Biology Reference
In-Depth Information
of the whole organism. Discrete animal behavioral assays are used
to test hypotheses about anatomical, neurochemical, neurophysi-
ological, and genetic substrates of behavior (
9, 10
). Many neuro-
muscular and psychiatric disorders exhibit characteristic behavioral
and sleep-related phenotypes. The application of behavioral assays
that examine or model specifi c symptoms of neurological or psy-
chiatric disorders is now a critical part of the development of new
central nervous system (CNS) therapeutic treatments in vivo.
Appropriate animal behavioral testing and paradigms are essential
for translational research that moves drug discoveries at the molec-
ular level toward clinical developments.
1.2. Current
Methodologies and
Technologies Used for
Monitoring Rodent
Spontaneous Activities
Direct human observation has been commonly used. Rodent home
cage-side assessments are often made in preliminary or initial stud-
ies by direct human observations. However, the presence of the
investigator near the home cage is likely to disrupt or infl uence
normal spontaneous activity (
11, 12
). Moreover, rodents are noc-
turnal species. Spontaneous activity is higher during the dark phase
of the circadian cycle than during the light phase. Therefore, it is
best observed by videotaping or infrared charge-coupled device
(CCD) camera recording the animal housing facility, and subse-
quently scored by the investigator in a blind manner. However, a
direct real-time behavioral observation or via offl ine video assess-
ment is laborious, time consuming, and often subjective. Video
cameras with computer-based image tracking systems have been
developed. Some sophisticated algorithms have also been refi ned
to increase the accuracy in respect with human scoring (
13-16
).
Most technologies employed for motor activity detection are
infrared (IR) motion detectors, photocell-based sensors, force bal-
ance and vibration sensors with transducers. These technologies
enable monitoring of rodent activity, movement, and positional
localization. A behavior registration system marketed as Laboratory
Animal Behavior Observation, Registration and Analysis System
(LABORAS™, Metris) uses a vibration sensor platform to record
vibrations evoked by animal movements, and the LABORAS soft-
ware translates these into the corresponding behaviors. This system
has been shown to be able to automatically register eating, drink-
ing, resting, and locomotion of mice or rats and can detect pharma-
cologically induced changes in behavior (
17
). It has not been shown
to measure sleep or other abnormal activity such as seizures.
Electroencephalograph and electromyograph monitoring is
the gold standard technology for monitoring sleep. Currently,
sleep is not routinely measured in animals subject to various drug
treatments, disease models, or genetic alteration partly due to the
diffi culty associated with the use of EEG and EMG. Analysis of
sleep/wake patterns in rodents requires extensive surgery, recov-
ery, attachment of wires or invasively implanted transmitters
during experiments, and extensive analysis of the resulting EEG
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