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How do visual cues exert stimulus control over hippocampal place cells and entorhinal head direction cells?

Research output: Contribution to conferencePosterpeer-review

Original languageEnglish
Publication statusPublished - Nov 2008
EventSociety for Neuroscience Annual meeting, 2008 - Washington DC, United States
Duration: 15 Nov 200819 Nov 2008

Conference

ConferenceSociety for Neuroscience Annual meeting, 2008
CountryUnited States
CityWashington DC
Period15/11/0819/11/08

Abstract

Visual cues help rats to maintain an internal representation of orientation. However, in a changing environment, it is important to choose the most informative cues to guide navigation. We hypothesise that cues are more informative when they maintain stable relative positions with other cues in the environment, as such stability allows the position of one cue to reliably predict the position of another.
To test this hypothesis, we recorded hippocampal CA1 place cells and entorhinal head direction cells in rats as they foraged for food pellets on a circular platform in a cue controlled environment. Four distinct visual cues were fixed onto black curtains surrounding the platform. Three of the cues made up the “stable” cue set, while the other was “unstable”. Between sessions, conflicts were introduced by changing the positions of all four cues such that only the relative relationships between the three stable cues remained fixed. The rats were given five conflict sessions per day for two days, followed by a probe day which included a session where two of the stable cues were removed, and the remaining stable cue was rotated in conflict with the unstable cue (the probe trial). This manipulation sequence was then repeated over the next three days.
CA1 cells showed partial remapping between consecutive cue conflict sessions. The cues that controlled the firing of any individual cell were not consistent between sessions. Thus, a cell might rotate with the unstable cue between sessions 1 and 2, but with the stable cues between sessions 2 and 3. Analysis of the cells that rotated between two consecutive conflict sessions revealed that, within each ensemble, the majority of cells (mean 70%) rotated coherently. For different conflict sessions, this coherent rotation followed the stable cues (44% of conflicts), the unstable cue (10%), the room cues (12%), or to an uncontrolled location (34%). During the probe trials, CA1 ensembles also rotated in a coherent fashion (80% of cells within each ensemble rotated together), but there was no preference for the stable cue.
Simultaneously recorded entorhinal head direction cells rotated coherently with each other during the cue conflict sessions and probe sessions. However, they followed a similar cue control pattern as the CA1 cells in that they followed either stable, unstable, room, or other cues in an unpredictable fashion.
Thus, contrary to our hypothesis, the set of cues that controls the activity of CA1 place cells and entorhinal head direction cells cannot be predicted by the relative stability of cues with respect to each other in a cue conflict situation.

Event

Society for Neuroscience Annual meeting, 2008

15/11/0819/11/08

Washington DC, United States

Event: Conference

ID: 18558087