The extracellular protease matrix metalloproteinase-9 is activated by inhibitory avoidance learning and required for long-term memory

Matrix metalloproteinases (MMPs) are a family of extracellularly acting proteolytic enzymes with well-recognized roles in plasticity and remodeling of synaptic circuits during brain development and following brain injury. However, it is now becoming increasingly apparent that MMPs also function in normal, nonpathological synaptic plasticity of the kind that may underlie learning and memory. Here, we extend this idea by investigating the role and regulation of MMP-9 in an inhibitory avoidance (IA) learning and memory task. We demonstrate that following IA training, protein levels and proteolytic activity of MMP-9 become elevated in hippocampus by 6 h, peak at 12-24 h, then decline to baseline values by approximately 72 h. When MMP function is abrogated by intrahippocampal infusion of a potent gelatinase (MMP-2 and MMP-9) inhibitor 3.5 h following IA training, a time prior to the onset of training-induced elevation in levels, IA memory retention is significantly diminished when tested 1-3 d later. Animals impaired at 3 d exhibit robust IA memory when retrained, suggesting that such impairment is not likely attributed to toxic or other deleterious effects that permanently disrupt hippocampal function. In anesthetized adult rats, the effective distance over which synaptic plasticity is impaired by a single intrahippocampal infusion of the MMP inhibitor of the kind that blocks IA memory is approximately 1200 microm. Taken together, these data suggest that IA training induces a slowly emerging, but subsequently protracted period of MMP-mediated proteolysis critical for enabling long-lasting synaptic modification that underlies long-term memory consolidation.     

Scientists Admitting to Plagiarism: A Meta-analysis of Surveys

We conducted a systematic review and meta-analysis of anonymous surveys asking scientists whether they ever committed various forms of plagiarism. From May to December 2011 we searched 35 bibliographic databases, five grey literature databases and hand searched nine journals for potentially relevant studies. We included surveys that asked scientists if, in a given recall period, they had committed or knew of a colleague who committed plagiarism, and from each survey extracted the proportion of those who reported at least one case. Studies that focused on academic (i.e. student) plagiarism were excluded. Literature searches returned 12,460 titles from which 17 relevant survey studies were identified. Meta-analysis of studies reporting committed (N = 7) and witnessed (N = 11) plagiarism yielded a pooled estimate of, respectively, 1.7 % (95 % CI 1.2–2.4) and 30 % (95 % CI 17–46). Basic methodological factors, including sample size, year of survey, delivery method and whether survey questions were explicit rather than indirect made a significant difference on survey results. Even after controlling for these methodological factors, between-study differences in admission rates were significantly above those expected by sampling error alone and remained largely unexplained. Despite several limitations of the data and of this meta-analysis, we draw three robust conclusions: (1) The rate at which scientists report knowing a colleague who committed plagiarism is higher than for data fabrication and falsification; (2) The rate at which scientists report knowing a colleague who committed plagiarism is correlated to that of fabrication and falsification; (3) The rate at which scientists admit having committed either form of misconduct (i.e. fabrication, falsification and plagiarism) in surveys has declined over time.     

Are perfectionism dimensions risk factors for anxiety symptoms? A meta-analysis of 11 longitudinal studies

Background: Over 50 years of theory and research implicates perfectionism in anxiety. However, it is unclear which (if any) perfectionism dimensions are risk factors for anxiety.

Objective: To address this, we conducted a meta-analysis testing whether socially prescribed perfectionism, concern over mistakes, doubts about actions, self-oriented perfectionism, and personal standards predict increases in anxiety.

Method: Our literature search yielded 11 relevant studies for inclusion, composed of children, adolescents, undergraduates, community adults, and psychiatric patients.

Results: Meta-analysis using random-effects models revealed concern over mistakes (r^+?=?.11), doubts about actions (r^+?=?.13), and personal standards (r^+?=?.08), but not socially prescribed perfectionism or self-oriented perfectionism, displayed significant small positive relationships with follow-up anxiety, after controlling for baseline anxiety.

Conclusion: Research is needed to understand the conditions under which the connection between perfectionism and anxiety becomes stronger (e.g., stress).     

How to do Better N400 Studies: Reproducibility,Consistency and Adherence to Research Standards in the Existing Literature

Neuropsychology Review - Given the complexity of ERP recording and processing pipeline, the resulting variability of methodological options, and the potential for these decisions to influence study...