Effects of food deprivation upon behavioral patterns and time budgeting of Aplysia fasciata

Effects of food deprivation upon time devoted to different behaviors in Aplysia fasciata were investigated. Time invested in mating, egg-laying, swimming, and movement in place was increased, and time spent immobile and crawling was decreased. Time of occurrence of behaviors was highly synchronized, but differed from that seen when food was available. Changes in behavior seem to be adaptive to conditions in which food is scarce: increased motility may lead to finding sites where food is present, while increased egg-laying and mating may ensure survival of progeny. Behavioral changes can be readily accounted for by removal of postingestive stimuli signaling satiation.     

Common regulation of feeding and mating in Aplysia fasciata: pheromones released by mating and by egg cordons increase feeding behavior.

We examined whether pheromones released by reproductive behaviors (mating and egg-laying) affect feeding behavior. A preliminary experiment demonstrated that the quantity of food eaten can be used to measure the effects of pheromones on feeding. Using this measure, we then showed that Aplysia that were prevented from mating, but that were in the same aquarium as mating conspecifics, eat more food than do Aplysia in a medium lacking mating animals. Mating and feeding were not temporally correlated, indicating that pheromones released by mating probably do not initiate feeding, but rather modulate feeding after it has begun. Aplysia that were in the same aquarium as freshly deposited egg cordons also ate more than did animals in a medium lacking eggs.     

Effects of conspecifics on feeding in Aplysia fasciata

The presence of other Aplysia in the environment increases the time spent feeding. This finding is consistent with the hypothesis that a common arousal mechanism modulates feeding and reproductive behaviors. The arousal level is presumably increased by pheromones released by additional animals.     

Motivational control of impulsive behavior interacts with choice opportunities

Impulsive behavior has been investigated through choice between a smaller/immediate reinforcer and a larger/delayed reinforcer, or through performance on a differential reinforcement of low rate (DRL) schedule. In the present study, we investigated a methodological divergence between these two procedures: in the former procedure, delay is a consequence of the subject's own choice, whereas in the later procedure, subjects are explicitly reinforced for delaying a response. In Experiment 1, 7 rats maintained at 80% of their free-feeding weights showed poorer efficiency of lever-pressing responses on a DRL 30-s schedule than when they were maintained at 90% of free-feeding weight. In Experiment 2, 16 rats were subjected to a concurrent chain schedule: the initial link was concurrent fixed ratio 1 fixed ratio 1, and each of these alternatives was followed by a short-DRL requirement with a one pellet reinforcer or a long-DRL requirement with a three pellet reinforcer. In one block of trials, rats were not allowed to choose between the two terminal links (forced-choice), whereas in the other block of trials rats were allowed to choose freely between the two terminal links (free-choice). Compared with rats maintained at 95% of their free-feeding weights, rats maintained at 80% of their free-feeding weights showed poorer efficiency in the terminal links’ DRL schedule performance (just as in Experiment 1), but this difference was shown only in the forced-choice blocks. These results indicate that motivational control of DRL schedule performance interacts with type of choice-making opportunity and highlight the direct comparison of motivational control of impulsive choice and DRL schedule performance.     

Sequencing of behaviors in Aplysia fasciata: integration of feeding, reproduction, and locomotion.

To begin studying the neural basis of higher-order decision-making in Aplysia fasciata, we examined individual bouts of behavior in various conditions of access to food and/or mates. We then determined rules governing transitions between bouts. The data indicate that a single intermediate condition, moving in place, may be centrally related to transitions between behaviors. In all conditions, over 85% of all transitions between behaviors were via moving in place. Moving in place tended to precede and follow other categories of activity (crawling, swimming, immobile), and feeding. Also, moving in place apparently represents a fixed proportion of all bouts of behavior. In each condition, moving in place represented approximately 40% of all bouts, while the number of bouts of other behaviors varied markedly. After a bout of moving in place there was a strong tendency for the animal to return to the behavior performed before moving in place. Additional preferred sequences of behavior were also seen. Courtship tended to precede mating, and crawling preceded swimming.     

Activity patterns and time budgeting of Aplysia fasciata under field and laboratory conditions

Activity patterns of Aplysia fasciata were observed in a protected port environment and in an aquarium. In both, major activities were feeding and mating, which collectively took up about 45% of the total time of the animals. Active behaviors occurred primarily at night; much of the day was spent in the inactive state. Activities were highly synchronized, with large numbers of animals performing the same behaviors simultaneously at a specific time. Mating and eating occurred primarily at different times; relatively few animals were observed performing these behaviors simultaneously. Many animals laying eggs were simultaneously mating as females.     

Daily variation of multiple behaviors in Aplysia fasciata: integration of feeding, reproduction, and locomotion

Daily variations in feeding, reproductive behaviors, and activity level were examined under three conditions: (1) animals had access to food and mates; (2) there was access only to food; (3) neither food nor mates were present. Behaviors differed in amplitude of variations from their daily mean value. Egg-laying had the strongest tendency to be clustered. Amplitude of variations in courtship and swimming was larger than those of immobility, crawling, and feeding, while moving in place was the least clustered behavior. Changes in state affected the tendency to be clustered. When food and mates were present, amplitude of variations became progressively larger for immobility, moving in place, crawling, and swimming. Behaviors differed in the degree to which variations were patterned as a 1/day oscillation. Relatively little of the variability in crawling, moving in place, courtship, and egg-laying was due to a 1/day oscillation under any condition. By contrast, a large proportion of the variability of immobility, swimming, mating, and eating was modulated by a 1/day oscillation in at least one condition. The contribution of a 1/day oscillation to variability differed in the conditions examined. For immobility and swimming, when food and mates were present, the 1/day component of variability became smaller. By contrast, presence of mates led to an increase in the 1/day component of variability modulating feeding. Daily peaks of swimming and feeding were in phase with one another, and out of phase with mating and feeding. The ratio of locomotion to inactivity is constant, independent of change in external conditions. However, this ratio varied throughout the day. When food and mates were absent, variations of immobility and swimming were strongly related to variations in the inactivity ratio. When food and mates were added, this tendency decreased. The data suggest that daily variations in occurrence of behaviors can be accounted for by interactions between oscillators affecting Aplysia behavior and motivational variables. A 1/day oscillator has strong effects on mating, swimming, and immobility. The effect of the oscillator is modified by changes in motivational state.     

Effects of food and mates on time budget in Aplysia fasciata: integration of feeding, reproduction, and locomotion

This study examines the time budgeted to different behaviors in Aplysia fasciata under three conditions: (1) animals have constant access to food and mates: (2) there is access to food, but not to mates; (3) neither food nor mates are present. The data suggest a number of rules underlying behavioral integration: (1) Feeding, reproductive behaviors, and activity seem to be natural categories for behavioral choice. Feeding and reproductive behaviors are controlled in tandem by a common arousal mechanism, while time left over after animals feed and reproduce is distributed in a fixed ratio between locomotion (crawling and swimming) and inactivity (immobility and movement in place). (2) Relative distribution between different forms of locomotion and inactivity is modified by changes in motivational state. More time is spent swimming than crawling when feeding and/or mating is prevented, while more time is spent moving in place than immobile when the arousal level is increased. (3) Feedback control of feeding and reproduction is asymmetric. Satiation of feeding inhibits the common arousal. In the absence of food, time spent on reproductive behaviors increases due to disinhibition of the common arousal. By contrast, positive feedback arising from sexual behavior excites the common arousal. When mating is prevented by removing potential mates, time spent feeding decreases. (4) Generally, animals choose between performing the three main categories of behavior. Although Aplysia simultaneously can feed and mate, or locomote and mate, they do so infrequently. By contrast, different types of reproductive behaviors (male mating, female mating, egg-laying) are commonly performed simultaneously.     

Motivational pursuits in the context of human sexual relationships

The current article examines how close relationships combine with individual differences in sex motives (Cooper, Shapiro, & Powers, 1998) to shape sexual experience. We first provide an overview of the motivational approach as it relates to sexual behavior and then describe 2 broad mechanisms (1 transactional, the other interactional) by which motives and relational context combine to shape behavior. Drawing on our past research, we review evidence showing that people select relationship contexts based partly on their motives and that these contexts in turn shape future motives and behavior; that partner motives shape sexual experience above and beyond one's own motives; and that both the broader relationship context and partner motives moderate the effects of one's own motives on sexual experience. We conclude that the nature of motivational pursuits cannot be adequately understood in the abstract, but rather we must take into account the relational context in which one's needs are pursued.     

Control of instrumental behavior by deprivation stimuli

In Experiment 1, rats were given one trial per day in a straight alley under food deprivation on half of the trials and under water deprivation on the other half. Wet mash was available in the goal box under food deprivation for Group H and under water deprivation for Group T, the other deprivation being nonrewarded for each group. After 15--18 trials both groups ran significantly faster on their rewarded than on their nonrewarded deprivation days. A third group showed that random variation of alley color retarded formation of the discrimination. A fourth group was run in a conditional discrimination in which under food deprivation wet mash was available in a black alley, nonreward in a white alley, and vice versa under water deprivation. This group took 114 trials to begin running significantly faster in their rewarded than in their nonrewarded alley under each deprivation. In Experiment 2, it was shown that prior learning about deprivation cues "blocks" learning about alley color when alley color is subsequently presented in compound with the deprivation cue but that when both alley color and deprivation cues are relevant from the start of training, the rat learns about both cues. It is suggested that previous studies have underestimated the importance of deprivation cues by using conditional discrimination designs, choice measures rather than speeds, and parameters that are not optimal for discrimination learning.     

Rapid and persistent suppression of feeding behavior induced by sensitization training in Aplysia

In Aplysia, noxious stimuli induce sensitization of defensive responses. However, it remains largely unknown whether such stimuli also alter nondefensive behaviors. In this study, we examined the effects of noxious stimuli on feeding. Strong electric shocks, capable of inducing sensitization, also led to the suppression of feeding. The use of multiple training protocols revealed that the time course of the suppression of feeding was analogous to that of sensitization. In addition, the suppression of feeding was present only at the time points in which sensitization was expressed. These results suggest that, in Aplysia, noxious stimuli may produce concurrent changes in neural circuits controlling both defensive and nondefensive behaviors.     

Mesencephalic participation in the control of sexual behavior in the female rat

Electric stimuli applied to both pudendal nerves evoked field potentials, unit responses, and multiunit responses in the ventrolateral midbrain, in and around the peripeduncular nucleus. Bilateral lesions placed in this region suppressed sexual behavioral responses (lordosis and courting behavior) of ovariectomized rats primed with 5, 10, 100, and 1,000 microgram of estradiol benzoate and 2 mg of progesterone per kilogram of body weight. It is proposed that the region in question represents a relay station for the integration of sensory and endocrine information concerned in the control of receptive sexual behavior in the female rat.     

Motivational control of motor performance by goal setting in a dual-task situation

Summary The goal-setting approach to task motivation is applied to examine the way in which subjects control their performance on two concurrently performed tasks under the guidance of different goals in a dual-task situation. The tasks were a simple auditory-manual reaction time (RT) task and a visual-manual pursuit-tracking task. The goal conditions assigned alternatively to the tasks differed with respect to goal specificity and feedback information (KR) given after the trials. It is shown that the improvement of performance in the task with hard, specific goals is achieved in both cases at the cost of the concurrently performed other task which, on the basis of a lack of feedback and a rather unspecific goal instruction, should have a lower priority. The data reveal some strategies hidden behind these overall changes of the average performance at both tasks. For the RT task, the adjustment to the different goals is mainly achieved by changes in the temporal control or preparatory processes as can be inferred from the RT distributions as well as from the analysis of some typical errors. For the tracking task, changes in the tracking accuracy within the overlapping RT intervals are the best indicators for the performance control under the different goal conditions.This research was supported by a grant from the Deutsche Forschungsgemeinschaft (Kl 408/4-2)     

Perceptions of coercive sexual behavior by males and females

In this study male and female subjects were given six vignettes depicting heterosexual interactions between acquaintances. The vignettes described sexual advances representing different points along a coerciveness continuum. The gender of the aggressor and the victim were varied. The subjects were then asked to indicate their perception of the degree of coerciveness involved. In addition, they were asked to attribute both positive and negative feelings to the victim. The results indicated that male subjects perceived these sexual advances as slightly more coercive when the victim was a female, whereas females perceived the advances as slightly more coercive when the victim was a male. Also, there was a tendency to view the low-coercion activities as more coercive when the males were the victim, whereas the opposite was true for the vignettes rated high on coercion, especially the one describing physical coercion. The attributions of positive and negative feelings tended to parallel the coerciveness ratings. Typically, the more coercive activity was seen as, the less positive feelings and more negative feelings the subjects attributed to the victim. The results were discussed in terms of stereotypical beliefs regarding the sexuality of males and females and attribution theory.     

Selectivity in paternal and infanticidal responses by male mice: effects of relatedness, location, and previous sexual partners.

Male mice tend to be infanticidal to unrelated infants but parental to their own offspring. The present study examines three hypotheses that might explain this apparent discrimination. There was no evidence of selective infanticide toward infants encountered for the first time on the basis of kinship, location, or cues associated with previous sexual partners. However, males tended to direct more paternal responses toward their own unfamiliar infants than toward unrelated infants, infants encountered in the male's home cage than those in the cage of another male, and when cues associated with a previous sexual partner were present. Data suggested that the responses of females to male intruders might influence the responses of those males. It was concluded that the infanticidal responses of male mice are mediated by a particular state of the male but that males in a noninfanticidal state may vary their paternal responsiveness on the basis of direct and indirect cues concerning relatedness.     

The relationship between borderline personality disorder and number of sexual partners

In this study, we examined the number of self-reported lifetime sexual partners between those with and without borderline personality disorder (BPD). Our hypothesis was that, due to the nature of the disorder, those with BPD would exhibit a greater number of lifetime sexual partners. Using a survey methodology in a consecutive sample of internal medicine outpatients (N = 354), we administered two self-report measures for BPD (the borderline personality scale of the Personality Diagnostic Questionnaire-4 and the Self-Harm Inventory), and queried participants, "How many sexual partners have you had in your lifetime?" Correlation coefficients and one-way ANOVAs were conducted to determine the relationship between BPD and the number of sexual partners. According to BPD status with the borderline personality scale of the Personality Diagnostic Questionnaire-4, we found that the mean number of sexual partners among BPD-positive participants was nearly double (p < .001) that of BPD-negative participants; according to BPD status with the Self-Harm Inventory, the mean number of sexual partners among BPD-positive participants was more than double (p < .001) that of BPD-negative participants. Compared to internal medicine outpatients without BPD, those with BPD exhibit a statistically significantly greater number of sexual partners.