Origin and Properties of Striatal Local Field Potential Responses to Cortical Stimulation: Temporal Regulation by Fast Inhibitory Connections

Evoked striatal field potentials are seldom used to study corticostriatal communication in vivo because little is known about their origin and significance. Here we show that striatal field responses evoked by stimulating the prelimbic cortex in mice are reduced by more than 90% after infusing the AMPA receptor antagonist CNQX close to the recording electrode. Moreover, the amplitude of local field responses and dPSPs recorded in striatal medium spiny neurons increase in parallel with increasing stimulating current intensity. Finally, the evoked striatal fields show several of the basic known properties of corticostriatal transmission, including paired pulse facilitation and topographical organization. As a case study, we characterized the effect of local GABAA receptor blockade on striatal field and multiunitary action potential responses to prelimbic cortex stimulation. Striatal activity was recorded through a 24 channel silicon probe at about 600 µm from a microdialysis probe. Intrastriatal administration of the GABAA receptor antagonist bicuculline increased by 65±7% the duration of the evoked field responses. Moreover, the associated action potential responses were markedly enhanced during bicuculline infusion. Bicuculline enhancement took place at all the striatal sites that showed a response to cortical stimulation before drug infusion, but sites showing no field response before bicuculline remained unresponsive during GABAA receptor blockade. Thus, the data demonstrate that fast inhibitory connections exert a marked temporal regulation of input-output transformations within spatially delimited striatal networks responding to a cortical input. Overall, we propose that evoked striatal fields may be a useful tool to study corticostriatal synaptic connectivity in relation to behavior

ER stress induced by the OCH1 mutation triggers changes in lipid homeostasis in Kluyveromyces lactis

In Kluyveromyces lactis yeast, OCH1 encodes for the α-1,6-mannosyltrasferase that adds the initial α-1,6-mannose to the outer-chains of N-glycoproteins. Kloch1-1 mutant cells showed altered calcium homeostasis and endoplasmic reticulum (ER) stress. Since ER plays a major role in lipid biosynthesis and lipid droplet (LD) formation, herein the impact of Och1p depletion on lipid homeostasis was investigated. Transcriptional profiles of genes involved in biosynthesis of fatty acids, their amount and composition changed in mutant cells. An increased amount of ergosterol was determined in these cells. Enhanced transcription of genes involved in both synthesis and mobilization of LDs was also found in Kloch1-1 cells, accompanied by a reduced amount of LDs. We provide evidence that ER alterations, determined by protein misfolding as a result of reduced N-glycosylation, induced altered lipid homeostasis in Kloch1-1 cells. Chemical chaperone 4-phenyl butyrate (4-PBA) slightly alleviated the LD phenotype in cells depleted of Och1p. Remarkably, complete suppression of ER stress, via increased expression of plasma membrane calcium channel subunit Mid1, fully restored lipid homeostasis in mutant cells. To further reinforce this finding, low numbers of LDs were observed in wild type cells when ER stress was triggered by DTT treatmen

Frauen/Männer, Kinder/Erwachsene

Der Autor stellt der grundlegenden Differenzlinie der feministischen Pädagogik, nämlich der Unterscheidung zwischen Männern und Frauen, die Differenzlinie Kinder/ Erwachsene, an der sich die allgemeine Pädagogik orientiert, als „konkurrierende Leitdifferenz“ gegenüber. In dem Überlegungshorizont, „welche Verbindungen, Irritationen, Zusammenstöße, Aufschaukelungen sich hierdurch ergeben“, versucht der Autor die „symbolischen Eigenarten der beiden Differenzen vergleichend zu beschreiben“ und „die Gemeinsamkeiten und die Unterschiede zwischen zwei Differenzen: der von Kindern und Erwachsenen und der von Männern und Frauen, zwischen pädagogischer Differenz und feministischer Differenz“ zu thematisieren. (DIPF/ ssch

Hydration of Sodium Alginate in Aqueous Solution

Alginates are naturally occurring biocompatible polysaccharides. They have a broad range of applications, mainly in connection to their ability to control the rheol. of aq. solns. Specifically, addn. of a small amt. of alginate (10% wt) leads to a ~100-fold increase in viscosity. Here we explore whether that pronounced retardation of the long-range correlations is accompanied by mol.-level changes of the water structure. We employ viscometry, dielec. spectroscopy (DS) and femtosecond IR (fs-IR) pump-probe spectroscopy to study water dynamics in sodium alginate solns. Remarkably, despite the large rheol. effects of alginates in soln., the rotational dynamics of water are remarkably similar to those obsd. in bulk water. Only a small subensemble of water mols. is slowed down significantly, amounting to 6 ± 2 water mols. per saccharide unit. Furthermore, DS measurements reveal an addnl. ~5 water mols. to be slowed down by the counterion (Na+). Our results reveal that the effect of alginate on the dynamics of water is restricted to the first hydration shell. This indicates that the large viscosity increase is detd. by the polysaccharide network, with large water pools present between the polysaccharide chains. [on SciFinder(R)

Blood: From Humor to Hematology

Today blood can be defined simply as the red liquid flowing through the arteries and veins of humans and other animals. But in early modern philosophy and science, blood acquired many different meanings: it transformed from being one of the four cardinal humors – believed to determine a person’s physical and mental qualities – into a raw material which was treated, studied, measured, and investigated. With the development of new methods and instruments, this vital fluid also came in a variety of shapes and sizes: it came to be understood as globules, as consisting of chemical elements, as having various temperatures and weights. Although medical treatments like bloodletting were slow to change, blood itself underwent a major revolution as the result of long and uncertain endeavors of study and experimentation. And considering the discovery of blood circulation as well as the development of hematology and blood chemistry, blood serves as a significant case study for the history of the scientific revolution. This article will discuss these major developments in the early modern study of blood