Interpretation of results of learning and
memory test batteries in mice: Is it
intelligence or anxiety, locomotion,
body weight, visual acuity, deafness
that we are measuring??
Richard E. Brown
Psychology Department,
Dalhousie University,
Halifax, Nova Scotia, Canada
Mouse models of Alzheimer Disease: Behavioural and
Neurological Studies
Mutation
APP V717F
Behavioural observations
impairment in radial arm maze
and object recognition
Neurological observations
Aβ-deposition; NFTs;
synaptic loss; astrocytosis and
microgliosis
Reference
Games et al.,
1995
APP London
decreased exploration; increased
neophobicisty; increased male
aggression
amyloid plaques
cerebrovascular angiopathy;
cholinergic fiber distortion
Moechars et al.,
1998
APP/RK
noephobicity; premature death
none reported
Moechars et al.,
1996
Tg C3-3
early impairment in acquiring
and learning Morris water maze.
Aβ-deposition; dystrophic
neurites
Borchelt et al.,
1996
Tg CRND8
none reported
Aβ-deposition; neuritic
pathology
Chishti et al.,
2001
Tg APPswe K1
none reported
human-like Aβ-deposition
Reaume et al.,
1996
APP96-YAC
none reported
none reported
Lamb et al., 1997
APPR1 40-YAC
none reported
elevated Aβ peptides
Lamb et al., 1997
NORBA
none reported
elevated Aβ peptides
Kawarab….
Examples of projects in my laboratory (2002)
1. MHC-congenic mice differ in anxiety and locomotor behaviour but not in learning
and memory. [Behavior Genetics, 1999, 29, 263 – 271.]
2. p75-NGF receptor knockout mice show age-related decline in learning and memory.
[Neurobiology of Aging, 2000, 21, 125 – 134.]
3. CD-1 mice. Effects of Ritalin on behavioural development. [Developmental
Psychobiology, 2001, 39, 216 – 228.]
4. C57BL/6J mice. Sex differences in effects of diazepam on avoidance learning.
[Pharmacology, Biochemistry and Behavior, 2002, 72 (1-2), 13 – 21.]
5. C57BL/6J vs DBA/2J: differences in anxiety, locomotor behaviour and learning and
memory. [Genes, Brain and Behavior, 2002, 1, 96-110.]
6. C57BL/6J vs DBA/2J: differences in hypothalamic structure and in parental
behaviour. [Brain Research, 2002, 952, 170 - 175.]
Examples of projects in my laboratory (cont.)
7. HS mice: Genetic and behavioural differences. [Neuroscience Abstracts, 2001, 31,
Abstract # 536.5.]
8. Colobomo mice: a mouse model of ADHD?
9. SHR rats: a rat model of ADHD? NeuroReport, 2003, 14, 769-772.
10. Cholinergic basal forebrain lesions in rats and mice (IgG sapporin): a model of
Alzheimer’s disease? A behavioural and histological analysis. Canadian Society for
Brain, Behaviour and Cognitive Science (CSBBCS) June 2003.
11. A phenotypic and molecular characterization of the fmr1-tm1Cgr Fragile X
mouse. Submitted to Genes, Brain and Behavior 2003.
12. Strain differences in response to pain.
13. JAX Phenome Project: Differences in anxiety, locomotor
behaviour and spatial learning in 14 strains of mice.
Strain
Type
MPDGroup
JAX Number
Hearing
Vision
129S1/SvImJ
IN
A
JAX 002448
Deaf
A/J
IN
A
JAX 000646
Deaf before 3 months
AKR/J
IN
B
JAX 000648
BALB/cByJ
IN
A
JAX 001026
BALB/Cj
IN
A’
JAX 000651
C3H/HeJ
IN
A
JAX 000659
C57BL/6J
IN
A
JAX 000664
Deaf after 16 months
CAST/Ei
WD
A
JAX 000928
Normal
DBA/2J
IN
A
JAX 000671
Deaf before 3 months
FVB/NJ
IN
A
JAX 001800
Pde66rd1
MOLF/Ei
WD
B
JAX 000550
Rd gene
SJL/J
IN
A
JAX 000686
Pde66rd1
SM/J
IN
B
JAX 000687
SPRET/Ei
WD
A
JAX 001146
Deaf after 16 months
Pde66rd1
Normal
PEOPLE IN OUR LAB
Developmental Tests
Learning & Memory
Teena Chase
Ria Neish
Karman Lock Carissa Martin
Alexa MacKay Darryl Babin
Autumn Mochinski
Heather Schellinck Aimee Wong
Lianne Stanford
Lisa Currie
Jordan Braun
Tim O’Leary
Ethological Tests
Research Assistants
Anna Lee
Tim Bredy
Tamara Bond
Mandi Arnold Rhian Gunn
Jenn Dixon
Vicki Savoie
American Psychologist, 1961, 16, 681-684
THE MISBEHAVIOR OF ORGANISMS
KELLER BRELAND AND MARIAN BRELAND
Animal Behavior Enterprises, Hot Springs, Arkansas
In our attempt to extend a behavioristically oriented approach to the engineering
control of animal behavior by operant conditioning techniques, we have fought a
running battle with the seditious notion of instinct. It might be of some interest to
the psychologist to know how the battle is going and to learn something about the
nature of the adversary he is likely to meet if and when he tackles new species in
new learning situations.
Thirty-eight species, totaling over 6,000 individual animals, have been conditioned,
and we have dared to tackle such unlikely subjects as reindeer, cockatoos, raccoons,
porpoises, and whales.
Emboldened by this consistent reinforcement, we have ventured further and further
from the security of the Skinner box. However, in this cavalier extrapolation, we
have run afoul of a persistent pattern of discomforting failures. These failures,
although disconcertingly frequent and seemingly diverse, fall into a very interesting
pattern. They all represent breakdowns of conditioned operant behavior.
The raccoon and the bank
A second instance involves a raccoon. The response
concerned the manipulation of money by the raccoon
The contingency for reinforcement was picking up the
coins and depositing them in a 5-inch metal box.
Raccoons condition readily, have good appetites, and
this one was quite tame and an eager subject. We anticipated no trouble. We started out by reinforcing him for
picking up a single coin. Then the metal container was
introduced, with the requirement that he drop the coin
into the container. Here we ran into the first bit of
difficulty: he seemed to have a great deal of trouble
letting go of the coin. He would rub it up against the
inside of the container, pull it back out, and clutch it firmly for several seconds. However, he
would finally turn it loose and receive his food reinforcement. Then the final contingency: we put
him on a ratio of 2, requiring that he pick up both coins and put them in the container.
Now the raccoon really had problems (and so did we). Not only could he not let go of the
coins, but he spent seconds, even minutes, rubbing them together (in a most miserly fashion), and
dipping them into the container. He carried on this behavior to such an extent that the practical
application we had in mind—a display featuring a raccoon putting money in a piggy bank—
simply was not feasible. The rubbing behavior became worse and worse as time went on, in spite
of nonreinforcement.
Breland & Breland 1961, pg 681-682
60
50
Time to platform (sec)
129S1
C57BL/6J
40
30
MORRIS WATER MAZE
20
10
0
Acq 1
Acq 2
Acq 3
Rev 1
Rev 2
Rev 3
A. Latency to escape platform. Latency decreased over days for both strains [F(5, 320) = 40.56, p < 0.0001];
129S1 mice had a greater latency on reversal day 1 than C57BL/6J mice [F(5, 320) = 6.44, p < 0.0134].
30
129S1
Quadrant duration (sec)
25
C57BL/6J
20
15
10
5
0
Correct
Opposite
Right
Left
B. Time spent searching escape platform in each quadrant on the probe trial. Both 129S1 and C57BL/6J mice
spent more time in the correct quadrant than the other quadrants [F(3, 192) =16.29, p < 0.0001].
MORRIS WATER MAZE
Acq 1
Acq 2
Acq 3
Rev 1
Rev 2
C3H/HEJ
C57BL/6J
Rev 3
60
50
Latency (sec)
40
30
20
10
0
129S1
A/J
Balb/cByJ
Molf/Ei
SJL/J
Different strains have significantly varied patterns of spatial learning
over both acquisition and reversal training days.
MORRIS WATER MAZE
40
35
Quadrant duration (sec)
30
25
129S1
A/J
AKR/J
Balb/cByJ
BALB/CJ
C3H/HEJ
C57BL/6J
Cast/Ei
DBA/2J
FVB/NJ
Molf/Ei
SJL/J
SM/J
SPRET/EI
There are
significant strain
differences for
time spent in
each quadrant
(p<0.0001)
Cfp1-J
20
15
10
5
0
Correct
Opposite
Right
Left
Vision Task - C57BL/6J N = 4 (2 male, 2 female) (13 - 16 weeks)
Visual Discrimination
100
80
% Correct
005 (f)
006 (f)
60
019 (m)
40
020 (m)
20
0
1
2
3
4
5
6
7
8
Days
Pattern Discrimination
Cell Sum for % Correct PDisc
100
80
005 (f)
60
006 (f)
019 (m)
40
020 (m)
20
0
1
2
3
4
5
6
7
8
Days
Visual Acuity
100
005 (f)
60
006 (f)
40
019 (m)
020 (m)
20
0
Spatial Frequency
0.67
0.64
0.62
0.57
0.55
0.53
0.43
0.32
-20
0.17
% Correct
80
Probe trial
d
100
60
80
50
DBA/2J
1400
100
1200
80
1000
40
60
800
60
600
40
30
40
20
20
200
0
0
Acq 1 Acq 2 Acq 3 Rev 1 Rev 2 Rev 3
0.64
0.62
0.57
0.55
0.53
0
0.43
0
0.32
10
0.17
20
400
% time in correct quad
Acq 1 Acq 2 Acq 3 Rev 1 Rev 2 Rev 3
h
100
60
80
50
100
1400
1200
80
1000
40
60
60
800
30
600
40
20
400
10
200
40
20
20
60
80
50
40
60
30
100
1200
80
1000
60
800
600
40
20
20
0.64
0.62
0.57
0.55
0.53
0.43
20
200
0
0
0.32
40
400
10
0
% time in correct quad
Rev 1 Rev 2 Rev 3
1400
Distance (cm)
0.64
0.62
0.57
0.55
0.53
0.43
0.32
0.17
Acq 1 Acq 2 Acq 3
Acq 1 Acq 2 Acq 3 Rev 1 Rev 2 Rev 3
100
0
0
0
0
0.17
% correct
BALB/cByJ
Acq 1 Acq 2 Acq 3
Rev 1 Rev 2 Rev 3
0
Acq 1 Acq 2 Acq 3
Rev 1 Rev 2 Rev 3
% time in correct quad
100
1300
60
r = .777
r^2 = .603
y = 26.166 + 29.296x
1200
50
80
1100
40
1000
30
900
r = -.931
r^2 = .867
y = 45.62 - 40.715x
20
700
600
0
500
0
60
40
800
10
-.1
r = -.834
r^2 = .696
y = 968.336 - 707.742x
.1 .2 .3 .4 .5 .6
Visual acuity threshold (c/deg)
20
-.1
.7
0
.1 .2 .3 .4 .5 .6
Visual acuity threshold (c/deg)
.7
1300
60
1100
40
1000
-.1
0
.1 .2 .3 .4 .5 .6
Visual acuity threshold (c/deg)
100
1200
50
0
r = -.870
r^2 = .758
y = 1483.894 - 9.648x
r = .726
r^2 = .527
y = 7.605+ .35x
80
60
900
30
800
r = -.908
r^2 = .825
y = 72.864 - .519x
20
10
40
700
20
600
500
0
40
50
60
70
80
% correct day 8
90
100
0
40
50
60
70
80
% correct day 8
90
100
40
50
60
70
80
% correct day 8
90
100
.7
22.5
BARNES MAZE
C57BL/6J, Male
20
C57BL/6J, Female
17.5
129S1, Male
129S1, Female
Errors
15
12.5
10
7.5
5
2.5
0
Acq 1
Acq 2
Acq 3
Acq 4
Rev 1
Rev 2
Rev 3
Rev 4
A. Errors per day over acquisitions and reversal. C57BL/6J mice made fewer errors than the 129S1 mice
(F(1,35) =20.830, p < .0001), females made fewer errors than males (F(1,35) = 7.024, p <.02). C57BL/6J
mice showed no sex difference while the 129S1 males made more errors than the 129S1 females.
160
C57BL/6J, Male
Quadrant duration (sec)
140
C57BL/6J, Female
120
129S1, Male
100
129S1, Female
80
60
40
20
0
Correct
Right
Quadrant
Left
Opposite
B. Time spent in each quadrant during the probe
test. 129S1 mice entered more quadrants than the
C57BL/6J (F(1,35) = 21.373, p <.0001). All mice,
regardless of strain or sex. spent the most time in the
correct quadrant followed by the opposite quadrant.
BARNES MAZE
Acq 1
Acq 2
Acq 3
Acq 4
Rev 1
Rev 2
Rev 3
Rev 4
300
Latency (sec)
250
200
150
100
50
Molf/Ei
FVB/NJ
DBA/2J
Cfp1-J
C57BL/6J
Balb/cJ
Balb/cByJ
A/J
129S1
0
There are significant strain differences in learning and memory
ability in the Barnes Maze (p < 0.0001).
BARNES MAZE
140
120
Duration (sec)
100
129S1
A/J
AKR/J
Balb/cByJ
Balb/cJ
C3H/HEJ
C57BL/6J
Cast/Ei
DBA/2J
FVB/NJ
Molf/Ei
SJL/J
SM/J
80
60
40
20
0
Correct
Right
Left
Strain difference significant at p < 0.0001
Opposite
Hearing Research. 130 (1999) 94-107.
Assessment of hearing in 80 inbred strains of mice by ABR threshold analyses.
Zheng Q Y a, Johnson KR a, Erway LCb
aThe Jackson Laboratory, Bar Harbor, ME 04609-1500, USA.
b Dept of Biological Sciences, University of Cinncinnati, OH, USA
Abstract
The com mon occurrence of hearing loss in both humans and mice, and the anatomical and
functional similarities of theirinner ears, attestto the potential of mice being used as modelsto
study inherited hearing loss. A large-scale, auditory screening projectis being undertaken at The
Jackson Laboratory (TJL)to identify mice with inherited hearing disorders. To assess hearing
sensitivity, atleast five mice from each inbred strain had auditory brainstem response (ABR)
thresholds determined. Thus far, we have screened 80 inbred strains of mice; 60 ofthem exhibited
homogeneous ABR threshold values not significantly different from those ofthe control strain
CBA/CaJ. This large database establishes a reliable reference for normal hearing mouse strains.
The following 16 inbred strains exhibited significantly elevated ABR thresholds before the age of 3
months: 129/J, 129/ReJ, 129/SvJ, A/J, ALR/LtJ, ALS/LtJ,BUB/BnJ, C57BLKS/J, C57BR/cdJ,
C57L/J, DBA/2J, I/LnJ, M A/MyJ, NOD/LtJ, NOR/LtJ, and SKH2/J. These hearing impaired strains
may serve as models for some forms of human non-syndromic hearing loss and aidin the
identification of the underlying genes.
Hearing and the Barnes Maze
(13 strain comparison; p = .0731)
100
r^2 = .263
r = .513
Y = 31.457 + .148 * X
Mean decibel level detected
90
A/J
80
70
C57Bl/6J
60
DBA/2J
50
40
30
20
0
25
50
75
100
125 150
175 200
225 250
Latency to enter escape box
Strains that can only detect click sounds at levels greater than 55 dB are considered to be hearing
impaired (C57Bl/6J, DBA/2J, A/J). Mean age of mice tested for hearing was 13 weeks (early
onset hearing loss), similar to the age they are tested in the Barnes Maze. Over time many of the
other strains may also exhibit late onset hearing loss.
ROTAROD
300
250
Latency (sec)
200
150
100
129S1, Male
129S1, Female
C57BL/6J, Male
50
C57BL/6J, Female
0
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Mean (± SEM) latency to fall from
the rotarod. C57BL/6J mice stayed
on the rotating rod longer than the
129S1 mice(F(1,36) = 13.524, p <
.001). Females stayed on the rod
longer than males(F(1,36) =
39.609, p < .0001). There was a
significant increase in latency over
days (F(6,216) = 74.492, p < .0001)
and a significant day by sex
interaction (F(2,216) = 6.693, p <
.0001).
ROTAROD
350
129S1
A/J
AKR/J
Balb/cByJ
BALB/CJ
C3H/HEJ
C57BL/6J
Cfp1-J
DBA/2J
FVB/NJ
Molf/Ei
SJL/J
SM/J
Mean Latency
300
250
200
150
100
50
0
1
2
3
4
5
6
7
Day
Strain differences for rotarod latency over days
significant at p < 0.0001.
140
Open Arm Duration (sec)
120
100
80
Female
60
Male
40
ELEVATED
PLUS MAZE
20
0
129S1
C57BL/6J
A. Mean time spent in the open arms. C57BL/6J mice spent more time on the open arms than 129S1 mice
[F(1,43) = 4.14, p < 0.05 ] Females spent more time in the open arms than males [F(1,43) = 4.75, p <0.05 ]
16
Stretch Attend Frequecy
14
12
10
Female
8
Male
6
4
2
0
129S1
C57BL/6J
B. Mean number of stretch attend
postures. 129S1 mice showed more
stretch attend postures thanC57Bl/6J
mice [F(1,43) = 20.83, p < 0.001 ] Males
showed more stretch-attend postures than
females [F(1,43) =7.97, p <0.01]
particularly in the 129S1 mice, as shown
by the significant interaction [F(1,43) =
6.04, p <0.05].
Cfp1-J
Peromyscous
C3H/HEJ
Balb/cByJ
A/J
SM/J
MOLF/Ei
SJL/J
Cast/Ei
BALB/CJ
AKR/J
129S1
200
C57BL/6J
225
FVB/NJ
DBA/2J
Zone Duration (sec)
ELEVATED PLUS MAZE
Closed
Center
Open
175
150
125
100
75
50
25
0
Time spent in each zone significant at p <0.0001.
200
Line X Frequency
180
160
129S1, Male
140
129S1, Female
120
C57BL/6J, Male
100
C57BL/6J, Female
80
60
OPEN FIELD
40
Day 1
Day 2
A. Mean number of line. C57BL/6J mice showed more line crosses (F(1,36) = 66.764, p <.0001) than
the129S3 mice. Line cross frequency decreased from day 1 to day 2 (F(1,36) = 21.717, p <.0001).
8
Stretch Attend Frequency
7
6
129S1, Male
5
129S1, Female
4
C57BL/6J, Male
3
C57BL/6J, Female
2
1
0
Day 1
Day 2
B.129S1 mice showed more stretch
attend postures (F(1,36) = 17.123, p
<.0001) than C57BL/6J mice. 129S1
females showed more stretch attends
than 129S1 males; C57BL/6J males
showed more stretch attends than
C57BL/6J females. Frequency of
stretch attend postures increased on day
2 for females but decreased on day 2
for males (F(1,36) = 7.014, p < .02)
(F(1,36) = 4.481, p < .05).
OPEN FIELD
300
Day 1
250
Line cross frequency
Day 2
200
150
100
50
SPRET/Ei
SM/J
SJL/J
Peromyscous
Molf/Ei
FVB/NJ
DBA/2J
Cfp1-J
Cast/Ei
C57BL/6J
C3H/HEJ
BALB/CJ
Balb/CbYj
AKR/J
A/J
129S1
0
Significant strain (p <0.0001) and day effects (p = 0.0091) are
observed in the open field test
CLASSICAL CONDITIONING OF ODOUR PREFERENCES
70
Time spent digging (sec)
60
50
40
cs+
cs-
30
20
10
0
C3H/HEJ
CAST/Ei
DBA/2J
SM/J
Time spent digging in CS+ and CS- odors during preference test. All strains showed a preference for the CS+
over the CS- odors [U(8,8)=7,P <0.01 ]. There were no strain differences in time spent digging overall.
ODOUR DISCRIMINATION TEST
70
60
Time spent digging (sec)
cs+
cs-
50
40
30
20
10
SM/J
SJL/J
Molf/Ei
FVB/NJ
DBA/2J
Cfp1-J
CAST/Ei
C3H/HEJ
Balb/CJ
Balb/cByJ
AKR/J
A/J
0
There are strain differences in time spent digging (p < 0.001); however, all
animals dug significantly more in the CS+ odor (p < 0.0001).
PS2N141I
none reported
age-dependent A_42
PS2 null knockout
none reported
none reported
Ps2 null
none reported
none reported
APOE4
motoric problems
APOE4 (C112R)
none reported
CNS axonopa thy and
hyper-phosphorylated
tau
none reported
APOE2
none reported
none reported
Hypomorphic ARG 61 none reported
APOEL
none reported
Raffni et al.,
2001
TAU P301L-JNPL3
severe motoric and
behavioural disturbances
Lewis et al.,
2000
TAU P301L
muscle weakness;
Wallerian degeneration
gliosis; axonal
degeneration; neural
lesions
pathologically enlarged
axons with NFTs
TAU G272V
none reported
filaments in
oligodendrocytes, spinal
cord and motor neurons
Gotz et al., 2001
TAU V337M
no Morris water maze
impairments; increased
spontaneous locomotion
irregular hippocampal
neurons with tau
filaments; cell death
Tanemura et al.,
2002
TAU 3-repeats
motor weakness
astrocytosis and axon al
degeneration
Ishihara et al.
1999
TAU 4-repeats
motor disturbances
Spittaels et al.,
1999
TAU 4 repeats A1217
deficit in motor
coordination
none reported
CNS axonal
degeneration;
astrogliosis
axonopa thy
PP2a
tau aggragation in soma
and dendrites of
pyramidal cells
Oyama et al.,
1998
Herreman et al.,
1994
Steiner et al.,
1999
Tesseur et al.,
2000
Huber et al.,
2000
…
Gotz et al., 2001
Probst et al.,
2001
Kins et al., 2001
Vision Task - DBA/2J N =4 (4 males) (30 - 33 weeks old)
Visual Discrimination
100
80
% Correct
007 (m)
008 (m)
60
009 (m)
40
010 (m)
20
0
1
2
3
4
5
6
7
8
Days
Pattern Discrimination
100
80
% Correct
007 (m)
008 (m)
60
009 (m)
40
010 (m)
20
0
1
2
3
4
5
6
7
8
Days
Visual Acuity
100
007
60
008
40
009
010
20
0
Spatial Frequency
0.67
0.64
0.62
0.57
0.55
0.53
0.43
0.32
-20
0.17
% Correct
80
Vision Task - MOLF/Ei N =4 (4 males)(30 - 33 weeks old)
Visual Discrimination
100
80
% Correct
011 (m)
012 (m)
60
013 (m)
40
014 (m)
20
0
1
2
3
4
5
6
7
8
Days
Pattern Discrimination
100
80
% Correct
011 (m)
012 (m)
60
013 (m)
40
014 (m)
20
0
1
2
3
4
5
6
7
8
Days
Visual Acuity
100
80
012 (m)
013 (m)
40
014 (m)
20
Spatial Frequency
0.67
0.64
0.62
0.57
0.55
0.53
0.43
0.32
0
0.17
% Correct
011 (m)
60
Vision Task - Balb/CByJ N =4 (2 male, 2 female)(14 - 17 weeks old)
Visual Discrimination
100
80
% Correct
015 (f)
016 (f)
60
017 (m)
40
018 (m)
20
0
1
2
3
4
5
6
7
8
Days
Pattern Discrimination
100
80
% Correct
015 (f)
016 (f)
60
017 (m)
40
018 (m)
20
0
1
2
3
4
5
6
7
8
Days
Visual Acuity
100
015 (f)
016 (f)
60
017 (m)
40
018 (m)
20
Spatial Frequency
0.67
0.64
0.62
0.57
0.55
0.53
0.43
0.32
0
0.17
% Correct
80
Morris Water Maze – Latency to find platform
60
Latency to platform (sec)
50
DBA/2J
40
30
20
10
0
Acq 1
Acq 2
Acq 3
Rev 1
Rev 2
Rev 3
60
C57BL/6J
C57BL/6J
Latency to platform (sec)
50
40
30
20
10
0
Acq 1
Acq 2
Acq 3
Rev 1
Rev 2
Rev 3
Morris Water Maze – Latency to find platform
60
Molf/ei
Latency to platform (sec)
50
40
30
20
10
0
Acq 1
Acq 2
Acq 3
Rev 1
Rev 2
Rev 3
60
Balb/cbyj
Latency to platform (sec)
50
40
30
20
10
0
Acq 1
Acq 2
Acq 3
Rev 1
Rev 2
Rev 3
Visual acuity and mean latency to find the platform in the reversal days
(4 – 6) in the Morris water maze for 4 strains of mice
Mean Rev L
Mean Rev Latency
Visual Acuity Th
…
…
Visual Acuity Th
…
1.000
-.989
-.989
1.000
50
Molf/ei
Mean Rev Latency
45
40
Balb/CbYj
35
30
25
C57BL/6J
20
DBA/2J
15
0
.1
.2
.3
.4
Visual Acuity Threshold
.5
.6
.7