School Finance Systems and Their Responsiveness to Performance Pressures: A Case Study of Texas

Details the mechanisms of and influences on the state's school finance system, changes caused by increased performance pressures, local officials' ability to allocate resources as deemed appropriate, and obstacles to linking resources to student learning

School Finance Systems and Their Responsiveness to Performance Pressures: A Case Study of North Carolina

Details the mechanisms of and influences on the state's school finance system, changes caused by increased performance pressures, local officials' views on alternative allocation of resources, and obstacles to linking resources to student learning

Administration of the GABAA receptor antagonist picrotoxin into rat supramammillary nucleus induces c-Fos in reward-related brain structures. Supramammillary picrotoxin and c-Fos expression

<p>Abstract</p> <p>Background</p> <p>Picrotoxin blocks GABA_Areceptors, whose activation typically inhibits neuronal firing activity. We recently found that rats learn to selectively self-administer picrotoxin or bicuculline, another GABA_Areceptor antagonist, into the supramammillary nucleus (SuM), a posterior hypothalamic structure localized anterior to the ventral tegmental area. Other drugs such as nicotine or the excitatory amino acid AMPA are also self-administered into the SuM. The SuM appears to be functionally linked with the mesolimbic dopamine system and is closely connected with other brain structures that are implicated in motivational processes, including the prefrontal cortex, septal area, preoptic area, lateral hypothalamic area and dorsal raphe nucleus. Here, we hypothesized that these brain structures are activated by picrotoxin injections into the SuM.</p> <p>Results</p> <p>Picrotoxin administration into the SuM markedly facilitated locomotion and rearing. Further, it increased c-Fos expression in this region, suggesting blockade of tonic inhibition and thus the disinhibition of local neurons. This manipulation also increased c-Fos expression in structures including the ventral tegmental area, medial shell of the nucleus accumbens, medial prefrontal cortex, septal area, preoptic area, lateral hypothalamic area and dorsal raphe nucleus.</p> <p>Conclusions</p> <p>Picrotoxin administration into the SuM appears to disinhibit local neurons and recruits activation of brain structures associated with motivational processes, including the mesolimbic dopamine system, prefrontal cortex, septal area, preoptic area, lateral hypothalamic area and dorsal raphe nucleus. These regions may be involved in mediating positive motivational effects triggered by intra-SuM picrotoxin.</p

Role of dopamine D1 and D2 receptors in the nucleus accumbens in mediating reward

The objectives of this study were to examine the involvement of D1 and D2 receptors within the nucleus accumbens (ACB) in mediating reinforcement. The intracranial self-administration (ICSA) of D1 and D2 agonists was used to determine whether activating D1 and/or D2 receptors within the ACB of Wistar rats is reinforcing. At concentrations of 0.25, 0.50, and 1.0 mM (25, 50, and 100 pmol/100 nl of infusion), neither the D1 agonist R(+)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol [SKF 38393 (SKF)] hydrochloride nor the D2 agonist (-)-quinpirole (Quin) hydrochloride was self-administered into the shell region of the ACB. On the other hand, equimolar mixtures of SKF and Quin (SKF+Quin), at concentrations of 0.25, 0.50, and 1.0 mM each, were significantly self-infused into the ACB shell. The core region of the ACB did not support the ICSA of SKF+Quin at any of these concentrations. Rats increased lever pressing when the response requirement was increased from a fixed ratio 1 (FR1) to FR3, and they responded significantly more on the infusion lever than they did on the control lever. Coadministration of either 0.50 mM R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4, 5-tetrahydro-1H-3-benzazepine (SCH 23390) hydrochloride, a D1 antagonist, or 0.50 mM S(-)-sulpiride, a D2 antagonist, completely abolished the ICSA of the mixture of SKF+Quin (each at 0.50 mM) into the ACB shell. The present results suggest that concurrent activation of D1- and D2-type receptors in the shell of the ACB had a cooperative effect on DA-mediated reward processes

Contrasting pressure evolution of f-electron hybridized states in CeRhIn5 and YbNi3 Ga9 : An optical conductivity study

Optical conductivity [σ (ω)] of CeRhIn5 and YbNi3Ga9 have been measured at external pressures to 10 GPa and at low temperatures to 6 K. Regarding CeRhIn5, at ambient pressure the main feature in σ (ω) is a Drude peak due to free carriers. With increasing pressure, however, a characteristic midinfrared (mIR) peak rapidly develops in σ (ω), and its peak energy and width increase with pressure. These features are consistent with an increased conduction (c)- f electron hybridization at high pressure and show that pressure has tuned the electronic state of CeRhIn5 from very weakly to strongly hybridized ones. As for YbNi3Ga9, in contrast, a marked mIR peak is observed already at ambient pressure, indicating a strong c- f hybridization. At high pressures, however, the mIR peak shifts to lower energy and becomes diminished and seems to merge with the Drude component at 10 GPa. Namely, CeRhIn5 and YbNi3Ga9 exhibit some opposite tendencies in the pressure evolution of σ (ω) and electronic structure. These results are discussed in terms of the pressure evolution of c- f hybridized electronic states in Ce and Yb compounds, in particular in terms of the electron-hole symmetry often considered between Ce and Yb