Inhibition of the LH Surge by Restraint Stress in Cyclic Rats: Studies on the Role of GABAA and GABAB Receptors

There is evidence that stress can alter the activity in the brain of gamma-aminobutyricacid (GABA), a neurotransmitter that has been implicated in the regulation of LH secretion. In the present study the role of GABA in the restraint stress-induced inhibition of the LH surge was investigated in the intact cyclic rat. Intracerebroventricular (icv) administration of the GABAA receptor agonist muscimol (0.1, 0.5 or 1 μg) 5 min before the presumed onset of the pro-oestrous LH surge (at 0900 h) caused a dose dependent suppression of the surge. A single dose of the GABAB receptor agonist baclofen (1 μg; icv) injected at 0855 h postponed the onset of the LH surge, and repeated injections at 0855 and 1130 h suppressed the surge. These data indicate that GABA-ergic activity in the brain can inhibit the LH surge in the cyclic rat via GABAA and GABAB receptors. Pro-oestrous rats were subjected to 5 hrs of restraint starting at 0855 h. Pretreatment with the GABAA receptor antagonist bicuculine (1 μg; icv) at 0840, 0940 and 1040 h or pretreatment with the GABAB receptor antagonist phaclofen (10 μg; icv) at 0840 h were ineffective in preventing the restraint-induced inhibition of the LH surge. The results suggest that GABAA and GABAB receptors are not involved in the inhibitory effect of restraint stress on the LH surge.     

Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Processing of temporal duration information in working memory after frontodorsal tumour excisions

This study aimed to test the hypothesis that impairments of temporal duration processing after frontal lobe lesions reflect deficits in executive monitoring functions rather than a domain-specific deficit in the maintenance of duration information in working memory. Patients with frontodorsal lesions, clinical controls with post-central lesions, and healthy controls performed recognition and classification tasks, which should allow for testing maintenance and monitoring functions, respectively. Results showed mild non-selective impairments of the frontal patients on both temporal and spatial recognition tasks, but a marked selective degradation on temporal classification while performance on spatial classification was unimpaired. This suggests that maintenance of duration information in working memory after frontal lesions is basically preserved but that, depending on executive task characteristics, there is a specific deficit in the strategic organization of this type of information.     

Bilingualism and adult differences in inhibitory mechanisms: evidence from a bilingual stroop task

The present investigation examined the functioning of inhibitory mechanisms in younger and older bilinguals using a bilingual version of the Stroop test. The study predicted different patterns of age related decline in inhibitory mechanisms (inter- and intralingual interference) in bilinguals depending on their level of proficiency. Consistent with expectations, older bilinguals were slower when they responded in their non-dominant language. Furthermore, older unbalanced bilinguals showed greater interlingual interference when they responded with their second language to visual stimuli written in their dominant language. Balanced bilinguals showed equivalent interference effects between all conditions. These findings suggest that manipulating two languages may enhance the efficiency of inhibitory mechanisms.     

The nature and treatment of stuttering as revealed by fMRI A within- and between-group comparison

This article reviews some of our recent functional magnetic resonance imaging (fMRI) studies of stuttering. Using event-related fMRI experiments, we investigated brain activation during speech production. Results of three studies comparing persons who stutter (PWS) and persons who do not stutter (PWNS) are outlined. Their findings point to a region in the right frontal operculum (RFO) that was consistently implicated in stuttering. During overt reading and before fluency shaping therapy, PWS showed higher and more distributed neuronal activation than PWNS. Immediately after therapy differential activations were even more distributed and left sided. They extended to frontal, temporal, and parietal regions, anterior cingulate, insula, and putamen. These over-activations were slightly reduced and again more right sided two years after therapy. Left frontal deactivations remained stable over two years of observation, and therefore possibly indicate a dysfunction. After therapy, we noted higher activations in persons who stutter moderately than in those who stutter severely. These activations might reflect patterns of compensation. We discuss why these findings suggest that fluency-inducing techniques might synchronize a disturbed signal transmission between auditory, speech motor planning, and motor areas.

Educational objectives: The reader will learn about and be able to: (1) identify regions of brain activations and deactivations specific for PWS; (2) describe brain activation changes induced by fluency shaping therapy; and (3) discuss the correlation between stuttering severity and brain activation.     

Reliability of Pass and Fail Decisions on Tests Employing Cut Scores

The study evaluated the reliability of pass and fail classifications for several teacher certification tests. Since these tests are used in the context of a cut score to classify examinees as pass and fail, evaluating the accuracy and consistency of these classifications is important. The classification accuracy and consistency statistics were estimated using the RELCLASS software. Results indicated the following. (1) The 29 teacher certification tests that were examined had a relatively high classification accuracy (0.827 to 0.999) and consistency (0.760 to 0.999). (2) Both classification accuracy and consistency increased as the difference between the mean and cut score increased. (3) Classification accuracy and consistency was higher for multiple-choice (MC) as compared to tests consisting of only constructed-response (CR) items or a combination of CR and MC items.     

Executive Functions in Children and Adolescents with Turner Syndrome: A Systematic Review and Meta-Analysis

Turner syndrome (TS) is a genetic disorder, affecting 1/2500 to 1/3000 live female births, induced by partial or total deletion of one X chromosome. The neurocognitive profile of girls with TS is characterized by a normal Verbal IQ and weaknesses in visual-spatial, mathematics, and social cognitive domains. Executive functions (EFs) impairments have also been reported in these young patients. However, methodological differences across studies do not allow determination of which EFs are impaired and what is the magnitude of these impairments. The aim of this review was to clarify the EF profile of children and adolescents with TS. Sixteen samples, from thirteen studies, were included in the current meta-analysis. EFs measures used in these studies were classified into working memory, inhibitory control, cognitive flexibility, or higher-order EFs tasks in accordance with Diamond’s model, Annual Review of Psychology, 64, 135–168 (2013). Results confirmed that girls with TS had significant executive impairments with effect sizes varying from small (inhibitory control) to medium (cognitive flexibility) and large (working memory, higher-order EFs). Analyses by task revealed that cognitive inhibition may be more impaired than the other inhibitory control abilities. Heterogeneity across cognitive flexibility measures was also highlighted. Between-sample heterogeneity was observed for three tasks and the impact of participants’ characteristics on EFs was discussed. This meta-analysis confirms the necessity to assess, in patients living with TS, each EF by combining both visual and verbal tasks. Results also underline that, when studying girls with TS’ executive profile, it is important to explore the impact of moderator variables, such as IQ, parental socio-economic status, TS karyotype, psychiatric comorbidities, and hormonal treatment status.     

Sexual Permissiveness: A Mozambique–France Comparison

The present study compared sexual permissiveness between African adults and European adults. The 301 participants (154 males, 147 females) living in the area of Maputo, Mozambique, and the 309 participants (157 males, 152 females) living in the area of Toulouse, France, were presented with the Portuguese and French versions of 7 permissiveness items taken from the Sexual Attitudes Scale devised by Hendrick & Hendrick (1987 ). Permissiveness scores were shown to be lower among Mozambican participants than among French participants. A clear effect of religious involvement on permissiveness was also demonstrated, and this effect was of the same magnitude in both samples.