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Conditioned taste aversion induced by wheel running is not due to novelty of the wheel
Physiology & Behavior 74 (2001) 53 – 56
Conditioned taste aversion induced by wheel running is not due to novelty of the wheel C. Donald Heth*, Peter Inglis, James C. Russell, W. David Pierce Department of Psychology, P-217 Biological Sciences Building, University of Alberta, Edmonton, Canada T6G 2E9 Received 15 November 2000; received in revised form 13 April 2001; accepted 24 April 2001
Abstract Under a within-subjects design, food- and water-restricted rats showed a significant reduction in consumption of a flavor associated with the opportunity to run compared to another flavor associated with a novel wheel without the opportunity to run. Furthermore, there was no evidence that consumption of the flavor paired with the novel wheel differed from a home cage control. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Conditioned taste aversion; Wheel running; Novelty; Activity anorexia
1. Introduction Rats exposed to food restriction and the opportunity to run often become severely anorexic [1– 3]. Lett and Grant [4] proposed that the anorexia could be due to a conditioned taste aversion (CTA) to food associated with wheel running. They supported this view with evidence that wheel running could establish a CTA to novel flavored liquids. Two groups of food- and water-restricted rats received pairings of either a salt or a sour flavor paired with a brief opportunity to run in a standard activity wheel. For each group, the unpaired flavor was presented in the rat’s home cage. After three conditioning trials, all rats received test opportunities to drink salt or sour flavors. Lett and Grant reported conditioned aversion to the flavor associated with access to a running wheel on the third conditioning trial and on the subsequent test. A possible confounding factor in the Lett and Grant experiment is the effect of transferring the rats from the home cage to a running wheel. Rats will show a decline in food intake when first transferred to an activity wheel [5]. A typical control for novelty of the wheel is to move experimental animals from their home cages to a locked running wheel. The putative effects of wheel running on food intake * Corresponding author. Tel.: +1-708-492-5216; fax: +1-780-4921768. E-mail address: [email protected] (C.D. Heth).
are then compared not only to those of a home cage condition, but also to those of the locked wheel. In their design, Lett and Grant did not compare CTA between locked and open wheel conditions; hence, novelty of the wheel could be a confounding factor in their experiment and could account for the aversion to the tastes. The present experiment controls for novelty of the wheel. In a within-subjects design, rats were exposed to three flavored solutions. One of these was presented prior to the opportunity to run in an open wheel; one was presented prior to exposure to a locked wheel; and one was presented in the home cage. If CTA does not depend upon novelty of the wheel, then rats should drink less of the flavor paired with the opportunity to run (open wheel) than of the flavor paired with the locked wheel (the novelty control). On the other hand, if novelty of the wheel is sufficient to produce CTA, then consumption of both flavors should differ from consumption of the flavor presented in the home cage.
2. Method Twelve male JCR:LA-cp rats from the University of Alberta medical research colony, 6 weeks of age at the start of the experiment and ranging in weight from 132 to 170 g (M = 155 g), were tested. Rats are highly active under conditions of food restriction at this age range [6]. The rats were individually housed in clear polycarbonate cages
0031-9384/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved. PII: S 0 0 3 1 - 9 3 8 4 ( 0 1 ) 0 0 5 5 3 - 4
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C.D. Heth et al. / Physiology & Behavior 74 (2001) 53–56
(47 27 20 cm) with wood chip bedding on a 12-h on/12-h off light schedule. Temperature was maintained between 20°C and 22°C. Food and water were freely available on wire cage tops, unless otherwise specified. Three solutions of orange, lemon –lime and cherry Kool Aid commercial flavor crystals were used. The solutions were made by dissolving 2 g of flavor crystals and 6 g of granulated sugar in 500 ml of distilled water. These three flavors were chosen from a set of six on the basis of pretest for discriminability. The solutions were dispensed through a Fisher 25-ml pipette (13-671-108E) mounted on the cage top of each individual chamber. Food consisted of a standard laboratory chow for rodents (Rodent Diet 5001; PMI International, Brentwood, MO). Twelve Wahmann standard rat running wheels, with a circumference of 1.1 m, were used to provide access to wheel running. Wheel turns were counted by two microswitches activated by a cam attached to the axle of the wheel. Microcomputer circuitry, running under computer control and data acquisition [7], ensured that a full revolution of the wheel was necessary and that rocking of the wheel was not recorded. The rats were placed in individual cages and given free access to food and water; water was presented during this period through standard cage water bottles and weighed daily 8 h after the start of the dark cycle. One hour after the start of the dark period on the third day, the standard water bottles were replaced with the pipettes. Seven hours later, food and water were removed. Beginning on the fourth day, rats were fed and watered according to the following schedule. Thirty minutes of access to the pipettes and to 5 g of food was provided 1 h after the beginning of the dark period. Two hours of access to fluid and to 10 g of food was also provided 8 h after the start of the dark cycle. Consequently, each rat received 15 g of food and 2.5 h of access to fluids through the pipette. Rats were weighed at the start of the second feeding period. Food and fluid consumption were measured daily. Rats received only water under this protocol for five consecutive days. On the ninth day, a series of daily conditioning trials began. Conditioning involved pairing a flavored solution with one of three experiences with the running wheels. The water in the pipettes was replaced by one of the three flavored solutions during the first 0.5-h feeding period. Immediately after this period, the rats were either kept in their home cages (Home Cage condition), were transferred to a running wheel (Wheel condition) or were transferred to the running wheel that was immobilized (Locked Wheel condition). Exposure to the wheels lasted 60 min and was followed by transferring the rat back to the home cage. Phase 1 of conditioning consisted of 9 days during which each of the three flavors was paired with one of the treatments using a within-subjects design. On the orange flavor days (Days 9, 12 and 15), one third of the rats received the Wheel treatment following flavor presentation;
one third received the Locked Wheel treatment; and one third received the Home Cage treatment. On the lemon– lime days (Days 10, 13 and 16), one half of the rats that received the Wheel treatment following orange was now given the Locked Wheel treatment, with the other half receiving the Home Cage treatment. The four rats that received the Locked Wheel on orange days were split into two subgroups receiving either Wheel or Home Cage treatment. The rats that received the Home Cage treatment following the orange flavor presentation were split into Wheel and Locked Wheel subgroups. On the cherry presentation days (Days 11, 14 and 17), all rats received the third remaining treatment. Phase 2 consisted of four consecutive days designed to test consumption of each flavor. Rats were kept in their home cages for these days, with no wheel exposures. One hour after the start of the dark cycle, the rats were given 30 min of access to food and different fluids in the pipettes over the 4 days. The first day, this fluid was water only. On the second test day, rats were presented with pipettes filled with the orange flavor. Lemon –lime and cherry were presented on the third and fourth test days, respectively. As in the first phase, water and 10 g of food were provided at the second feeding, 8 h after the start of the dark cycle. Phases 3 and 4 were replications of Phases 1 and 2, with each rat receiving the same pairings of flavor and experimental condition. The test sequence of flavors during Phase 4 was altered, however, and consisted of lemon –lime on the second test day, followed by orange and cherry.
3. Results Body weights increased linearly during the experimental phases. Over this time, rats usually ate all of their 15 g daily food supply (morning and afternoon sessions), with 0 – 3 g left over. Consumption of flavors paired with the opportunity to run (Wheel) systematically declined over the two
Fig. 1. Number of wheel revolutions for sessions during which a flavored liquid was paired with 1 h of access to a running wheel (mean ± S.E.M.).
C.D. Heth et al. / Physiology & Behavior 74 (2001) 53–56
55
Fig. 2. Consumption of flavored liquid associated with the opportunity to run (Wheel), with novelty of the wheel (Locked Wheel) and with the home cage (Home Cage) for Phases 2 and 4 tests (mean ± S.E.M.).
phases of conditioning (Phases 1 and 3) in accord with an acquisition-like process of CTA. In contrast, over the same two phases, consumption increased for flavors associated with either a Locked Wheel or Home Cage setting, with a greater increase in the latter condition. During Phases 1 and 3, rats received 1 h of access to the running wheel on Wheel treatment days. Fig. 1 shows that over the course of these days, the rate of wheel running increased from approximately 150 to about 500 revolutions per hour and then leveled off. A within-subjects analysis of variance (ANOVA) indicated a reliable effect of repeated access to the running wheel [ F(5,55) = 27.88, MSe = 8847.39, P < .01]. The principal data of the study are the amounts consumed by the rats during the two test phases. A preliminary ANOVA with two tests, three experimental treatments and six combinations of flavors assigned to treatments revealed no significant main effect of flavor assignment or interaction of assignment with test or treatment. Consequently, results were collapsed across flavor assignment for all subsequent analyses. The effects of experimental treatments on fluid consumption for Phase 2 are shown in the left panel of Fig. 2, while those for Phase 4 are shown in the right panel. A within-subjects ANOVA using two tests and three experimental treatments indicated a significant effect of test [ F(1,22) = 15.18, MSe = 1.94, P < .01], of experimental treatment [ F(2,22) = 20.65, MSe = 6.25, P < .01] and a significant interaction of test and experimental treatment [ F(2,22) = 7.98, MSe = 0.72, P < .01]. Planned contrasts indicated that the Wheel treatment differed from the Locked Wheel [ F(1,22) = 18.18, P < .01], but that the Locked Wheel treatment did not reliably differ from the Home Cage treatment [ F(1,22) = 2.66]. The difference between the Wheel and Locked Wheel treatments increased between the first and second tests [ F(1,22) = 13.44, P < .01]. There
was no evidence of correlation between consumption on the test days and amount of wheel running.
4. Discussion The present experiment was conducted to determine whether novelty of the wheel could be a confounding factor in the demonstration of CTA produced by opportunity to run in an activity wheel. The principal comparison is between the open wheel treatment and that of the locked wheel. The results showed a significant reduction in consumption of the flavor associated with the opportunity to run compared to the flavor associated with a novel wheel without the opportunity to run. Furthermore, there was no evidence that consumption of the flavor paired with the novel wheel differed from the home cage control. The overall pattern of results indicates that CTA is due to the pairing of a flavored liquid with the opportunity to run and not an effect of novelty of the wheel. We were unable to detect a correlation between the amount of running and consumption of the flavor paired with the Wheel treatment. Either the amount of running is not important for CTA, or the correlation was attenuated by the within-subjects design. That is, the days of the Wheel treatment were not consecutive, but were interspersed with days of Locked Wheel and Home Cage treatments. The interpolation of alternate treatments could have obscured such a correlation. Our findings coincide with Ref. [4] and show that a flavor paired with the opportunity to run is consumed less than a flavor that is not so paired. It remains to be determined whether the decline in consumption is due to the same mechanisms as those involved in taste aversion learning [8]. Unlike the injection of emetic drugs, wheel running is an operant behavior with endogenous rates
56
C.D. Heth et al. / Physiology & Behavior 74 (2001) 53–56
functionally tied to variables of feeding, light – dark experience and thirst. Both the present experiment and that of Lett and Grant were conducted under conditions of food and water restriction. One question is whether the opportunity to run on a wheel would produce a decline in consumption when animals are given food and water ad libitum.
References [1] Epling WF, Pierce WD, Stefan L. A theory of activity-based anorexia. Int J Eating Disord 1983;3:27 – 46. [2] Pierce WD, Epling WF. Theoretical developments in activity anorexia. In: Epling WF, Pierce WD, editors. Activity anorexia: theory, research and treatment. Mahwah, NJ: Lawrence Erlbaum, 1996. pp. 23 – 41.
[3] Pierce WD, Epling WF, Boer DP. Deprivation and satiation: the interrelations between food and wheel running. J Exp Anal Behav 1986;46: 199 – 210. [4] Lett BT, Grant VL. Wheel running induces conditioned taste aversion in rats trained while hungry and thirsty. Physiol Behav 1996;59: 699 – 702. [5] Routttenberg A. ‘‘Self-starvation’’ of rats living in activity wheels: adaptation effects. J Comp Physiol Psychol 1968;66:234 – 8. [6] Jakubczak LF. Age differences in the effects of terminal food deprivation (starvation) on activity, weight loss, and survival of rats. J Gerontol 1967;22:421 – 6. [7] Morse AD, Hunt TN, Wood GO, Russell TC. Diurnal variation of intensive running in food-deprived rats. Comp J Physiol Pharmacol 1995;73:1519 – 23. [8] Revusky SH, Grant J. Learned associations over long delays. In: Bower TH, editor. The psychology of learning and motivation, vol. 4. New York: Academic Press, 1970;73. pp. 1 – 84.
Conditioned taste aversion induced by wheel running is not due to novelty of the wheel C. Donald Heth*, Peter Inglis, James C. Russell, W. David Pierce Department of Psychology, P-217 Biological Sciences Building, University of Alberta, Edmonton, Canada T6G 2E9 Received 15 November 2000; received in revised form 13 April 2001; accepted 24 April 2001
Abstract Under a within-subjects design, food- and water-restricted rats showed a significant reduction in consumption of a flavor associated with the opportunity to run compared to another flavor associated with a novel wheel without the opportunity to run. Furthermore, there was no evidence that consumption of the flavor paired with the novel wheel differed from a home cage control. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Conditioned taste aversion; Wheel running; Novelty; Activity anorexia
1. Introduction Rats exposed to food restriction and the opportunity to run often become severely anorexic [1– 3]. Lett and Grant [4] proposed that the anorexia could be due to a conditioned taste aversion (CTA) to food associated with wheel running. They supported this view with evidence that wheel running could establish a CTA to novel flavored liquids. Two groups of food- and water-restricted rats received pairings of either a salt or a sour flavor paired with a brief opportunity to run in a standard activity wheel. For each group, the unpaired flavor was presented in the rat’s home cage. After three conditioning trials, all rats received test opportunities to drink salt or sour flavors. Lett and Grant reported conditioned aversion to the flavor associated with access to a running wheel on the third conditioning trial and on the subsequent test. A possible confounding factor in the Lett and Grant experiment is the effect of transferring the rats from the home cage to a running wheel. Rats will show a decline in food intake when first transferred to an activity wheel [5]. A typical control for novelty of the wheel is to move experimental animals from their home cages to a locked running wheel. The putative effects of wheel running on food intake * Corresponding author. Tel.: +1-708-492-5216; fax: +1-780-4921768. E-mail address: [email protected] (C.D. Heth).
are then compared not only to those of a home cage condition, but also to those of the locked wheel. In their design, Lett and Grant did not compare CTA between locked and open wheel conditions; hence, novelty of the wheel could be a confounding factor in their experiment and could account for the aversion to the tastes. The present experiment controls for novelty of the wheel. In a within-subjects design, rats were exposed to three flavored solutions. One of these was presented prior to the opportunity to run in an open wheel; one was presented prior to exposure to a locked wheel; and one was presented in the home cage. If CTA does not depend upon novelty of the wheel, then rats should drink less of the flavor paired with the opportunity to run (open wheel) than of the flavor paired with the locked wheel (the novelty control). On the other hand, if novelty of the wheel is sufficient to produce CTA, then consumption of both flavors should differ from consumption of the flavor presented in the home cage.
2. Method Twelve male JCR:LA-cp rats from the University of Alberta medical research colony, 6 weeks of age at the start of the experiment and ranging in weight from 132 to 170 g (M = 155 g), were tested. Rats are highly active under conditions of food restriction at this age range [6]. The rats were individually housed in clear polycarbonate cages
0031-9384/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved. PII: S 0 0 3 1 - 9 3 8 4 ( 0 1 ) 0 0 5 5 3 - 4
54
C.D. Heth et al. / Physiology & Behavior 74 (2001) 53–56
(47 27 20 cm) with wood chip bedding on a 12-h on/12-h off light schedule. Temperature was maintained between 20°C and 22°C. Food and water were freely available on wire cage tops, unless otherwise specified. Three solutions of orange, lemon –lime and cherry Kool Aid commercial flavor crystals were used. The solutions were made by dissolving 2 g of flavor crystals and 6 g of granulated sugar in 500 ml of distilled water. These three flavors were chosen from a set of six on the basis of pretest for discriminability. The solutions were dispensed through a Fisher 25-ml pipette (13-671-108E) mounted on the cage top of each individual chamber. Food consisted of a standard laboratory chow for rodents (Rodent Diet 5001; PMI International, Brentwood, MO). Twelve Wahmann standard rat running wheels, with a circumference of 1.1 m, were used to provide access to wheel running. Wheel turns were counted by two microswitches activated by a cam attached to the axle of the wheel. Microcomputer circuitry, running under computer control and data acquisition [7], ensured that a full revolution of the wheel was necessary and that rocking of the wheel was not recorded. The rats were placed in individual cages and given free access to food and water; water was presented during this period through standard cage water bottles and weighed daily 8 h after the start of the dark cycle. One hour after the start of the dark period on the third day, the standard water bottles were replaced with the pipettes. Seven hours later, food and water were removed. Beginning on the fourth day, rats were fed and watered according to the following schedule. Thirty minutes of access to the pipettes and to 5 g of food was provided 1 h after the beginning of the dark period. Two hours of access to fluid and to 10 g of food was also provided 8 h after the start of the dark cycle. Consequently, each rat received 15 g of food and 2.5 h of access to fluids through the pipette. Rats were weighed at the start of the second feeding period. Food and fluid consumption were measured daily. Rats received only water under this protocol for five consecutive days. On the ninth day, a series of daily conditioning trials began. Conditioning involved pairing a flavored solution with one of three experiences with the running wheels. The water in the pipettes was replaced by one of the three flavored solutions during the first 0.5-h feeding period. Immediately after this period, the rats were either kept in their home cages (Home Cage condition), were transferred to a running wheel (Wheel condition) or were transferred to the running wheel that was immobilized (Locked Wheel condition). Exposure to the wheels lasted 60 min and was followed by transferring the rat back to the home cage. Phase 1 of conditioning consisted of 9 days during which each of the three flavors was paired with one of the treatments using a within-subjects design. On the orange flavor days (Days 9, 12 and 15), one third of the rats received the Wheel treatment following flavor presentation;
one third received the Locked Wheel treatment; and one third received the Home Cage treatment. On the lemon– lime days (Days 10, 13 and 16), one half of the rats that received the Wheel treatment following orange was now given the Locked Wheel treatment, with the other half receiving the Home Cage treatment. The four rats that received the Locked Wheel on orange days were split into two subgroups receiving either Wheel or Home Cage treatment. The rats that received the Home Cage treatment following the orange flavor presentation were split into Wheel and Locked Wheel subgroups. On the cherry presentation days (Days 11, 14 and 17), all rats received the third remaining treatment. Phase 2 consisted of four consecutive days designed to test consumption of each flavor. Rats were kept in their home cages for these days, with no wheel exposures. One hour after the start of the dark cycle, the rats were given 30 min of access to food and different fluids in the pipettes over the 4 days. The first day, this fluid was water only. On the second test day, rats were presented with pipettes filled with the orange flavor. Lemon –lime and cherry were presented on the third and fourth test days, respectively. As in the first phase, water and 10 g of food were provided at the second feeding, 8 h after the start of the dark cycle. Phases 3 and 4 were replications of Phases 1 and 2, with each rat receiving the same pairings of flavor and experimental condition. The test sequence of flavors during Phase 4 was altered, however, and consisted of lemon –lime on the second test day, followed by orange and cherry.
3. Results Body weights increased linearly during the experimental phases. Over this time, rats usually ate all of their 15 g daily food supply (morning and afternoon sessions), with 0 – 3 g left over. Consumption of flavors paired with the opportunity to run (Wheel) systematically declined over the two
Fig. 1. Number of wheel revolutions for sessions during which a flavored liquid was paired with 1 h of access to a running wheel (mean ± S.E.M.).
C.D. Heth et al. / Physiology & Behavior 74 (2001) 53–56
55
Fig. 2. Consumption of flavored liquid associated with the opportunity to run (Wheel), with novelty of the wheel (Locked Wheel) and with the home cage (Home Cage) for Phases 2 and 4 tests (mean ± S.E.M.).
phases of conditioning (Phases 1 and 3) in accord with an acquisition-like process of CTA. In contrast, over the same two phases, consumption increased for flavors associated with either a Locked Wheel or Home Cage setting, with a greater increase in the latter condition. During Phases 1 and 3, rats received 1 h of access to the running wheel on Wheel treatment days. Fig. 1 shows that over the course of these days, the rate of wheel running increased from approximately 150 to about 500 revolutions per hour and then leveled off. A within-subjects analysis of variance (ANOVA) indicated a reliable effect of repeated access to the running wheel [ F(5,55) = 27.88, MSe = 8847.39, P < .01]. The principal data of the study are the amounts consumed by the rats during the two test phases. A preliminary ANOVA with two tests, three experimental treatments and six combinations of flavors assigned to treatments revealed no significant main effect of flavor assignment or interaction of assignment with test or treatment. Consequently, results were collapsed across flavor assignment for all subsequent analyses. The effects of experimental treatments on fluid consumption for Phase 2 are shown in the left panel of Fig. 2, while those for Phase 4 are shown in the right panel. A within-subjects ANOVA using two tests and three experimental treatments indicated a significant effect of test [ F(1,22) = 15.18, MSe = 1.94, P < .01], of experimental treatment [ F(2,22) = 20.65, MSe = 6.25, P < .01] and a significant interaction of test and experimental treatment [ F(2,22) = 7.98, MSe = 0.72, P < .01]. Planned contrasts indicated that the Wheel treatment differed from the Locked Wheel [ F(1,22) = 18.18, P < .01], but that the Locked Wheel treatment did not reliably differ from the Home Cage treatment [ F(1,22) = 2.66]. The difference between the Wheel and Locked Wheel treatments increased between the first and second tests [ F(1,22) = 13.44, P < .01]. There
was no evidence of correlation between consumption on the test days and amount of wheel running.
4. Discussion The present experiment was conducted to determine whether novelty of the wheel could be a confounding factor in the demonstration of CTA produced by opportunity to run in an activity wheel. The principal comparison is between the open wheel treatment and that of the locked wheel. The results showed a significant reduction in consumption of the flavor associated with the opportunity to run compared to the flavor associated with a novel wheel without the opportunity to run. Furthermore, there was no evidence that consumption of the flavor paired with the novel wheel differed from the home cage control. The overall pattern of results indicates that CTA is due to the pairing of a flavored liquid with the opportunity to run and not an effect of novelty of the wheel. We were unable to detect a correlation between the amount of running and consumption of the flavor paired with the Wheel treatment. Either the amount of running is not important for CTA, or the correlation was attenuated by the within-subjects design. That is, the days of the Wheel treatment were not consecutive, but were interspersed with days of Locked Wheel and Home Cage treatments. The interpolation of alternate treatments could have obscured such a correlation. Our findings coincide with Ref. [4] and show that a flavor paired with the opportunity to run is consumed less than a flavor that is not so paired. It remains to be determined whether the decline in consumption is due to the same mechanisms as those involved in taste aversion learning [8]. Unlike the injection of emetic drugs, wheel running is an operant behavior with endogenous rates
56
C.D. Heth et al. / Physiology & Behavior 74 (2001) 53–56
functionally tied to variables of feeding, light – dark experience and thirst. Both the present experiment and that of Lett and Grant were conducted under conditions of food and water restriction. One question is whether the opportunity to run on a wheel would produce a decline in consumption when animals are given food and water ad libitum.
References [1] Epling WF, Pierce WD, Stefan L. A theory of activity-based anorexia. Int J Eating Disord 1983;3:27 – 46. [2] Pierce WD, Epling WF. Theoretical developments in activity anorexia. In: Epling WF, Pierce WD, editors. Activity anorexia: theory, research and treatment. Mahwah, NJ: Lawrence Erlbaum, 1996. pp. 23 – 41.
[3] Pierce WD, Epling WF, Boer DP. Deprivation and satiation: the interrelations between food and wheel running. J Exp Anal Behav 1986;46: 199 – 210. [4] Lett BT, Grant VL. Wheel running induces conditioned taste aversion in rats trained while hungry and thirsty. Physiol Behav 1996;59: 699 – 702. [5] Routttenberg A. ‘‘Self-starvation’’ of rats living in activity wheels: adaptation effects. J Comp Physiol Psychol 1968;66:234 – 8. [6] Jakubczak LF. Age differences in the effects of terminal food deprivation (starvation) on activity, weight loss, and survival of rats. J Gerontol 1967;22:421 – 6. [7] Morse AD, Hunt TN, Wood GO, Russell TC. Diurnal variation of intensive running in food-deprived rats. Comp J Physiol Pharmacol 1995;73:1519 – 23. [8] Revusky SH, Grant J. Learned associations over long delays. In: Bower TH, editor. The psychology of learning and motivation, vol. 4. New York: Academic Press, 1970;73. pp. 1 – 84.