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.     

Beziehungsmuster und Beziehungskonflikte

Zusammenfassung  Die Veränderung pathogenetisch bedeutsamer Beziehungsmuster gilt als wesentliches psychotherapeutisches Behandlungsziel. Um zielgerichtete Veränderungen von Beziehungsstrukturen zu erreichen, bedarf es sowohl einer Diagnostik und Beschreibung solcher Beziehungsmuster, einer darauf zielenden Behandlungstechnik als auch einer Verlaufskontrolle und Evaluation der angestrebten Veränderungen. Nach einem Überblick über verschiedene Methoden zur Erfassung von Beziehungsmustern wird die Methode des Zentralen-Beziehungskonflikt-Themas (ZBKT) von Luborsky näher beschrieben; ausgewählte Ergebnisse der ZBKT-Forschung werden dargestellt und die Methode kritisch bewertet.

Luminance thresholds for the Bezold-Brücke hue shift

This study presents data on the luminance difference at which a hue difference is first perceived between two identical spectral lights. Thresholds were obtained for both luminance increments and decrements from a 2.00 log troland standard for wavelengths between 470 nm and 690 nm. A predicted luminance threshold for each wavelength was calculated based on wavelength discrimination data and the Purdy constant hue contours; i.e. that luminance at which the constant hue contour intersects the wavelength discrimination bound for a given wavelength. A generally good agreement was obtained between observed and predicted values.     

Studienbezogene Belastungen, Lebensqualität und Beziehungserleben bei Medizinstudenten

In a cross-sectional study of medical students we examined educational strains, health feeling, and relationship patterns. Work stress was measured using the questionnaire by Jurkat et al., health-related quality of life was measured using the Short Form- (SF-)36 Health Survey, and relationship patterns to the partner as well as to a friend were mapped using“Beziehungsmusterfragebogen“ (BeMus). Study stress was assessed as being high by 60% of the students. Consequently, 39% had not enough time for their partners und 29% had no time for own interests. The mental health averaged significantly below the norm. A high workload and discontent correlated with aggressiveness, especially in the partnership, whereas loving care towards the partner or friend correlated with a high level of satisfaction and a lower strain level. Therefore, an improvement of psychosocial competence in medical students as well as a practice-oriented preparation for the profession is needed.     

Mechanisms of perceptual timing: Beat-based or interval-based judgements?

Summary What is the nature of the human timing mechanism for perceptual judgements about short temporal intervals? One possibility is that initial periodic events, such as tones, establish internal beats which continue after the external events and serve as reference points for the perception of subsequent events. A second possibility is that the timer records the intervals produced by events. Later, the stored intervals can be reproduced or compared to other intervals. A study by Schulze (1978) provided evidence favoring beat-based timing. In contrast, our two experiments support an interval theory. The judgements of intervals between tones is not improved when the events are synchronized with internal beats established by the initial intervals. The conflict between the two sets of results may be resolved by the fact that an interval timer can recycle from one interval to the next, thus operating in a beat-like mode. However, a timer of this sort is just as accurate when comparing intervals that are off the beat.     

Do perception and motor production share common timing mechanisms: A correlational analysis

The two experiments of this study exploited individual variation in timing ability to ask whether the production of time intervals by different motor effectors and the judgement of perceptually based time intervals all share common timing mechanisms. In one task subjects produced a series of taps, attempting to maintain constant intervals between them. Individual differences in variability of the produced intervals correlated across the effectors of finger and foot. That is, people that were ‘good timers’ with one effector tended to be ‘good timers’ with another. Besides timing motor production, the subjects also judged durations of brief perceptual events. The acuity of perceptual judgements correlate substantially with regularity of motor production. Further results involving maximum speed of motor production suggested that variability of motor timing comes from two sources, one source in common with perception, and hence called clock variability, and the other source in common with motor speed, and hence called motor implementation variability. The second experiment showed that people high in skill on the piano were better at both types of timing on the average than control subjects with no expertise.     

Self-Attitudes and Suicidal Behavior

Findings are reported concerning the hypothesized relationship between adoption of suicidal responses (ideation, threats, attempts) and antecedent negative self-attitudes. Data were provided by junior high school student (N = 3,148) responses to questionnaires administered three times at annual intervals. Antecedent negative self-attitudes were measured by a seven-item self-derogation scale at the first testing. Adoption of suicidal responses was indicated by earlier denial and subsequent affirmation of the response (self-reports). Findings indicate that suicidal behaviors are responses (whether or not subsequently continued) to experiences of negative self-attitudes in the more recent past. However, whether or not suicidal behaviors are related to self-derogating feelings in the more remote past can be seen as a function of a sex-social-class-mode of suicidal response interaction.