The volumes of the fornix in schizophrenia and affective disorders: A post-mortem study

Structural and functional pathology of limbic structures including the hippocampus are frequently replicated in schizophrenia. Although the fornix is the main afferent system of the hippocampus to the septal nuclei and the hypothalamus (especially the mammillary bodies), relatively few studies have investigated structural changes of the fornix in schizophrenia. We measured the volume of the fornix in post-mortem brains in 19 patients with schizophrenia, 9 patients with bipolar disorder, 7 patients with unipolar depression, and 14 control subjects by planimetry of serial sections. The volumes, the mean cross-sectional areas, and the anterior to posterior distances of the fornix did not differ among patients with schizophrenia, bipolar disorder, unipolar depression, and control subjects. No lateralization existed between the right and the left fornices in among patients in the diagnostic groups and the control subjects. The fornix does not show morphometrical abnormalities in patients with schizophrenia, bipolar disorder and unipolar depression compared with control subjects, which might indicate that the fornix is not a primary focus of structural changes in these diseases.     

Daytime sleepiness during transition into daylight saving time in adolescents: Are owls higher at risk?

BackgroundIndividuals differ in their biological rhythms and preferences for time of day. Here, we looked at the transition into daylight saving time (DST) in adolescents. As adolescents tend to be evening types, one may expect that they suffer from a transition into DST.MethodsTo assess these changes, we measured daytime sleepiness and morningness–eveningness preference (CSM score) in adolescents.ResultsDaytime sleepiness correlated with age and CSM score. Older pupils and evening types showed a higher sleepiness. Daytime sleepiness was higher after the transition until the third week after. Older pupils and pupils scoring higher on eveningness reported higher daytime sleepiness after the transition, suggesting that these pupils suffer most from the change. Using cut-off scores for larks and owls, we found that owls showed higher sleepiness than larks.ConclusionAs one consequence, class and school performance tests should not take place in the first week(s) after the transition into DST.     

Untersuchungen über „tonische“ und „nichttonische“ Wirbeltiermuskeln

Zusammenfassung Die Umklammerungshaltung des Frosches und die Schutzhaltung der Schildkröte (Zurückziehen des Kopfes, der Extremitäten und des Schwanzes unter den Schild) werden genauer beschrieben. Beide können in ganz normaler Weise durch rein muskuläre Acetylcholinwirkung nachgeahmt werden. Dies beruht darauf, daß das Acetylcholin in spezifischer Auswahl nur die Umklammerungsmuskeln bzw. die Retractoren in starke Dauerkontraktion bringt, deren Gegenmuskeln dagegen gar nicht oder wenigstens wesentlich schwächer. Auch für andere Reize, zumal für den mechanischen Reiz besteht der gleiche Unterschied. Der vonSommerkamp zuerst erhobene Befund, daß sich die Skeletmuskeln des Frosches an ihrer Reaktion dem Acetylcholin gegenüber erkennbar in tonische und nicht tonische unterscheiden lassen, wird somit bestätigt und zugleich für den Frosch wie auch für die Schildkröte wesentlich erweitert. Vor allem aber wird gezeigt, daß die Verteilung der tonischen und nichttonischen Muskeln keine zufällige ist, sondern eine biologisch äußerst zweckmäßige im Sinne der Sicherstellung obengenannter, biologisch wichtiger Dauerhaltungen.     

Activation of neurokinin receptors modulates K and Cl channel activity in cultured astrocytes from rat cortex

Short application of the neurokinin receptor agonist substance P (SP) leads to a biphasic depolarization of astrocytes cultured from rat cortex. The rapid and transient depolarizing event lasted few seconds, the slow one several minutes. In some cells, only the slow depolarizing component was observed. During the slow depolarizing event, the sensitivity of the membrane potential for a change in the K+ gradient decreased, indicating a decrease in the relative K+ permeability of the membrane. The rapid SP-induced depolarization could be reversed, when the membrane potential was depolarized to about 0 mV by elevation of the extracellular K+ concentration, indicating a reversal potential close to the Cl- equilibrium potential. When the membrane was clamped close to the resting membrane potential using the whole-cell patch-clamp technique, SP induced a biphasic inward current with a similar time course as the SP-induced membrane depolarization. Evaluating current-to-voltage curves indicated a conductance decrease during the slow inward current with a reversal potential of the SP-dependent current close to the K+ equilibrium potential. The mean open time of single K+ channels, measured in the cell-attached configuration of the patch-clamp technique, decreased after application of SP. In contrast, the mean open time of single Cl- channels increased. We conclude that activation of neurokinin receptors in astrocytes modulates the activity of K+ and Cl- channels, leading to a complex depolarization of the membrane potential.