Si. Wiener et al., INERTIAL, SUBSTRATAL AND LANDMARK CUE CONTROL OF HIPPOCAMPAL CA1 PLACE CELL-ACTIVITY, European journal of neuroscience, 7(11), 1995, pp. 2206-2219
Hippocampal 'place cells' discharge when a rat occupies a location tha
t is fixed in relation to environmental landmarks. A principal goal of
this study was to determine whether hippocampal place cell activity c
ould be influenced by inertial cues. Water-deprived rats were trained
in a square-walled open field in a dark room. The behavioural task req
uired alternating visits to water reservoirs in the centre and in the
four corners of the arena. The rat and arena were rotated in total dar
kness through +/-90, 180 or 270 degrees. The next water reward was the
n presented in the corner at the same position relative to the outside
room as before the rotation. A cue card was later illuminated in this
corner as a visual cue for the extra-arena (room) reference frame. fi
fteen out of 97 recorded hippocampal CA1 complex spike cells had spati
ally selective discharges in non-central parts of the arena. After are
na rotations, the firing fields of three units shifted between corners
of the arena to maintain a fixed orientation relative to the room. Th
is indicates that the hippocampus updated its representation of the po
sition and heading direction of the rat using vestibular-derived input
s concerning rotation angle. Other spatially selective discharges were
guided to landmark cues (cue card or position of the reward: two unit
s) or arena-locked 'substratal' cues (eight units). In six cells, plac
e cell activity suddenly ceased or appeared following rotations. These
results provide evidence for contributions of inertial as well as sub
stratal and landmark information to hippocampal spatial representation
s.