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A monitoring technique providing quantitative rodent behavior analysis
PhyMology and Behavior, Vol. 9, pp. 6"/5-679, Brain Research Publications Inc., 1972. Printed in U.S.A.
BRIEF COMMUNICATION A Monitoring Technique Providing Quantitative Rodent Behavior Analysis 1 DANIEL L. ELY, JOHN A. HENRY, JAMES P. HENRY, ROLAND D. RADER
University of Southern California, Department of Physiology, 815 I¢. 37th Street, Los Angeles, California 90007, U.S.A. (Received 11 May 1972) ELY, D. L., J. A. HENRY, J. P. HENRY, AND R. D. RADER. A monitoring technique providing quantitive rodent behavior analysis. PHYSIOL. BEHAV. 9(4) 675-679, 1972.-Behavior profiles of mice with different social roles can be monitored by dorsally or ventrally implanting small Alnico VIII magnets in the animal. The magnetically tagged mice trigger electronic checkpoints at colony nest boxes and a Hall Effect detector activates counting circuits, timers, and an event recorder. This new teehnique allows complete freedom of movement since there is no external hardware and permits behavioral analysis while the animal is socially interacting in a home environment. Behavior profile
Hall effect
Magnetic tagging
Social role
DURING the past 10 years, our laboratory has been investigating the social behavior of mice as well as the physiological, psychological, and biochemical correlates of behavior. Until now we have been primarily concerned with the group as a whole rather than with individuals. However it was observed that certain males nested with females, while others were scarred and lived in latrine areas [2]. Since CBA mice (Mus musculus) readily form a social hierarchy when provided a properly structured environment our next step was to devise a method to detect individual animals while they were socially interacting in their home environment. Beagley and Gallistel [1] developed a technique whereby head movements of an unrestrained rat were detected by means of a light spring connected to a strain gauge. Along similar lines Hake, Enoch, and Kelly [4] developed a technique which measured general activity of rats used in brain stimulation experiments by means of a flexible stimulation connector. A different technique capable of monitoring hundreds of rats by means of implantable passive resonant circuits has been described by Friauf [3]. The technique we developed employs small Alnico VIII implantable magnets and Hall Effect detectors located at portals to nest boxes in a colony. This technique permits long term behavior measurement without the necessity of external hardware attached to the animal. Therefore, this system allows an ethological approach whereby the animal
Territoriality
can be continuously monitored during social interaction. METHOD The population cage design consisted of 8 nest boxes (7 x 11 x 5 in.) interconnected by an 18-in. right-angle spur which led into a 5-ft-square plastic tubular runway (1.6 in. dia.) (Fig. 1). The total length of runway available to the mice was 32 ft, and the total runway and nest box area was 8.3 square ft. Small Alnico VIII magnets (1/16 x 3/16 in. Supplier: Permag Pacific Corp., Los Angeles) were either dorsally or ventrally implanted in 5 males and 12 females. Dorsally the magnet was implanted parallel to the body axis between the shoulder muscle fibers. Ligatures were anchored around each end of the magnet and secured to the surrounding tissue, which was then pulled over the magnet to allow rapid encapsulation. Ventrally the magnet was inserted through a small incision in the skin and attached to the external abdominal wall, and the surrounding tissue was pulled over the magnet. Care must be taken to insure body axis alignment during the implantation otherwise difficulty arises in magnetization. After a two-week recovery period the mice were introduced into a population cage. A dorsal-magnet mouse and a ventral-magnet mouse were magnetized by placing them in an electromagnetic coil (4 in. long and 1 5/8 in. in dia., consisting of 1 lb of 18 A.W.G. copper enameled wire) for 2 see using a direct current. The mice were demagnetized by pulling them
This work was supported in part by the National Institutes of Health Grant No. MH 19441-01. 675
676
ELY, HENRY, ttENR¥ AND RAI)tR
FIG. 1. Eight-box population cage with Hall Effect detectors.
through an a.c. magnetic field as quickly as possible. Using this procedure one dorsally- and one ventrally-tagged mouse could be monitored simultaneously. The tagged mice triggered the Hall Effect detectors located at each nest box entrance which then activated counting circuits, timers, and an event recorder (Fig. 2). Figure 3 shows the recording console which housed the timers, counters, and strip chart for the dorsally- and ventrally-tagged animals. Figure 4 shows the Hall Effect detection circuit. The first section of the circuit is a Hall Generator BH700. This device produces a differential voltage proportional to the magnetic flux and perpendicular to the sensor surface. A 2W 27~ resistor is used to create a constant current source of 180 ma. The signal is greater than _+ 1 mV under ideal conditions. An inexpensive operational amplifier (741C) is used to amplify the differential signal of the Hall Effect. A 1 Ks2 potentiometer is used to provide a null. Once the system is turned on it seldom requires adjustment. The output of the amplifier is limited with zener diodes to
protect the input of the comparators. The comparators operate as a bithreshold detector. The output of the comparator goes to a high logic level (5 V) when the input exceeds -+ 1 V. High threshold (6.5 V) logic was selected because of its noise immunity. The detection circuits do not require the higher speed of standard DTL or T 2 L. The electrical environment tends to be noisy because of the use of 1 10 V a.c. inductive devices. A logic translator is used to make the signals from the comparator compatible with the logic circuitry. The translator consists of a T ~ L gate and an RTL inverter. The first device after the logic translator is a retriggerable pulse stretcher. The grounded input to the OR gate puts the device in the pulse stretching mode. There is a distinct advantage in using a long time constant and the device's retriggerability. The mice have a tendency to stop, back up, or hesitate in a portal. As long as the comparator output is high, the output of the pulse stretcher remains high. The generation of further pulses by
RODENT BEHAVIOR MONITORING TECHNIQUE
677
FIG. 2. Foreground: Implantable Alnico VII magnet. Left: Detached Hall Effect device. Background: Mouse passing through portal triggering the Hall Effect. the comparator due to movements of the mouse only increases the amount of time the pulse stretcher remains high. A 68 u F capacitor gives a time delay of 0.4 sec, however, Tout = Tin + 0.3 R Cext + 35 p d f in this equation; R is an internal resistor of 20 K. Tin is dependent on how the mouse traverses the portal. This feature helps the system to avoid errors when the animal does not pass the portal properly. At the end of the time interval established by the pulse stretcher the trailing edge causes a toggle to change states. This device decides whether the mouse is entering or leaving the portal on a binary count. Initially the toggle output Tn is low; the first pass causes it to go high and turn a clock event recorder channel and LED on. While the pulse stretcher is high, R n is low; this condition resets all other toggles in the circuit for that mouse. Thus when a mouse enters a portal and then backs away, the next portal activated will reset T n to a low state, turning the associated recording channels off. This technique prevents t h e large accumulation of errors and creates a situation in which the logic recognizes that a mouse cannot be in two places simultaneously. The reset signal R n is used to gate a triac which increments an entry/exit counter. The counter is an ITT 110 V a.c. 60 electromechanical counter. The time signal T n from the toggle is used to control a light-emitting diode for visual indication and controls the drive circuitry to an
event recorder channel and to an elapsed time indicator. The LED is an HP 5 0 8 2 - 4 4 0 3 solid state lamp. Two Simpson miniature 10-channel event recorders are used which permit a continuous quantitative analysis of behavior. This technique requires minimal maintenance and it has functioned continuously for 6 months with the only maintenance being a resetting of the null potentiometer across the Hall Effect so that 0 V were generated at the amplifier output. RESULTS
The behavioral data obtained has provided information regarding general activity of each animal (entry-exits/hr) and specific behavior profiles, such as maternal behavior, patrol activity (entry into 4 or more boxes in < 8 rain), and dominant and subordinate behavior patterns. During the first m o n t h of social interaction the males compete for social position and not until then can a marked physical difference among the males be observed. The dominant male exhibits a glossy coat and an absence of scarring; whereas, the subordinates have ruffled coats and various degrees of scarring. However, the magnetic detection system offers the capability of detecting behavioral differences between individuals during the first week of social interaction prior to obvious physical changes. As can be seen in Fig. 5, the behavior patterns of a low- and
678
ELY, H E N R Y , H E N R Y AND R A D E R
EARLY DETECTION AND STAB+LITY OF BEHAVIOR PROFILES
BOX ~
+1
HOUR
~gw
ACTIVITY 8'th WEEK
O.S
0
?
2(5
23
~,T
33
28
;,7
. _ _
HIGH ACTIVITY ]St
PATROLS WOME 24 MRS BOX
ENTRY-EXItS
LOW ACTIVITY lit WEEK
/,
WEE~
i
ill
h
Ill
i ~I
i , I
II
I
llI" HIGH
u ~
lltl
5
ACTIVITY
lhl IIII II
5
8fh WEEK 6
{ (iiiu . . I lUll t
' I~ I i I It , ]) I
,
12
i k[)
18
I H ~IP [ PI
II II II
i ~ l Ii '
I ~
llli( lh I1~1111. r[I ~1
. r , , , m, roll, 24
6
~2
HOURS
FIG. 5. Early detection and stability of behavior profiles.
PATROL
BOX #
B E H A V I O R (CONTROLC~'7)
II
2
34
6 7 B
P
P
PP
P
I
19
HG. 3. The recording console housing the timers, counters, and event recorder for the dorsally- and ventrally-tagged animals.
20
22
21
P'PATROL(VISITS 4 OR M O R E BOXES IN
23
HOURS
'~8 MIN.)
FIG. 6. Patrol behavior pattern found often in dominant animals. TESTOSTERONE ADMINISTRATION TO A SUBORDINATE MALE
,s~,s d~ l-.(:
CONTROL L [ L ~ I - +
l TESTOSTE~N~
F
ENTRY-EXITS 24 HRS
pATROLS 24 HRS
31
0
66
2
34
O
V~-
~
(IMG/3OGM) 8 ~ I ~ i
T
--
/
RODENT BEHAVIORAL ANALYSIS CIRCUITS
r.. rmE ~ ~x
12
18
24
6
12
HOURS
FIG. 4. Hall Effect magnetic detection circuit,
FIG. 7. Testosterone-induced behavioral change in a subordinate male.
RODENT BEHAVIOR MONITORING TECHNIQUE
679
high-activity male can be detected during the first week and are stable for a period of 8 weeks. A specific behavior pattern commonly found in the dominant individual is the patrol pattern whereby the animal visits 4 or more of the 8 nest boxes in rapid succession (< 8 min), checking the inhabitants of each box (Fig. 6). In general, the dominant males had 3 times the general activity and 8 times the patrol activity of the rival males, which, in turn, had higher activity rates and patrol activity than the subordinates. It was found that the detection system was also sensitive to behavioral changes induced by the administration of a hormone or drug. Figure 7 shows a subordinate male that was subcutaneously administered a maintenance dose of testosterone ( mg/30 g). There was a 100% increase in his entry-exits/hr and a generally aroused state for 24 hr. However, there was no significant change in his patrol behavior since this is a behavioral characteristic of the dominant animal which probably would require a longer period to develop or induce. Another behavioral modification was observed by placing an entire colony on coffee via their drinking bottles. They received a dose/day which would be equivalent to a human heavy-coffee-drinker (30 mg/kg). Figure 8 shows the dramatic behavioral change of a female after two weeks on coffee. The behavioral profile shows that the female was hyperactive for almost 18 hr and then turns completely off for 6 hr. Usually the animals show periodic activity with sleeping cycles of 2 - 3 hr. Maternal behavior can also be monitored, including the amount of time a mother spends with her young. Figure 9 shows a pregnant female two days prior to parturition in which she spends most of her time in box No. 8. Immediately after parturtition in box No. 8, the mother starts to shuttle the babies to other areas (boxes No. 1 and No. 2) because other females in the colony are intruding upon her territory and litter. These behavior patterns were easily detectable using the magnetic detection system which provided continuous behavior monitoring in a natural setting with no external hardware on the animal. This system can be used in behavioral studies, drug studies, and activity rhythm studies. We are now engaged in developing an 8-box population cage in which there are functional areas which will attempt to elicit specific activities, such as an activity wheel area, feeding area, nesting area, latrine area, and living area. This will permit a more detailed analysis of behavior and a greater capability for differentiating social roles. We are also developing the capability to detect 8 mice simultaneously, utilizing the polar orientation of the implanted magnet. This system will then be interfaced with a Cincinnati Milacron CIP/2100 minicomputer. This offers the exciting opportunity to simultaneously monitor many individuals and record subtle social interactions not easily detectable without a computer.
LJ~44 CONTROL
1
2 WEEKS ON
COFFEE (3XIO "2 MG/GM) I
24
6
I
12 HOURS
FIG. 8. Coffee-induced behavioral change in a female.
BEHAVIOR (PARTURITION)
MATERNAL
BOX~
2 DAYS 4 PRIOR TO PARTURITION
M H !
I
I
I DAY PRIOR TO PARTURITION
I
PARTURITION
I
POSTPARTUM-JTlUl l) II "15~-~ ~ 24
~ "t 6
12
I
I
18
24
HOURS
FIG. 9. Parturition-induced behavioral change in a pregnant female.
REFERENCES
1. 2.
Beagley, W. K. and C. R. GaUistel. Versatile behavior monitering technique for rodents. Physiol. Behav. 7: 273-276, 1971. Ely, D. L. Physiological and Behavioral Differentiation of Social Roles in a Population Cage of Magnetically Tagged CBA Mice. Ph.D. dissertation, University of Southern California, Los Angeles, June, 1971.
3. 4.
Friauf, W. S. Rats: Their comings and goings. IEEE Proceedings 1969 Nat. Telemetering Conference. (Washington, D. C., April 22-24), pp. 34-38. Hake, D. F., V. Enoch and J. F. Kelly. A simple method for measuring the general activity of rats in brain stimulation and other studies. J. exp. Analysis Behav. 16: 63-65, 1971.
BRIEF COMMUNICATION A Monitoring Technique Providing Quantitative Rodent Behavior Analysis 1 DANIEL L. ELY, JOHN A. HENRY, JAMES P. HENRY, ROLAND D. RADER
University of Southern California, Department of Physiology, 815 I¢. 37th Street, Los Angeles, California 90007, U.S.A. (Received 11 May 1972) ELY, D. L., J. A. HENRY, J. P. HENRY, AND R. D. RADER. A monitoring technique providing quantitive rodent behavior analysis. PHYSIOL. BEHAV. 9(4) 675-679, 1972.-Behavior profiles of mice with different social roles can be monitored by dorsally or ventrally implanting small Alnico VIII magnets in the animal. The magnetically tagged mice trigger electronic checkpoints at colony nest boxes and a Hall Effect detector activates counting circuits, timers, and an event recorder. This new teehnique allows complete freedom of movement since there is no external hardware and permits behavioral analysis while the animal is socially interacting in a home environment. Behavior profile
Hall effect
Magnetic tagging
Social role
DURING the past 10 years, our laboratory has been investigating the social behavior of mice as well as the physiological, psychological, and biochemical correlates of behavior. Until now we have been primarily concerned with the group as a whole rather than with individuals. However it was observed that certain males nested with females, while others were scarred and lived in latrine areas [2]. Since CBA mice (Mus musculus) readily form a social hierarchy when provided a properly structured environment our next step was to devise a method to detect individual animals while they were socially interacting in their home environment. Beagley and Gallistel [1] developed a technique whereby head movements of an unrestrained rat were detected by means of a light spring connected to a strain gauge. Along similar lines Hake, Enoch, and Kelly [4] developed a technique which measured general activity of rats used in brain stimulation experiments by means of a flexible stimulation connector. A different technique capable of monitoring hundreds of rats by means of implantable passive resonant circuits has been described by Friauf [3]. The technique we developed employs small Alnico VIII implantable magnets and Hall Effect detectors located at portals to nest boxes in a colony. This technique permits long term behavior measurement without the necessity of external hardware attached to the animal. Therefore, this system allows an ethological approach whereby the animal
Territoriality
can be continuously monitored during social interaction. METHOD The population cage design consisted of 8 nest boxes (7 x 11 x 5 in.) interconnected by an 18-in. right-angle spur which led into a 5-ft-square plastic tubular runway (1.6 in. dia.) (Fig. 1). The total length of runway available to the mice was 32 ft, and the total runway and nest box area was 8.3 square ft. Small Alnico VIII magnets (1/16 x 3/16 in. Supplier: Permag Pacific Corp., Los Angeles) were either dorsally or ventrally implanted in 5 males and 12 females. Dorsally the magnet was implanted parallel to the body axis between the shoulder muscle fibers. Ligatures were anchored around each end of the magnet and secured to the surrounding tissue, which was then pulled over the magnet to allow rapid encapsulation. Ventrally the magnet was inserted through a small incision in the skin and attached to the external abdominal wall, and the surrounding tissue was pulled over the magnet. Care must be taken to insure body axis alignment during the implantation otherwise difficulty arises in magnetization. After a two-week recovery period the mice were introduced into a population cage. A dorsal-magnet mouse and a ventral-magnet mouse were magnetized by placing them in an electromagnetic coil (4 in. long and 1 5/8 in. in dia., consisting of 1 lb of 18 A.W.G. copper enameled wire) for 2 see using a direct current. The mice were demagnetized by pulling them
This work was supported in part by the National Institutes of Health Grant No. MH 19441-01. 675
676
ELY, HENRY, ttENR¥ AND RAI)tR
FIG. 1. Eight-box population cage with Hall Effect detectors.
through an a.c. magnetic field as quickly as possible. Using this procedure one dorsally- and one ventrally-tagged mouse could be monitored simultaneously. The tagged mice triggered the Hall Effect detectors located at each nest box entrance which then activated counting circuits, timers, and an event recorder (Fig. 2). Figure 3 shows the recording console which housed the timers, counters, and strip chart for the dorsally- and ventrally-tagged animals. Figure 4 shows the Hall Effect detection circuit. The first section of the circuit is a Hall Generator BH700. This device produces a differential voltage proportional to the magnetic flux and perpendicular to the sensor surface. A 2W 27~ resistor is used to create a constant current source of 180 ma. The signal is greater than _+ 1 mV under ideal conditions. An inexpensive operational amplifier (741C) is used to amplify the differential signal of the Hall Effect. A 1 Ks2 potentiometer is used to provide a null. Once the system is turned on it seldom requires adjustment. The output of the amplifier is limited with zener diodes to
protect the input of the comparators. The comparators operate as a bithreshold detector. The output of the comparator goes to a high logic level (5 V) when the input exceeds -+ 1 V. High threshold (6.5 V) logic was selected because of its noise immunity. The detection circuits do not require the higher speed of standard DTL or T 2 L. The electrical environment tends to be noisy because of the use of 1 10 V a.c. inductive devices. A logic translator is used to make the signals from the comparator compatible with the logic circuitry. The translator consists of a T ~ L gate and an RTL inverter. The first device after the logic translator is a retriggerable pulse stretcher. The grounded input to the OR gate puts the device in the pulse stretching mode. There is a distinct advantage in using a long time constant and the device's retriggerability. The mice have a tendency to stop, back up, or hesitate in a portal. As long as the comparator output is high, the output of the pulse stretcher remains high. The generation of further pulses by
RODENT BEHAVIOR MONITORING TECHNIQUE
677
FIG. 2. Foreground: Implantable Alnico VII magnet. Left: Detached Hall Effect device. Background: Mouse passing through portal triggering the Hall Effect. the comparator due to movements of the mouse only increases the amount of time the pulse stretcher remains high. A 68 u F capacitor gives a time delay of 0.4 sec, however, Tout = Tin + 0.3 R Cext + 35 p d f in this equation; R is an internal resistor of 20 K. Tin is dependent on how the mouse traverses the portal. This feature helps the system to avoid errors when the animal does not pass the portal properly. At the end of the time interval established by the pulse stretcher the trailing edge causes a toggle to change states. This device decides whether the mouse is entering or leaving the portal on a binary count. Initially the toggle output Tn is low; the first pass causes it to go high and turn a clock event recorder channel and LED on. While the pulse stretcher is high, R n is low; this condition resets all other toggles in the circuit for that mouse. Thus when a mouse enters a portal and then backs away, the next portal activated will reset T n to a low state, turning the associated recording channels off. This technique prevents t h e large accumulation of errors and creates a situation in which the logic recognizes that a mouse cannot be in two places simultaneously. The reset signal R n is used to gate a triac which increments an entry/exit counter. The counter is an ITT 110 V a.c. 60 electromechanical counter. The time signal T n from the toggle is used to control a light-emitting diode for visual indication and controls the drive circuitry to an
event recorder channel and to an elapsed time indicator. The LED is an HP 5 0 8 2 - 4 4 0 3 solid state lamp. Two Simpson miniature 10-channel event recorders are used which permit a continuous quantitative analysis of behavior. This technique requires minimal maintenance and it has functioned continuously for 6 months with the only maintenance being a resetting of the null potentiometer across the Hall Effect so that 0 V were generated at the amplifier output. RESULTS
The behavioral data obtained has provided information regarding general activity of each animal (entry-exits/hr) and specific behavior profiles, such as maternal behavior, patrol activity (entry into 4 or more boxes in < 8 rain), and dominant and subordinate behavior patterns. During the first m o n t h of social interaction the males compete for social position and not until then can a marked physical difference among the males be observed. The dominant male exhibits a glossy coat and an absence of scarring; whereas, the subordinates have ruffled coats and various degrees of scarring. However, the magnetic detection system offers the capability of detecting behavioral differences between individuals during the first week of social interaction prior to obvious physical changes. As can be seen in Fig. 5, the behavior patterns of a low- and
678
ELY, H E N R Y , H E N R Y AND R A D E R
EARLY DETECTION AND STAB+LITY OF BEHAVIOR PROFILES
BOX ~
+1
HOUR
~gw
ACTIVITY 8'th WEEK
O.S
0
?
2(5
23
~,T
33
28
;,7
. _ _
HIGH ACTIVITY ]St
PATROLS WOME 24 MRS BOX
ENTRY-EXItS
LOW ACTIVITY lit WEEK
/,
WEE~
i
ill
h
Ill
i ~I
i , I
II
I
llI" HIGH
u ~
lltl
5
ACTIVITY
lhl IIII II
5
8fh WEEK 6
{ (iiiu . . I lUll t
' I~ I i I It , ]) I
,
12
i k[)
18
I H ~IP [ PI
II II II
i ~ l Ii '
I ~
llli( lh I1~1111. r[I ~1
. r , , , m, roll, 24
6
~2
HOURS
FIG. 5. Early detection and stability of behavior profiles.
PATROL
BOX #
B E H A V I O R (CONTROLC~'7)
II
2
34
6 7 B
P
P
PP
P
I
19
HG. 3. The recording console housing the timers, counters, and event recorder for the dorsally- and ventrally-tagged animals.
20
22
21
P'PATROL(VISITS 4 OR M O R E BOXES IN
23
HOURS
'~8 MIN.)
FIG. 6. Patrol behavior pattern found often in dominant animals. TESTOSTERONE ADMINISTRATION TO A SUBORDINATE MALE
,s~,s d~ l-.(:
CONTROL L [ L ~ I - +
l TESTOSTE~N~
F
ENTRY-EXITS 24 HRS
pATROLS 24 HRS
31
0
66
2
34
O
V~-
~
(IMG/3OGM) 8 ~ I ~ i
T
--
/
RODENT BEHAVIORAL ANALYSIS CIRCUITS
r.. rmE ~ ~x
12
18
24
6
12
HOURS
FIG. 4. Hall Effect magnetic detection circuit,
FIG. 7. Testosterone-induced behavioral change in a subordinate male.
RODENT BEHAVIOR MONITORING TECHNIQUE
679
high-activity male can be detected during the first week and are stable for a period of 8 weeks. A specific behavior pattern commonly found in the dominant individual is the patrol pattern whereby the animal visits 4 or more of the 8 nest boxes in rapid succession (< 8 min), checking the inhabitants of each box (Fig. 6). In general, the dominant males had 3 times the general activity and 8 times the patrol activity of the rival males, which, in turn, had higher activity rates and patrol activity than the subordinates. It was found that the detection system was also sensitive to behavioral changes induced by the administration of a hormone or drug. Figure 7 shows a subordinate male that was subcutaneously administered a maintenance dose of testosterone ( mg/30 g). There was a 100% increase in his entry-exits/hr and a generally aroused state for 24 hr. However, there was no significant change in his patrol behavior since this is a behavioral characteristic of the dominant animal which probably would require a longer period to develop or induce. Another behavioral modification was observed by placing an entire colony on coffee via their drinking bottles. They received a dose/day which would be equivalent to a human heavy-coffee-drinker (30 mg/kg). Figure 8 shows the dramatic behavioral change of a female after two weeks on coffee. The behavioral profile shows that the female was hyperactive for almost 18 hr and then turns completely off for 6 hr. Usually the animals show periodic activity with sleeping cycles of 2 - 3 hr. Maternal behavior can also be monitored, including the amount of time a mother spends with her young. Figure 9 shows a pregnant female two days prior to parturition in which she spends most of her time in box No. 8. Immediately after parturtition in box No. 8, the mother starts to shuttle the babies to other areas (boxes No. 1 and No. 2) because other females in the colony are intruding upon her territory and litter. These behavior patterns were easily detectable using the magnetic detection system which provided continuous behavior monitoring in a natural setting with no external hardware on the animal. This system can be used in behavioral studies, drug studies, and activity rhythm studies. We are now engaged in developing an 8-box population cage in which there are functional areas which will attempt to elicit specific activities, such as an activity wheel area, feeding area, nesting area, latrine area, and living area. This will permit a more detailed analysis of behavior and a greater capability for differentiating social roles. We are also developing the capability to detect 8 mice simultaneously, utilizing the polar orientation of the implanted magnet. This system will then be interfaced with a Cincinnati Milacron CIP/2100 minicomputer. This offers the exciting opportunity to simultaneously monitor many individuals and record subtle social interactions not easily detectable without a computer.
LJ~44 CONTROL
1
2 WEEKS ON
COFFEE (3XIO "2 MG/GM) I
24
6
I
12 HOURS
FIG. 8. Coffee-induced behavioral change in a female.
BEHAVIOR (PARTURITION)
MATERNAL
BOX~
2 DAYS 4 PRIOR TO PARTURITION
M H !
I
I
I DAY PRIOR TO PARTURITION
I
PARTURITION
I
POSTPARTUM-JTlUl l) II "15~-~ ~ 24
~ "t 6
12
I
I
18
24
HOURS
FIG. 9. Parturition-induced behavioral change in a pregnant female.
REFERENCES
1. 2.
Beagley, W. K. and C. R. GaUistel. Versatile behavior monitering technique for rodents. Physiol. Behav. 7: 273-276, 1971. Ely, D. L. Physiological and Behavioral Differentiation of Social Roles in a Population Cage of Magnetically Tagged CBA Mice. Ph.D. dissertation, University of Southern California, Los Angeles, June, 1971.
3. 4.
Friauf, W. S. Rats: Their comings and goings. IEEE Proceedings 1969 Nat. Telemetering Conference. (Washington, D. C., April 22-24), pp. 34-38. Hake, D. F., V. Enoch and J. F. Kelly. A simple method for measuring the general activity of rats in brain stimulation and other studies. J. exp. Analysis Behav. 16: 63-65, 1971.