Present address: Picower Center for Learning and Memory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building E18-366, Cambridge, MA 02139.
Electrophysiological characterization of interlaminar entorhinal connections: an essential link for re-entrance in the hippocampal–entorhinal system
Article first published online: 9 DEC 2003
European Journal of Neuroscience
Volume 18, Issue 11, pages 3037–3052, December 2003
How to Cite
Kloosterman, F., Van Haeften, T., Witter, M. P. and Lopes da Silva, F. H. (2003), Electrophysiological characterization of interlaminar entorhinal connections: an essential link for re-entrance in the hippocampal–entorhinal system. European Journal of Neuroscience, 18: 3037–3052. doi: 10.1111/j.1460-9568.2003.03046.x
- Issue published online: 9 DEC 2003
- Article first published online: 9 DEC 2003
- Received 24 June 2003, revised 27 August 2003, accepted 1 September 2003
- current source density analysis;
- entorhinal cortex;
- in vivo;
The hippocampal formation communicates with the neocortex mainly through the adjacent entorhinal cortex. Neurons projecting to the hippocampal formation are found in the superficial layers of the entorhinal cortex and are largely segregated from the neurons receiving hippocampal output, which are located in deep entorhinal layers. We studied the communication between deep and superficial entorhinal layers in the anaesthetized rat using field potential recordings, current source density analysis and single unit measurements. We found that subiculum stimulation was able to excite entorhinal neurons in deep layers. This response was followed by current sinks in superficial layers. Both responses were subject to frequency dependent facilitation, but not depression. Selective blockade of deep layer responses also abolished subsequent superficial layer responses. This clearly demonstrates a functional deep-to-superficial layer communication in the entorhinal cortex, which can be triggered by hippocampal output. This pathway may provide a means by which processed hippocampal output is integrated or compared with new incoming information in superficial entorhinal layers, and it constitutes an important link in the process of re-entrance of activity in the hippocampal–entorhinal network, which may be important for consolidation of memories or retaining information for short periods.