Bidirectional control of social hierarchy by synaptic efficacy in medial prefrontal cortex

Dominance hierarchy has a profound impact on animals' survival, health, and reproductive success, but its neural circuit mechanism is virtually unknown. We found that dominance ranking in mice is transitive, relatively stable, and highly correlates among multiple behavior measures. Recording from layer V pyramidal neurons of the medial prefrontal cortex (mPFC) showed higher strength of excitatory synaptic inputs in mice with higher ranking, as compared with their subordinate cage mates. Furthermore, molecular manipulations that resulted in an increase and decrease in the synaptic efficacy in dorsal mPFC neurons caused an upward and downward movement in the social rank, respectively. These results provide direct evidence for mPFC's involvement in social hierarchy and suggest that social rank is plastic and can be tuned by altering synaptic strength in mPFC pyramidal cells.     

The architecture of cognitive control in the human prefrontal cortex

The prefrontal cortex (PFC) subserves cognitive control: the ability to coordinate thoughts or actions in relation with internal goals. Its functional architecture, however, remains poorly understood. Using brain imaging in humans, we showed that the lateral PFC is organized as a cascade of executive processes from premotor to anterior PFC regions that control behavior according to stimuli, the present perceptual context, and the temporal episode in which stimuli occur, respectively. The results support an unified modular model of cognitive control that describes the overall functional organization of the human lateral PFC and has basic methodological and theoretical implications.     

Mnemonic function of the dorsolateral prefrontal cortex in conflict-induced behavioral adjustment

Our cognitive abilities in performing tasks are influenced by experienced competition/conflict between behavioral choices. To determine the role of the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) in the conflict detection-resolution process, we conducted complementary lesion and single-cell recording studies in monkeys that were resolving a conflict between two rules. We observed conflict-induced behavioral adjustment that persisted after lesions within the ACC but disappeared after lesions within the DLPFC. In the DLPFC, activity was modulated in some cells by the current conflict level and in other cells by the conflict experienced in the previous trial. These results show that the DLPFC, but not the ACC, is essential for the conflict-induced behavioral adjustment and suggest that encoding and maintenance of information about experienced conflict is mediated by the DLPFC.     

Selective attention from voluntary control of neurons in prefrontal cortex

Animals can learn to voluntarily control neuronal activity within various brain areas through operant conditioning, but the relevance of that control to cognitive functions is unknown. We found that rhesus monkeys can control the activity of neurons within the frontal eye field (FEF), an oculomotor area of the prefrontal cortex. However, operantly driven FEF activity was primarily associated with selective visual attention, and not oculomotor preparation. Attentional effects were untrained and were observed both behaviorally and neurophysiologically. Furthermore, selective attention correlated with voluntary, but not spontaneous, fluctuations in FEF activity. Our results reveal a specific association of voluntarily driven neuronal activity with "top-down" attention and suggest a basis for the use of neurofeedback training to treat disorders of attention.     

Recovery of function after serial ablation of prefrontal cortex in the rhesus monkey

Rhesus monkeys with one-stage or serial ablation of sulcus principalis (prefrontal association cortex) were compared on three spatial tasks. On all tests, the serial monkeys made fewer errors than did the monkeys with onestage lesions. These results indicate that partial recovery of function can occur after extensive destruction of association cortex in the mature primate brain if the damage is distributed over a number of operations.     

Dissociating the role of the dorsolateral prefrontal and anterior cingulate cortex in cognitive control

Theories of the regulation of cognition suggest a system with two necessary components: one to implement control and another to monitor performance and signal when adjustments in control are needed. Event-related functional magnetic resonance imaging and a task-switching version of the Stroop task were used to examine whether these components of cognitive control have distinct neural bases in the human brain. A double dissociation was found. During task preparation, the left dorsolateral prefrontal cortex (Brodmann's area 9) was more active for color naming than for word reading, consistent with a role in the implementation of control. In contrast, the anterior cingulate cortex (Brodmann's areas 24 and 32) was more active when responding to incongruent stimuli, consistent with a role in performance monitoring.     

Fast-forward playback of recent memory sequences in prefrontal cortex during sleep

As previously shown in the hippocampus and other brain areas, patterns of firing-rate correlations between neurons in the rat medial prefrontal cortex during a repetitive sequence task were preserved during subsequent sleep, suggesting that waking patterns are reactivated. We found that, during sleep, reactivation of spatiotemporal patterns was coherent across the network and compressed in time by a factor of 6 to 7. Thus, when behavioral constraints are removed, the brain's intrinsic processing speed may be much faster than it is in real time. Given recent evidence implicating the medial prefrontal cortex in retrieval of long-term memories, the observed replay may play a role in the process of memory consolidation.     

D1 dopamine receptors in prefrontal cortex: involvement in working memory

The prefrontal cortex is involved in the cognitive process of working memory. Local injections of SCH23390 and SCH39166, selective antagonists of the D1 dopamine receptor, into the prefrontal cortex of rhesus monkeys induced errors and increased latency in performance on an oculomotor task that required memory-guided saccades. The deficit was dose-dependent and sensitive to the duration of the delay period. These D1 antagonists had no effect on performance in a control task requiring visually guided saccades, indicating that sensory and motor functions were unaltered. Thus, D1 dopamine receptors play a selective role in the mnemonic, predictive functions of the primate prefrontal cortex.     

Neurons in monkey prefrontal cortex that track past or predict future performance

Although frontal cortex is thought to be important in controlling behavior across long periods of time, most studies of this area concentrate on neuronal responses instantaneously relevant to the current task. In order to investigate the relationship of frontal activity to behavior over longer time periods, we trained rhesus monkeys on a difficult oculomotor task. Their performance fluctuated during the day, and the activity of prefrontal neurons, even measured while the monkeys waited for the targets to appear at the beginning of each set of trials, correlated with performance in a probabilistic rather than a determinist manner: neurons reflected past or predicted future performance, much more than they reflected current performance. We suggest that this activity is related to processes such as arousal or motivation that set the tone for behavior rather than controlling it on a millisecond basis, and could result from ascending pathways that utilize slow, second-messenger synaptic processes.     

Alpha 2-adrenergic mechanisms in prefrontal cortex associated with cognitive decline in aged nonhuman primates

This study provides evidence that the alpha 2-adrenergic receptor agonist clonidine ameliorates the cognitive deficits exhibited by aged nonhuman primates through drug actions at alpha 2 receptors. Furthermore, pharmacological profiles in animals with lesions restricted to the dorsolateral prefrontal cortex indicate that this area may be the site of action for some of clonidine's beneficial effects. These results demonstrate that alpha-adrenergic systems contribute to cognitive function and suggest a new strategy for treating memory disorders in aged humans.     

Motor control by sensory cortex

Classical studies of mammalian movement control define a prominent role for the primary motor cortex. Investigating the mouse whisker system, we found an additional and equally direct pathway for cortical motor control driven by the primary somatosensory cortex. Whereas activity in primary motor cortex directly evokes exploratory whisker protraction, primary somatosensory cortex directly drives whisker retraction, providing a rapid negative feedback signal for sensorimotor integration. Motor control by sensory cortex suggests the need to reevaluate the functional organization of cortical maps.     

信息公平与社会主义新农村信息化建设

农村信息化是新农村建设的重要内容,信息公平成为构建社会主义新农村的必然要求。笔者从城乡信息不公平的现状、形成的客观因素和带来的危害性出发,提出了消除城乡数字鸿沟,推进农村信息化的主要战略措施。     

经济学与肥料学中报酬递减律的同一性及其问题

肥料报酬递减律是施肥学上的经典理论,但其并非植根于肥料研究,而是移植于经济学。研究分析表明,肥料是经济学投入中重要的可变要素,施肥量和作物产量具有一一对应的函数关系,投资和劳动必须借助于影响产量增减变化的可变因素才能起作用。但由于时代的局限性,经济学未能深入研究施肥量与产量的函数关系,因此,经济学报酬递减律缺乏专业研究结果的支持。已有的研究结果证明,肥料报酬递减律是施肥理论和施肥试验方法不完善与计算失误下得出的结论,并非科学规律。     

黑龙江省香稻米品种稻花香2号香味减弱原因及对策

黑龙江省优质香米稻花香2号是该省粮食产业的知名名片,但是近年来出现香味减弱的情况,对其原因进行深入研究,认为品种退化、生育期影响、环境因素影响、土壤肥力影响及晾晒时间过长是导致稻花香2号香味减弱的原因,并在此基础上提出避免香米香味减弱的对策。     

Anterior prefrontal function and the limits of human decision-making

The frontopolar cortex (FPC), the most anterior part of the frontal lobes, forms the apex of the executive system underlying decision-making. Here, we review empirical evidence showing that the FPC function enables contingent interposition of two concurrent behavioral plans or mental tasks according to respective reward expectations, overcoming the serial constraint that bears upon the control of task execution in the prefrontal cortex. This function is mechanistically explained by interactions between FPC and neighboring prefrontal regions. However, its capacity appears highly limited, which suggests that the FPC is efficient for protecting the execution of long-term mental plans from immediate environmental demands and for generating new, possibly more rewarding, behavioral or cognitive sequences, rather than for complex decision-making and reasoning.     

权利保障法中的请求权制度

请求权制度是民法的核心内容,请求权包括防御请求权、保全请求权和救济请求权。     

Spatial coordination of cytokinetic events by compartmentalization of the cell cortex

During cytokinesis, furrow ingression and plasma membrane fission irreversibly separate daughter cells. How actomyosin ring assembly and contraction, vesicle fusion, and abscission are spatially coordinated was unknown. We found that during cytokinesis septin rings, located on both sides of the actomyosin ring, acted as barriers to compartmentalize the cortex around the cleavage site. Compartmentalization maintained diffusible cortical factors, such as the exocyst and the polarizome, to the site of cleavage. In turn, such factors were required for actomyosin ring function and membrane abscission. Thus, a specialized cortical compartment ensures the spatial coordination of cytokinetic events.