Physiology & Behavior, Vol. 47, pp. 641-646. ©Pergamon Press plc, 1990. Printed in the U.S.A.
0031-9384/90 $3.00 + .00
Thermal Correlates of Tonic Immobility and Social Isolation in Chickens T I M O T H Y J. E D D Y A N D G O R D O N G. G A L L U P , JR. t
Department o f Psychology, State University o f N e w York at Albany, Albany, N Y 12222 R e c e i v e d 14 N o v e m b e r 1989
EDDY, T. J. AND G. G. GALLUP, JR. Thermal correlates of tonic immobility and social isolation in chickens. PHYSIOL BEHAV 47(4) 641-646, 1990.--Previous research has shown that core temperature in chickens drops following the induction of tonic immobility (TI), while hyperthermic trends emerge shortly after response termination. Other research has shown that birds placed in social isolation also become hyperthermic. Since testing for TI is usually carried out while animals are isolated, there is a question as to whether the hyperthermic reaction after the termination of TI has any relation to the episode of TI itself as opposed to being due to the effects of social isolation per se. The present series of studies found that although social isolation did produce significantly longer durations of TI and that the core temperature of isolated birds was affected, when core temperatures were independently raised or lowered, no significant differences were found in TI durations relative to controls. Additionally, in contrast to core temperature changes, shank temperature showed the opposite effect, while another peripheral temperature measure, wing temperature, remained stable. Chickens
Shank temperature
Core temperature
Tonic immobility
Social isolation
data reported by Gentle et al., it is important to determine whether temperature changes were global, as previously suspected, or could have differed as a function of the site or location of temperature recording (core vs. shank). In the present study in addition to core and shank temperature, another measure of peripheral temperature (under the wing) was also taken. The rationale for using a between subjects design in this study is based on previous data from our laboratory which indicated that when a within subject design is used for multiple, simultaneous temperature recordings, birds remain somewhat restrained throughout the recording procedure due to the numerous probes attatched to the body (as opposed to during the immobility restraining procedure alone), and temperature patterns under these conditions show extreme variability and no discernible pattern.
INTEREST in tonic immobility (TI) has undergone a resurgence since the 1960's. Tonic immobility has been studied in a variety of animals ranging from crustacea to rabbits and in humans has been implicated as playing a role in rape-induced paralysis (15), catatonic schizophrenia (5), and even reactions of surviving passengers aboard airplanes that crash (9). The response is induced by some form of restraint, and is characterized by inhibition of the righting reflex, parkinsonian-like tremors, and reduced heart rate among numerous other characteristics (4). The point of departure for the following studies concerns a report by Nash, Gallup and Czech (12) who found that during tonic immobility the cloacal core temperature of young chickens fell below baseline, and that immediately after the TI episode, core temperatures became hyperthermic, or rebounded above the initial baseline. The Nash et al. study was designed primarily to describe psycho-physiological changes that occurred during TI, however, and no attempt was made to identify what factors may have been involved in such effects. Recent data provided by Gentle, Jones and Woolley (7) with adult birds show trends in shank temperature which are diametrically opposed to the core temperature data, where shank temperatures increase during the TI episode and fall during the termination of the response. These apparently anomolous findings were addressed in the first experiment.
METHOD
Subjects The subjects were 45 experimentally naive three-week-old Production Red chickens (Gallus gallus) obtained from a commercial hatchery at one day of age. All subjects were group-housed in commercial brooders with continuous access to food and water during a 14-hour photoperiod.
Apparatus EXPERIMENT 1
A Sensortech Thermalert (Model TH-8) temperature monitor was used to determine core, shank, and wing temperatures in all of
Given the contradictory results of the Nash et al. study and the
~Requests for reprints should be addressed to Gordon G. Gallup, Jr., Psychology Department, SUNY at Albany, 1400 Washington Avenue, Albany, NY 12222.
641
642
EDDY AND GALLUP
TABLE 1 MEAN ( - SEM) TEMPERATUREAS A FUNCTIONOF SITE OF RECORDINGDURINGTONIC IMMOBILITY Phases of TI Site of Recording
n
Core
15
Shank Wing
PI
1
M
T
PT
41.367 41.060 40.973 41.193 41.567 (--_0.045) (_+0.038) (_+0.042) (_+0.045) (__+0.035) 15 32.900 33.280 33.787 33.300 32.567 (--+0.310) (_+0.324) (--+0.236) (---0.380) (___0.406) 15 39.429 39.629 39.950 39.900 39.591 (_+0.188) (_+0.170) (_+0.158) (-+0.408) (_+0.260)
PI: Preinduction, I: Induction, M: Midpoint, T: Termination, PT: Posttermination.
the following experiments. Temperatures were measured in degrees Celsius. Stopwatches were used to time the duration of TI and temperature recording intervals. Procedure
All testing took place during the midportion of the photoperiod which occured between 10:00 a.m. and 4:00 p.m. Single birds were randomly chosen from one of three group brooders and transported individually to the testing room in a cardboard box and randomly assigned to one of three conditions (core, shank, or wing temperature recording). For core temperature readings, the bird was held in one hand and the temperature probe was gently inserted into the cloaca to a depth of approximately 2 cm. The wire from the probe was then looped toward the front of the bird and attached to the bird's keel (rostral-ventral surface) with masking tape. For the shank condition, a surface temperature probe was attached to the bird's right shank with medical tape. For the wing temperature condition, a surface temperature probe was placed between the radius and ulna bones on the surface of the skin and securely attached with masking tape with the wire from the probe extending toward the posterior of the bird. Each of these procedures allowed the bird unrestricted movement during the testing session. For each condition, initial temperature was recorded and TI was then induced by manually restraining the bird for 15 seconds on its right side. Throughout the course of TI, the bird's temperature was recorded every 30 seconds until a righting reflex occurred. The bird's temperature was also recorded 45--60 seconds after the termination of TI, at which point the TI duration score was noted. Since the bird's temperature was monitored every 30 seconds, the experimenter remained in the room seated on a chair facing the bird, at a distance of approximately 0.5 m for the entire testing session. After the procedure, temperatures from the midpoint of the TI episode and the last temperature reading before response termination were noted and used in the analysis. Hence, five temperature scores were targeted for each TI response: preinduction, induction, midpoint, termination, and posttermination. RESULTS An analysis of variance of location of temperature sampled by stage of TI indicated that significant differences exist for each of these factors, F(2,42), p
0031-9384/90 $3.00 + .00
Thermal Correlates of Tonic Immobility and Social Isolation in Chickens T I M O T H Y J. E D D Y A N D G O R D O N G. G A L L U P , JR. t
Department o f Psychology, State University o f N e w York at Albany, Albany, N Y 12222 R e c e i v e d 14 N o v e m b e r 1989
EDDY, T. J. AND G. G. GALLUP, JR. Thermal correlates of tonic immobility and social isolation in chickens. PHYSIOL BEHAV 47(4) 641-646, 1990.--Previous research has shown that core temperature in chickens drops following the induction of tonic immobility (TI), while hyperthermic trends emerge shortly after response termination. Other research has shown that birds placed in social isolation also become hyperthermic. Since testing for TI is usually carried out while animals are isolated, there is a question as to whether the hyperthermic reaction after the termination of TI has any relation to the episode of TI itself as opposed to being due to the effects of social isolation per se. The present series of studies found that although social isolation did produce significantly longer durations of TI and that the core temperature of isolated birds was affected, when core temperatures were independently raised or lowered, no significant differences were found in TI durations relative to controls. Additionally, in contrast to core temperature changes, shank temperature showed the opposite effect, while another peripheral temperature measure, wing temperature, remained stable. Chickens
Shank temperature
Core temperature
Tonic immobility
Social isolation
data reported by Gentle et al., it is important to determine whether temperature changes were global, as previously suspected, or could have differed as a function of the site or location of temperature recording (core vs. shank). In the present study in addition to core and shank temperature, another measure of peripheral temperature (under the wing) was also taken. The rationale for using a between subjects design in this study is based on previous data from our laboratory which indicated that when a within subject design is used for multiple, simultaneous temperature recordings, birds remain somewhat restrained throughout the recording procedure due to the numerous probes attatched to the body (as opposed to during the immobility restraining procedure alone), and temperature patterns under these conditions show extreme variability and no discernible pattern.
INTEREST in tonic immobility (TI) has undergone a resurgence since the 1960's. Tonic immobility has been studied in a variety of animals ranging from crustacea to rabbits and in humans has been implicated as playing a role in rape-induced paralysis (15), catatonic schizophrenia (5), and even reactions of surviving passengers aboard airplanes that crash (9). The response is induced by some form of restraint, and is characterized by inhibition of the righting reflex, parkinsonian-like tremors, and reduced heart rate among numerous other characteristics (4). The point of departure for the following studies concerns a report by Nash, Gallup and Czech (12) who found that during tonic immobility the cloacal core temperature of young chickens fell below baseline, and that immediately after the TI episode, core temperatures became hyperthermic, or rebounded above the initial baseline. The Nash et al. study was designed primarily to describe psycho-physiological changes that occurred during TI, however, and no attempt was made to identify what factors may have been involved in such effects. Recent data provided by Gentle, Jones and Woolley (7) with adult birds show trends in shank temperature which are diametrically opposed to the core temperature data, where shank temperatures increase during the TI episode and fall during the termination of the response. These apparently anomolous findings were addressed in the first experiment.
METHOD
Subjects The subjects were 45 experimentally naive three-week-old Production Red chickens (Gallus gallus) obtained from a commercial hatchery at one day of age. All subjects were group-housed in commercial brooders with continuous access to food and water during a 14-hour photoperiod.
Apparatus EXPERIMENT 1
A Sensortech Thermalert (Model TH-8) temperature monitor was used to determine core, shank, and wing temperatures in all of
Given the contradictory results of the Nash et al. study and the
~Requests for reprints should be addressed to Gordon G. Gallup, Jr., Psychology Department, SUNY at Albany, 1400 Washington Avenue, Albany, NY 12222.
641
642
EDDY AND GALLUP
TABLE 1 MEAN ( - SEM) TEMPERATUREAS A FUNCTIONOF SITE OF RECORDINGDURINGTONIC IMMOBILITY Phases of TI Site of Recording
n
Core
15
Shank Wing
PI
1
M
T
PT
41.367 41.060 40.973 41.193 41.567 (--_0.045) (_+0.038) (_+0.042) (_+0.045) (__+0.035) 15 32.900 33.280 33.787 33.300 32.567 (--+0.310) (_+0.324) (--+0.236) (---0.380) (___0.406) 15 39.429 39.629 39.950 39.900 39.591 (_+0.188) (_+0.170) (_+0.158) (-+0.408) (_+0.260)
PI: Preinduction, I: Induction, M: Midpoint, T: Termination, PT: Posttermination.
the following experiments. Temperatures were measured in degrees Celsius. Stopwatches were used to time the duration of TI and temperature recording intervals. Procedure
All testing took place during the midportion of the photoperiod which occured between 10:00 a.m. and 4:00 p.m. Single birds were randomly chosen from one of three group brooders and transported individually to the testing room in a cardboard box and randomly assigned to one of three conditions (core, shank, or wing temperature recording). For core temperature readings, the bird was held in one hand and the temperature probe was gently inserted into the cloaca to a depth of approximately 2 cm. The wire from the probe was then looped toward the front of the bird and attached to the bird's keel (rostral-ventral surface) with masking tape. For the shank condition, a surface temperature probe was attached to the bird's right shank with medical tape. For the wing temperature condition, a surface temperature probe was placed between the radius and ulna bones on the surface of the skin and securely attached with masking tape with the wire from the probe extending toward the posterior of the bird. Each of these procedures allowed the bird unrestricted movement during the testing session. For each condition, initial temperature was recorded and TI was then induced by manually restraining the bird for 15 seconds on its right side. Throughout the course of TI, the bird's temperature was recorded every 30 seconds until a righting reflex occurred. The bird's temperature was also recorded 45--60 seconds after the termination of TI, at which point the TI duration score was noted. Since the bird's temperature was monitored every 30 seconds, the experimenter remained in the room seated on a chair facing the bird, at a distance of approximately 0.5 m for the entire testing session. After the procedure, temperatures from the midpoint of the TI episode and the last temperature reading before response termination were noted and used in the analysis. Hence, five temperature scores were targeted for each TI response: preinduction, induction, midpoint, termination, and posttermination. RESULTS An analysis of variance of location of temperature sampled by stage of TI indicated that significant differences exist for each of these factors, F(2,42), p
