Spatial variables and the feature-positive effect

Pigeons were trained in discriminations where S+ and S? shared common visual elements but were distinguished by the presence or absence of a visual feature. When S+ contained the distinctive feature (the feature-positive condition), the pigeons rapidly learned to withold responses to S?: The learning rate was not markedly affected by changes in the relative size of the feature and the common element. When S? contained the distinctive feature (the feature-negative condition), the pigeons learned to withhold responses to S? more rapidly when the feature was large relative to the common element than when the feature was small relative to the common element. This effect was observed when the stimuli were present at the locus of response and when the stimuli were remote from the locus of response. To explain these results, and the results of generalization tests, it was proposed that the effectiveness of the feature in suppressing responding to the common element during feature-negative training depended on the relative size of the feature and the common element.     

The ameliorating effect of oroxylin A on scopolamine-induced memory impairment in mice

Oroxylin A is a flavonoid and was originally isolated from the root of Scutellaria baicalensis Georgi., one of the most important medicinal herbs in traditional Chinese medicine. The aim of this study was to investigate the ameliorating effects of oroxylin A on memory impairment using the passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by administering scopolamine (1 mg/kg, i.p.) or diazepam (1 mg/kg, i.p.). Oroxylin A (5 mg/kg) significantly reversed cognitive impairments in mice by passive avoidance and the Y-maze testing (P<.05). Oroxylin A also improved escape latencies in training trials and increased swimming times and distances within the target zone of the Morris water maze (P<.05). Moreover, the ameliorating effects of oroxylin A were antagonized by both muscimol and diazepam (0.25 mg/kg, i.p., respectively), which are GABA(A) receptor agonists. Furthermore, oroxylin A (100 microM) was found to inhibit GABA-induced inward Cl(-) current in a single cortical neuron. These results suggest that oroxylin A may be useful for the treatment of cognitive impairments induced by cholinergic dysfunction via the GABAergic nervous system.     

Processing the intensity of dichotic syllables

Subjects were required to match the intensity levels of the left- and right-ear members of dichotically presented nonsense syllables. When subjects matched the overall average intensities of a sequence of differing dichotic pairs no ear differences were observed. When repetitions of single dichotic pairs were matched right-ear syllables were judged louder than left-ear syllables. The results support a model predicting left-hemisphere superiority in a task permitting higher-level encoding of speech input.