Caloric restriction alters seizure disposition and behavioral profiles in seizure-prone (fast) versus seizure-resistant (slow) rats.

Caloric restriction (CR), primarily known for extending life span, has proven anticonvulsant in several seizure models and antiepileptogenic in a strain of inherently seizure susceptible mice. Our animal model consisted of a seizure-prone (Fast) strain that naturally exhibits attention-deficit/hyperactivity disorder (ADHD)-like behaviors and a comparison seizure-resistant (Slow) strain; we evaluated CR’s effect on the typical seizure sensitivities and behavioral profiles of each strain. Fast and Slow rats were fed ad libitum or were calorically restricted to 80% of free-feeding body weight. Rats were then tested in the open field (hyperactivity), Morris water maze (learning and attention), and restraint (impulsivity) paradigms and finally kindled from the amygdala. Ultimately, CR abolished signs of abnormal hyperactivity in the Fast strain and retarded their kindling rates, making it the first manipulation to demonstrate an antiepileptogenic effect in this animal model. CR also shortened seizure durations in fully kindled Slow rats but had no effect on their kindling rates, implying a differential effect of CR on genotype. These results clearly endorse further investigation into the potential benefits of CR for both epilepsy and ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ruling out postnatal origins to attention-deficit/hyperactivity disorder (ADHD)-like behaviors in a seizure-prone rat strain.

Adult Fast (seizure-prone) and Slow (seizure-resistant) kindling rat strains exhibit divergent behaviors in paradigms relevant to attention-deficit/hyperactivity disorder (ADHD) in humans. Similar dissociations in rodent behavior have been linked to disparities in early life experience, suggesting that differential maternal care or postnatal interactions may underlie these behaviors. Consequently, the authors compared maternal behavior and preweaning pup weights in these 2 strains under control and cross-fostered conditions and examined its effects on subsequent adult offspring behavior. Ultimately, several distinct maternal behaviors were apparent between the 2 strains under control conditions, and some of those behaviors were then malleable by pup condition. Yet, in spite of the resultant complex maternal patterns across groups, all offspring showed behavioral phenotypes akin to their genetic strain. Thus, a specific postnatal environment is unlikely to underwrite ADHD-like behaviors in the seizure-prone Fast rats, which implicates a genetic or prenatal origin for the ADHD phenotype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beyond diathesis stress: Differential susceptibility to environmental influences.

Evolutionary-biological reasoning suggests that individuals should be differentially susceptible to environmental influences, with some people being not just more vulnerable than others to the negative effects of adversity, as the prevailing diathesis-stress view of psychopathology (and of many environmental influences) maintains, but also disproportionately susceptible to the beneficial effects of supportive and enriching experiences (or just the absence of adversity). Evidence consistent with the proposition that individuals differ in plasticity is reviewed. The authors document multiple instances in which (a) phenotypic temperamental characteristics, (b) endophenotypic attributes, and (c) specific genes function less like “vulnerability factors” and more like “plasticity factors,” thereby rendering some individuals more malleable or susceptible than others to both negative and positive environmental influences. Discussion focuses upon limits of the evidence, statistical criteria for distinguishing differential susceptibility from diathesis stress, potential mechanisms of influence, and unknowns in the differential-susceptibility equation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypnotic susceptibility in patients with conversion disorder.

Conversion disorder has been associated with hypnotic susceptibility for over a century and is currently still believed to be a form of autohypnosis. There is, however, little empirical evidence for the relation between hypnotic susceptibility and conversion symptoms. The authors compared 50 patients with conversion disorder with 50 matched control patients with an affective disorder on measures of hypnotic susceptibility, cognitive dissociation, and somatoform dissociation. Conversion patients were significantly more responsive to hypnotic suggestions than control patients. In addition, conversion patients showed a significant correlation between hypnotic susceptibility and the number of conversion complaints. These results provide the first evidence of a relationship between hypnotic susceptibility and the presence and number of conversion symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of prior information on susceptibility to an emotional appeal.

"The hypothesis of this study was that persons who have received neutral information with respect to an object lower their evaluation of the object to a lesser extent after hearing an emotional appeal against it than persons who have not received such neutral information. The hypothesis was tested in an experiment done in high school classes, using an object with which the subjects had little or no prior acquaintance. The results confirmed the hypothesis." From Psyc Abstracts 36:04:4GG50L. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Septal influences on operant responding in the rat.

In 3 experiments with a total of 74 male albino Sprague-Dawley rats, the afferent and efferent connections of the septum with the hippocampus (fornix) or with the hypothalamus and lower brain stem (medial forebrain bundle) were transected by means of an encephalotome near the point where these pathways enter or leave the septal area. A transection of the fornix that produced minimal direct damage to cellular components of the septum or hippocampus reproduced the effects of large septal lesions on responding in several temporally defined paradigms that involve periods of response suppression (DRL, discriminated Sidman avoidance, FI). Transection of the medial forebrain bundle fibers that interconnect the septum with the hypothalamus and lower brain stem did not affect behavior in any of these paradigms. It is suggested that these observations be viewed in the context of the results of earlier investigations by the authors (see record 1974-27002-001), R. J. Carey (see record 1969-13784-001), and J. M. McDougall et al (see record 1969-13791-001), which showed that transection of the medial forebrain bundle reproduces several other components of the septal lesion syndrome. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between stress and depression in first onsets versus recurrences: A meta-analytic review.

S. M. Monroe and K. L. Harkness (see record 2005-02750-005) reviewed the empirical evidence supporting R. M. Post's (see record 1992-43211-001) kindling model, which suggests the 1st episode of depression is more likely to be preceded by major stressors than are subsequent episodes. Their review highlighted the diverse interpretations of Post's premise in the current literature and the changes in research methods that have contributed to this interpretive shift. The authors conducted a meta-analysis (N=13 studies) to test Post's premise that integrated early and recent research and examined potential moderators. A proportion difference effect size was used. Results indicated that 1st onsets of depression were more likely than recurrences to be preceded by severe life events, supporting Post's premise. The moderator analyses suggested that support may be most evident in patient samples and may vary according to age and gender, with less support for Post's premise evidenced in younger samples and in women. Although these results are preliminary, as the analysis included a small number of studies, they suggest that future research should further examine factors that influence the stress-depression relationship with successive recurrences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Material-specific memory in temporal lobe epilepsy: Effects of seizure laterality and language dominance.

This study investigated the effects of seizure laterality and language dominance on material-specific memory in temporal lobe epilepsy (TLE). Left TLE (LTLE) patients with left-hemisphere language dominance (LHLD) showed significantly higher nonverbal than verbal memory capacity, whereas right TLE patients with LHLD showed significantly better verbal than nonverbal memory capacity. LTLE patients with non-left-hemisphere language dominance (NLHLD) showed significantly better verbal memory capacity compared with LTLE patients with LHLD. Thus, selective verbal or nonverbal memory deficits that are dependent on side of seizure onset were apparent in patients with LHLD but not in patients with NLHLD. Relative sparing of verbal memory capacity in LTLE patients with NLHLD may reflect interhemispheric reorganization of verbal memory function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of confidence and motivation on susceptibility to informational social influence.

"The general hypothesis… was that the individual's acceptance of the judgments of others varies as function of: (a) the relative confidence he has in his own judgment; and (b) his motivational orientation toward the task with which he was confronted… . conformity (as measured through a modified Crutchfield apparatus) was found to: (a) increase as the subjective probability that S was receiving information from the others increased; and (b) decrease as the frequency of errors made by the 'majority' increased. Motivational effects induced by the instruction that the task reflected the individual's intelligence resulted in a decrease in… [errors]." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned effects of kindling three different sites in the hippocampal complex of the rat.

Rats received kindling stimulations to the perirhinal cortex (PRh), ventral hippocampus (VH), or dorsal hippocampus (DH) in 1 environment and an equivalent number of sham stimulations in a 2nd environment. The PRh-kindled rats displayed rapid kindling and a swift emergence of conditioned interictal defensiveness. In contrast, the VH- and DH-kindled rats displayed much slower kindling and slow or no conditioning, respectively. No effects of conditioning on the convulsions, comparable with those associated with amygdala kindling, were observed. These results establish the generality of some of the previously reported kindling-related conditioned effects, confirm the site specificity of some of these effects, and suggest that the convulsions, rather than the stimulations, function as the unconditioned stimuli for the conditioning of interictal behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in executive processing predict susceptibility to interference in verbal working memory.

Recent theories have suggested that resistance to interference is a unifying principle of executive function and that individual differences in interference may be explained by executive function (M. J. Kane & R. W. Engle, 2002). Measures of executive function, memory, and perceptual speed were obtained from 121 older adults (ages 63-82). We used structural equation modeling to investigate the relationships of these constructs with interference in a working memory task. Executive function was best described as two related subcomponent processes: shifting and updating goal-relevant representations and inhibition of proactive interference. These subcomponents were distinct from verbal and visual memory and speed. Individual differences in interference susceptibility and recollection were best predicted by shifting and updating and by resistance to proactive interference, and variability in familiarity was predicted by resistance to proactive interference and speed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Severe and nonsevere events in first onsets versus recurrences of depression: Evidence for stress sensitization.

Overall, research has evidenced support for Post's (1992) model, which asserts that the 1st episode of depression is more likely to be associated with severe life events than are subsequent episodes. In spite of this, there are significant gaps in the understanding of the stress–depression association. This study aimed to address three gaps by (a) identifying the explanatory model underlying the association (stress sensitization vs. stress autonomy), (b) elucidating how the role of stress changes with successive episodes, and (c) examining the role of nonsevere events. The impact and occurrence of severe and nonsevere events in a 5-year longitudinal study of late-adolescent women were examined using Cox regression models. Overall, we found support for the stress sensitization model over the stress autonomy model. Specifically, the impact of nonsevere (but not severe) events was greater in individuals with a history of depression compared with those with no history of depression. In addition, the occurrence of severe (but not nonsevere) events was greater for 1st onsets than recurrences. These effects were modified by event independence. The results were discussed in terms of the underlying mechanisms of the stress–depression association and future directions for research were elaborated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maternal influences on ontogeny of suckling and feeding rhythms in the rat.

Conducted 4 experiments to assess the effects of both maternal and endogenous factors on the ontogeny of nocturnal feeding in the rat. Day and night weight gain was determined in the sighted or blind litters of sighted or blind Sprague-Dawley dams and in young weaned at 15 days of age. It is concluded that sighted dams impose a diurnal milk-intake pattern on their young. The nocturnal patterns of solid-food intake began at 19 days of age. Blind litters also displayed nocturnal feeding when kept with sighted dams, but only until 35 days of age. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relative susceptibility of two rating scales to disturbances resulting from shifts in stimulus context.

A simple and a complex rating scale were compared with respect to their resistance to distorting effects produced by limited and shifting stimulus contexts. These 9-point scales assessed "shifting in the value of common stimuli as a function of context" and "loss of refinement or correlational accuracy." Results favored the detailed rating scale with judgmental equivalence and accuracy. Utility of creating experimental stress tests for rating scale evaluation is implied. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and vestibular influences on head-direction cells in the anterior thalamus of the rat.

As a rat navigates through space, head-direction cells provide an ongoing signal of its momentary directional heading. This directional signal is thought to be generated, in part, by a dead-reckoning mechanism that uses angular motion information to constantly update the directional representation. This study investigated what kinds of angular motion information might be used for dead reckoning. Anterior thalamic head-direction cells were recorded from rats in a rotatable, cylindrical chamber, which could independently deliver visual motion cues and vestibular cues. Results suggest that both of these angular motion cues have an influence on head-direction cells and may thus be used for dead reckoning. The authors conclude that vestibular and visual movement cues work interactively, along with visual landmarks and motor signals, to determine the directional frame of reference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in utilizing control to cope with job demands: Effects on susceptibility to infectious disease.

This study examined the interactive effects of job demands, control, and individual characteristics on upper respiratory illnesses and immune function. Having high job control appeared to lessen the linkage between job demands and poor health among individuals with high self-efficacy and those who perceived that they were not often responsible for negative job outcomes. Conversely, having high job control exacerbated the association between job demands and poor health among inefficacious individuals. Implications for promoting more healthful work environments and facilitating employee coping are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential susceptibility to discipline: The moderating effect of child temperament on the association between maternal discipline and early childhood externalizing problems.

This study investigated the interaction of child temperament and maternal discipline in the prediction of externalizing problems in early childhood. Interaction effects were evaluated in a sample of 227 one- to three-year-old children with relatively high externalizing problems scores on the Child Behavior Checklist/1 1/2-5. Child temperament was reported by the mothers, maternal discipline was observed in a laboratory session, and child outcome measures included both mother-reported externalizing problems and observed physical aggression. Results indicate that children with difficult temperaments are more susceptible to negative discipline (i.e., they showed more externalizing problems) as well as more susceptible to positive discipline (i.e., they showed fewer externalizing problems and less physical aggression), as compared with children with relatively easy temperaments. These findings provide empirical evidence for the differential susceptibility hypothesis and suggest directions for enhancing the effectiveness of interventions aimed at reducing early childhood externalizing problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Not all rat strains are equal: Differential unconditioned fear responses to the synthetic fox odor 2,4,5-trimethylthiazoline in three outbred rat strains.

Predator odors induce unconditioned fear in rats; however, the synthetic predator odor 2,4,5-trimethylthiazoline (TMT) either elicits robust fear behavior (e.g., freezing) or no fear responses at all. The authors investigated whether this is due to the use of different outbred rat strains. TMT induced robust freezing in Sprague-Dawley and Long-Evans rats but not in Wistar rats. All 3 strains avoided TMT, but Wistar rats were less sensitive to TMT. Wistar rats are capable of freezing; all 3 strains displayed the same amount of odor-cue conditioned freezing. Thus, TMT is a robust unconditioned fear stimulus in rats, and prior negative results from other laboratories were due to the choice of a rat strain (Wistar) that is less responsive to TMT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing mode causally influences emotional reactivity: Distinct effects of abstract versus concrete construal on emotional response.

Three studies are reported showing that emotional responses to stress can be modified by systematic prior practice in adopting particular processing modes. Participants were induced to think about positive and negative scenarios in a mode either characteristic of or inconsistent with the abstract-evaluative mind-set observed in depressive rumination, via explicit instructions (Experiments 1 and 2) and via implicit induction of interpretative biases (Experiment 3), before being exposed to a failure experience. In all three studies, participants trained into the mode antithetical to depressive rumination demonstrated less emotional reactivity following failure than participants trained into the mode consistent with depressive rumination. These findings provide evidence consistent with the hypothesis that processing mode modifies emotional reactivity and support the processing-mode theory of rumination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personality influences on change in smoking behavior.

Objective: To investigate associations between personality traits in early adulthood (and changes in them) and change in smoking status. Design: Prospective, longitudinal study of a general-population birth cohort. Main Outcome Measures: We measured smoking at ages 18, 26, and 32, and personality at ages 18 and 26 using the Multidimensional Personality Questionnaire (Tellegen & Waller, in press). We assessed personality’s ability to predict future smoking, and assessed how changes in personality traits relate to change in smoking status. Results: Higher aggression and alienation at age 18 predicted smoking at 26; higher self-control and traditionalism at age 18 predicted nonsmoking at 26; and higher alienation at age 26 predicted persistence of smoking to age 32. Personality change between 18 and 26 was associated with change in smoking behavior; those who stopped smoking decreased more than others in negative emotionality and increased more in constraint. Conclusion: These findings suggest that interventions fostering personality change may be effective in reducing smoking and indicate appropriate targets for such antismoking interventions in young people. In particular, high alienation predicted smoking persistence, perhaps due to resistance to existing antismoking messages; we discuss approaches that may overcome this. (PsycINFO Database Record (c) 2010 APA, all rights reserved)