Procedural justice, stress appraisal, and athletes' attitudes.

In this study the authors examined a model in which procedural justice may serve as an external-situational resource that improves athletes' appraisals of stress and enhances their attitudes toward their team. Eighty-one Israeli male athletes were questioned on the degree of procedural justice employed on their team, how they appraised stress, and their attitudes toward their team. Results showed that higher procedural justice was associated with more positive appraisals of stress as a challenge and greater team loyalty and commitment and that the relationship of procedural justice to team commitment and loyalty was mediated by how stress is appraised. Findings integrate the cognitive-phenomenological model of stress/coping with the relational factors of the procedural justice approach and extend their validity to the field of sport. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual models of software artifacts

According to constructivism, learning takes place by constructing cognitive structures based upon current, perhaps naive, knowledge and new experiences. In the case of software artifacts like programming languages and applications, current knowledge is not a solid base upon which to build viable new knowledge. Therefore, we conjecture that explicit conceptual models constructed by educators should be able to improve the performance of users in their interaction with software artifacts, in our case the popular word processor MS-Word. The experiments described in this paper support this idea: we found that learners who used our conceptual models were able to analyze and solve problems conceptually, while learners who used task-oriented learning materials of equivalent scope employed aimless trial and error.     

Neuronal migration disorders: heterotopic neocortical neurons in CA1 provide a bridge between the hippocampus and the neocortex

Neuronal migration disorders have been involved in various pathologies, including epilepsy, but the properties of the neural networks underlying disorders have not been determined. In the present study, patch clamp recordings were made from intrahippocampal heterotopic as well as from neocortical and hippocampal neurons from brain slices of rats with prenatally methylazoxymethanol-induced cortical malformation. We report that heterotopic neurons have morphometrical parameters and cellular properties of neocortical supragranular neurons and are integrated in both neocortical and hippocampal networks. Thus, stimulation of the white matter induces both antidromic and orthodromic response in heterotopic and neocortical neurons. Stimulation of hippocampal afferents evokes a monosynaptic response in the majority of heterotopic neurons and a polysynaptic all-or-none epileptiform burst in the presence of bicuculline to block gamma-aminobutyric acid type A inhibition. Furthermore, hippocampal paroxysmal activity generated by bath application of bicuculline can spread directly to the neocortex via the heterotopia in methylazoxymethanol-treated but not in naive rats. We conclude that heterotopias form a functional bridge between the limbic system and the neocortex, providing a substrate for pathological conditions.     

Neocortex in the hippocampus: an anatomical and functional study of CA1 heterotopias after prenatal treatment with methylazoxymethanol in rats

Migration disorders cause neurons to differentiate in an abnormal heterotopic position. Although significant insights have been gained into the etiology of these disorders, very little is known about the anatomy of heterotopias. We have studied heterotopic masses arising in the hippocampal CA1 region after prenatal treatment with methylazoxymethanol (MAM) in rats. Heterotopic cells were phenotypically similar to neocortical supragranular neurons and exhibited the same temporal profile of migration and neurogenesis. However, they did not express molecules characteristic of CA1 neurons such as the limbic-associated membrane protein. Horseradish peroxidase injections in heterotopia demonstrated labeled fibers not only in the neocortex and white matter but also in the CA1 stratum radiatum and stratum lacunosum. To study the pathophysiological consequences of this connectivity, we compared the effects of neocortical and limbic seizures on the expression of Fos protein and on cell death in MAM animals. After metrazol-induced seizures, Fos-positive cells were present in CA1 heterotopias, the only hippocampal region to be activated with the neocortex. By contrast, kainic acid-induced seizures caused a prominent delayed cell death in limbic regions and in CA1 heterotopias. Together, these results suggest that neocortical heterotopias in the CA1 region are integrated in both the hippocampal and neocortical circuitry.     

Learned helplessness and learned resourcefulness: Effects of noncontingent success and failure on individuals differing in self-control skills.

In Exp I, 72 undergraduates were assessed using the Self-Control Schedule and received noncontingent success-, failure-, or no-feedback on a task that ostensibly assessed therapeutic abilities. Ss were subsequently tested on insolvable puzzles. In Exp II, 72 undergraduates followed the same procedure as in Exp I but were subsequently tested on solvable anagrams. Results show that the performance of Ss with low resourcefulness (LR) in self-control skills on the insolvable puzzles was debilitated by the helplessness induction, while Ss with high resourcefulness (HR) and LR Ss showed equal helplessness-induced deficits on the anagrams. As predicted from the self-control model, HR Ss more frequently checked statements indicating positive self-evaluations and task-oriented thoughts and less frequently checked negative self-evaluations than did LR Ss during exposure to uncontrollability in both experiments. It is concluded that the self-control model best accounts for Ss' self-reactions during exposure to uncontrollability or failure, while the learned helplessness model accounts for the generalization of helplessness from uncontrollable situations to controllable ones. The list of self-referent statements used in the experiments is appended. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Giant depolarizing potentials: the septal pole of the hippocampus paces the activity of the developing intact septohippocampal complex in vitro

In neonatal hippocampal slices, recurrent spontaneous giant depolarizing potentials (GDPs) provide neuronal synchronized firing and Ca2+ oscillations. To investigate the possible role of GDPs in the synchronization of neuronal activity in intact neonatal limbic structures, we used multiple simultaneous electrophysiological recordings in the recently described preparation of intact neonatal septohippocampal complex in vitro. Combined whole-cell (in single or pairs of cells) and extracellular field recordings (one to five simultaneous recording sites) from the CA3 hippocampal region and various parts of the septum indicated that spontaneous GDPs, which can be initiated anywhere along the longitudinal hippocampal axis, are most often initiated in the septal poles of hippocampus and propagate to medial septum and temporal poles of both hippocampi simultaneously. GDPs were abolished in the medial septum but not in the hippocampus after surgical separation of both structures, suggesting hippocampal origin of GDPs. The preferential septotemporal orientation of GDP propagation observed in the intact hippocampus was associated with a corresponding gradient of GDP frequency in isolated portions of hippocampus. Accordingly, most GDPs propagated in the septotemporal direction in both septal and temporal hippocampal isolated halves, and whereas GDP frequency remained similar in the septal part of hippocampus after its surgical isolation, it progressively decreased in more temporally isolated portions of the hippocampus. Because GDPs provide most of the synaptic drive of neonatal neurons, they may modulate the development of neuronal connections in the immature limbic system.     

GABAA, NMDA and AMPA receptors: a developmentally regulated 'ménage à trois'

The main ionotropic receptors (GABAA, NMDA and AMPA) display a sequential participation in neuronal excitation in the neonatal hippocampus. GABA, the principal inhibitory transmitter in the adult CNS, acts as an excitatory transmitter in early postnatal stage. Glutamatergic synaptic transmission is first purely NMDA-receptor based and lacks functional AMPA receptors. Therefore, initially glutamatergic synapses are 'silent' at resting membrane potential, NMDA channels being blocked by Mg2+. However, when GABA and glutamatergic synapses are coactivated during the physiological patterns of activity, GABAA receptors can facilitate the activation of NMDA receptors, playing the role conferred to AMPA receptors later on in development. Determining the mechanisms underlying the development of this 'ménage à trois' will shed light not only on the wide range of trophic roles of glutamate and GABA in the developing brain, but also on the significance of the transition from neonatal to adult forms of plasticity.     

NG-nitro-L-arginine methyl ester reduces necrotic but not apoptotic cell death induced by reversible focal ischemia in rat

During cerebral ischemia, nitric oxide (NO) production via stimulation of NO synthase, is likely one of the major events leading to neuronal death. Recently, we have demonstrated that after reversible focal ischemia, apoptosis was implicated in the penumbra whereas necrosis was prominent in the ischemic core. We have now examined the effect of a non-specific inhibitor of NO synthase, NG-nitro-L-arginine methyl ester (L-NAME, 3 ing kg-1 i.p., 5 min and 3 h after the onset of ischemia), on the progress of apoptotic and necrotic nuclei following transient focal cerebral ischemia, using DNA electrophoresis and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL assay). Our results indicated that L-NAME prevented the loss of necrotic, but not apoptotic cells.