Depotentiation of vdccLTP Requires NMDAR Activation

Long-term potentiation is an enduring increase in synaptic efficacy following repeated stimulation of afferent fibers that is thought to underlie memory. In area CA1 of the hippocampus at least two forms of synaptic potentiation coexist at the same synapses; nmdaLTP and vdccLTP. NmdaLTP is induced by Ca2+ entry through NMDARs and is dependent on serine/threonine kinase activation, while vdccLTP is induced through Ca2+ entry through VDCCs and is dependent on tyrosine kinase activation. Depotentiation is a mechanism known to reverse nmdaLTP through phosphatase activation. The depotentiation of vdccLTP has not been previously investigated. We used hippocampal slices (area CA1) from male Long-Evans rats to induce vdccLTP with a 200-Hz tetanus in the presence of 50 microM APV. The 200-Hz tetanus resulted in a slowly developing vdccLTP that remained stable for at least 30 min. Thirty minutes after vdccLTP was induced, a low-frequency tetanus (3, 10, 20, 30, or 40 Hz) was applied in the presence of APV in an attempt to depotentiate vdccLTP. The 3- and 10-Hz low-frequency tetani resulted in no depotentiation. The 20- and 30-Hz tetani partially depotentiated vdccLTP (by approximately 13%), whereas the 40-Hz tetanus resulted in further potentiation. When APV was washed out prior to the 3-Hz low-frequency tetanus, the vdccLTP was completely depotentiated--presumably by NMDAR mechanisms. Our results indicate that vdccLTP is resistant to depotentiation under low-frequency stimulation conditions that readily depotentiate nmdaLTP. As tetanus frequencies are increased a small depotentiation is observed, suggesting that vdccLTP can be depotentiated to a small extent. When NMDARs are unblocked, vdccLTP can be completely depotentiated by a 3-Hz low-frequency tetanus, suggesting that vdccLTP can be depotentiated via activation of NMDAR mechanisms.     

Producing simple utterances: How far ahead do we plan?

The subjects were presented pictures depicting a man, woman, girl, or boy touching, kicking, greeting, or standing beside one of the others. The subjects, constrained to using only these names, produced utterances whose lengths and grammatical forms were prespecified. The latencies for subject-verb utterances (e.g., The man is greeting) were longer than for naming the actors (e.g., The man). However, the latencies for subject-verb utterances when the actor was already known were shorter than for naming the actions (e.g., Greeting). Together these results imply that some, but not all, verb selection is performed before subject-verb utterances are initiated. Three control experiments eliminated alternative interpretations. Finally, it was demonstrated that the same degree of advance planning occurs before the initiation of subject-verb-object utterances (e.g., The man is greeting the woman).     

Mismatching the opponent's offers in negotiation

Mismatching in negotiation involves responding with high demands to the opponent's low demands and with low demands to the opponent's high demands. Prior research has shown that the opponent's demands are often mismatched but that this effect is attenuated when information is available about the outcomes achieved by the opponent from the available alternatives. The present research showed that mismatching was also attenuated when the negotiator knew the location of the opponent's limit (the alternative beyond which the opponent would not concede). Two new interpretations of the attenuation effect were suggested on the basis of this finding. In addition, women were found to engage in more mismatching than men, being particularly likely to exploit a soft opponent.     

Contextual sensitivity in young children's drawings

Previous research has examined the characteristic errors made by young children when drawing from a three-dimensional array. The aim of the present research was to investigate the influence of context in copying tasks. In a series of three experiments children between the ages of 4 and 7 years were presented with contrasting models to copy. These included cups and sugar bowls in various combinations and orientations. In each experiment the children's copies were scored for inclusion or omission of the occluded handle on the model. The results showed that nearly one third of the children did not respond consistently by either copying accurately or by always including the occluded handle. Instead the findings pointed to a large group of children whose responses were directed by the type of context present within the arrays.     

The interaction of cognitive styles and classroom environment in determining first-graders' behavior

This study investigates the importance of two “person” variables, reflection impulsivity and divergent thinking, and one “situation” variable, the classroom climate of first-grade classrooms, for the classroom adaptation of first-graders. Three types of classrooms differing in classroom climate were selected: open, intermediate, and traditional. Subjects were the children (n = 189) in these classrooms. Classroom adaptation variables included self concept, school attendance, and teacher ratings of classroom behavior, overall academic rank, and personal preference. Both main effect and interactional relationships between “person” and “situation” variables and classroom adaptation were hypothesized. Classroom environment was found to affect degree of classroom disturbance manifested by the children with students in open classrooms exhibiting most and students in the intermediate classrooms exhibiting least. Boys in the open classrooms had higher achievement anxiety and lower teacher preference ratings than boys in traditional or intermediate classrooms. Reflective children obtained higher ratings as self-reliant learners and, for boys, reflection was related to low classroom disturbance and high achievement anxiety. Interactional relationships between classroom environment and reflection-impulsivity were also found for boys. Divergent thinking was not related to classroom adjustment for boys. Girls high in divergent thinking were higher in school involvement and achievement anxiety and more preferred by teachers.     

Language and speech recovery in a case of viral encephalitis

The speech and language recovery course of a 47-year-old man with viral encephalitis is described. Over a 3-month period, the patient was evaluated six times using the same selected battery of tests. Results show that viral encephalitis can deleteriously affect communicative performance and that improvement in medical status is accompanied by rapid and dramatic gains on most standard speech and language measures. For this case changes appeared related to improved auditory attention and retention, increased efficiency in word retrieval, and improved mental status.     

Dimensional separability or flexibility of attention? Age trends in perceiving configural stimuli

The hypothesis that perceptual development proceeds from less to greater dimensional separability was tested by giving a speeded classification task to first and fouth graders. In Experiment 1, children sorted line drawings of a cartoon figure into two piles according to his eyes (open or closed) or his mouth (smiling or frowning). First graders exhibited the pattern characteristic of integral dimensions: An interference effect was found when dimensions were combined orthogonally and a facilitation effect when dimensions were correlated, relative to a condition in which only one dimension varied. Fourth graders exhibited an optional separable pattern: There was facilitation in the correlated condition but no interference in the orthogonal condition. These results support the hypothesis that development proceeds toward greater flexibility of attention rather than simply toward increasing separability. A flexible field hypothesis of visual attention was suggested to explain how older children can exercise such optional separability. This hypothesis correctly predicted the asymmetrical relation between dimensions found in Experiments 2 and 3: For both first and fourth graders, the eyes of a cartoon figure (open or closed) and his location (right or left) were nonseparable when the eyes were relevant and separable (or optional separable) when location was relevant.     

Intellectual realism in children's drawings of cubes

Ninety-six children copied simple line drawings of perspective views of cubes and similar designs unlikely to be seen as representing objects. The views of cubes were copied much less accurately than the non-object patterns, and the errors made in copying the cubes involved replacement of properties specific to the single perspective view by properties more appropriate to the object itself. Some copies were drawn with the child continually looking at the model and unable to see his own copy, others were drawn in the normal way. Copies made in the former way were more accurate, but even under these conditions cubes were copied less accurately than the non-object patterns. The disadvantage of object pictures, as far as literal copying accuracy is concerned, was still present at 9 1/2 years of age, but was less than at 7 1/2. Two possible explanations are discussed. One is in terms of computational complexity, the other in terms of graphic motor schema. On the basis of the drawings obtained a few suggestions are made about the content and development of the data-structures for cubes.     

Auditory lateralization: An effect of rhythm

Recall of monaurally presented semantically anomalous sentences, which had either neutral or rhythmic timing, was tested at the right ear, at the left ear, and on transfer from one ear to the other. The component words, being computer stored digitized waveforms, had identical acoustic structure in the two conditions. In the rhythmic condition there was not only an overall advantage in the second half of the experiment but also an asymmetric transfer effect such that this advantage did not appear when the left ear was tested after the right. It is proposed that functional lateralization be viewed as an adaptive, dynamic, organizational factor.