The Journal of Neuroscience, November 15, 2002, 22(22):10009-10017
Vestibular Information Is Required for Dead Reckoning in the Rat
Douglas G.
Wallace,
Dustin J.
Hines,
Sergio M.
Pellis, and
Ian Q.
Whishaw
Canadian Centre for Behavioural Neuroscience, University of
Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
Dead reckoning is an on-line form of spatial navigation used by an
animal to identify its present location and return directly to a
starting location, even after circuitous outward trips. At present, it
is not known which of several self-movement cues (efferent copy from
movement commands, proprioceptive information, sensory flow, or
vestibular information) are used to compute homeward trajectories. To
determine whether vestibular information is important for dead
reckoning, the impact of chemical labyrinthectomy was evaluated in a
test that demanded on-line computation of a homeward trajectory. Rats
were habituated to leave a refuge that was visible from all locations
on a circular table to forage for large food pellets, which they
carried back to the refuge to eat. Two different probe trials were
given: (1) the rats foraged from the same spatial location from a
hidden refuge in the light and so were able to use visual cues to
navigate; (2) the same procedure took place in the dark, constraining
the animals to dead reckon. Although control rats carried food directly
and rapidly back to the refuge on both probes, the rats with vestibular
lesions were able to do so on the hidden refuge but not on the dark
probe. The scores of vestibular reflex tests predicted the dead
reckoning deficit. The vestibular animals were also impaired in
learning a new piloting task. This is the first unambiguous
demonstration that vestibular information is used in dead reckoning and
also contributes to piloting.
Key words:
dead reckoning; spatial navigation and dead reckoning; spatial navigation and vestibular system; vestibular system and dead
reckoning; vestibular reflexes; food hoarding
Copyright © 2002 Society for Neuroscience 0270-6474/02/222210009-09$05.00/0
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