MS/DBB network to critically contribute to hippocampal theta rhythmogenesis.

scholarly journals Co-activation of nAChR and mGluR induces γ oscillation in rat medial septum diagonal band of Broca slices

2014 ◽  
Vol 35 (2) ◽  
pp. 175-184
Author(s):  
Ya-li Wang ◽  
Jian-gang Wang ◽  
Gao-xiang Ou-yang ◽  
Xiao-li Li ◽  
Zaineb Henderson ◽  
...  
Keyword(s):  
Medial Septum ◽  
Diagonal Band ◽  
Co Activation ◽  
Diagonal Band Of Broca

scholarly journals The endomembrane system of cholinergic and non-cholinergic neurons in the medial septal nucleus and vertical limb of the diagonal band of Broca: a cytochemical and immunocytochemical study.

1990 ◽  
Vol 38 (4) ◽  
pp. 563-571 ◽  
Author(s):  
G Palacios
Keyword(s):  
Cholinergic Neurons ◽  
Medial Septum ◽  
Projection Neurons ◽  
Lamellar Bodies ◽  
Endomembrane System ◽  
Electron Microscopic ◽  
Diagonal Band ◽  
Diagonal Band Of Broca ◽  
Well Differentiated ◽  
Microscopic Morphology

Coronal vibratome sections of the rostral part of the medial septum (MS) and vertical limb of the diagonal band of Broca (VDB) nuclei were studied by an immunocytochemical technique using a monoclonal antibody against choline acetyltransferase (ChAT) and a double histochemical method for detection of acid phosphatase (AcPase) and nucleoside diphosphatase (NDPase) activity. The electron microscopic morphology of ChAT-immunoreactive and non-immunoreactive neurons was compared with similar neurons showing both AcPase and NDPase activity. ChAT-labeled and non-labeled neurons were well differentiated by the organization of the endomembrane system and especially by the structure of the rough endoplasmic reticulum (RER) and associated lamellar bodies. These results support the theory that the peculiar ultrastructure of the lamellar bodies in each neuron is related to the pattern of organization of the endomembrane system and its function. The significance of the lamellar bodies is discussed, and the data of the present work, together with findings described by other investigators. These data suggest that these bodies are predominant in efferent projection neurons in the basal forebrain nuclei.

scholarly journals A distinctive subpopulation of medial septal slow-firing neurons promote hippocampal activation and theta oscillations

2011 ◽  
Vol 106 (5) ◽  
pp. 2749-2763 ◽  
Author(s):  
Hao Zhang ◽  
Shih-Chieh Lin ◽  
Miguel A. L. Nicolelis
Keyword(s):  
Medial Septum ◽  
Theta Oscillations ◽  
Short Term ◽  
Neuronal Ensembles ◽  
Gamma Range ◽  
Diagonal Band ◽  
Hippocampal Activity ◽  
Diagonal Band Of Broca ◽  
Hippocampal Theta ◽  
Relationship Of

The medial septum-vertical limb of the diagonal band of Broca (MSvDB) is important for normal hippocampal functions and theta oscillations. Although many previous studies have focused on understanding how MSVDB neurons fire rhythmic bursts to pace hippocampal theta oscillations, a significant portion of MSVDB neurons are slow-firing and thus do not pace theta oscillations. The function of these MSVDB neurons, especially their role in modulating hippocampal activity, remains unknown. We recorded MSVDB neuronal ensembles in behaving rats, and identified a distinct physiologically homogeneous subpopulation of slow-firing neurons (overall firing <4 Hz) that shared three features: 1) much higher firing rate during rapid eye movement sleep than during slow-wave (SW) sleep; 2) temporary activation associated with transient arousals during SW sleep; 3) brief responses (latency 15∼30 ms) to auditory stimuli. Analysis of the fine temporal relationship of their spiking and theta oscillations showed that unlike the theta-pacing neurons, the firing of these “pro-arousal” neurons follows theta oscillations. However, their activity precedes short-term increases in hippocampal oscillation power in the theta and gamma range lasting for a few seconds. Together, these results suggest that these pro-arousal slow-firing MSvDB neurons may function collectively to promote hippocampal activation.

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