Object recognition test in mice paper 2013

2014-12-08

Object recognition test in mice paper 2013

Marianne Leger1,3, Anne Quiedeville1,3, Valentine Bouet1, Benoît Haelewyn2, Michel Boulouard1, Pascale Schumann-Bard1 & Thomas Freret
France Nature protocols 2013 paper

The objects in their paper are about 8-cm high and 3.2-cm wide and 9.5 cm high, 2.5 cm deep, and 3.2 cm wide
They used legos and a tissue culture flask filled with sand.

a mouse is presented with two
similar objects during the first session, and then one of the two objects is replaced by a new object during a second session.
the amount of time taken to explore the new object provides an index of recognition memory.
with a short intersession interval
(e.g., 6 h), this procedure can be performed in 4, 2 or 1 d, respectively, according to the duration of the habituation phase.
the measure of the absolute time
spent exploring each object during each session (a fixed duration
of classically 3 or 5 min)
Access to novelty (e.g., an object or an environment) can elicit
approach behaviors in rats.
Thus, a rodent that remembers the familiar object will spend
more time exploring the novel object.
However, mice are not little rats and
thus may neither behave in a similar way nor use similar strate-
gies
An additional variation is whether or not a habitu-
ation phase is performed. Some protocols preface the test phase
with a habituation phase to the apparatus and to the procedure
to reduce stress and to avoid a potential neophobic response
the use of a 3-d habituation phase
has been the most commonly used in mice
It consists of expo-
sure to an open-field apparatus twice a day for 3 d before the test
(3 min for each session). A shorter habituation phase, consisting
of a single exposure to the apparatus, has also been proposed16,22
but its usefulness remains a matter of debate.
For example, the maximal ISI duration for observ-
ing significant performances between different strains of mice
was limited to 4 h in the protocol of Sik et al.20, whereas it was
24 h for Frick and Gresack
the habit-
uation phase consists of two 5-min exposures to the apparatus per
day separated by 6 h, during 3 d before the test phase
As rodents have difficulty in discriminating colors, the experi-menter should focus on the brightness and texture of the objects
In the experiments reported here, we used common objects that
differ in shape and texture; both of these objects can be climbed
onto by mice, and both stand out against the background: towers
of Lego bricks (8-cm high and 3.2-cm wide, built in white, blue,
yellow, red and green bricks) and Falcon tissue culture flasks filled
with sand (9.5 cm high, 2.5 cm deep and 5.5 cm wide, transparent
plastic with a blue bottle cap)
mice were housed in a reversed light-dark cycle and were
always tested in the dark phase (active phase between 08:00 and
20:00). The familiarization session was always carried out during
the morning (from 09:00).
Here we chose to
score object exploration whenever the mouse sniffed the object
or touched the object while looking at it (i.e., when the distance
between the nose and the object was less than 2 cm)
Climbing
onto the object (unless the mouse sniffs the object it has climbed
on) or chewing the object does not qualify as exploration.
acknowledging that
rodents explore primarily by sniffing, video-tracking systems based
on nose-point detection are more reliable than packages based on
the center point of the animal
Adjust the luminosity of the room to obtain 15 lux in the center
of the open field
video camera placed above the arena.
The experi-
menter should be at least 1 m from the open field so that the mouse cannot
see him or her directly
necessary to reach the 20-s criterion of total exploration
maximum session time).
the open field with 70% (vol/vol) ethanol to minimize
olfactory cues.