A rodent model for detection of oxygen based explosives and propellants
Marina Vilardo, Ben Katz and Kimberly Kirkpatrick
Rearing response (RR) training, and search and
odor detection (SOD) training:
Butyric acid group (n = 4) and MEK group (n = 4)
Phase
Pre-Training
RR1
RR2
Baseline
SOD1a/SOD1b
SOD2
SOD3
Description
Acclimation to the apparatus
Shaping of the rearing response
Target odor training (with sucrose)
Target odor alone; 6 sessions x 6 trials
Target + one distracter odor; 8 sessions x 6 trials
Target + 2 distracter odors; 8 sessions x 6 trials
Target + 5 distracter odors; 8 sessions x 6 trials
Results (Continued)
80
H (Butyric acid)
FA (Propionic acid)
FA (Acetic acid)
FA (MEK)
FA (Acetone)
FA
A ((Hydrogen
d
peroxide)
id )
FA (empty)
60
40
20
0
Percent Hits/False Alarms
80
60
H (Butryic acid)
FA (empty)
40
20
100
Peercent Hits/False Alarmss
Baseline: Butyric acid
100
Baseline: MEK
80
60
H (MEK)
FA (empty)
40
20
0
1
2
3
4
5
6
3
4
5
6
Sessions
Sessions
Figure 1. Rats in both groups showed initial false alarms to empty cups, but
by Session 3 were performing at a high level of accuracy in identifying the
target odor.
0
1
2
SOD 1a: Butryic acid
100
80
60
H (Butyric acid)
FA (Acetic acid)
40
FA (empty)
20
100
SOD 1a: MEK
80
60
40
H (MEK)
FA (Acetone)
FA (empty)
20
0
1 2 3 4 5 6 7 8
4 5 6 7 8
Sessions
Sessions
Figure 2. Both the groups showed initial false alarms to the novel distracters,
but then acquired high hit rates by the end of SOD 1a. There were very few
false alarms to empty cups.
0
1
2
3
SOD 3: MEK
80
60
40
20
H (MEK)
FA (Acetone)
FA (Hydrogen peroxide)
FA (Butyric acid)
FA (Propionic acid)
FA (A
(Acetic
i acid)
id)
FA (empty)
0
4 5 6 7 8
1 2 3 4 5 6 7 8
Sessions
Sessions
Figure 3. During the final test phase (SOD 3) with all five distracters, both
groups maintained high-level accuracy, showing few false alarms even to the
novel odors from the other group of compounds. This indicates that the rats
can generalize
li their
th i performance
f
to
t the
th target
t
t compounds
d even when
h
challenged with novel distracters.
1
Results
100
Percent Hits/False Alarms
SOD 3: Butyric Acid
100
Percent Hits/False Alarms
Apparatus:
•4 x 4 (16 holes) open field maze
matrix with four entry doors
•Cups recessed in the holes
•Randomly selected cup(s) contained
a vial with an odor-infused
odor infused cotton
ball
•All cups filled with bedding
Perccent Hits/False Alarms
Method
Method (Continued)
Perccent Hits/False Alarms
Introduction
Explosives containing peroxide, such as acetone
peroxide and methyl ethyl ketone peroxide (MEKP)
have been used in a number of recent terrorist attacks.
Liquid explosives and explosives buried in plastic
containers, such as improvised explosive devices
(IEDs) used by insurgents in Afghanistan,
Afghanistan are hard to
detect with metal detectors. Currently the Hero Rat
project (www.herorat.org) uses Gambian pouched rats
to search and alert for buried landmines in several
African countries. Previous studies have shown that
laboratory rats can be trained to detect nitrogen-based
explosive
l i odors
d (Marshall,
(M h ll Doty,
D
L
Lucero, and
d Slotnick,
Sl i k
1981; Nolan, Weinstein, and Weinstein, 1978;
Weinstein, Weinstein, and Drozdenko, 1992), and
contraband items (Otto, Brown, and Long, 2002). The
present study examined the ability of Sprague-Dawley
rats to successfully
y search, discriminate, and alert for
several explosives and propellants - Butyric acid
(10%), Propionic acid (10%), Acetic acid (10%), MEK
(10%), Acetone (20%), and Hydrogen peroxide (20%).
KANSAS STATE UNIVERSITY
2
3
Conclusions
The present results indicated that laboratory rats can be
trained to detect and discriminate among substances
that are relatives of ingredients
g
used in liquid
q
explosives. Initially, the rats made false alarm errors to
empty cups (Figure 1) and to the first distracter odor
(Figure 2) they encountered. However, with a
relatively small amount of training (18-36 trials), they
were able to inhibit errors and display a high hit-rate
for both targets.
targets Once they had learned to inhibit false
alarms in SOD 1a (Figure 2), they were able to transfer
their training to previously non-presented odors
(SOD3; Figure 3). The results indicate that laboratory
rats are a potentially viable model for training search
and alert behaviors for oxygen-based explosives.
R f
References
Marshall, D., Doty, R., Lucero, D., & Slotnick, B. (1981). Odor detection in the rat for the vapours of three related perflourocarbons and
ethylene glycol dinitrate. Chemical Senses, 6, 421-433.
Nolan, R., Weinstein, S., & Weinstein, C. (1978). Electroencephalographic studies of specifically-conditioned explosives detecting rats.
In: Proceedings of the New Concepts Symposium and Workshop on Detecting and Identification of Explosives, pp. 201-205.
Otto, J., Brown, M. F., & Long III, W. (2002). Training rats to search and alert on contraband odors. Applied Animal Behaviour Science,
77, 217-232.
Weinstein, S., Weinstein, C., & Drozdenko, R. (1992). The challenge of biodetection for screening persons carrying explosives. In:
Proceedings of the First International Symposium on Explosive DetectionTechnology. FAA Technical Center, Alantic City
International Airport, NJ.
Correspondence may be addressed to Kimberly Kirkpatrick (kirkpatr@ksu.edu) or Marina Vilardo (chaton@ksu.edu), Department of Psychology, Kansas State University, Manhattan, KS 66506