Unpacking the cognitive map: The parallel map theory of hippocampal function.

Abstract

In the parallel map theory, the hippocampus encodes space with 2 mapping systems. The bearing map is constructed primarily in the dentate gyrus from directional cues such as stimulus gradients. The sketch map is constructed within the hippocampus proper from positional cues. The integrated map emerges when data from the bearing and sketch maps are combined. Because the component maps work in parallel, the impairment of one can reveal residual learning by the other. Such parallel function may explain paradoxes of spatial learning, such as learning after partial hippocampal lesions, taxonomic and sex differences in spatial learning, and the function of hippocampal neurogenesis. By integrating evidence from physiology to phylogeny, the parallel map theory offers a unified explanation for hippocampal function.

Comparative Cognition, Hippocampal Function, and Recollection

“…Many of these studies have been interpreted as supporting the notion that the hippocampus is selectively involved in spatial cognition and, in particular, in the creation and use of cognitive maps (Bingman, Ioale, Casini, & Bagnoli, 1988;Sherry, Jacobs, & Gaulin, 1992;Salas, Broglio, & Rodriguez, 2003;Jacobs & Schenk, 2003). However, this interpretation is challenged by several of the studies outlined above that demonstrate a critical role for the hippocampus in a variety of non-spatial memory tasks.…”

Metabolic Activation Pattern of Distinct Hippocampal Subregions during Spatial Learning and Memory Retrieval

“…Then a substantial improvement in performance starting from day 5 up to day 9 of training was observed. It is purported that such enhanced performance could be because of the establishment of a so-called cognitive map (O'Keefe and Nadel, 1978) with a complementary role of the dentate/CA3 and CA1 modules (Jacobs and Schenk, 2003). Such a map could be created by extraction of episodic information across the numerous trials of the task.…”

Spatial memory: are lizards really deficient?

“…Although previous studies have determined that lizards can use sun compass cues for orienting [5], it is unclear whether they can use visual cues as well. Two studies have claimed demonstration of spatial memory using visual cues in snakes [6,7]; however, the methodology of those studies has been criticized [2,3]. Specifically, these studies used only one distal intramaze cue, and snakes were oriented towards that cue during the trials; thus, snakes could have been using egocentric encoding of the cue rather than true spatial memory.…”