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Howard Eichenbaum" The hippocampus in space and time "

Abstract :


In humans, hippocampal function is generally recognized as supporting episodic memory, which is defined by its temporal organization (a sequence of events that compose an episode).
By contrast, in rats, many believe that the hippocampus creates maps of the environment and supports spatial navigation, characterized spatial organization. How do we reconcile the episodic memory and spatial mapping views of hippocampal function? Here I will discuss evidence that, during learning of what happens where, hippocampal place cells map the locations of events in their spatial context. In addition, I will describe recent findings that, during learning of what happens when in spatial and non-spatial sequences, hippocampal neurons encode specific moments in the course of temporally extended experiences (“time cells”, as contrasted with “place cells”) and map specific events within their temporal context. These findings support an emerging view that the hippocampus supports episodic memory by creating a “scaffolding” for the organization of events within their spatial and temporal context.

Selected publications

NMDA signaling in CA1 mediates selectively the spatial component of episodic memory.Place R, Lykken C, Beer Z, Suh J, McHugh TJ, Tonegawa S, Eichenbaum H, Sauvage MM.Learn Mem. 2012 Mar 14;19(4):164-9. doi: 10.1101/lm.025254.111.
New approach illuminates how memory systems switch.McKenzie S, Eichenbaum H.Trends Cogn Sci. 2012 Feb;16(2):102-3. Epub 2011 Dec 2.

A mechanism for the formation of hippocampal neuronal firing patterns that represent what happens where.Tort AB, Komorowski R, Kopell N, Eichenbaum H.Learn Mem. 2011 Oct 21;18(11):718-27. doi: 10.1101/lm.2307711. Print 2011.

Amygdala lesions selectively impair familiarity in recognition memory.
Farovik A, Place RJ, Miller DR, Eichenbaum H. Nat Neurosci. 2011 Sep 25;14(11):1416-7. doi: 10.1038/nn.2919.

Eichenbaum, H. Hippocampus: Cognitive processes and neural representations that underlie declarative memory. Neuron. 2004 Sep; 44:109-120.

Fortin NJ, Wright SP, Eichenbaum H. Recollection-like memory retrieval in rats is dependent on the hippocampus. Nature. 2004 Sep: 431:188-190.

Fortin NJ, Agster KL, Eichenbaum HB. Critical role of the hippocampus in memory for sequences of events. Nat Neurosci. 2002 May;5(5):458-62.

Scientific focus :

The hippocampus plays a critical role in memory formation, but our understanding of just what the hippocampus does and how it performs its functions are still issues of considerable controversy. To enhance our knowledge about hippocampal function, we are pursuing a combination of neuropsychological studies of the nature of memory loss in animals with damage to the hippocampus and related cortical areas, and we are pursuing electrophysiological recording studies that seek to determine how information is represented by the hippocampus and associated cortical areas.

Georges Di Scala et Colette Fabrigoule