The Septum as a Pacemaker for the Hippocampal Theta Rhythm

1991 ◽  
pp. 87-98
Author(s):  
Robert Miller
Keyword(s):  
Theta Rhythm ◽  
Hippocampal Theta Rhythm ◽  
Hippocampal Theta

Hippocampal theta rhythm is reduced by suppression of the H-current in septohippocampal GABAergic neurons

2004 ◽  
Vol 19 (8) ◽  
pp. 2299-2309 ◽  
Author(s):  
Changqing Xu ◽  
Subimal Datta ◽  
Min Wu ◽  
Meenakshi Alreja
Keyword(s):  
Theta Rhythm ◽  
Gabaergic Neurons ◽  
Hippocampal Theta Rhythm ◽  
Hippocampal Theta

Disruption of the anterior thalamic head direction signal following reduction of the hippocampal theta rhythm.

2020 ◽  
Vol 134 (6) ◽  
pp. 577-594
Author(s):  
Ivylynn A. Pastor ◽  
Mitzi Y. Hurtado ◽  
Cassidy R. Gibson ◽  
Clark Fitzgerald ◽  
Jeffrey L. Calton
Keyword(s):  
Theta Rhythm ◽  
Head Direction ◽  
Hippocampal Theta Rhythm ◽  
Hippocampal Theta

GABAergic mediation of hippocampal theta rhythm induced by stimulation of the vagal nerve

2019 ◽  
Vol 147 ◽  
pp. 110-123 ◽  
Author(s):  
Adam Broncel ◽  
Renata Bocian ◽  
Paulina Kłos-Wojtczak ◽  
Jan Konopacki
Keyword(s):  
Theta Rhythm ◽  
Vagal Nerve ◽  
Hippocampal Theta Rhythm ◽  
Hippocampal Theta ◽  
Stimulation Of

scholarly journals GABAergic Control of the Ascending Input From the Median Raphe Nucleus to the Limbic System

2005 ◽  
Vol 94 (4) ◽  
pp. 2561-2574 ◽  
Author(s):  
Shaomin Li ◽  
Viktor Varga ◽  
Attila Sik ◽  
Bernat Kocsis
Keyword(s):  
Limbic System ◽  
Theta Rhythm ◽  
Raphe Nucleus ◽  
Median Raphe ◽  
Median Raphe Nucleus ◽  
Hippocampal Theta Rhythm ◽  
Theta Waves ◽  
Short Period ◽  
Hippocampal Theta ◽  
Median Raphé

The median raphe nucleus (MRN) is the primary source of serotonergic afferents to the limbic system that are generally considered to suppress hippocampal theta oscillations. GABA receptors are expressed in the MRN by serotonergic and nonserotonergic cells, including GABAergic and glutamatergic neurons. This study investigated the mechanisms by which the fluctuating GABA tone in the MRN leads to induction or suppression of hippocampal theta rhythm. We found that MRN application of the GABAA agonist muscimol (0.05–1.0 mM) or GABAB agonist baclofen (0.2 mM) by reverse microdialysis had strong theta promoting effects. The GABAA antagonist bicuculline infused in low concentrations (0.1, 0.2 mM) eliminated theta rhythm. A short period of theta activity of higher than normal frequency preceded hippocampal desynchronization in 46% of rats. Bicuculline in larger concentrations (0.5, 1.0, 2.0 mM) resulted in a biphasic response of an initial short (<10 min) hippocampal desynchronization followed by stable theta rhythm that lasted as long as the infusion continued. The frequency and amplitude of theta waves were higher than in control recordings and the oscillations showed a conspicuous intermittent character. Hippocampal theta rhythm elicited by MRN administration of bicuculline could be completely (0.5 mM bicuculline) or partially (1.0 mM bicuculline) blocked by simultaneous infusion of the GABAB antagonist CGP35348 . Our findings suggest that the GABAergic network may have two opposing functions in the MRN: relieving the theta-generators from serotonergic inhibition and regulating the activity of a theta-promoting circuitry by the fluctuating GABA tone. The two mechanisms may be involved in different functions.

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