Enhancement of glutamate release by L-fucose changes effects of glutamate receptor antagonists on long-term potentiation in the rat hippocampus

In previous studies L-fucose has been shown to facilitate long-term memory formation and to enhance and prolong long-term potentiation (LTP). To search for possible presynaptic or postsynaptic mechanisms that are affected by L-fucose, we examined the effect of L-fucose on (1) inhibition of LTP induction via glutamate receptors by antagonists, (2) paired-pulse facilitation, and (3) presynaptic transmitter release. Coapplication of 0.2 mM L-fucose with the competitive N-methyl-D-aspartate (NMDA) receptor antagonist, D-2-amino-5-phosphonovalerate (AP5), or coapplication of 0.2 mM L-fucose in the presence of an inhibitor for class I/II metabotropic glutamate receptors, (S)-alpha-methyl-4-carboxyphenylglycine (MCPG), reversed LTP blockade in the CA1-region of hippocampal slices. In contrast, L-fucose had no effect on the LTP blockade by the noncompetitive NMDA ion-channel blocker (5R,10S)-(+)-5-Methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine hydrogen maleate (MK-801). Paired-pulse facilitation, which is a primarily presynaptic phenomenon of short-term plasticity, was decreased in the presence of 0.2 mM L-fucose. Furthermore, L-fucose enhanced the K(+)-stimulated release of [(3)H]-D-aspartate from preloaded hippocampal slices in a concentration-dependent manner. These observations demonstrate an influence of L-fucose on transmitter release that in turn can increase transmitter availability at postsynaptic glutamate receptors. This effect of L-fucose may contribute to the LTP facilitation seen in vitro and in vivo as well as to improvement in memory formation.     

Task-dependent role for dorsal striatum metabotropic glutamate receptors in memory

The effect of post-training intradorsal striatal infusion of metabotropic glutamate receptor (mGluR) drugs on memory consolidation processes in an inhibitory avoidance (IA) task and visible/hidden platform water maze tasks was examined. In the IA task, adult male Long-Evans rats received post-training intracaudate infusions of the broad spectrum mGluR antagonist α-methyl-4-carboxyphenylglycine (MCPG; 1.0, 2.0 mM/0.5 μL), the group I/II mGluR agonist 1-aminocyclopentane-1,3-carboxylic acid (ACPD; 0.5 or 1.0 μM/0.5 μL), or saline immediately following footshock training, and retention was tested 24 h later. In the visible- and hidden-platform water maze tasks, rats received post-training intracaudate infusions of ACPD (1.0 μM), MCPG (2.0 mM), or saline immediately following an eight-trial training session, followed by a retention test 24 h later. In the IA task, post-training infusion of ACPD (0.5 and 1.0 μM) or MCPG (1.0 and 2.0 mM) impaired retention. In the IA and visible-platform water maze tasks, post-training infusion of ACPD (1.0 μM), or MCPG (2.0 mM) impaired retention. In contrast, neither drug affected retention when administered post-training in the hidden-platform task, consistent with the hypothesized role of the dorsal striatum in stimulus-response habit formation. When intradorsal striatal injections were delayed 2 h post-training in the visible-platform water maze task, neither drug affected retention, indicating a time-dependent effect of the immediate post-training injections on memory consolidation. It is hypothesized that MCPG impaired memory via a blockade of postsynaptic dorsal striatal mGluR's, while the impairing effect of ACPD may have been caused by an influence of this agonist on presynaptic “autoreceptor” striatal mGluR populations.     

Means-end coherence,stringency, and subjective reasons

Intentions matter. They have some kind of normative impact on our agency. Something goes wrong when an agent intends some end and fails to carry out the means she believes to be necessary for it, and something goes right when, intending the end, she adopts the means she thinks are required. This has even been claimed to be one of the only uncontroversial truths in ethical theory. But not only is there widespread disagreement about why this is so, there is widespread disagreement about in what sense it is so. In this paper I explore an underdeveloped answer to the question of in what sense it is so, and argue that resolving an apparent difficulty with this view leads to an attractive picture about why it is so.

Core self-evaluations interact with cognitive ability to predict academic achievement

Extant research suggests that core self-evaluations (CSE) is associated with various work-related criteria, but such research often focuses on main effects when predicting subjective outcomes. Drawing upon psychological theories involving self-concept and motivation, we investigated both the main and interactive effects of CSE and cognitive ability when predicting an objective outcome. Specifically, results indicated that high CSE strengthened the positive relation between cognitive ability and academic achievement. Study contributions and limitations are discussed.     

Investigating the Relation between Gender Typicality and Pressure to Conform to Gender Norms

Sex Roles - Previous research suggested that gender typicality and pressure to conform to gender norms were unrelated; however, this may have been due to how gender typicality was assessed (i.e.,...     

Wickedness,Idleness and Basic Income

Res Publica - This paper critically analyses the position that basic income schemes foster idleness and thereby create harm. The view is based on an alleged empirical link between idleness and...     

Contextual Definition and Ontological Commitment

According to the standard view, Kant held that hypothetical imperatives are universally binding edicts with disjunctive objects: take-the-means-or-don't-have-the-end. But Kant thought otherwise. He held that they are edicts binding only on some—those who have an end.