Hippocampal and cortical activity during sexual behavior in the female rat.

Hippocampal and cortical activity were studied during sexual behavior in the female rat. Hippocampal theta appeared during her soliciting behavior. High-frequency theta accompanying the male's pursuit slowed when the male mounted the female and then increased in frequency during the brief continuation of lordosis following mounts without vaginal penetration. During prolonged lordosis after intromissions and ejaculations, slow theta continued. No changes in cortical frequencies were observed during mounts, intromissions, or ejaculations. During immobility (standing, sitting, and lying down) hippocampal activity became slow and irregular. High-amplitude hippocampal and, eventually, cortical spindles developed during immobility as sexual exhaustion was approached. Immobility and its accompanying electroencephalographic spindling are interpreted as indicative of a sexual satiety or inhibitory process.     

Transection of direct anterior thalamic afferents from the hippocampus: effects on activity and active avoidance in rats

This investigation demonstrates the importance of the direct hippocampo-anterior thalamic component of the postcommissural fornix in the control of general locomotion and active avoidance. Transection of anterior thalamic afferents from the hippocampal formation (subicular cortex), at the point where they exit from the fornix posterior to the septum, is sufficient to enhance bidirectional active avoidance acquisition and increase general activity. This transection may also interrupt fibers to or from other thalamic nuclei and the anterior septum. However, destruction of connections of the anterior septum with the hippocampus, habenula, and thalamus by transection in the coronal plane anterior to the descending fornix columns, without damage to the subiculothalamic fibers, increases general activity levels without damage to the subiculothalamic fibers, increases general activity levels without affecting active avoidance behavior. The activity increase in this case resembles that seen after septal lesions rather than that seen after hippocampal lesions. Thus, destruction of a single fornix component contributing afferents to the anterior thalamic nuclei reproduces at least part of the hippocampal syndrome. This suggests that these fibers contribute significantly to the control of these behaviors and may mediate active avoidance changes resulting from hippocampal and fornix damage.     

Septal lesions and biting attacks in rats bidirectionally selected for emotionality

Twenty-nine colonies composed of one female and two male rats of high or low emotional strain were established. A dominant male of each colony was identified based on its attacks on an intruder rat. It was found that dominant males of the low emotional strain colonies were significantly more aggressive than those of the high emotional strain. Septal lesions or sham operations were given to dominant males of both strain colonies. Intruder tests were followed and several aggressive behaviors were measured by VTR observation. Biting attacks of the high emotional strain decreased for 10 days after septal latencies were shortened by septal lesions. Lesions X Strain interaction was significant. These results suggest that septal lesion effects on biting attacks are influenced by artificial genetic operations.     

缰核在抑郁症中的作用:研究和治疗的新途径

缰核是哺乳动物神经系统中连接前脑和中脑的重要节点,这一古老的核团因其与抑郁症的密切联系,近来获得国内外研究者的关注.缰核接受来自边缘系统、基底神经节等的传入信号,向下投射到中脑5-羟色胺系统和多巴胺系统.在应激条件下缰核免疫活动增强,向下游的投射信号增强,以此调节单胺类递质释放,参与抑郁症的发病机制,并且参与抗抑郁治疗的起效途径.这些证据提示缰核在抑郁症中具有重要作用,将成为研究和治疗的新途径.未来研究应从缰核与上下游核团的神经联系、与丘脑-垂体-肾上腺轴的相互影响、以及与免疫激活的交互作用等方面进一步探索,为研究抑郁症病理机制和治疗方法提供线索.     

Intra-habenular injection of 6-hydroxydopamine produces impaired acquisition of DRL operant behavior

The anatomical connections of the habenula complex indicate it provides a relay between limbic forebrain and midbrain. Somewhat paradoxically, consequences of nonspecific lesion of the habenula are ambiguous with little change in basic response evident within simple behavioral paradigms. However, the potential functional importance for this relay has more recently been indicated by the demonstration of deficits in the ability of lesioned animals to alter behavior appropriate to both internal and external stimuli in more demanding behavioral tasks. Doubts concerning the importance of the habenula remain because of the large number of descending fibers of passage through the habenula. To provide more substantive evidence, 6-hydroxydopamine was injected into the habenula of rats to provide more limited lesion of catecholaminergic terminals. Animals were subsequently trained on an operant DRL 20-s schedule for which deficits have been reported following nonspecific lesion of the habenula. Lesioned animals showed a tendency to overrespond and were significantly less efficient on the schedule with decreased number of reinforcements received relative to controls. While the neurotoxic lesion procedure used does not differentiate noradrenergic and dopaminergic damage, the importance of intact catecholaminergic systems within the habenula for effective DRL acquisition is consistent with the suggested importance of the habenula for feedback regulation of dopamine within the ventral tegmental area through ascending dopamine fibers to the habenula.     

Female lordotic behavior mediated by monoamines in male rats.

Direct application of serotonergic of beta-adrenergic receptor blockers to anterior or posterior areas of the hypothalamus induced lordosis in intact estrogen-primed male rats. Such treatment with an alpha-adrenergic blocker or systemic administration of progesterone failed to increase lordosis. Centrally elicited lordosis did not occur without estrogen priming. Anatomical and neurochemical similarity may exist in the brain mechanism mediating lordotic behavior in male and female adult rats.     

Neonatal androgenic stimulation and adult sexual behavior in male and female golden hamsters.

Neonatally and adult castrated male hamsters as well as neonatally androgenized and nonandrogenized female hamsters were tested for both mounting and lordosis behaviors during treatment with either testosterone or ovarian hormones. Neonatal androgenization facilitated mounting behavior in adult animals administered either testosterone or ovarian hormones and suppressed lordosis behavior in adult ovarian-hormone-treated animals. Early androgen effects on the display of lordosis behavior during adult testosterone treatment were complex and varied with the exact timing of perinatal endogenous or exogenous androgenization. Species differences in hormone-behavior relationships and the possible role of perinatal androgenization in the development of rodents' ability to aromatize androgens were discussed.     

The effects of lateral, medial, or complete septal lesions on positive conditioned suppression in rats

This study investigated the effects of lateral, medial, or complete septal lesions in rats on lever pressing and US-approach behaviors during the presentation of a light followed by two free food pellets. Ten days after surgery, groups of rats received 20 sessions of a random interval (RI) 60-s schedule of food reinforcement. The positive conditioned suppression paradigm consisted of 20 sessions of a 10-s light paired with free food while the rats were responding on the RI 60-s schedule. All groups of rats significantly suppressed lever pressing during the 10-s light presentation. During the last four sessions of the 10-s light condition, rats with lateral septal lesions had a significant increase in food-tray entries during the light presentation, while the other groups decreased lever pressing without a change in food-tray entries during the 10-s light presentation. Although rats with septal damage generally have difficulty inhibiting responses in a variety of operant situations, rats with lateral, medial, or complete septal lesions showed no impairment in positive conditioned suppression. This study also suggests that when the spatial arrangement of the CS and the type of US were manipulated to minimize sign-tracking and goal-tracking behaviors, emotional reactions during the presentation of the CS must be considered a factor influencing positive conditioned suppression.     

Central progesterone induces female sexual behavior in estrogen-primed intact males rats

Progesterone induced high levels of female lordotic behavior in 10 of 17 intact, estrogen-primed male rats when it was applied directly to the medial preoptic-anterior hypothalamic area. All 17 males previously had shown lordosis when the serotonergic antagonist methysergide was applied to the same central sites. Few males responded to systemic progesterone and none to intracralial cholesterol. Intradiencephalic Metycaine, a local anesthetic, induced lordosis in eight male that previously had responded to central progesterone. These data indicate that estrogen and progesterone act synergistically to induce lordosis in male rats when progesterone is administered directly to sensitive brain sites.     

Aggressive behavior in female hamsters: the hormonal basis for fluctuations in female aggressiveness correlated with estrous state

The frequency and sequencing of aggressive behaviors by naive female hamsters change during series of brief encounters, probably because of the lack of stable dominance relations. Such initial encounters seem most representative of interactions likely in free-ranging hamsters and have been emphasized in studies of the hormonal mediation of female aggression. Nonestrous females exhibit intense aggression toward conspecifics of either sex. Estrous females are not aggressive and spend much time in lordosis, indicative of sexual receptivity. The inhibition of fighting on estrous day depends on estrogen and progesterone. Whereas oil-injected adrenalectomized-ovariectomized females fight at high levels, comparable with intact nonestrous females, the combination of 17 beta-estradiol benzoate and progeterone suppresses fighting completely. In contrast, replacement of estradiol, progesterone, or testosterone propionate individually has on consistent effect. Hypophysectomized females also fight at high levels, indicating that pituitary hormones are not required for vigorous aggression. Further, individual anterior pituitary hormones did not produce marked changes in fighting. These results emphasize the roles of estrogen and progesterone in synchronizing aggression with current reproductive state.     

The GM1 ganglioside hastens the reduction of hyperemotionality after septal lesions

The purpose of the present study was to assess the effects of ganglioside treatment on changes in emotional, activity, and avoidance behaviors following septal brain damage. Rats were treated with GM1-gangliosides either before and after septal lesions, or only after septal lesions and tested for emotionality on 10 consecutive days beginning on the second day after surgery. The ganglioside treatment decreased the emotionality of rats with septal damage on the first test day, and enhanced their rate of recovery to control levels of emotionality. Septal rats treated with gangliosides had activity, rearing, and avoidance behaviors equivalent to nontreated septal rats; however, lesioned rats treated with GM1 showed reduced intertrial crossings during avoidance conditioning. These results suggest that the changes in emotional behavior of septal rats treated with GM1 occur shortly after the lesion.     

Vaginal stimulation in rats induces prolonged lordosis responsiveness and sexual receptivity.

Sexual receptivity to males resulted from stimulation of the vagina with a glass rod in previously unreceptive ovariectomized, estrogen-treated rats. Several minutes of rejection behavior preceded the receptivity. In a second study, manual palpation was used to determine the duration of the lordosis response facilitation. Initially, all females were unresponsive to manual flank-perineum stimulation (palpation). Vaginal stimulation plus palpation, which together elicit lordosis, facilitated subsequent lordosis responses to palpation. This effect persisted for several hours after the vaginal stimulation was applied. Vaginal stimulation alone, which was ineffective in eliciting lordosis, also facilitated lordosis in response to subsequent palpation. Repeated palpation did not facilitate lordosis. These prolonged effects were independent of hormone treatment.     

Dextrorphan effects on cocaine and brainstem perturbation

Dextrorphan is a noncompetitive blocker of N-methyl-D-aspartate (NMDA) receptors. Since NMDA blockers are known to reduce the locomotor stimulatory and toxic effects of cocaine, it was speculated that dextrorphan would attenuate cocaine-induced behavioral excitatory motor activity associated with and without mechanical perturbation of the brainstem. Technique: Motor activity was recorded following dextrorphan and/or cocaine challenge in 25 SHR rats. Ten were naive subjects. Mini-osmotic pumps delivering cocaine (2.5 mg/0.49 ul/hr) were placed in 15 subjects, and infusion was halted after the third infusion day. On the fifth day either a dextrorphan (25 mg/kg, subcutaneous) or a dextrorphan and cocaine (40 mg/kg, intraperitoneal) challenge was done. Ten rats had bipolar electrode implants in the bilateral brainstem. Five were treated with DC current lesions in each of 12 days over a 3-week period. The effects of brainstem lesions on escape behavior were also evaluated in those five subjects. Results: In the naive subjects, dextrorphan reduced motor activity (P=.0001), whereas combined cocaine and dextrorphan increased motor activity (P=0.04). In lesioned subjects, dextrorphan decreased motor activity (P=0.0001). In electrode implant subjects, combined dextrorphan and cocaine challenge decreased the motor activity (P=0.04). Hyperactivity in the electrode implant group was greater than in the lesioned subjects. Midbrain electrolytic lesions attenuated escape behavior. A variety of behaviors were produced by brainstem lesions. Conclusions: Dextrorphan and brainstem lesions reduced motor hyperactivity and escape behavior. In electrode implant subjects dextrorphan counteracted the expected cocaine excitatory motor effects. Dextrorphan did not activate nor facilitate seizures.     

Permanent and transient effects of repeated preweaning stress on social and sexual behaviors of rats

We have reported that exposure of preweaning male and female rats to a model of unpredictable mild physical stressors (Neo-A) can decrease the behavioral and hormonal responses to acute and chronic stress as adults. In this paper we have analyzed the effect of Neo-A on development of social behaviors, including aggressiveness, social dominance, and sexual behavior in adulthood. The subjects were divided into two groups: Neo-A (daily exposed to unpredictable mild stresses- from day 2 up to day 15 of suckling; n = 30 litters) and controls (C) (undisturbed rats, except for testing, during the same period of life; n = 26 litters). When day 6 pups were submitted to a social clustering test the Neo-A group showed a higher rate of litter-mate clustering than C. The 35 days Neo-A males and Neo-A females submitted to a social behavior test after 24 h of social isolation also showed higher scores of time spent in active social interaction than controls, as well as a higher ratio of animals showing aggressive playing. A second social behavior test performed after 48 h of social isolation at days 75-80 of age revealed that only Neo-A females displayed increased social behavior and aggressive behaviors, whereas controls did not. A water competition test performed at 24 and 48 h after water deprivation showed that Neo-A adult males spent more time in possession of the drinking device and drank more frequently than C. When adult proestrous females were exposed to a sexual behavior test, the Neo-A group showed shorter latency and higher scores of lordosis quotient. These results support the view that exposure to this model of repeated mild stress early in life stimulates the development of social behavior, dominance and sexual behavior.     

Substance use, suicidal ideation and attempts in children and adolescents

Using data from a community sample of youth ( N = 1,458; ages 9-17), this study assessed the association between adolescent substance use/abuse and suicidal behaviors. Suicide attempts were strongly associated with alcohol abuse and dependence, followed by frequent cigarette smoking. The associations remained significant even after controlling for depression. The associations between substance use/abuse and suicidal ideation were no longer significant after controlling for depression. These findings highlight the important role that substance use plays in adolescent suicidal behaviors.     

Effects of midbrain central gray lesions on spontaneous and electrically induced aggression in the rat

Large electrolytic lesions were placed in the midbrain central gray of male rats. Their effects on hypothalamically induced aggression, switch-off behaviour, and locomotion were investigated. A number of these animals were also tested for territorial intermale aggression in order to compare electrically induced and spontaneous aggression. Large lesions resulted in an increase of the current threshold to induce aggression by hypo-thalamic stimulation. Smaller, but still quite large, lesions decreased the threshold current for hypothalamic aggression. After the operation a decrease in the threshold for switch-off was present, both in the experimental and the control group. Current thresholds for locomotion were decreased after the lesions only in the experimental group. Spontaneous aggression was temporarily decreased after the lesion. No indication was found that other behavioural elements of the animal were distorted by the lesion. The parallel between the effects on spontaneous and electrically induced aggression makes it attractive to ascribe a role to the neural circuit of hypothalamus and central gray in territorial aggression. However, even with large lesions the animals were still capable of fighting, hence the central gray is not indispensable. An attempt was made to explain the differential effects that differently sized central gray lesions have on hypothalamic aggression.     

Gender and the relationship between perceived fairness of pay or promotion and job satisfaction.

Brockner and Adsit (1986) found that satisfaction with an exchange relationship was more strongly related to perceptions of equity among men than women. Kahn (1972) reported that men were more likely than women to distribute outcomes to individuals in direct proportion to their input. We evaluated potential gender differences among 12,979 personnel in 30 different organizational systems in (a) correlations between fairness and job satisfaction scores and (b) standardized group differences in the perceived amounts of pay and promotion fairness and expressed levels of facet and global job satisfaction. The fairness-satisfaction relationship was not higher for men, and there were no practical differences in fairness perceptions and job satisfaction between men and women.     

Ontogeny of aggressive-sexual behavior between males in lines of Japanese quail (Coturnix coturnix japonica) selected for male mating frequency

Japanese quail from lines bidirectionally selected for high and low male mating frequency and from the random-bred base population were observed in an ontogenetic study of aggressive-sexual behavior. Quail were reared in sex-intermingled flocks until 28 days of age at which time half of the males from each line were housed as all-male flocks and half were transferred to individual cages. At 41 days of age, individually caged males exhibited mounting behavior to win encounters with other males. By 45 days, males from the high and control lines exhibited significantly more aggressive-sexual behavior than those from the low lines. Line x Rearing Experience interactions for mounting behavior at 45 and 56 days of age were due to the individually caged high- and control-line males' winning encounters by mounts; those maintained in flocks rarely mounted. Although some low-line males won encounters by mounts, occurrence of this behavior was infrequent. Males maintained in flocks were placed in individual cages at 57 days of age. When these males were compared with those housed in individual cages from 28 days of age, at 84 days of age and older, the Line x Rearing Experience interaction observed previously disappeared, and only differences among genetic lines were evident. Genetic and rearing experience effects are discussed as influencing agonistic and sexual behaviors.     

Psychopathology of adolescent suicide: hopelessness, coping beliefs, and depression

Two studies of adolescents examined the relation of several cognitive variables and depression to suicide-related behaviors. Study 1 compared hopelessness and depression in 281 high school students. Unlike research with adults, depression was significantly related to suicidal behaviors, even after hopelessness was statistically controlled. When depression was controlled, hopelessness was unrelated to suicidal behaviors for boys and only modestly related for girls. Study 2 examined depression, hopelessness, survival-coping beliefs, fear of social disapproval, and social desirability in relation to suicidal behaviors in 53 male juvenile delinquents. Again, hopelessness did not account for a significant proportion of the variance in suicide. Depression was uniquely related to past suicide attempts. Survival-coping beliefs were associated with self-predicted future suicide and other suicidal behaviors. Survival-coping beliefs are discussed as a cognitive buffer to suicidal ideation in adolescence.     

Altering the proportion of components in a mixed fixed-ratio schedule

Pigeons were trained under a schedule consisting of a number of fixed-ratio 100 components followed by a single fixed-ratio 10 component. The proportion of fixed-ratio 100 to fixed-ratio 10 components was varied according to several ascending and descending series within the range of 99:1 to 1:1. When this proportion was reduced to about 20:1 and below, the pause following each fixed-ratio 100 gradually decreased in length. Primes, a burst of responses at the start of the fixed-ratio 100 component, increased in frequency, and then decreased when the proportion became extremely low. Also, when the relative frequency of fixed-ratio 10 components was very high, primes were seldom observed in the first fixed-ratio 100 component following a fixed-ratio 10 component, but were distributed evenly throughout the remaining fixed-ratio 100 components.