Apraxia and Alzheimer’s Disease: Review and Perspectives

Apraxia is one of the cognitive deficits that characterizes Alzheimer\u27s disease. Despite its prevalence and relevance to diagnosing Alzheimer\u27s disease, this topic has received little attention and is without comprehensive review. The review herein is aimed to fill this gap by first presenting an overview of the impairment caused in different clinical situations: pantomime of tool use, single tool use, real tool use, mechanical problem solving, function and manipulation knowledge tasks, and symbolic/meaningless gestures. On the basis of these results, we then propose alternative interpretations regarding the nature of the underlying mechanisms impaired by the disease. Also presented are principal methodological issues precluding firm conclusions from being drawn

Effect of obesity on the expression of nutrient receptors and satiety hormones in the human colon

Background: Receptors located on enteroendocrine cells (EECs) of the colon can detect nutrients in the lumen. These receptors regulate appetite through a variety of mechanisms, including hormonal and neuronal signals. We assessed the effect of obesity on the expression of these G-protein coupled receptors (GPCRs) and hormones at both mRNA and protein level. Methods: qPCR and immunohistochemistry were used to examine colonic tissue from cohorts of patients from the Netherlands (proximal and sigmoid tissue) and the United Kingdom (tissue from across the colon) and patients were grouped by body mass index (BMI) value (BMI < 25 and BMI ≥ 25). Results: The mRNA expression of the hormones/signaling molecules serotonin, glucagon, peptide YY (PYY), CCK and somatostatin were not significantly different between BMI groups. GPR40 mRNA expression was significantly increased in sigmoid colon samples in the BMI ≥ 25 group, but not proximal colon. GPR41, GPR109a, GPR43, GPR120, GPRC6A, and CaSR mRNA expression were unaltered between low and high BMI. At the protein level, serotonin and PYY containing cell numbers were similar in high and low BMI groups. Enterochromaffin cells (EC) showed high degree of co-expression with amino acid sensing receptor, CaSR while co-expression with PYY containing L-cells was limited, regardless of BMI. Conclusions: While expression of medium/long chain fatty acid receptor GPR40 was increased in the sigmoid colon of the high BMI group, expression of other nutrient sensing GPCRs, and expression profiles of EECs involved in peripheral mechanisms of appetite regulation were unchanged. Collectively, these data suggest that in human colonic tissue, EEC and nutrient-sensing receptor expression profiles are not affected despite changes to BMI

Judging the impact of leadership-development activities on school practice

The nature and effectiveness of professional-development activities should be judged in a way that takes account of both the achievement of intended outcomes and the unintended consequences that may result. Our research project set out to create a robust approach that school staff members could use to assess the impact of professional-development programs on leadership and management practice without being constrained in this judgment by the stated aims of the program. In the process, we identified a number of factors and requirements relevant to a wider audience than that concerned with the development of leadership and management in England. Such an assessment has to rest upon a clear understanding of educational leadership,a clearly articulated model of practice, and a clear model of potential forms of impact. Such foundations, suitably adapted to the subject being addressed, are appropriate for assessing all teacher professional development

A cognitive-based model of tool use in normal aging: Which components are at work?

While several cognitive domains have been widely investigated in the field of aging, the age-related effects on tool use are still an open issue and hardly any studies on tool use and aging is available. A significant body of literature has indicated that tool use skills might be supported by at least two different types of knowledge, namely, mechanical knowledge and semantic knowledge. However, neither the contribution of these kinds of knowledge to familiar tool use, nor the effects of aging on mechanical and semantic knowledge have been explored in normal aging. The aim of the present study was to fill this gap. To do so, 98 healthy elderly adults were presented with three tasks: a classical, familiar tool use task, a novel tool use task assessing mechanical knowledge, and a picture matching task assessing semantic knowledge. The results showed that aging has a negative impact on tool use tasks and on knowledge supporting tool use skills. We also found that aging did not impact mechanical and semantic knowledge in the same way, confirming the distinct nature of those forms of knowledge. Finally, our results stressed that mechanical and semantic knowledge are both involved in the ability to use familiar tools

Mechanical problem-solving strategies in left-brain damaged patients and apraxia of tool use

Left brain damage (LBD) can impair the ability to use familiar tools (apraxia of tool use) as well as novel tools to solve mechanical problems. Thus far, the emphasis has been placed on quantitative analyses of patients’ performance. Nevertheless, the question still to be answered is, what are the strategies employed by those patients when confronted with tool use situations? To answer it, we asked 16 LBD patients and 43 healthy controls to solve mechanical problems by means of several potential tools. To specify the strategies, we recorded the time spent in performing four kinds of action (no manipulation, tool manipulation, box manipulation, and tool-box manipulation) as well as the number of relevant and irrelevant tools grasped. We compared LBD patients’ performance with that of controls who encountered difficulties with the task (controls−) or not (controls+). Our results indicated that LBD patients grasped a higher number of irrelevant tools than controls+ and controls−. Concerning time allocation, controls+ and controls− spent significantly more time in performing tool-box manipulation than LBD patients. These results are inconsistent with the possibility that LBD patients could engage in trial-and-error strategies and, rather, suggest that they tend to be perplexed. These findings seem to indicate that the inability to reason about the objects’ physical properties might prevent LBD patients from following any problem-solving strategy

Apraxie et maladie d’Alzheimer : revue et perspectives

Alzheimer’s disease is characterized by the progressive impairment of cognitive functions. Whereas the study of amnesia, aphasia, agnosia and dysexecutive impairments to a lesser extent has been well documented, apraxia has received little attention [1]. The aim of this review is to fill this gap by presenting an overview of the praxis impairment, which typically appears in the course of the disease. This review focuses on transitive gestures (i.e., tool use tasks) and intransitive gestures (i.e., symbolic and meaningless). On the basis of these results, we propose interpretations as to the nature of the underlying mechanisms impaired by the disease. Finally, we provide some answers to help clinicians to better understand and assess the apraxic disorders in Alzheimer’s disease

Bases neurocognitives de l’utilisation d’outils

L’utilisation d’outils est un trait définitoire de l’espèce humaine. En conséquence, la question des bases neurocognitives sous-tendant cette capacité devrait être au cœur des préoccupations des psychologues et des neuroscientifiques. Pourtant, depuis l’émergence de la psychologie scientifique à la fin du xxe siècle, cette question n’a reçu que peu d’intérêt. Une raison majeure à ce manque d’intérêt provient de la croyance que l’utilisation reposerait avant tout sur des connaissances sur la manipulation, comme si l’utilisation d’outils ne demandait pas de capacités intellectuelles ou de raisonnement, mais uniquement de savoir quel est le geste à réaliser avec un outil donné. Cette croyance a alimenté pendant plus d’un siècle, et alimente toujours, les principaux modèles des troubles d’utilisation d’outils dans le champ de la neuropsychologie. Cette mini-revue vise à présenter comment les avancées récentes en psychologie et en neurosciences cognitives ont contribué à réviser l’idée que la manipulation est centrale à l’utilisation d’outils, en proposant de nouveaux modèles théoriques basés sur l’hypothèse qu’utiliser un outil nécessite des capacités de raisonnement spécifique

Processing of functional fine scale ceramic structures by ink-jet printing

International audienceThis review illustrates the potentiality of ink-jet printing for the fabrication of functional fine scale ceramic structures corresponding to two different kinds of micro-pillar arrays i.e. (i) PZT skeletons, etc..

Ferroelectric and Incipient Ferroelectric Properties of a Novel Sr_(9-x)PbxCe2Ti2O36 (x=0-9) Ceramic System

Sr_(9-x)PbxCe2Ti12O36 system is derived from the perovskite SrTiO3 and its chemical formula can be written as (Sr_(1-y)Pby)0.75Ce0.167TiO3. We investigated dielectric response of Sr_(9-x)PbxCe2Ti12O36 ceramics (x = 0-9) between 100 Hz and 100 THz at temperatures from 10 to 700 K using low- and high-frequency dielectric, microwave (MW), THz and infrared spectroscopy. We revealed that Sr9Ce2Ti12O36 is an incipient ferroelectric with the R-3c trigonal structure whose relative permittivity e' increases from 167 at 300 K and saturates near 240 below 30 K. The subsequent substitution of Sr by Pb enhances e' to several thousands and induces a ferroelectric phase transition to monoclinic Cc phase for x>=3. Its critical temperature Tc linearly depends on the Pb concentration and reaches 550 K for x=9. The phase transition is of displacive type. The soft mode frequency follows the Barrett formula in samples with x=3. The MW dispersion is lacking and quality factor Q is high in samples with low Pb concentration, although the permittivity is very high in some cases. However, due to the lattice softening, the temperature coefficient of the permittivity is rather high. The best MW quality factor was observed for x=1: Q*f=5800 GHz and e'=250. Concluding, the dielectric properties of Sr_(9- x)PbxCe2Ti12O36 are similar to those of Ba_(1-x)SrxTiO3 so that this system can be presumably used as an alternative for MW devices or capacitors.Comment: subm. to Chem. Mate