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remote memory [keywords]
- Long-term mild-intensity exercise regimen preserves prefrontal cortical volume against aging. [JOURNAL ARTICLE]
- Int J Geriatr Psychiatry 2014 Oct 29.
It has been suggested that exercise improves cognitive function and increases cerebral volume even in older people. However, the relation between cognitive function and brain volume is unclear. We evaluated the longitudinal change of cognitive function and gray matter volume due to mild-intensity exercise over 2 years, and the residual effects 6 months post-exercise.Subjects were 110 healthy older individuals over 65 years old in Tone town, Ibaraki prefecture. Seventy-five participants were voluntarily enrolled in the exercise group. A mild-intensity calisthenics regimen, which consisted of home-based and club-based programs for as long as 2 years, was employed as the intervention for the exercise group.The exercise group showed significant improvement in attentional shift over the course of the observation period including a 6-month follow-up. Neuroimaging analysis revealed the significant preservation of bilateral prefrontal volume in the exercise group with small-volume corrections, although this effect faded after intervention. Furthermore, the longitudinal changes in attentional shift and memory were positively correlated with the prefrontal volumetric changes.Our results suggest that mild-intensity exercise could prevent prefrontal volume reduction due to aging and impede cognitive decline. Copyright © 2014 John Wiley & Sons, Ltd.
- Long-term memory in experiments and numerical simulations of hydrodynamic and magnetohydrodynamic turbulence. [JOURNAL ARTICLE]
- Phys Rev E Stat Nonlin Soft Matter Phys 2014 May; 89(5-1):053005.
We analyze time series stemming from experiments and direct numerical simulations of hydrodynamic and magnetohydrodynamic turbulence. Simulations are done in periodic boxes, but with a volumetric forcing chosen to mimic the geometry of the flow in the experiments, the von Kármán swirling flow between two counterrotating impellers. Parameters in the simulations are chosen to (within computational limitations) allow comparisons between the experiments and the numerical results. Conducting fluids are considered in all cases. Two different configurations are considered: a case with a weak externally imposed magnetic field and a case with self-sustained magnetic fields. Evidence of long-term memory and 1/f noise is observed in experiments and simulations, in the case with weak magnetic field associated with the hydrodynamic behavior of the shear layer in the von Kármán flow, and in the dynamo case associated with slow magnetohydrodynamic behavior of the large-scale magnetic field.
- 1/f. [JOURNAL ARTICLE]
- Phys Rev E Stat Nonlin Soft Matter Phys 2014 Feb; 89(2-1):022718.
Aquaporins (AQPs), which transport water molecules across cell membranes, are involved in many physiological processes. Recently, it is reported that the water-water interactions within the channel are broken at the aromatic/arginine selectivity filter (ar/R region), which prevents proton transportation [U. K. Eriksson et al., Science 340, 1346 (2013)]. However, the effects of the conformational fluctuations of amino acids on water transportation remain unclear. Using all-atom molecular dynamics simulations, we analyze water transportation and fluctuations of amino acids within AQP1. The amino acids exhibit 1/f fluctuations, indicating possession of long-term memory. Moreover, we find that water molecules crossing the ar/R region obey a non-Poisson process. To investigate the effect of 1/f fluctuations on water transportation, we perform restrained molecular dynamics simulations of AQP1 and simple Langevin stochastic simulations. As a result, we confirm that 1/f fluctuations of amino acids contribute to water transportation in AQP1. These findings appreciably enhance our understanding of AQPs and suggest possibilities for developing biomimetic nanopores.
- Word length effect in free recall of randomly assembled word lists. [Journal Article]
- Front Comput Neurosci 2014.:129.
In serial recall experiments, human subjects are requested to retrieve a list of words in the same order as they were presented. In a classical study, participants were reported to recall more words from study lists composed of short words compared to lists of long words, the word length effect. The world length effect was also observed in free recall experiments, where subjects can retrieve the words in any order. Here we analyzed a large dataset from free recall experiments of unrelated words, where short and long words were randomly mixed, and found a seemingly opposite effect: long words are recalled better than the short ones. We show that our recently proposed mechanism of associative retrieval can explain both these observations. Moreover, the direction of the effect depends solely on the way study lists are composed.
- Variations in the stimulus salience of cocaine reward influences drug-associated contextual memory. [JOURNAL ARTICLE]
- Addict Biol 2014 Oct 28.
Drugs of abuse act as reinforcers because they influence learning and memory processes resulting in long-term memory of drug reward. We have previously shown that mice conditioned by fixed daily dose of cocaine (Fix-C) or daily escalating doses of cocaine (Esc-C) resulted in short- and long-term persistence of drug memory, respectively, suggesting different mechanisms in acquisition of cocaine memory. The present study was undertaken to investigate the differential contribution of N-methyl-D-aspartate receptor (NMDAR) subunits in the formation of Fix-C and Esc-C memory in C57BL/6J mice. Training by Esc-C resulted in marked elevation in hippocampal expression of Grin2b mRNA and NR2B protein levels compared with training by Fix-C. The NR2B-containing NMDAR antagonist ifenprodil had similar attenuating effects on acquisition and reconsolidation of Fix-C and Esc-C memory. However, the NMDAR antagonist MK-801 had differential effects: (1) higher doses of MK-801 were required for post-retrieval disruption of reconsolidation of Esc-C memory than Fix-C memory; and (2) pre-retrieval MK-801 inhibited extinction of Fix-C memory but it had no effect on Esc-C memory. In addition, blockade of NMDAR downstream signaling pathways also showed differential regulation of Fix-C and Esc-C memory. Inhibition of neuronal nitric oxide synthase attenuated acquisition and disrupted reconsolidation of Fix-C but not Esc-C memory. In contrast, the mitogen-activating extracellular kinase inhibitor SL327 attenuated reconsolidation of Esc-C but not Fix-C memory. These results suggest that NMDAR downstream signaling molecules associated with consolidation and reconsolidation of cocaine-associated memory may vary upon changes in the salience of cocaine reward during conditioning.
- Garlic extract attenuates brain mitochondrial dysfunction and cognitive deficit in obese-insulin resistant rats. [JOURNAL ARTICLE]
- Appl Physiol Nutr Metab 2014 Oct 28.:1-7.
Oxidative stress in the obese-insulin resistant condition has been shown to affect cognitive as well as brain mitochondrial functions. Garlic extract has exerted a potent antioxidant effect. However, the effects of garlic extract on the brain of obese-insulin resistant rats have never been investigated. We hypothesized that garlic extract improves cognitive function and brain mitochondrial function in obese-insulin resistant rats induced by long-term high-fat diet (HFD) consumption. Male Wistar rats were fed either normal diet or HFD for 16 weeks (n = 24/group). At week 12, rats in each dietary group received either vehicle or garlic extract (250 and 500 mg·kg(-1)·day(-1)) for 28 days. Learning and memory behaviors, metabolic parameters, and brain mitochondrial function were determined at the end of treatment. HFD led to increased body weight, visceral fat, plasma insulin, cholesterol, and malondialdehyde (MDA) levels, indicating the development of insulin resistance. Furthermore, HFD rats had cognitive deficit and brain mitochondrial dysfunction. HFD rats treated with both doses of garlic extract had decreased body weight, visceral fat, plasma cholesterol, and MDA levels. Garlic extract also improved cognitive function and brain mitochondrial function, which were impaired in obese-insulin resistant rats caused by HFD consumption.
- Deployable, portable, and temporary hospitals; one state's experiences through the years. [Journal Article]
- Am J Disaster Med 2014; 9(3):195-210.
This article will review the use of temporary hospitals to augment the healthcare system as one solution for dealing with a surge of patients related to war, pandemic disease outbreaks, or natural disaster. The experiences highlighted in this article are those of North Carolina (NC) over the past 150 years, with a special focus on the need following the September 11, 2001 (9/11) attacks. It will also discuss the development of a temporary hospital system from concept to deployment, highlight recent developments, emphasize the need to learn from past experiences, and offer potential solutions for assuring program sustainability. Historically, when a particular situation called for a temporary hospital, one was created, but it was usually specific for the event and then dismantled. As with the case with many historical events, the details of the 9/11 attacks will fade into memory, and there is a concern that the impetus which created the current temporary hospital program may fade, as well. By developing a broader and more comprehensive approach to disaster responses through all-hazards preparedness, it is reasonable to learn from these past experiences, improve the understanding of current threats, and develop a long-term strategy to sustain these resources for future disaster medical needs.
- The Detrimental Effect of Interference in Multiplication Facts Storing: Typical Development and Individual Differences. [JOURNAL ARTICLE]
- J Exp Psychol Gen 2014 Oct 27.
The difficulty in memorizing arithmetic facts is a general and persistent hallmark of math learning disabilities. It has recently been suggested that hypersensitivity to interference could prevent a person from storing arithmetic facts. The similarity between arithmetic facts would provoke interference, and learners who are hypersensitive to interference would therefore encounter difficulties in storing arithmetic facts in long-term memory. In this study, we created a measure of the interference weight for each multiplication by measuring the overlap of digits between multiplications. First, we tested whether the interference parameter could predict performance across multiplications by analyzing the data from undergraduates published by Campbell (1997). The interference parameter substantially predicted performance across multiplications. Similarly, the performance across multiplications was substantially determined by the interference parameter in 3rd-grade children, 5th-grade children, and undergraduates we tested. Second, we tested whether people with poor arithmetic facts abilities were particularly sensitive to the interference parameter. We tested this hypothesis in typical development by analyzing the data from the 3rd-grade children, 5th-grade children, and undergraduates. We analyzed data with regard to atypical development from a published case study of dyscalculia as well as from 4th-grade children, with either poor or good multiplication skills, tested twice 1 year apart. Results showed that the individual sensitivity to the interference parameter determined part of the individual differences in multiplication performance in all data sets. These findings show that the learning of multiplications is particularly interference prone because of feature overlap and that people who are sensitive to this parameter therefore encounter difficulties in memorizing arithmetic facts. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
- Musical practice and cognitive aging: two cross-sectional studies point to phonemic fluency as a potential candidate for a use-dependent adaptation. [Journal Article]
- Front Aging Neurosci 2014.:227.
Because of permanent use-dependent brain plasticity, all lifelong individuals' experiences are believed to influence the cognitive aging quality. In older individuals, both former and current musical practices have been associated with better verbal skills, visual memory, processing speed, and planning function. This work sought for an interaction between musical practice and cognitive aging by comparing musician and non-musician individuals for two lifetime periods (middle and late adulthood). Long-term memory, auditory-verbal short-term memory, processing speed, non-verbal reasoning, and verbal fluencies were assessed. In Study 1, measures of processing speed and auditory-verbal short-term memory were significantly better performed by musicians compared with controls, but both groups displayed the same age-related differences. For verbal fluencies, musicians scored higher than controls and displayed different age effects. In Study 2, we found that lifetime period at training onset (childhood vs. adulthood) was associated with phonemic, but not semantic, fluency performances (musicians who had started to practice in adulthood did not perform better on phonemic fluency than non-musicians). Current frequency of training did not account for musicians' scores on either of these two measures. These patterns of results are discussed by setting the hypothesis of a transformative effect of musical practice against a non-causal explanation.
- Long-Term Potentiation at Spinal C-Fiber Synapses: a Target for Pathological Pain. [JOURNAL ARTICLE]
- Curr Pharm Des 2014 Oct 27.
Long-term potentiation (LTP), referring to a lasting increase in efficacy of synaptic transmission, is a common mechanism of memory storage in central nervous system (CNS). LTP at C-fiber synapses in spinal dorsal horn is considered as a synaptic model of pathological pain, as the spinal LTP is only induced by noxious electrical and natural stimuli but not by innoxious ones and LTP-inducible stimulation is capable of leading to lasting behavioral signs of pathological pain in human and in animals. The molecular mechanisms of spinal LTP at C-fiber synapses are similar to hippocampal LTP in following aspects. Induction of LTP depends on postsynaptic Ca2+ rise resulting from opening of N-methyl-D-aspartate channels (NMDA) and voltage-gated calcium channels (VGCCs), and Ca2+ release from intracellular store; Early-phase LTP (<3h) needs activation of intracellular protein kinase A (PKA), protein kinase C (PKC), calcium/calmodulin-dependent protein kinase II (CaMKII), phospholipase C (PLC) and release of nitric oxide (NO); Late-phase LTP (>3h) is dependent on de novo protein synthesis; Activation of either dopamine D1 receptors or PKA, and extrogenous brain-derived neurotrophic factor (BDNF) or ATP directly induces late-phase LTP. Therefore, the drugs targeting at the above molecules may impair memory function of hippocampus. The striking difference between hippocampal LTP and spinal LTP at C-fiber synapses is that activation of glial cells and the over-expression of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-beta (IL-1β), inhibit LTP in hippocampus, but promote LTP in spinal dorsal horn. The drugs targeting at the neuroinflammatory process may not only attenuate pathological pain but also improve memory in hippocampus.