Emotional and Anxiety Assessments in CNS Disorders - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 249

1.4.3. Notes

The open fi eld test provides simultaneous measures of locomotion,
exploration, and anxiety. The rodents show some risk-assessment
behaviors in the open fi eld test. The stretch attend postures indicate
a high level of anxiety. Defecation and urination are considered as
anxiety behaviors ( 10 ).

2. Cued and
Contextual Fear
Conditioning
(Emotional
Memory Task)

Fear is one of the potent emotional stimuli and is an adaptive
component of response to potentially aversive condition. Too much
memory of previous fearful experience results in many psychiatric
problems (e.g., post-traumatic stress disorder, PTSD). Cumulative
studies found that the brain circuitry is involved in the regulation
of fear condition. The amygdala circuitry was found to be crucial
in subserving fear conditioning. The lesion of amygdale profoundly
impairs the acquisition and retention of fear conditioning ( 14 ).
The hippocampus was found to be involved in the mediation
of context learning when a fearful event occurs, but there is no
conclusion of the role of hippocampus in cued or contextual fear
conditioning. It was reported that the damage of hippocampus in
rodent resulted in failure of associating cue and/or context to the
electric shock. However, several recent studies found that lesion
of hippocampus had no effect on fear conditioning memory.
The measurement in the cued and contextual fear conditioning is
a freezing behavior that occurs following pairing of an uncondi-
tioned stimulus (US), such as electric foot shock to a conditioned
stimulus (CS), such as a familiar environment or the presence of a
particular tone.
Fear conditioning is a highly conserved form of behavior, so it
has been widely used in laboratory rodents. In clinical pratice, fear
conditioning has been used as a model for PTSD, although this
model is still diffi cult to account for some syndromes of PTSD in
human.
Overall, fear conditioning is a useful behavioral model to study
on the formation and recall of emotional memory.

The size of the conditioning chamber varies. Typical size is
26 × 21 × 10 cm. The grid fl oor is made of stainless steel rods
1.5 mm in diameter and spaced 0.5 cm for mice or 1.2 cm for rats.
The chamber is constructed to be easily cleaned and can be viewed
from outside. The inside of the sound-attenuating chamber has a
fan to circulate air, light, and speaker. The exactly same chamber
must be used for contextual conditioning. If the chamber is also
used for cued conditioning, it is important for the chamber to be
easily changed to another context, which involves changes in the
fl oor (e.g., wire grid, materials), inside dimension, or odor by using
food essence. Shock generator and scrambler, which deliver 0.1- to

2.1. Materials
and Equipment