The role of neuropeptide Y in the amygdala on corticotropin-releasing factor receptor-mediated behavioral stress responses in the rat

Neuropeptide Y (NPY) is one of the most abundant peptides in the brain and has been shown to be a critical regulator of emotionality, most notably for its effect in decreasing anxiety-like behaviors. The stress response in both humans and animals has been shown to involve a cascade of biological events initiated by corticotropin releasing factor (CRF), another centrally acting peptide. Interestingly, NPY and CRF are present in similar brain regions mediating stress responses and may act in an opposing fashion. The basolateral nucleus of the amygdala (BLA) is a distinct division of the amygdala and contains CRF receptors and the highest concentration of NPY neurons. The current study investigates the behavioral effects in rodents when NPY is injected directly into the BLA prior to the pharmacological stressor, urocortin I (Ucn; a CRF receptor agonist) or the emotional stressor, restraint. The animals that underwent restraint were evaluated in the social interaction (SI) test, while those injected with Ucn into the BLA were assessed in the two floor choice test, a modified version of the conditioned-place avoidance paradigm. The results showed that injections of NPY into the BLA prior to Ucn significantly blocked the development of the avoidance behavior in the two floor choice test and the decrease in SI time that is usually seen following restraint stress. These results provide further support that an interaction between NPY and CRF within the BLA may be critical for maintaining a normal homeostatic emotional state.     

Bimodal score distributions and the Myers-Briggs Type Indicator: fact or artifact?

We examined Myers-Briggs Type Indicator (MBTI) score distributions computed using item response theory (IRT) to assess the generalizability of earlier bimodality reports that have been cited in support of the "type" versus "trait" view of personality. Using the BILOG IRT program to score a sample of approximately 12,000 individuals who participated in leadership development programs, theta score distributions for the 4 dimensions of the MBTI computed using 10 (the BILOG default) versus 50 quadrature points were compared. Results indicated that past reports of bimodality were artifacts caused by BILOG's default use of a small number of quadrature points; when larger numbers of points were used, score distributions became strongly center-weighted. Although our findings are not supportive of the "type"-based hypothesis, the extremely high correlations between theta scores (rs > .996) suggest that no practical differences would be expected as a function of the number-of-quadrature-points decision.     

Item method directed forgetting diminishes false memory

Directed forgetting may reduce DRM false memory illusion by interfering with meaning processing. Participants were presented with a list composed of six 10-word semantically associated sub-lists, and they were either (a) asked to remember all list items of (b) asked to remember all associates from sub-lists and to forget all associates from other sub-lists. All participants were requested to recall and recognise list items. Although directed forgetting effects have been previously reported only for true responses in the DRM paradigm with the list method, we also found directed forgetting for false responses with the item method. Such forgetting instructions reduced both verbatim and meaning processing, decreasing both the intrusion and the false alarm rate. These results are consistent with two-process explanations of DRM false memories, such as fuzzy-trace theory, and add to our understanding of false memory editing.     

Role of stress, corticotrophin releasing factor (CRF) and amygdala plasticity in chronic anxiety

Stress initiates a series of neuronal responses that prepare an organism to adapt to new environmental challenges. However, chronic stress may lead to maladaptive responses that can result in psychiatric syndromes such as anxiety and depressive disorders. Corticotropin-releasing factor (CRF) has been identified as a key neuropeptide responsible for initiating many of the endocrine, autonomic and behavioral responses to stress. The amygdala expresses high concentrations of CRF receptors and is itself a major extrahypothalamic source of CRF containing neurons. Within the amygdala, the basolateral nucleus (BLA) has an important role in regulating anxiety and affective responses. During periods of stress, CRF is released into the amygdala and local CRF receptor activation has been postulated as a substrate for stress-induced alterations in affective behavior. Previous studies have suggested that synaptic plasticity in the BLA contributes to mechanisms underlying long-term changes in the regulation of affective behaviors. Several studies have shown that acute glutamate receptor-mediated activation, by either GABA-mediated disinhibition or CRF-mediated excitation, induces long-term synaptic plasticity and increases the excitability of BLA neurons. This review summarizes some of the data supporting the hypotheses that stress induced plasticity within the amygdala may be a critical step in the pathophysiology of the development of chronic anxiety states. It is further proposed that such a change in the limbic neural circuitry is involved in the transition from normal vigilance responses to pathological anxiety, leading to syndromes such as panic and post-traumatic stress disorders.     

Fits and Starts: A Mother-Infant Case-Study Involving Intergenerational Violent Trauma and Pseudoseizures Across Three Generations

This case-study presents in detail the clinical assessment of a 29-year-old mother and her daughter who first presented to infant mental health specialists at age 16-months, with a hospital record suggesting the presence of a dyadic disturbance since age 8-months. Data from psychiatric and neurological assessments, as well as observational measures of child and mother are reviewed with attention to issues of disturbed attachment, intergenerational trauma, and cultural factors for this inner-city Latino dyad. Severe maternal affect dysregulation in the wake of chronic, early-onset violent-trauma exposure manifested as psychogenic seizures, referred to in the mother's native Spanish as "ataques de nervios," the latter, an idiom of distress, commonly associated with childhood trauma and dissociation. We explore the mechanisms by which the mothers' reexperiencing of violent traumatic experience, together with physiologic hyperarousal and associated negative affects, are communicated to the very young child and the clinician-observer via action and language from moment to moment during the assessment process. The paper concludes with a discussion of diagnostic and treatment implications by Drs. Marshall, Gaensbauer, and Zeanah.     

70-kHz vocalizations by male mice do not inhibit aggression in lactating mice

Two experiments investigated the relationship between adult male 70-kHz vocalizations and aggression by lactating female mice (Mus domesticus). Intact, vocalizing males, surgically devocalized males, and naturally nonvocalizing males were used to assess the effects of high frequency vocalizations on maternal aggression. The emission of high frequency vocalizations promoted aggressive behavior by the females. In both experiments, lactating females attacked the vocalizing males more rapidly and showed a higher incidence of aggressive behaviors toward these males than they did to the nonvocalizing male. We suggest that these vocalizations are only one of many situational cues that the female uses to determine her final behavioral response.     

On the gender differential use of listener responsiveness

It is argued that claims of gender differences in back channel behavior should not be uncritically accepted; there are limitations in previous research that make such acceptance questionable. The frequency of back channel behavior was examined over a portion of the early life span (Grades 4 and 9, and college). Twenty-minute structured conversations of 90 dyads (30 male, 30 female, and 30 mixed gender) were scored for eight types of back channels. There was a nonsignificant dyad gender effect for all measures, indicating that back channel frequency did not vary across dyads of different gender composition. The Age × Dyad Gender interaction was significant for only one of the eight back channel types, indicating that age had little effect on the gender-related use of back channel behavior. Although females produced more of some types of back channels than males, there was no difference in back channel frequency between males and females in opposite-gender interaction for any of the eight measures. We conclude that wholesale acceptance of gender differences in back channel behavior is not warranted.     

The effect of time-out release contingencies on changes in child noncompliance

This project evaluated the effect of time-out release contingencies on changes in child noncompliance to maternal instructions. Twenty-four clinic-referred, noncompliant, preschool children served as subjects. Each child was assessed under baseline conditions and then under one of three experimental conditions: Parent Release, Child Release, or Control. Children in the Parent Release and Child Release conditions experienced time-out contingent upon noncompliance. Temporal and behavioral time-out release contingencies were present in the Parent Release condition but not in the Child Release condition. A spanking procedure was used to inhibit premature escape from time-out for children in the Parent Release group. The results indicated that both time-out groups demonstrated increased compliance ratios. However, improvement associated with the Child Release condition was considered to be clinically insignificant.The authors wish to express their appreciation to Dave DeLawyer, Larry Snapp, and Mike Samac for their assistance in conducting the study.