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At least 37 records · Page 2Linked to original sources
PubMed2002

Forced swimming test and fluoxetine treatment: in vivo evidence that peripheral 5-HT in rat platelet-rich plasma mirrors cerebral extracellular 5-HT levels, whilst 5-HT in isolated platelets mirrors neuronal 5-HT changes.

Low levels of central serotonin (5-HT) have been related to the state of depression, and 5-HT is the major target of the newer antidepressant drugs such as selective serotonin reuptake inhibitors (SSRIs). Neurons and platelets display structural and functional similarities, so that the latter have been proposed as a peripheral model of central functions. In particular, in blood more than 99% of 5-HT is contained in platelets, so that one could consider changes in 5-HT levels in platelets as a mirror of changes in central 5-HT. Here, this hypothesis has been studied via the analysis of the influence of: (1) the forced swimming test (FST, which has been proved to be of utility to predict the clinical efficacy of antidepressants in rodents) and (2) treatment with the SSRI fluoxetine upon 5-HT levels monitored in brain regions and in peripheral platelets by means of electrochemical in vivo and ex vivo measurements. The results obtained confirm that the FST increases immobility; furthermore they show a parallel and significant decrease in cerebral (brain homogenate) and peripheral (in platelet-rich plasma, PRP) voltammetric 5-HT levels following the FST in naive rats. In addition, subchronic treatment with fluoxetine was followed by a significant increase in 5-HT levels in PRP, while the same SSRI treatment performed within the FST resulted in a decrease in the 5-HT levels in PRP. However, this decrease was inferior to that observed without SSRI treatment. These data suggest that there is an inverse relationship between immobility and the levels of 5-HT in PRP and that these peripheral 5-HT levels are sensitive to: (1) the FST, (2) the treatment with fluoxetine and (3) the combination of both treatments, i.e. SSRI + FST. It has been reported that SSRI treatment at first inhibits the 5-HT transporter in brain, resulting in increased extracellular 5-HT, while following sustained SSRI treatments decreased intracellular levels of central 5-HT were observed. Accordingly, the present data show that the initial block of 5-HT reuptake is revealed by the selective increase in 5-HT levels (extracellular content) measured in PRP (not in insulated platelets, IPs) the 1st day of fluoxetine treatment. The initial action of this SSRI upon the 5-HT transporter in brain has also been confirmed by in vivo voltammetric data showing selective increase in the serotonergic signal following local injection of fluoxetine into the brain region studied. Successively, the major effect monitored is a decrease in 5-HT levels, which is more evident in IPs than in PRP. However, it is known that following 2 weeks treatment with an SSRI, 5-HT autoreceptors are desensitized and the serotonin synthesis is restored, together with the intracellular 5-HT levels. The present data showing that the levels of 5-HT in IPs tend to return to control values 12 days after the beginning of chronic fluoxetine treatment suggest that 5-HT levels in IPs (intracellular environment) mirror the influence of SSRI treatment upon the central 5-HT system. On the other hand, at day 12 of the chronic fluoxetine treatment, 5-HT content remains low in PRP. Similarly, low levels of 5-HT have been monitored in brain homogenate of rats chronically treated with fluoxetine. This would support the similarity between PRP preparation and brain homogenate as in both cases cells are disrupted by sample preparation. In conclusion this work supports the literature in proposing platelets as a peripheral model of central functions. In particular, the present data support the idea that peripheral 5-HT platelet levels can reflect the state of the central 5-HT system in conditions of depression. Furthermore, the main outcome of this study is that PRP may mirror central extracellular 5-HT levels, whilst IPs mirror neuronal 5-HT changes.

Animals↗
PubMed2003

Speaking with a mirror: engagement of mirror neurons via choral speech and its derivatives induces stuttering inhibition.

'Choral speech', 'unison speech', or 'imitation speech' has long been known to immediately induce reflexive, spontaneous, and natural sounding fluency, even the most severe cases of stuttering. Unlike typical post-therapeutic speech, a hallmark characteristic of choral speech is the sense of 'invulnerability' to stuttering, regardless of phonetic context, situational environment, or audience size. We suggest that choral speech immediately inhibits stuttering by engaging mirror systems of neurons, innate primitive neuronal substrates that dominate the initial phases of language development due to their predisposition to reflexively imitate gestural action sequences in a fluent manner. Since mirror systems are primordial in nature, they take precedence over the much later developing stuttering pathology. We suggest that stuttering may best be ameliorated by reengaging mirror neurons via choral speech or one of its derivatives (using digital signal processing technology) to provide gestural mirrors, that are nature's way of immediately overriding the central stuttering block.

Humans↗
PubMed2002

Method for deriving the complete solution set for three-mirror anastigmatic telescopes with two spherical mirrors.

The "plate-diagram" method of quantifying and manipulating the Seidel aberrations of an optical system has been used to develop a procedure that has successfully determined the complete solution set of three-mirror anastigmats in which two surfaces are left strictly spherical. The procedure also readily identified solutions in which the Petzval sum is zero, and four distinct families of flat-field three-mirror anastigmats with two mirrors strictly spherical have thus been found. The success of the method is strong support for the argument that algebraic approaches to optical design can yield results distinctly superior to currently favored optimization-based design methods, at least for some types of optical systems.

Journal Article↗
PubMed1997

Neglect: mirror, mirror, on the wall--is the left side there at all?

Visuo-spatial neglect has long been thought of as a disorder of attention, but a recent experiment shows that, when images from the left side are reflected by a mirror into the 'good' hemispace, neglect patients behave as if the object were behind, or in, the mirror - as if the left side of their world did not 'exist'.

Attention↗
PubMed1996

"Mirror, mirror on the wall, who...?": towards a model of visual self-recognition.

Self-recognition and self-awareness are processes fundamental to human development. This report describes the case of an 80-year-old woman who demonstrated the ''mirror sign'', an inability to recognise the reflection of oneself in a mirror. An attempt has been made to provide a cognitive neuropsychological explanation for this profound impairment in visual self-recognition, incorporating current cognitive theories of delusion formation and, specifically, delusions involving distorted appreciation of the self or others. We speculate that the impairment in visual self-recognition arises from deficits in visual and personal semantic memory related to bilateral hippocampal lesions, and that the greater extent of impairment in visual self-recognition compared with that for other familiar persons is possible evidence for a specific self-recognition process, represented as a separate ''self-identity node'' in the current face-processing model of Bruce and Young (1986).

Journal Article↗
PubMed2001

Mirror, mirror on the wall, can the brain tell right from left at all?

A reflection on the difficulties associated with the differentiation of right from left in visual space and the way in which these difficulties are changed by looking at a mirror image. This leads to a consideration of how signals from right and left fields are stored in the visual regions of the cerebral cortex and the role of different functional streams in the storage and retrieval of this information. Attention is directed to the way in which the use of mirror images may influence the interpretation of visually-based behaviour following defects in the functional streams in the brain.

Journal Article↗
PubMed1994

Mirror-image tumors in mirror-image twins.

Genetic factors are known to play a role in causing lung cancer. Twin cases of bronchioloalveolar, squamous, and anaplastic bronchogenic carcinoma have been previously reported. We describe mirror-image twins with adenocarcinoma of the lung occurring in mirror-image locations. They shared smoking and an occupational risk, carpentry, in addition to identical genetic backgrounds.

Adenocarcinoma↗
PubMed1983

Mirror, mirror on the wall ... comments on the chimeric face task used by Roszkowski and Snelbecker (1982).

A critique is presented of the chimeric face task used as a measure of cerebral laterality by M. J. Roszkowski and G. E. Snelbecker (1982, Brain and Cognition, 1, 404-409). Problems arise because the faces used are not true mirror images of each other, but in fact differ in facial details. Data are presented to illustrate that the earlier results are not caused by cerebral laterality but by the fact that the two drawings are not equally happy--even when placed in the same left-right orientation.

Dominance, Cerebral↗
PubMed1995

Mirror, mirror on the wall: reflections from failure to establish a truly uniform national health care policy.

When the author gazed into the proverbial mirror and asked if the U.S. health care system was the fairest of them all, it shattered. In this article, Thompson tells why the system is broken and what failure to fix it means to physician executives. He suggests that we, as Americans, must reinvent ourselves by realigning our value systems and and stifling our obsession with profit before trying to reinvent health care.

Delivery of Health Care↗
PubMed1985

Chimpanzee (Pan troglodytes) spatial problem solving with the use of mirrors and televised equivalents of mirrors.

Two adult male chimpanzees reached through a hole in the wall of their home cage and, by tracking the images of their hands and of an otherwise hidden target object in a mirror or closed-circuit television picture, moved their hands in whichever direction was necessary to make contact with the target object. They discriminated between live video images and tapes and performed effectively when the target objects were presented in novel locations and when the video picture was presented at random in different orientations. There was thus no consistent relation between the location of images on the monitor and the location of their real-world counterparts. Comparable performances in monkeys and nonprimates seem unlikely.

Animals↗
PubMed1996

Mirror, mirror ... on the wall, who are the healthiest Americans of all?

The Dartmouth Atlas of Health Care puts a human face on how this country's precious health care resources are divvied up--market by market by market. Dr. John Wennberg spent 30 years researching the project, and the end result may profoundly influence how patients are treated in the future. But in holding up a mirror to the American health care system, does the atlas pose more questions than it answers?

Atlases as Topic↗