RT Journal Article
SR Electronic
T1 Synergy of Direct and Indirect Cholinergic Septo-Hippocampal Pathways Coordinates Firing in Hippocampal Networks
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 8394
OP 8410
DO 10.1523/JNEUROSCI.4460-14.2015
VO 35
IS 22
A1 Dannenberg, Holger
A1 Pabst, Milan
A1 Braganza, Oliver
A1 Schoch, Susanne
A1 Niediek, Johannes
A1 Bayraktar, Melike
A1 Mormann, Florian
A1 Beck, Heinz
YR 2015
UL http://www.jneurosci.org/content/35/22/8394.abstract
AB The medial septum/diagonal band of Broca complex (MSDB) is a key structure that modulates hippocampal rhythmogenesis. Cholinergic neurons of the MSDB play a central role in generating and pacing theta-band oscillations in the hippocampal formation during exploration, novelty detection, and memory encoding. How precisely cholinergic neurons affect hippocampal network dynamics in vivo, however, has remained elusive. In this study, we show that stimulation of cholinergic MSDB neurons in urethane-anesthetized mice acts on hippocampal networks via two distinct pathways. A direct septo-hippocampal cholinergic projection causes increased firing of hippocampal inhibitory interneurons with concomitantly decreased firing of principal cells. In addition, cholinergic neurons recruit noncholinergic neurons within the MSDB. This indirect pathway is required for hippocampal theta synchronization. Activation of both pathways causes a reduction in pyramidal neuron firing and a more precise coupling to the theta oscillatory phase. These two anatomically and functionally distinct pathways are likely relevant for cholinergic control of encoding versus retrieval modes in the hippocampus.