Spatial Firing Properties of Hippocampal CA1 Populations in an Environment Containing Two Visually Identical Regions

By William E. Skaggs, Bruce L. McNaughton. 1998

Populations of 10-39 CA1 pyramidal cells were recorded from four rats foraging for food reward in an environment consisting of two nearly identical boxes connected by a corridor. For each rat, a higher-than-chance fraction of cells had similarly shaped spatial firing fields in both boxes, but other cells had completely different fields in the two boxes. The level of correlation of fields in the two boxes differed greatly across rats and, for three of the four rats, across recording sessions. Thus, the factors controlling the level of correlation are likely to be subtle. Two control manipulations were performed. First, the two boxes were physically interchanged. In no case did firing fields move along with the boxes. Second, on the final session of recording, the rat was started in the south box, after having been started in the north box for every previous session. For at least two of the four rats, the north fields from the previous session were instantiated in the south during the first visit of the second session, but thereafter reverted. Thus neither differences between the physical boxes nor sensory input from outside the apparatus could account for the differences in firing fields: most likely they were caused by a combination of learned expectations and a neural mechanism for remembering movements. These findings could be explained either by hypothesizing a more sophisticated attractor-map architecture than has been proposed previously, or by hypothesizing that the hippocampus conjunctively encodes both map information and some other type of information.

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Citations in the corpus

Intracellular features predicted by extracellular recordings in the hippocampus in vivo. (2000, methodology): “…separated unit clusters by the presently used methods (range: 1–20 per tetrode) (Csicsvari et al. 1998, 1999a; Czurko et al. 1999; Gray et al. 1995; Harris et al. 2000; ; O'Keefe and Recce 1993; Skaggs and McNaughton 1998; Skaggs et al. 1996; Tanila et al. 1997; Wilson and McNaughton 1993).”
What Learning Systems do Intelligent Agents Need? Complementary Learning Systems Theory Updated. (2016, unknown): “What algorithmic functionalities and implementational schemes are desirable for an external memory module, both for human learners and for arti ﬁ cial agents?”
The neuroscience of learning: beyond the Hebbian synapse. (2013, background): “In multichamber or multiarm environments, a place cell may fire in different places in different chambers or arms (Gothard et al. 1996a,b; Shapiro et al. 1997; Skaggs & McNaughton 1998).”
Prospective and retrospective memory coding in the hippocampus. (2003, background): “contextual inputs can activate different charts (Skaggs and McNaughton, 1998).”
Design Principles of the Hippocampal Cognitive Map (2014, result): “Consistent with this idea, experiments have shown that place fields become distorted around barriers [32, 40].”