Plasma corticosterone and renin activity during two-way active avoidance learning in spontaneously hypertensive and Wistar-Kyoto rats

The spontaneously hypertensive rat (SHR) exhibits increased sympathetic and behavioral responses to several types of environmental stress compared to its normotensive progenitor, the Wistar-Kyoto rat (WKY). The aim of the present study was to investigate response-dampening mechanisms in the SHR. This study examines whether learning to control a stressful environment reduces behavioral and neuroendocrine activation in the SHR. Twelve SHR and 12 WKY were subjected to daily sessions (S) of 20 trials of signaled two-way active avoidance. Another 12 SHR served as maturation controls. Blood samples were collected immediately after S 1, S 5, and S 14 and plasma level of corticosterone (p-CS) and plasma renin activity (PRA) were measured. There was an insignificant tendency for the SHR to exhibit larger increases in p-CS in response to stress than the WKY did. By S 5 both groups had attained the avoidance task. However, the level of p-CS was the same as after S 1, showing that activation is independent of the number of shock pulses received and performance. Postsession p-CS decreased between S 5 and 14, slightly more so in the SHR than in the WKY. The SHR exhibited lower PRA than the WKY, but there were no significant effects of exposure to the avoidance schedule. Behaviorally, the SHR exhibited shorter latency to escape in the first trial than the WKY did. The SHRs were hyperactive compared to the WKY, showing more ambulation and rearing behavior. The maturation control SHR reached the same mean arterial pressure as the SHRs which were tested. After S 14, signal duration was shortened from 10 to 3 s for six additional sessions. Both p-CS and PRA increased, while at the same time ambulation and rearing behavior decreased. These data show that the relationship between behavioral control and adrenocortical activation is normal in the SHR in spite of differences in behavior. The present results also confirm previous data on hyperreactivity to footshocks in two-way active avoidance tasks in the SHR.     

Stress ulcer and open-field behavior of spontaneously hypertensive,normotensive, and Wistar rats

Spontaneously hypertensive rats (SHRs) and the normotensive Wistar/Kyoto (WKY) rat were observed, along with Wistar rats (which represent the parent strain), on various open-field behaviors. All three strains were subsequently exposed to the activity-stress (A-S) ulcerogenic procedure. SHR and Wistar rats were very active in most open-field measures as compared with WKY rats, but only SHRs were active during the A-S treatment. WKY rats were very ulcer prone and had significantly more ulcers than SHRs, which in turn had more ulcers than Wistar rats. It was anticipated that Wistar rats would resemble the WKY rats, but in most measures the Wistars resembled the SHRs. The study suggests that although WKY rats function as an appropriate control for hypertension studies, these rats may be inappropriate as controls for other physiological and behavioral studies.     

合作指数与社会距离对合作行为的影响

利用囚徒困境范式,考察了合作指数CI（0.1~0.9）与社会距离（亲密、陌生）对个体合作行为的影响。结果发现,社会距离和合作指数均会对合作行为产生影响,两者的交互效应不显著;合作率会受到合作指数的促进作用,但不会随合作指数的增高立即增长;在CI = 0.1~0.9这9个水平下,亲密被试间的合作率均显著高于陌生被试间的合作率。这一结果说明,合作指数对合作行为的促进作用存在阈值;社会距离缩小可促进个体的合作倾向增强,并更快地达到合作水平;合作指数与社会距离相互独立地影响合作行为。     

The toll of ethnic discrimination on sleep architecture and fatigue.

Most work on ethnicity tends to focus on daytime health rather than how aspects of ethnicity affect nighttime functioning. The current study examined how discrimination and ethnic identity relate to sleep architecture and fatigue in 37 African Americans and 56 Caucasian Americans. The authors conducted sleep monitoring with standard polysomnography. African Americans had less slow-wave sleep and reported more physical fatigue than did Caucasian Americans (ps < .05). The authors conducted path analyses to examine relationships between ethnic identity, perceived discrimination, sleep, and fatigue. Perceived discrimination mediated ethnic differences in Stage 4 sleep and physical fatigue. Individuals who reported experiencing more discrimination had less Stage 4 sleep and reported experiencing greater physical fatigue (ps < .05). Although ethnic identity did not mediate ethnic differences in sleep latency, there was a significant relationship between ethnic identity and sleep latency, indicating that individuals who felt more connected to their ethnic group had more difficulty falling asleep while in the hospital (p < .05). These observations suggest that the effects of stress related to one's ethnic group membership carry over into sleep.     

Infant physiological regulation and maternal risks as predictors of dyadic interaction trajectories in families with a preterm infant

This longitudinal study examined predictors of rates of growth in dyadic interaction quality in children born preterm who did not experience significant neurological findings during neonatal intensive care unit (NICU) hospitalization. Multiple methods were used to collect data from 120 preterm infants (48% girls, 52% boys) and their mothers. Infant heart rate variability (HRV), gestational age, neonatal health, feeding route, and maternal socioeconomic (SES) risks were assessed at NICU discharge (mean of 36 weeks postconception). Mother-child interactions were observed at 4, 9, 16, and 24 months postterm and analyzed with hierarchical linear modeling. On average, children's quality of play, interest, and attention increased over time while their dysregulation and irritability decreased, whereas average maternal positive affect and involvement declined in quality (ps < .05), although there was individual variation in rates of change. Mothers of infants with higher postfeeding HRV (i.e., vagal regulation) exhibited less decrease in positive affect and involvement between 4 months and 24 months, compared with mothers of infants with lower HRV (p < .05). Although infants with higher postfeeding HRV showed less positive affect and communication at 4 months, they exhibited significantly greater increases in positive affect and social competence and decreases in dysregulation and irritability between 4 months and 24 months, compared with infants with lower HRV (ps < .05). Dyads experiencing more SES risks showed less optimal interactions at 4 months; this difference remained as children grew older (ps < .05). Results have implications for our understanding of social development in preterm infants.     

Avoidance responding in pigeons

Four pigeons were trained in a one-way shuttle box avoidance situation. Three of the birds met the criterion of 90% avoidances; the fourth, although frequently avoiding successfully, was too erratic to meet the criterion. Avoidance responding in two of the birds was subsequently extinguished, showing that the response was true avoidance, and not escape from the buzzer warning stimulus. In Experiment 2, the three birds that had met criterion in Experiment 1 were trained in a two-way avoidance task, and all three met the criterion of 90% avoidances. The shuttle box therefore provides a rapid and reliable method of obtaining avoidance performance in pigeons.     

Spontaneously hypertensive Wistar-derived male rats are more aggressive than those of their normotensive progenitor strain

We compared a group of spontaneously hypertensive rats (SHRs) to a group of Wistar-Kyoto (WKY) rats on each of the three most commonly studied forms of aggressive behavior in rats: muricide, intraspecific aggression, and shock-induced fighting (SIF). A significantly higher proportion of SHRs were muricidal; they also fought more at the lowest shock level. A trend for a higher incidence of intraspecific offense behaviors by SHRs was not significant. SHR flinch and jump thresholds were lower than the respective WKY thresholds. Although there were no significant correlations between shock thresholds and any aspects of SIF, the possibility that strain differences in shock sensitivity may contribute to differences in SIF cannot be ruled out. Within strains, there were no correlations among the different forms of aggression. Several different inherited characteristics may be associated with the accentuation of different forms of aggression in SHRs.     

Need associations and psychopathology.

The 1960 Picture Identification Test (PIT) provides association scores for 210 need dyads derived from 21 Murray needs. Association scores for 16 clinical-control group pairs were analyzed for differences by t test. The clinical groups represented schizophrenic, neurotic, sex disturbance, and behavior disorder categories. Assertive needs produced the largest number od dyads which discriminated (p less than .05) clinical and control groups. Schizophrenic groups had the largest number of differences from normal controls. Schizophrenics tended to under-associate pairs of Assertive needs, as compared to normals, whereas other groups tended to over-associate these needs. Clinical groups in general over-associated 379 need dyads and under-associated 99 dyads (p less than .05). These results suggest that the frustations of maladjusted people, with regard to need association, are most generally related to insuficient conceptual differentiation of needs.     

Approach–avoidance of facial affect is moderated by the presence of an observer-irrelevant trigger

This study examined whether approach–avoidance related behaviour elicited by facial affect is moderated by the presence of an observer-irrelevant trigger that may influence the observer’s attributions of the actor’s emotion. Participants were shown happy, disgusted, and neutral facial expressions. Half of these were presented with a plausible trigger of the expression (a drink). Approach–avoidance related behaviour was indexed explicitly through a questionnaire (measuring intentions) and implicitly through a manikin version of the affective Simon task (measuring automatic behavioural tendencies). In the absence of an observer-irrelevant trigger, participants expressed the intention to avoid disgusted and approach happy facial expressions. Participants also showed a stronger approach tendency towards happy than towards disgusted facial expressions. The presence of the observer-irrelevant trigger had a moderating effect, decreasing the intention to approach happy and to avoid disgusted expressions. The trigger had no moderating effect on the approach–avoidance tendencies. Thus the influence of an observer-irrelevant trigger appears to reflect more of a controlled than automatic process.     

Differential Male and Female Responses to Inadmissible Sexual History Information Regarding a Rape Victim

Two experiments were conducted to assess the effects of exposure to sexual activity information regarding a rape victim. The results of the first experiment indicated that men had a greater tendency to attribute a female target person's sexual activity to dispositional causes than did women. In the second experiment, subjects read an acquaintance rape scenario suggesting that the victim had a promiscuous sexual past. They were instructed either to ignore this sexual history information when making judgments (inadmissible condition) or to use whatever information that they felt was appropriate (admissible condition). Control subjects were given no information regarding the victim's sexual past. Thus, the design was a 2 (Sex of Subject) x 3 (Information Admissibility: Admissible, Inadmissible, or Control) factorial. The results indicated: (a) When compared to those in the inadmissible condition, victim perceptions from subjects in the admissible condition were less favorable, (b) victim perceptions from male subjects were less favorable than those from female subjects, and (c) male subjects in the inadmissible condition attributed more responsibility to the victim than did the controls whereas female subjects in the inadmissible condition attributed less responsibility to the victim than did controls. Possible bases of these findings are discussed.     

Emotionality in selectively bred strains of rats mediates prior shock effects on escape-avoidance conditioning.

Rats of the Maudsley Reactive and Maudsley Non-reactive strains were given 25 trials of escape-avoidance conditioning after exposure to inescapable shock. Prior shock exposure (PSE) did not affect avoidance or escape latencies, but decreased the number of avoidances made by the Maudsley non-reactive animals and increased the number of their failures to escape. The results are interpreted as demonstrating an interference with the classical conditioning of a conditioned emotional response, through a reduction in the information content of the CS following PSE. The strain differences are interpreted as due to the non-reactive animals being especially sensitive to PSE.     

小学生在交通情境中的视觉搜索：发展的观点

为探讨小学生在交通情境中的视觉搜索发展特点,研究以一、二、四和六年级小学生,以及成人为被试,采用“找不同”任务和过马路决策眼动任务进行实验。结果发现,一、二年级小学生“找不同”的效率低于成人;一年级小学生冒险及错失过马路比例均较高;小学生的眼跳特征与成人相似,但对兴趣区的关注低于成人;女生错失过马路比例高于男生,视觉搜索水平及搜索策略的性别差异不显著。研究表明,小学生的视觉搜索能力随年龄逐渐提高,但搜索的有效性低于成人,性别分化不明显。     

Diagnosing behavior-disordered early adolescents as a function of cultural differences

The tendency of non-Indian teachers to rate American Indian early adolescents (11-year olds) as behaviorally disordered more frequently than similarly behaving non-Indian children is examined. To test this hypothesis, the observed number of students rated as behavior-disordered by non-Indian teachers were compared with the expected number. A chi-square test revealed no significant tendency for this pattern to occur chi 2 = 2.04 less than .05, df = 1).     

Neonatal sex and birth-order effects on behaviors of mothers and temporary caretakers during bottle-feeding

This study examined the effects of neonatal sex and birth order on maternal caretaking patterns for pre-attachment behaviors shown by mothers and instrumental behaviors seen in both mothers and temporary caretakers. Observational category scores were obtained for mothers of 20 newborn infants and for temporary caretakers observed in a 15 min bottle-feeding situation. A repeated measures analysis of variance design was used to partition categories into caretaking classifications and to evaluate the effects of infant sex and birth order. Significant main effects for caretaker (p less than .05) were obtained: six mother-high, pre-attachment categories, and seven mother-low, instrumental behavior categories. Maternal scores sensitive to infant sex and birth order were identified from Caretaker x Sex x Birth Order interactions (p less than .05). Birth order differences affected maternal behaviors directed toward sons more substantially than those directed toward daughters. Mothers held first-born sons upright in tactual contact with the trunk, whereas daughters were held supine on the lap and exposed to frequent maternal smiling.     

Effects of posttraining treatments in the posterior cingulate cortex on short- and long-term memory for inhibitory avoidance in rats

Adult male Wistar rats were bilaterally implanted with indwelling cannulae in the caudal region of the posterior cingulate cortex. After recovery, animals were trained in a step-down inhibitory avoidance task (3.0-s, 0.4-mA foot shock) and received, right after training, a 0.5-microl infusion of vehicle (phosphate-buffered saline, pH 7.4), of the GABA(A) receptor agonist muscimol (0.1 or 0.5 microg), of the cAMP-dependent protein kinase (PKA) stimulant Sp-cAMPS (0.1 or 0.5 microg), or of the PKA inhibitor Rp-cAMPS (0.1 or 0.5 microg). Animals were tested twice, 1.5 h and, again, 24 h after training, in order to examine the effects of these agents on short- and long-term memory, respectively. Muscimol (0.5 but not 0.1 microg) hindered retention for both short- and long-term memory (p <.05). Rp-cAMPS (0.1 or 0.5 microg) hindered retention for short-term memory (p <.05). In addition, these animals showed lower, but not significantly lower, latencies than controls in the test session for long-term memory (p >.10). A trend toward an amnesic effect on long-term memory was also observed after Sp-cAMPS infusion at 0.1 microg (p <.10). These results show that strong stimulation of GABAergic synapses in the caudal region of the rat posterior cingulate cortex right after training impairs short- and long-term memory (the latter less dramatically). The same occurs by inhibiting PKA activity with regard to STM and possibly to LTM.     

Events of parental divorce: Stressfulness ratings by children,parents, and clinicians

The stressfulness, for the "typical" child, of 62 events that occur to children of divorce was rated by children of divorce (n = 58), their custodial parents (n = 58), and clinicians (n = 50). In addition, a larger group of children (n = 123) rated the goodness or badness of the events that had happened to them. The rank orderings of the mean stress ratings for the typical child made by children, parents, and clinicians were highly correlated. However, when the absolute stress value of the events was compared across raters, children rated 10 events as significantly less stressful than did parents (p less than .05); parents' and clinicians' ratings differed for 9 events, parents rating 7 as less stressful (p less than .05). Children rated 19 events as less stressful than did clinicians (p less than .05). The rank ordering of the children's mean ratings of events actually experienced correlated highly with the rank orderings of the children's mean ratings of the negative events for the typical child.     

Investigating spatial vision and dynamic attentional selection using a gaze-contingent multiresolutional display

This study examined spatial vision and attentional selection using a gaze-contingent multiresolutional display, with a dynamic, gaze-centered, high-resolution window and lower resolution periphery. Visual search times and eye movements from 15 participants in a 3 x 3 design (Window Radius x Peripheral Resolution) suggest that contrast sensitivity as a function of retinal eccentricity affects attentional selection and visual processing. Smaller windows led to longer search times and shorter saccades; lower peripheral resolution also shortened saccades (all ps < .05) as a result of avoiding fixating degraded areas. Fixation durations, although longer for smaller windows (p < .05), were unaffected by whether the next saccade went within or outside the window. These results are explained through (a) competition among potential saccade targets where above-threshold filtering reduces an object's relative salience and (b) generally disrupted visual processing.     

Primitive drive-dominated thinking: relationship to acute schizophrenia and sociopathy.

To investigate primitive drive-dominated thinking in schizophrenic disorders and sociopathic behavior, responses on the Rorschach and other personality tests of 171 acute psychiatric patients were assessed using Holt's system. Results suggested that: (a) Acute schizophrenics were high on primitive drive content, but this was also characteristic of some nonschizophrenics, and other types of disturbed thinking were even more prominent in schizophrenics. (b) There were no significant differences between process and reactive schizophrenics in expression of primitive drive content. (c) Males showed more drive-dominated thinking than females (p less than .10), although sex was not a powerful variable. (d) Depressives showed less drived-dominated thinking than nondepressive (p less than .05). (e) Patients high on sociopathic or rule-breaking behavior tended to show more primitive drive-dominated thinking (p less than .01).     

Prior exposure to inescapable electric shock in rats affects extinction behavior after the successful acquisition of an escape response

In Expt 1, rats exposed to 64 inescapable electric shocks in a restrainer or merely restrained were later given either 0, 5, 15 or 30 escape/avoidance training trials with a two-way shuttlebox procedure that does not lead to interference with escape acquisition due to prior exposure to inescapable shock. After escape training all rats were given an escape/avoidance extinction procedure in which shock was inescapable. The rats which had received prior exposure to inescapable shock responded less often and with longer latencies in extinction than did the restrained rats. Experiment 2 demonstrated that this effect is caused by the inescapability of the initial shock treatment. These results were explained in terms of (a) associative interference which minimized the effect of shuttlebox escape training for the preshocked subjects, and (b) a stronger tendency to recognize the presence of an inescapable shock situation during extinction for the preshocked subjects. The relationship between these results and previous work demonstrating that exposure to the escape contingency mitigates the effects of inescapable shock exposure was also discussed.     

Negative cognitions and avoidance in emotional problems after bereavement: a prospective study

Cognitive behavioural conceptualisations of grief propose that negative cognitions and avoidance strategies play a key role in emotional problems after bereavement. In the current study, this assumption was examined. Ninety-seven individuals who had lost a relative less than 5 months ago completed questionnaires tapping background and loss-related variables, negative cognitions (about the self, life, the future, and one's own grief reactions), avoidance, and symptoms of complicated grief (CG) and depression. Of these mourners, 70 people (72%) completed symptom measures again 6 months later at T2 (7-10 months after the loss), and 60 (62%) completed symptoms measures still 9 months later at T3 (16-19 months after the loss). Among other things, results showed that all four cognitive variables and the avoidance variable were strongly associated with concurrent and prospective symptom levels, even when the influence of relevant background/loss-related variables was controlled. In addition, independent of initial symptom levels, most of the cognitive variables predicted later CG and depression. The avoidance variable only predicted additional variance in depression at T3 beyond T1 symptom levels. Findings indicate that negative cognitions are important in emotional problems after bereavement and that the role of avoidance in the development of these problems needs further scrutiny.