Coherence among Head Direction Cells before Eye Opening in Rat Pups
Bjerknes, Tale L.; Langston, Rosamund Fay; Kruge, Ingvild Ulsaker; Moser, Edvard Ingjald; Moser, May-Britt
Journal article, Peer reviewed
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http://hdl.handle.net/11250/2388206Utgivelsesdato
2014Metadata
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Sammendrag
Mammalian navigation is thought to depend on an internal
map of space consisting of functionally specialized cells
in the hippocampus and the surrounding parahippocampal
cortices [1–7]. Basic properties of this map are present
when rat pups explore the world outside of their nest for
the first time, around postnatal day 16–18 (P16–P18) [8–
10]. One of the first functions to be expressed in navigating
animals is the directional tuning of the head direction cells
[8, 9]. To determine whether head direction tuning is
expressed at even earlier ages, before the start of exploration,
and to establish whether vision is necessary for the
development of directional tuning, we recorded neural
activity in pre- and parasubiculum, or medial entorhinal
cortex, from P11 onward, 3–4 days before the eyelids
unseal. Head direction cells were present from the first
day of recording. Firing rates were lower than in adults,
and preferred firing directions were less stable, drifting
within trials and changing completely between trials. Yet
the cells drifted coherently, i.e., relative firing directions
were maintained from one trial to the next. Directional tuning
stabilized shortly after eye opening. The data point to
a hardwired attractor network for representation of head direction
in which directional tuning develops before vision
and visual input serves primarily to anchor firing direction
to the external world.