Biology Reference
In-Depth Information
This test measures the number of arms entered and the sequence
of entries. A high alternation rate suggests the presence of preserved
cognition. Measured parameters include (a) the fi rst arm entered—
the animal should enter the previously blocked arm fi rst on the sec-
ond trial; (b) amount of time spent in each arm; and (c) total number
of arm entries (rats (
94, 99
); mice (
95, 97
); and monkeys (
107
)).
Rats, mice, pigs, cats, and monkeys have been evaluated in T-mazes
to study cognition, short-term memory, and spatial working mem-
ory. In rodents, normally, on the second trial, the initially unvisited
arm should be visited fi rst (spontaneous alternation).
The tested animal is started at the base of the T-shaped maze
and allowed to enter one goal arm with the other arm being closed.
The second trial is given in quick succession with both arms open.
Different varieties of the test have been utilized (particularly for
pigs and cats), adding L-shaped returns to the construction of the
maze, additional trials, and various delays to test various aspects
of memory and cognition (mice (
97, 108
); rats (
94, 99
); pigs
(
109, 110
); cats (
111
); and monkeys (
112, 113
)).
6.7. T-Maze
6.8. Other Types
of Mazes
A number of protocols utilizing context conditioning can be per-
formed with the above-mentioned and other types of mazes [e.g.,
zero maze, cross-maze, elevated-plus maze (EPM), and 3D maze]
to test different aspects of cognition, memory, and anxiety in rats,
mice, and pigs (mice (
92, 114, 115
); rats (
94, 99
); rats and mice
(
95
); pigs (
116
); and primates (
117, 118
)). An original 12-section
maze has been used by Jansen et al. (
119
) to evaluate spatial mem-
ory in pigs. An original “triple T water maze” was successfully used
by Hammel et al. (
120
) in pigs. Virtual computer mazes allowing
concurrent imaging of the brain have been utilized in monkeys for
various aspects of memory and problem solving (
121-123
).
The passive avoidance learning paradigm has been used to assess
memory and learning to avoid noxious stimuli in rodents and mon-
keys. A rat or mouse is placed in the cage consisting of two compart-
ments: one painted white and another—black. The fl oor of the black
compartment can be electrifi ed to provide mild foot shock. Rats and
mice naturally prefer a dark compartment, but they must learn to
avoid a mild aversive stimulus (in this case, mild foot shock) by
remaining in the well-lit side of a two-chamber apparatus and not
entering the dark, where it receives the aversive stimulus. Measures
for passive avoidance learning in rodents include escape/avoidance
latencies and percentage of failures in test and control groups.
Monkeys are presented with aversive or potentially dangerous
stimuli (e.g., rubber snake, syringe, capture net, or large doll
“staring” forward) and a range of fear-related behaviors, including
defensive behavior, tension behavior, body postures, gaze direction,
etc., are recorded (rats (
52, 94
); mice (
92, 97, 114
); and monkeys
(
124, 125
)).
6.8.1. Passive Avoidance
Learning
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