Calcium-activated proteases are critical for refilling depleted vesicle stores in cultured sensory-motor synapses of Aplysia

Aplysia motoneurons cocultured with a presynaptic sensory neuron exhibit homosynaptic depression when stimulated at low frequencies. A single bath application of serotonin (5HT) leads within seconds to facilitation of the depressed synapse. The facilitation is attributed to mobilization of neurotransmitter-containing vesicles from a feeding vesicle store to the depleted, readily releasable pool by protein kinase C (PKC). Here, we demonstrate that the calpain inhibitors, calpeptin, MG132, and ALLN, but not the proteasome inhibitors, lactacystin and clasto-lactacystin beta-lactone, block 5HT-induced facilitation of depressed synapses. Likewise the 5HT-induced enhancement of spontaneous miniature potentials (mEPSPs) frequency of depressed synapses is significantly reduced by calpeptin. In contrast, neither the facilitation of nondepressed synapses nor the enhancement of their mEPSPs frequency is affected by the inhibitor. The data suggest that action potentials-induced calcium influx activate calpains. These, in turn, play a role in the refilling processes of the depleted, releasable vesicle store.     

Model's Race: A Peripheral Cue in Advertising Messages?

Based on the Elaboration Likelihood Model and Social Categorization Theory, an experiment examined minority viewers' use of racial cues on exposure to product advertising. A total of 160 Black adults from a southeastern city rated a garment bag advertisement that featured either a White or a Black model and contained either strong or weak message arguments. Consistent with both theoretical notions, product and advertising evaluations were more favorable given a Black than a White model, but only for Black participants who identify strongly with Black culture. Blacks who identify weakly with Black culture evaluated the product and advertisement similarly given a White or a Black model. The results also showed that the Black model's race motivated Blacks, particularly those with strong racial attitudes, to process the message in a biased manner. In particular, the Black (versus White) model's race positively influenced the Black participants' thoughts about the product, which in turn yielded more favorable product evaluations. The findings suggest that Blacks appear to engage in biased processing (and not simple cue processing) when exposed to Black models in advertising messages.     

Analyse d'une Sepreuve d'image mentale chez des adolescents presentant des difficultis d'apprentissage scolaire1

Le travail faisant l'objet de cet article s'inscrit dans le cadre d'un programme de recherche plus large qui s'intéresse à la variabilité individuelle des processus cognitifs et à son influence éventuelle sur les lois générates du développement de l'intelligence. Une partie des résultats a déjàété présentée dans d'autres publications auxquelles le lecteur pourra se référer pour plus de détails (par exemple, Rieben et al., 1983). Nous nous contenterons de les décrire brièvement afin d'introduire l'aspect spécifique sur lequel nous nous sommes centrées ici.