The Journal of Neuroscience, July 2, 2008, 28(27):6773-6786; doi:10.1523/JNEUROSCI.5329-07.2008
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Behavioral/Systems/Cognitive
Discharge Properties of Hippocampal Neurons during Performance of a Jump Avoidance Task
Pierre-Pascal Lenck-Santini,1
André A. Fenton,2 and
Robert U. Muller2
1Dartmouth Medical School, Lebanon, New Hampshire 03755, and 2Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, New York 11203
Correspondence should be addressed to Pierre-Pascal Lenck-Santini, Dartmouth Medical School, 1 Medical Center Drive, Lebanon, NH 03755. Email: lenck{at}dartmouth.edu
We recorded single hippocampal cells while rats performed a jump avoidance task. In this task, a rat was dropped onto the metal floor of a 33 cm gray wooden cube and was given a mild electric shock if it did not jump up onto the box rim in <15 s. We found that many hippocampal pyramidal cells and most interneurons discharged preferentially at the drop, the jump, or on both events. By simultaneously recording the hippocampal EEG, we found that the discharge of most of the event-related pyramidal cells was modulated by the theta rhythm and moreover that discharge precessed with theta cycles in the same manner seen for pyramidal cells in their role as place cells. The elevations of firing rate at drop and jump were accompanied by increases in theta frequency. We conclude that many of the features of event-related discharge can be interpreted as being equivalent to the activity of place cells with firing fields above the box floor. Nevertheless, there are sufficient differences between expectations from place cells and observed activity to indicate that pyramidal cells may be able to signal events as well as location.
Key words: hippocampus; place cells; theta rhythm; acetylcholine; jump avoidance; memory
Received Dec. 1, 2007;
revised April 11, 2008;
accepted May 1, 2008.
Correspondence should be addressed to Pierre-Pascal Lenck-Santini, Dartmouth Medical School, 1 Medical Center Drive, Lebanon, NH 03755. Email: lenck{at}dartmouth.edu
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[Abstract]
[Full Text]
[PDF]
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