Assessments of Cognitive Function Following Traumatic Brain Injury - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 219

2.3. Water T-Maze

The water T-maze has been used in TBI research to investigate
working memory defi cits. However, it should be noted that the
T-maze has been used less frequently than the traditional MWM
tasks described above and thus one standard protocol has not been
established. Two similar protocols have been used to investigate
impairments in the initial stages of memory processing and forma-
tion (working memory) using the water T-maze. In the fi rst proto-
col published by Milman et al. ( 19 ), signifi cant impairments in
working memory were reported at 30 days post-injury following
mild-weight-drop injury. The second protocol used a variant of
the DNMP (Delayed Non-Matching to Place) tasks to investigate
delay dependent memory impairments in TBI ( 20 ). This study
found that lateral-FPI of moderate severity produced delay depen-
dant memory impairment similar to than observed in human TBI.
Below we will present the detailed procedures reported by Whiting
and Hamm ( 20 ). More studies confi rming the results of the above
studies in other injury models are needed.

A T-maze is constructed of clear Plexiglass, with an inside width of
10 cm and a height of 40-50 cm. The T-maze is submerged in a
standard MWM tank (180 cm × 45 cm) with opaque water. The stem
of T-maze is approximately 70 cm long, and the crosspiece 140 cm
long, so that each arm of the T is 70 cm. Located at the end of each
arm in the T are removable goal platforms (5 cm). The T-maze is
submerged in opaque water at a depth that leaves the goal platform
1 cm below the water. A removable Plexiglass divider is necessary
to block off arms of the crosspiece.

2.3.1. Water T-Maze:
Apparatus

Using the water T-maze, animals undergo training in a variant of
the DNMP task. Beginning at 10 days post-injury, all animals are
habituated to the water T-maze 1 day prior to testing. During
habituation, animals are trained to reliably swim down the stem of
the T-maze to fi nd the goal platform at the end of the maze and
required to remain on the platform for 30 s.
Habituation training is followed by 5 days of acquisition training,
with 15 trials per day, in a forced choice/free choice alteration
paradigm. Each acquisition trial is divided into two stages, a sample
(forced choice) phase followed by a test (free choice) phase. At the
start of each trial, goal platforms are located at the end of each arm,
but the divider is inserted so that the animal is forced to swim in to
the open arm. Once the animal has reached the platform, it is
picked up and returned to the starting area to begin the choice
phase of the trial. Between the sample and choice phase, the exper-
imenter removes the divider and the goal platform from the arm to
which the rat previously swum. The platform in the previously
blocked arm remains in place. The delay between the forced and
free choice trials during acquisition is typically 10 s. On the test
run, the animal is rewarded for swimming to the arm opposite
to that swam in the forced choice trial. The animals are deemed to

2.3.2. Water
T-Maze-DNMP: Procedure