title: The head-direction signal is critical for navigation requiring a cognitive map but not for learning a spatial habit.
abstract: Head-direction (HD) cells fire as a function of an animal's directional heading in the horizontal plane during two-dimensional navigational tasks [1]. The information from HD cells is used with place and grid cells to form a spatial representation (cognitive map) of the environment [2, 3]. Previous studies have shown that when rats are inverted (upside down), they have difficulty learning a task that requires them to find an escape hole from one of four entry points but that they can learn it when released from one or two start points [4]. Previous reports also indicate that the HD signal is disrupted when a rat is oriented upside down [5, 6]. Here we monitored HD cell activity in the two-entry-point version of the inverted task and when the rats were released from a novel start point. We found that despite the absence of direction-specific firing in HD cells when inverted, rats could successfully navigate to the escape hole when released from one of two familiar locations by using a habit-associated directional strategy. In the continued absence of normal HD cell activity, inverted rats failed to find the escape hole when started from a novel release point. The results suggest that the HD signal is critical for accurate navigation in situations that require a flexible allocentric cognitive mapping strategy, but not for situations that utilize habit-like associative spatial learning.
authors.affiliation: Department of Psychology, University of New Hampshire, Durham, NH 03824, USA.
authors.forename: Brett
authors.initials: B
authors.lastname: Gibson
authors.forename: William N
authors.initials: WN
authors.lastname: Butler
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Taube
mesh_terms: D000200:Action Potentials; D000818:Animals; D020643:Anterior Thalamic Nuclei / Q000502:physiology*; D003071:Cognition; D005260:Female; D007858:Learning; D009043:Motor Activity; D009949:Orientation; D051381:Rats; D020318:Rats, Long-Evans; D013028:Space Perception
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