Biology Reference
In-Depth Information
Animal moving paths and rotations
: Movement pattern and
regional distribution can also be tracked by IR detection with the
SmartCage™ system. Travel in different zones (the analysis pro-
gram can divide the home cage fl oor between 2 and 12 zones), the
times spent in different zones, and the distance traveled in each
zone are automatically calculated and used as indicators to assess
the structure of locomotor activity. In wakeful state, the locomotor
activity of mice presented obvious regional and temporal proper-
ties. Mice preferred to stay in zones where food and water are
provided, and frequently visit the peripheral zones in a cycling
manner, but seldom the center zones within a 24-h period.
One cycling or rotation of the mouse's movement can also be
calculated using a three-point egocentric method of reference along
the
x-
and
y
-axis and achieved by the accumulated 360° turn.
Circling behavior starting from the mouse's right side (i.e., clock-
wise) is designated as (+) positive direction, while left turning, is
anticlockwise cycling and is designated (−) negative direction. The
net rotation is the summation of the left and right circling with (−)
and (+) indicating predominant left and right rotation, respectively
in the chosen time block. In normal animals the net rotation is close
to zero. In animals treated with the NMDA antagonist MK-801
there is a clear difference in the movement patterns when compared
to vehicle controls (Fig.
4
). This difference in circling pattern is also
evident in certain disease models. For example, in the mouse stroke
model of middle cerebral artery (MCA) occlusion the animal pre-
dominantly cycled in one direction depending on which side of the
MCA was occluded. As a note, the SmartCage™ system can only
record an animal making large cycles but not turning in the same
place due to the limitations of spatial resolution (data not shown).
Sleep or inactive
: Mice show obvious circadian variation of activity as
they are more inactive/asleep (60-70%) in the day and more active/
awake during the night. The SmartCage™ system is capable of indi-
rectly detecting sleep using the fl oor-sensor. During sleep, the
rodent's chest lies fl atly on the fl oor and makes regular respirations
(2.5-3 Hz, for mice) which can be detected by the fl oor-sensor in
the SmartCage™ system. The regular and smaller waveforms act as
a sleep biomarker (
21, 24
). In our initial validation experiments,
simultaneous EEG/EMG recordings were conducted in the same
mice (
n
= 7) while they were monitored by the SmartCage™ fl oor-
sensor system. The analog EEG and EMG signals were amplifi ed
and fi ltered and then AD-converted at 128 Hz.
Electroencephalograph signals were subjected to fast-Fourier
transformation (FFT) analysis yielding power spectra between 0.5
and 40.0 Hz, with a 0.5-Hz frequency resolution every 2 s, and
then averaged every 10 s. The total sleep including both rapid eye
movement (REM) and slow wave sleep (SWS) was determined by
manual scoring of the EEG/EMG signals in 10-s segments. The
results based on EEG/EMG signals were used to validate auto-
matic sleep scoring using fl oor-sensor recordings. The SmartCage™
Search WWH ::
Custom Search