Neural analogs of associative learning in {\it Aplysia\/}: Experimental and theoretical approaches

A change in synaptic strength arising from the activation of two neuronal pathways at approximately the same time is a form of associative plasticity and may underlie classical conditioning. Previously, a cellular analog of a classical conditioning protocol has been demonstrated to produce short-term associative plasticity at the connections between sensory and motor neurons in Aplysia. A similar training protocol produced long-term (24 hour) enhancement of excitatory postsynaptic potentials (EPSPs). EPSPs produced by sensory neurons in which activity was paired with a reinforcing stimulus were significantly larger than unpaired controls 24 hours after training. To examined whether the associative plasticity observed at these synapses may be involved in higher-order forms of classical conditioning, a neural analog of contingency was developed. In addition, computer simulations were used to analyze whether the associative plasticity observed in Aplysia could, in theory, account for second-order conditioning and blocking. ^

Lettre aux auteurs juifs d'un mémoire adressé à Mr. Teller

par J. A. de Luc

Mémoire an die hohe Stände-Versammlung des Königreichs Baiern : über verschied'ne gegen die Juden gemachte Anträge ; nebst einigen Wünschen u. Bitten

von Samson Wolf Rosenfeld

Associative processing and paranormal belief

In the present study we introduce a novel task for the quantitative assessment of both originality and speed of individual associations. This 'BAG' (Bridge-the-Associative-Gap) task was used to investigate the relationships between creativity and paranormal belief. Twelve strong 'believers' and 12 strong 'skeptics' in paranormal phenomena were selected from a large student population (n > 350). Subjects were asked to produce single-word associations to word pairs. In 40 trials the two stimulus words were semantically indirectly related and in 40 other trials the words were semantically unrelated. Separately for these two stimulus types, response commonalities and association latencies were calculated. The main finding was that for unrelated stimuli, believers produced associations that were more original (had a lower frequency of occurrence in the group as a whole) than those of the skeptics. For the interpretation of the result we propose a model of association behavior that captures both 'positive' psychological aspects (i.e., verbal creativity) and 'negative' aspects (susceptibility to unfounded inferences), and outline its relevance for psychiatry. This model suggests that believers adopt a looser response criterion than skeptics when confronted with 'semantic noise'. Such a signal detection view of the presence/absence of judgments for loose semantic relations may help to elucidate the commonalities between creative thinking, paranormal belief and delusional ideation.

Mémoire sur une médaille en l'honneur de Louis-le-Débonnaire, presenté à l'Academie royale des sciences et belles lettres de Bruxelles, le 6 décembre 1834

par Eliacin Carmoly

Rapport fait à l'Académie Royale de Metz, sur le mémoire relatif à l'origine des nos chiffres et à l'Abacus des Pythagoriciens, par M. J. H. Vincent, pp. : Séance du 26 avril 1840

par Gerson-Lévy

Recueil des travaux rédigés en mémoire du jubilé scientifique de M. Daniel Chwolson ... : 1846-1896

[Hrsg.: David Gunzburg]

Rapport fait à l'Académie Royale de Metz, sur le mémoire relatif à l'origine des nos chiffres et à l'Abacus des Pythagoriciens, par M. J. H. Vincent, pp. : Séance du 26 avril 1840

par Gerson-Lévy ...