Induction and activity-dependent reversal of persistent LTP and LTD in lateral perforant path synapses in vivo

The reversibility of long-term potentiation (LTP) and heterosynaptic long-term depression (LTD) lasting weeks was examined in the lateral perforant path of freely moving adult Sprague-Dawley rats. LTP lasting weeks was rapidly reversed within minutes by high-frequency heterosynaptic stimulation of the medial perforant path, in an N-methyl-D-aspartate receptor-dependent manner. LTP reversal also occurred, albeit more slowly and to a lesser extent, when animals were given 1-3 weeks of overnight exposure to an enriched environment (EE). LTD likewise was reversed upon repeated EE exposure. A covert similarity between the degrees of LTP and LTD reversal was revealed when the small potentiation effect of EE treatment by itself on lateral path responses was taken into account. Despite its ability to reverse previously acquired synaptic plasticity, two weeks of EE treatment had no effect on animals' retention of the platform location in a spatial watermaze task, although it did facilitate new learning. These data are in agreement with the hypothesis that hippocampal synapses retain the capacity for rapid synaptic change even when otherwise relatively stable plasticity has previously been induced. Slow reversal of such plasticity did not correlate with a loss of memory retention, possibly because either slow changes permit reorganization of representations such that both old and new information can be accommodated, or else the new information is synaptically represented in orthogonal fashion to the old information.     

The Legacy of Adolf Meyer''s Comparative Approach: Worcester Rats and the Strange Birth of the Animal Model

The breeding of albino rats had an enormous impact on experimental psychology in the twentieth century. Rats were, and for many questions still remain, the "standard animal" for laboratory research in neurology, psychology, and physiology. Albert Meyer was one of the figures most responsible for developing the albino rat as an experimental model. Despite Meyer's pioneering work with albino rats, his rat research has received only sparse attention. Little is known about the way in which the animal served Meyer's more famous psychiatric program. In this article, the author discusses the role that albino rats played in Meyer's animal research. He then turn to the contrast between the way in which Meyer viewed the animal's role in research and the way rats were later used as a laboratory "standard" to assure scientific generality. This comparison highlights the changes that occurred in comparative psychology in the twentieth century, and it further clarifies some of the concerns associated with the use of animal models today.     

What language shall I borrow? The poetry of Rainer Maria Rilke and the care of souls

This article suggests that the reality of the world is socially constructed through the words and narratives chosen and used. These social constructions may be from science and technology, business and economics, or poetry and metaphors, and as such each shapes a different world. The work of the poet Rainer Maria Rilke is used to illustrate how the power of words and images shape and form the world. The implications of the use of language for the care of souls are discussed.     

Episodic and semantic components of the compound-stimulus strategy in the explicit task-cuing procedure

The explicit task-cuing procedure is commonly used to study executive control processes involved in set switching, but performance in this task-switching procedure may be accomplished without switching tasks. Subjects may perform both tasks by using a compound-stimulus strategy, in which subjects encode the cue, encode the target, and use the combination as a compound retrieval cue to choose the appropriate response. We manipulated the number of targets (8, 16,32, or 640) that subjects experienced in a four-cue/two-task procedure to separate episodic and semantic memory retrieval components of the compound-stimulus strategy. Cue repetitions were faster than task repetitions, and task repetitions were only slightly faster than task alternations, suggesting that cue repetition effects account for the bulk of the difference between repetitions and alternations. We found the same effects with all target set sizes. The results are consistent with use of a semantic compound-stimulus strategy.     

The cost of a voluntary task switch

Task-switching paradigms are widely used to study executive control. However, standard paradigms may not require active control to switch tasks. We examined voluntary task switching by having subjects choose which task to perform on a series of bivalent stimuli. Subjects performed parity or magnitude judgments on single digits. Instructions were to perform the two tasks equally often and in a random order. The response-to-stimulus interval (RSI) was either 100 or 1,000 ms, manipulated between blocks. Task alternations were slower than task repetitions, and this switch cost was greater at the short RSI than at the long RSI (310 and 94 ms, respectively). Additionally, subjects produced more task repetitions than expected if the tasks were performed in a random sequence. These results show costs associated with a voluntary task switch, when subjects must actively control the choice of the task to be performed.     

Evidence for an Error Monitoring Deficit in Attention Deficit Hyperactivity Disorder

We studied error monitoring in ADHD and control children in a task requiring inhibition of a motor response. The extent of slowing following successful (stopped) and failed (nonstopped) inhibition was compared across groups. We also measured the time required to inhibit a response (stop signal reaction time, SSRT). Compared to controls, ADHD participants slowed less following nonstopped responses. Slowing did not vary with comorbid reading, oppositional, conduct or anxiety disorder, sex or ADHD subtype. Slowing after nonstopped responses was marginally, although significantly correlated with total ADHD symptoms and with age. ADHD participants had significantly longer SSRT than controls, but SSRT was not significantly correlated with slowing. The apparent deficit in error monitoring in ADHD and its independence from the inhibition deficit observed in ADHD has implications for executive control models of ADHD, performance problems associated with the disorder and for component theories of executive control.     

Moderators of the Relation Between Popularity and Depressive Symptoms in Children: Processing Strength and Friendship Value

Children with low (n = 25) and high (n = 38) peer-rated popularity completed an emotional Stroop task, using negative social words, a self-report measure of friendship value relative to other domains of competence, and the Child Depression Inventory (CDI). Six months later, they completed the CDI again. In regression analyses, after controlling for prior CDI scores, social status interacted significantly with both Stroop and value measures (separate regressions). For unpopular children, both greater friendship valuing and greater negative social word Stroop interference predicted increases in depressive symptoms. In contrast, neither predictor was significant for popular children. In a third regression that included friendship value and Stroop interference as joint predictors of depression change, their effects remained significant and independent. We discuss these findings' implications for 3 models of depression; Champion and Power's social-cognitive theory of depression (L. A. Champion and M. J. Power, 1995), Pyszczynski and Greenberg's self-regulatory perseveration theory of depression (T. Pyszczynski & J. Greenberg, 1992), and Harter's model of global self-worth (S. Harter, 1985).     

Effects of Paired and Unpaired Eye-Blink Conditioning on Purkinje Cell Morphology

This experiment addressed (1) the importance of conjunctive stimulus presentation for morphological plasticity of cerebellar Purkinje cells and inhibitory interneurons and (2) whether plasticity is restricted to the spiny branches of Purkinje cells, which receive parallel fiber input. These issues were investigated in naive rabbits and in rabbits that received paired or unpaired presentations of the conditioned stimulus (CS) and unconditioned stimulus (US). To direct CS input to the cerebellar cortex, pontine stimulation served as the CS. Air puffs to the cornea served as the US. Paired condition rabbits received pontine stimulation for 350 msec paired with a coterminating 100-msec air puff. Unpaired condition rabbits received the same stimuli in a pseudorandom order at 1- to 32-sec intervals. Rabbits were trained for a mean of 12 days. Naive rabbits received no treatment. In Golgi-stained Purkinje neurons in lobule HVI, total dendritic length, main branch length, total spiny branch length, and number of spiny branch arbors were all greater in the naive group than in the paired and unpaired groups, which did not differ. No differences were found between the hemispheres ipsilateral and contralateral to the trained eye. The dendritic length and number of branches for inhibitory interneurons did not differ across groups. The Purkinje cell morphological changes detected with these methods do not appear to be uniquely related to the conjunctive activation of the CS and US in the paired condition.     

成人日常问题解决的老化研究

日常问题解决能力是近十几年来老年心理学中研究比较活跃的一个领域。本文介绍了有关日常问题解决研究的四种理论,即心理测量的智力内隐理论、形式后思维的辨证思维理论、信息加工理论和社会认知与智慧理论,及其初步的研究成果,并进一步指出在理论上整合和在实践中开展干预的研究方向。     

When it helps to be misled: Facilitative effects of increasing the frequency of conflicting stimuli in a Stroop-like task

Three experiments are reported that involve responding to the meaning or position of a word (Above or Below) presented above or below a fixation point. Position and word meaning conflicted (Above/below or Below/above) or were compatible (Above/above or Below/below), and the relative frequency of conflicting trials was varied. Experiment 1 required responses to the word and its position. Compatibility and frequency had no effect in the spatial task, but interacted strongly in the word task: Compatible stimuli were processed faster when conflicting trials were rare (20% conflicting), but conflicting stimuli were processed faster when they were frequent (80% conflicting). Experiments 2 and 3 used the word task only and extended these findings to intermediate (20%, 40%, 60%, and 80% conflicting) and more extreme (10%, 20%, 80%, and 90% conflicting) frequencies, respectively. The advantage for conflicting stimuli when they were frequent was taken as evidence for a strategy involving dividing attention between reported and unreported dimensions.