Coordinate high-frequency pattern of stimulation and calcium levels control the induction of LTP in striatal cholinergic interneurons

Current evidence appoints a central role to cholinergic interneurons in modulating striatal function. Recently, a long-term potentiation (LTP) of synaptic transmission has been reported to occur in these neurons. The relationship between the pattern of cortico/thalamostriatal fibers stimulation, the consequent changes in the intracellular calcium concentration ([Ca2+]i), and the induction of synaptic plasticity was investigated in striatal cholinergic interneurons from a rat corticostriatal slice preparation by means of combined electrophysiological intracellular recordings and microfluorometric techniques. Different protocols of stimulation were considered, varying both the frequency and the duration of the train of stimuli. High-frequency stimulation (HFS) (three trains at 100 Hz for 3 sec, 20-sec interval) induced a rise in [Ca2+]i, exceeding by fivefold the resting level, and caused a LTP of synaptic transmission. Tetanic stimulation delivered at lower frequencies (5-30 Hz) failed to induce long-term changes of synaptic efficacy. The observed elevation in [Ca2+]i during HFS was primarily mediated by L-type high-voltage activated (HVA)-Ca2+ channels, as it was fully prevented by nifedipine. Conversely, blockade of NMDA and AMPA glutamate receptor did not affect either LTP or the magnitude of the [Ca2+]i rise. Interestingly, the pharmacological analysis of the post-tetanic depolarizing postsynaptic potential (DPSP) revealed that LTP was attributable, to a large extent, to the potentiation of the GABA(A)-mediated component. In conclusion, the expression of LTP in striatal cholinergic interneurons is a selective response to a precise stimulation pattern of induction requiring a critical rise in [Ca2+]i.     

Leptin functioning in eating disorders

Leptin is an adipocyte-derived hormone, which is involved predominantly in the long-term regulation of body weight and energy balance by acting as a hunger suppressant signal to the brain. Leptin is also involved in the modulation of reproduction, immune function, physical activity, and some endogenous endocrine axes. Since anorexia nervosa (AN) and bulimia nervosa (BN) are characterized by abnormal eating behaviors, dysregulation of endogenous endocrine axes, alterations of reproductive and immune functions, and increased physical activity, extensive research has been carried out in the last decade in order to ascertain a role of this hormone in the pathophysiology of these syndromes. In this article, we review the available data on leptin physiology in patients with eating disorders. These data support the idea that leptin is not directly involved in the etiology of AN or BN. However, malnutrition-induced alterations in its physiology may contribute to the genesis and/or the maintenance of some clinical manifestations of AN and BN and may have an impact on the prognosis of AN.     

Autocracy bias in informal groups under need for closure

Two experiments investigated the tendency of groups with members under high (vs. low) need for cognitive closure to develop an autocratic leadership structure in which some members dominate the discussion, constitute the "hubs" of communication, and influence the group more than other members. The first experiment found that high (vs. low) need for closure groups, as assessed via dispositional measure of the need for closure, manifested greater asymmetry of conversational floor control, such that members with autocratic interactional style were more conversationally dominant and influential than less autocratic members. The second experiment manipulated the need for closure via time pressure and utilized a social network analysis. Consistent with expectation, groups under time pressure (vs. no pressure) showed a greater asymmetry of participation, of centrality, and of prestige among the group members, such that the more focal members were perceived to exert the greater influence over the groups' decisions.     

Psychache and suicidality in adult mood disordered outpatients in Brazil

Shneidman (e.g., 1998) has theorized that psychache--general psychological and emotional pain that reaches intolerable intensity--is an important suicide-related variable, and indeed, represents a source of suicidal behavior. This conceptualization, while prominent and clinically and intuitively appealing, has received relatively little empirical scrutiny. In this study, we determined whether an index closely related to psychache, psychological quality of life, would display a special and resilient association to suicidality among 60 adult psychiatric outpatients in Brazil. All patients underwent structured clinical interviews and completed various clinical and quality-of-life measures. We found that the association between psychological quality of life and suicidality remained, even when depression, hopelessness, and other domains of quality of life were controlled. Psychache appears to deserve its place among key suicide-related variables, and deserves the attention of clinicians working with suicidal people.     

Neuropsychological Evaluation of Everyday Memory

The evaluation of everyday memory (EM) was reviewed and reconceptualized. EM has established new objectives of study and the development of new methods to reach these objectives . At the basic level, this approach has already produced important discoveries and the development of new principles about memory and functioning. At the clinical level, this new area of investigation has resulted in evaluating deficits of EM, which is defined as what daily life functions remain impaired after a deficit pathology has occurred. A type of evaluation has evolved that is oriented toward treatment and extremely useful in designing rehabilitation programs for individuals with alterations in memory.     

Ethnic Minority Psychologists: Whom They Mentor and Benefits They Derive From the Process

Ethnic minority psychologists were found to be prolific mentors of both ethnic minority and European American protégés. Mentoring benefits were not related to ethnic similarity.     

Some further tests of the brief confinement effect and the SSDR account of flooding

Although brief confinement in novel or fearful places may occasionally produce flooding-like effects with regard to hastening avoidance response extinction, the results of the three experiments reported here indicate that this is not as robust a phenomenon as is flooding. Experiments 1 and 2 found that any tendency for a brief confinement effect to occur is likely to result from the use of a procedure where extinction is started on the grid floor as opposed to on the ledge of a jump-up box. Experiment 3 found no evidence at all that confinement in either a novel or a fearful place can hasten the extinction of a more well-learned jump-up response than that studied in previous experiments, even when the grids extinction procedure was used. Overall these results do not support the SSDR account of flooding, which has derived its chief support from experiments demonstrating a brief confinement effect.     

Recognition memory in mentally retarded persons

The continuous recognition memory of retarded and normal subjects was assessed. The stimuli were magazine pictures, arranged so that lags of up to 250 pictures occured. The overall performance of the retarded subjects was poorer, in terms of hit rate or d′. However, the differences were present at 0 lag and the slopes of the forgetting curves were similar in both groups. It was concluded that differences between these subjects were due to a perception related process and not to memory.     

One-year prediction of cognitive decline following cognitive-stimulation from real-world data

Clinical evidence based on real-world data (RWD) is accumulating exponentially providing larger sample sizes available, which demand novel methods to deal with the enhanced heterogeneity of the data. Here, we used RWD to assess the prediction of cognitive decline in a large heterogeneous sample of participants being enrolled with cognitive stimulation, a phenomenon that is of great interest to clinicians but that is riddled with difficulties and limitations. More precisely, from a multitude of neuropsychological Training Materials (TMs), we asked whether was possible to accurately predict an individual's cognitive decline one year after being tested. In particular, we performed longitudinal modelling of the scores obtained from 215 different tests, grouped into 29 cognitive domains, a total of 124,610 instances from 7902 participants (40% male, 46% female, 14% not indicated), each performing an average of 16 tests. Employing a machine learning approach based on ROC analysis and cross-validation techniques to overcome overfitting, we show that different TMs belonging to several cognitive domains can accurately predict cognitive decline, while other domains perform poorly, suggesting that the ability to predict decline one year later is not specific to any particular domain, but is rather widely distributed across domains. Moreover, when addressing the same problem between individuals with a common diagnosed label, we found that some domains had more accurate classification for conditions such as Parkinson's disease and Down syndrome, whereas they are less accurate for Alzheimer's disease or multiple sclerosis. Future research should combine similar approaches to ours with standard neuropsychological measurements to enhance interpretability and the possibility of generalizing across different cohorts.     

Is There A Simple,Pedestrian Arithmetic Sentence Which Is Independent Of Zfc?

We show that the P < NP conjecture can beformulated as a Pi₂ ⁰ sentence, and explore some of theconsequences of that fact. This paper summarizes recent workby the author with N. C. A. da Costa on the P相似文献