Biology Reference
In-Depth Information
the surgery (it is disqualified if not able to cross for 3 consecutive
trials in a total of 15 trials). From the day after surgery trials are
repeated for 5 days, with the pegs in place, and the time taken
to cross the beam is recorded. It is taken as a successful trial if
the animal crosses the beam within 30 s. Unsuccessful trials
and the distance traveled from the starting point towards the
goal box in fifths of total length are recorded. Mice: Mice are
made to walk on a 2 mm thick wire that is held taut between
two poles (50 cm tall) 50 cm apart on a wooden platform that
is padded with soft material. This entire assembly can be placed
into a large plastic container (Fig.
4
) (see Notes 11 and 12).
2. Beam Balancing Task: The rat is made to balance at the center
of a 1 m wooden beam (1.5 cm width) that is set 1 m above the
ground (Fig.
4
). The beam is cleaned with alcohol between the
trials. The trial is carried out in the following steps: (a) timer is
set to zero and the noise generator is turned off; (b) the light
source used for the beam walking is turned off and the room
lights are turned on; (c) with the timer button in the
non-preferred hand the animal is lowered on to the center of
beam length wise and allowed to balance; (d) timer is set on;
(e) hand is held 8 in. below the beam so that the animal will
not fall to the floor; (f) if the animal balances itself for 60 s for
three trials on the day of surgery (before surgery) it qualifies
for the surgery. Three trials are repeated every day, on days 1-5
after the surgery. The duration in seconds for which the animal
balances on the beam is recorded. Unsuccessful attempts (if it
balancing for less than 60 s) are recorded.
3. Morris water maze task: The maze tank is filled with water up
to ten inches and white soluble nontoxic, tempura paint is
added to make the platform invisible (Fig.
5
). The water level
is maintained at 2 cm above the plexiform platform. The water
is maintained at room temperature. The east, north and west
of the room have a cross, triangle and circle signs and there are
lights towards the south (these signs and lights serve as visual
clues for the rats). The trials are conducted on days (11-15
after surgery). The rat is placed in the water facing the north,
south, east or west (4 trials every day) and the order of trials
every day and across the days (11-15) are randomized. The
same random order is followed every day. If the rat does not
find the platform for 120 s the rat is picked up and placed on
the platform for 30 s. Once the rat finds the platform by itself
it is left over on the platform for 30 s. The rat is given a rest of
4 min between the trials. The rat is kept warm with a heating
lamp. On the last day the rat is given two extra trials. One trial
consists of placing the rat in the south direction and without
the placement of platform and allowed to swim for 120 s. This
allows us to find the time spent in the quadrant with platform
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