Biomedical Engineering Reference
In-Depth Information
animal could be identifi ed and recorded in a photo picture. Isothermal tracking in
thermotaxis is a prominent example for using this method (Biron et al.
2006
; Mori
and Ohshima
1995
).
1.3.2
Computerized Methods
Computer-based automated regulation and image-processing methods promote effi -
ciency of assays for
C. elegans
and digging out the essence of behavioral compo-
nents. Combination of motorized stage with image-processing systems or tracking
a freely moving animal has become already conventional for recording movies of
C. elegans
behavior (Hoshi and Shingai
2006
; Ramot et al.
2008a
). Exploiting such
computational systems enabled to obtain various kinds of characters that never have
been otherwise obtained in a quantitative manner. Migration speed is one of dynamic
properties that refl ect the internal state of an animal. Speed is usually defi ned using
the center of target animal's body, namely, center of mass of the animal in a binary
image (Fig.
1.2b
). Since speed data often contain fl uctuation caused by its defi ni-
tion, one should consider managing the fl uctuation. Similar to the approach in
Sect.
1.5
, combination of speed and neuronal activity uncovers functions of specifi c
neuron or molecule (Kawano et al.
2011
).
C. elegans
uses undulatory locomotion
for migration. When we measure curvature along anterior-posterior axis, patterns of
curvature change exhibit particular behaviors: fl ows of a bend from head to tail
denote forward movement, and conversely, reverse fl ows denote backward move-
ment (Fig.
1.2c
). This curvature map can capture speed of locomotion, and it also
enables to identify typical patterns of movement like swimming (Fang-Yen et al.
2010
; Pierce-Shimomura et al.
2008
). Vast numbers of quantitative measurement
can be acquired by automated methods; it enables to illuminate the mechanisms
from macro view. For example, histogram of duration time between turns shows
exponential decrease (Fig.
1.2d
, Miyara et al.
2011
). These data would be useful for
establishing mathematical models because reliably fi tted data support hypothesis to
construct a mathematical model. Thus, automated acquisition for quantitative data
has possibility to accelerate modeling studies and it may lead to draw the integrated
view of whole behavioral regulation mechanisms.
1.4
Use of GECIs
GECIs are highly compatible with
C. elegans
studies because of transparent body,
exhaustive anatomical information, and abundant cell-specifi c promoters. Indeed,
the fi rst use of fl uorescent protein for multicellular organism has established with
C. elegans
(Chalfi e et al.
1992
). Two calcium probes are mainly used for
C. elegans
studies because of its high sensitivity. These two, Cameleons and GCaMPs, have
