Spatial representation and memory in the hippocampal formation

March 15, 2012
at 10 am

• Collin Lever, Senior Lecturer, Durham University, UK

Abstract:
The hippocampal formation contains different types of spatial cells, supporting its important role in spatial cognition and memory. These include place cells, grid cells, head direction cells, speed cells, and a type we recently discovered, called the boundary vector cell (BVC). I will introduce all these cells, then focus primarily on place cells and BVCs.

It seems that grid cells and BVCs play complementary, and perhaps interactive, roles in the construction of allocentric spatial representations: grids use self-motion inputs while BVCs use cues from the external environment, namely boundaries such as walls and drops. I will describe the BVC model and its background (e.g see Barry et al, 2006, Lever et al, 2002), and present published (Lever et al, 2009) and unpublished work on the BVCs themselves, considering their possible functions.

In another research line, I will briefly present our recent study on CA1 place cells which support models by Hasselmo and colleagues suggesting an important role for the theta oscillation in separating encoding and retrieval states. We show that novelty elicits a later theta phase of firing in CA1 place cells (replicating Lever et al, 2010), and present evidence to suggest that acetylcholine alters the balance between encoding and retrieval.

References:
Lever C, Burton S, Jeewajee A, Wills TJ, Cacucci F, Burgess N, O'Keefe J (2010) Environmental novelty elicits a later theta phase of firing in CA1 but not subiculum. Hippocampus 20: 229-34
Lever C, Burton S, Jeewajee A, O'Keefe J, Burgess N (2009). Boundary vector cells in the subiculum of the hippocampal formation. Journal of Neuroscience, 29: 9771-9777
Barry C, C Lever, R Hayman, T Hartley, S Burton, J O’Keefe, K Jeffery, N Burgess, (2006) The boundary vector cell model of place cell firing and spatial memory. Reviews in the Neurosciences 17: 71-97
C Lever, T Wills, F Cacucci, N Burgess, J O’Keefe (2002) Long-term plasticity in the hippocampal place cell representation of environmental geometry. Nature, 416: 90-94