QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, June 24, 2009, 29(25):8094-8102; doi:10.1523/JNEUROSCI.5665-08.2009

This Article Full Text Full Text (PDF) Supplemental Data Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Hangya, B. Articles by Varga, V. PubMed PubMed Citation Articles by Hangya, B. Articles by Varga, V.

 Previous Article  |  Next Article 

Behavioral/Systems/Cognitive
GABAergic Neurons of the Medial Septum Lead the Hippocampal Network during Theta Activity

Balázs Hangya,¹ Zsolt Borhegyi,¹ Nóra Szilágyi,² Tamás F. Freund,¹ and Viktor Varga¹

¹Laboratory of Cerebral Cortex Research, Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary, and ²Department of Physiology and Neurobiology, Eötvös Loránd University, H-1117 Budapest, Hungary

Correspondence should be addressed to Balázs Hangya, Laboratory of Cerebral Cortex Research, Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony utca 43, H-1083 Budapest, Hungary. Email: hangyab{at}koki.hu

Information processing in the hippocampus critically relies on its reciprocal interaction with the medial septum (MS). Synchronization of the septo-hippocampal system was demonstrated during both major hippocampal activity states, the regular theta rhythm and the large amplitude irregular activity. Previous experimental and modeling data suggest that the MS provides rhythmic drive to the hippocampus, and hippocampo-septal feedback synchronizes septal pacemaker units. However, this view has recently been questioned based on the possibility of intrahippocampal theta genesis. Previously, we identified putative pacemaker neurons expressing parvalbumin (PV) and/or the pacemaker hyperpolarization-activated and cyclic nucleotide-gated nonselective cation channel (HCN) in the MS. In this study, by analyzing the temporal relationship of activity between the PV/HCN-containing medial septal neurons and hippocampal local field potential, we aimed to uncover whether the sequence of events during theta formation supports the classic view of septal drive or the challenging theory of hippocampal pacing of theta. Importantly, by implementing a circular statistical method, a temporal lead of these septal neurons over the hippocampus was observed on the course of theta synchronization. Moreover, the activity of putative hippocampal interneurons also preceded hippocampal local field theta, but by a shorter time period compared with PV/HCN-containing septal neurons. Using the concept of mutual information, the action potential series of PV/HCN-containing neurons shared higher amount of information with hippocampal field oscillation than PV/HCN-immunonegative cells. Thus, a pacemaker neuron population of the MS leads hippocampal activity, presumably via the synchronization of hippocampal interneurons.

---

Received Nov. 20, 2008; revised April 8, 2009; accepted May 19, 2009.

Correspondence should be addressed to Balázs Hangya, Laboratory of Cerebral Cortex Research, Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony utca 43, H-1083 Budapest, Hungary. Email: hangyab{at}koki.hu

This article has been cited by other articles:

				S. Ma, F. E. Olucha-Bordonau, M. A. Hossain, F. Lin, C. Kuei, C. Liu, J. D. Wade, S. W. Sutton, A. Nunez, and A. L. Gundlach Modulation of hippocampal theta oscillations and spatial memory by relaxin-3 neurons of the nucleus incertus Learn. Mem., October 30, 2009; 16(11): 730 - 742. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help