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At least 19 recordsLinked to original sources
PubMed2005

Mirror, mirror on the wall: viewing a mirror reflection of unilateral hand movements facilitates ipsilateral M1 excitability.

Primary motor cortex (M1) excitability is modulated by both ipsilateral limb movement and passive observation of movement of the contralateral limb. An interaction of these effects within M1 may account for recent research suggesting improved functional recovery of the impaired arm following stroke by viewing a mirror reflection of movements of the unimpaired arm superimposed over the (unseen) impaired arm. This hypothesis was tested in the present study using single-pulse transcranial magnetic stimulation (TMS) in eight neurologically healthy subjects. Excitability of M1 ipsilateral to a phasic, unilateral hand movement was measured while subjects performed paced (1 Hz), unilateral index finger-thumb opposition movements. Motor evoked potentials (MEPs) were obtained from the inactive first dorsal interosseous (FDI) in each of four viewing conditions: Active (viewing the active hand), Central (viewing a mark positioned between hands), Inactive (viewing the inactive hand) and Mirror (viewing a mirror-reflection of the active hand in a mirror oriented in the mid-sagittal plane) and with both hands at rest (Rest). MEPs were significantly enhanced during ipsilateral hand movement compared with the Rest condition (P<0.05). Largest MEPs were obtained in the Mirror condition, and this was significant compared with both the Inactive and Central viewing conditions (P<0.05). There was no difference between the dominant and non-dominant hand. Excitability of M1 ipsilateral to a unilateral hand movement is facilitated by viewing a mirror reflection of the moving hand. This finding provides neurophysiological evidence supporting the application of mirror therapy in stroke rehabilitation.

Adult↗
PubMed2001

Mirror, mirror on the wall, who is the ugliest of them all? The psychopathology of mirror gazing in body dysmorphic disorder.

UNLABELLED: Patients with Body Dysmorphic Disorder (BDD) may spend many hours in front of a mirror but little is known about the psychopathology or the factors that maintain the behaviour. A self-report mirror gazing questionnaire was used to elicit beliefs and behaviours in front of a mirror. Two groups were compared, which consisted of 55 controls and 52 BDD patients. RESULTS: Prior to gazing, BDD patients are driven by the hope that they will look different; the desire to know exactly how they look; a belief that they will feel worse if they resist gazing and the desire to camouflage themselves. They were more likely to focus their attention on an internal impression or feeling (rather than their external reflection in the mirror) and on specific parts of their appearance. They were also more likely to practise showing the best face to pull in public or to use "mental cosmetic surgery" to change their body image than controls. BDD patients invariably felt worse after mirror gazing and were more likely to use ambiguous surfaces such as the backs of CDs or cutlery for a reflection. CONCLUSION: Mirror gazing in BDD consists of a series of complex safety behaviours. It does not follow a simple model of anxiety reduction that occurs in the compulsive checking of obsessive-compulsive disorder. The implications for treatment are discussed.

Adult↗
PubMed1985

The common mirror dream, dreamer, and the dream mirror.

From the widely diverse category of so-called mirror dreams, we have differentiated the most frequent, which we have designated the common mirror dream (CMD). It is one in which the dreamer at some point looks into a mirror and reports seeing himself, a part of himself or a distorted though recognizable version of himself. Mirror dreams, including CMDs, are distinctly uncommon. Every dreamer of CMDs in our series had felt enjoined by the mother (in most cases with the father's collusion) not to see and regard her clearly and not to be an accurately reflecting mirror for her. The intensity with which the maternal injunction against accurate visual perception and evaluation was feared was an important distinguishing feature in our patients with CMDs. The essence of the CMD has been hypothesized to be a reciprocal, reverberating, visual-exhibitionistic dyad representative of the mother-child relationship. The dream mirror may represent the wish that the analyst-mother counter a feared parental injunction against accurate visual perception and evaluation so as to correct the distorted perceptions of self and objects and provide visual affirmation of the value and integrity of the self-representation. For some patients, defense against the dangers of castration and loss of maternal love was accomplished by the mirror mechanisms of magically transforming images in the mirror, the ease of creating illusion in the mirror, and a fetishistic mechanism of visually reintrojecting a phallic symbol from the mirror. Our data failed to confirm many of the hypotheses of previous contributors as to specific symbolic meanings of the dream mirror. More relevant than the symbolism of the dream mirror are the many functions of the dream mirror for the dreamer. These are analyzed and discussed.

Adult↗
PubMed2003

Mirror apraxia affects the peripersonal mirror space. A combined lesion and cerebral activation study.

Mirror apraxia is a condition in which patients with lesions of the posterior parietal cortex have deficits in reaching to objects presented through a mirror. The aim of the present study was to investigate possible mechanisms underlying this disorder. First, we addressed the question of whether mirror apraxia is exhibited to the same extent in peripersonal and in body space. Four patients with lesions of the posterior parietal lobe on either side and with marked mirror apraxia were required to reach for objects that were presented to them through a mirror and located either in body space (i.e. on the body surface) or in peripersonal space (i.e. in the reaching distance). Whereas reaching for objects located in body space was flawless in all patients, the performance deteriorated when the same objects were transferred to the peripersonal space. Although the objects were located only a few centimetres above the body surface, the patients reached towards the virtual object in the mirror. Based on these results we suggest that mirror apraxia may originate from a dissociation between the representations of body schema and peripersonal space and that objects located on the body surface become integrated into the body schema. In the second part of the study, using positron emission tomography study (PET), we studied the cerebral activation pattern during reaching to objects presented through a mirror in the peripersonal space in healthy subjects. The results show that increased neural activity in the anterior part of the intraparietal sulcus and in the dorsal premotor cortex was bound to the transformation of the target position from the mirror space to the real space. In contrast, the activity related to object localization in the mirror occurred at the parieto-occipital junction. Both mirror and arm transformation involved the medial posterior part of the superior parietal lobule, putatively area V6a. The results demonstrate that acting through a mirror is processed in a number of cortical areas of the dorsal stream.

Aged↗
PubMed1999

Mirror agnosia and mirror ataxia constitute different parietal lobe disorders.

We describe two new clinical syndromes, mirror agnosia and mirror ataxia, both characterized by the deficit of reaching for an object through a mirror in association with a lesion of either parietal lobe. Clinical investigation of 13 patients demonstrated that the impairments affected both sides of the body. In mirror agnosia, the patients always reached toward the virtual object in the mirror and they were not capable of changing their behavior even after presentation of the position of the object in real visual space. In mirror ataxia (resembling optic ataxia) although some patients initially tended to reach for the virtual object in the mirror, they soon learned to guide their arms toward the real object, all of them producing many directional errors. Both patient groups performed poorly on mental rotation, but only the patients with mirror agnosia were impaired in line orientation. Only 1 of the patients suffered from neglect and 3 from apraxia. Magnetic resonance imaging showed that in mirror agnosia the common zone of lesion overlap was scattered around the posterior angular gyrus/superior temporal gyrus and in mirror ataxia around the postcentral sulcus. We propose that both these clinical syndromes may represent different types of dissociation of retinotopic space and body scheme, or likewise, of allocentric and egocentric space normally adjusted in the parietal lobe.

Adult↗
PubMed1998

The mirror chamber test for testing anxiolytics: is there a mirror-induced stimulation?

A new murine model of anxiety, namely the mirror chamber test, is based on the assumption that, like many species, mice show approach-avoidance behavior when they are confronted by a mirror. It has been suggested that the mirror chamber is a specific and a quantitatively/qualitatively different measure of anxiety than that implicated in other behavioral models such as the elevated plus-maze and the head-dipping assays. The aim of the present study was to investigate whether there was indeed a specific mirror effect by replacing the mirrors in the chamber by either white or dark-gray tiles. Balb/c, DBA-derived, and C57 BL/6j mice were tested under these three experimental conditions. The results indicated that Balb/c and DBA-derived mice avoided the mirror, white and gray chambers similarly while C57 BL/6j mice entered more readily and spent more time in the gray chamber than in the mirrored or white chambers. Thus, depending on the strain of mouse studied, a brightness or a position effect in the chamber could explain the avoidance behavior observed. These results suggest that there is no need to invoke a specific mirror effect.

Animals↗
PubMed2006

Bilateral mirror writing movements (mirror dystonia) in a patient with writer's cramp: functional correlates.

A recent prospective analysis on writer's cramp showed that up to 44.6% of patients in a series of 65 presented mirror dystonia, defined as involuntary movements of the resting hand, abnormal posture, tremor, and jerks occurring while writing with the opposite hand. A clinical case is presented, with videotape evidence of right-handed writer's cramp, with mirror movements elicited while writing using either hand. Functional magnetic resonance imaging studies are compared both to those of a normal patient and to those from a patient with writer's cramp but lacking mirror dystonia. Widespread bilateral activation of cortical motor areas contralateral to the mirror movements in patients with writer's cramp and mirror movements suggests, that bilateral activation of the primary motor cortex may account for the appearance of these mirror movements. Further studies need to be conducted to determine whether mirror movements in dystonic patients appear as a result of loss of intra- and/or interhemispheric cortical inhibition or are simply a consequence of the sustained effort these patients need to exert while writing using a dystonic hand.

Dominance, Cerebral↗
PubMed1995

Persistent mirror movements: force and timing of "mirroring" are task-dependent.

A simple isometric motor task was used to quantify intended and unintended finger movements in two subjects (father and son) with persistent mirror movements. One hand voluntarily changed grip force between thumb and index finger at different amplitudes and frequencies, while the other hand was to maintain a constant force. During all experimental conditions the "steady" hand showed insuppressible, highly cross-correlated contractions, compatible with bilateral distribution of a single motor command to the spinal cord. However, these associated movements were not strictly mirror images, nor did they show a fixed relationship to the voluntary movements across experimental conditions. The ratio of mirror to voluntary movement ranged from 1.4 to 19.1% and from 3.4 to 78.4% in the two subjects and was directly related to voluntary strength and speed. At maximum speed, mirror activity tended to precede voluntary activity, while it was delayed in slow force changes. Comparable time lags were not found in control subjects instructed to simulate mirror movements. We conclude that neuronal mechanisms in addition to bilateral corticomotoneuronal connections are at work in persistent mirror movements.

Adult↗
PubMed2004

Can mirroring reveal image distortion? Illusory distortion induced by mirroring.

Artists claim that they can find unwanted distortions in their works easily by checking mirror images, suggesting that our sensitivity to distortion is different between normal and mirror images. In this study, participants observed distorted faces in which the left eye was displaced vertically, and judged which of the eyes was higher in both normal and mirror images. The results suggest that mirroring changed the perceptual definition of distortion, rather than sensitivity to it. It is concluded that the distortions that were 'detected' in the mirror images were illusory distortions induced by mirroring. A similar effect was also observed when the images were tilted by 45 degrees clockwise or counterclockwise.

Humans↗
PubMed2006

Surface electromyography shows increased mirroring in Parkinson's disease patients without overt mirror movements.

Patients with Parkinson's disease (PD) may present mirror movements (MM). Transcranial magnetic stimulation data indicate that these movements reflect an abnormal enhancement of the "physiological mirroring" that can be observed in healthy adults during complex and effortful tasks. It was hypothesized that, in PD, enhanced mirroring is caused by a failure of basal ganglia output to support the cortical network that is responsible for the execution of strictly unimanual movements. If so, it is likely that subtle alterations of voluntary unimanual motor control are also present in PD patients without overt MM. We tested this hypothesis by using surface electromyographic (EMG) techniques in 12 mildly to moderately affected PD patients without overt MM, and in 2 control groups (12 age-matched and 10 young healthy volunteers). Subjects performed unilateral phasic thumb abduction during a sustained tonic contraction of the opposite abductor pollicis brevis. All patients were tested on dopaminergic therapy. On a separate day, 7 of 12 patients were re-tested after withdrawal of medication. During this task, involuntary mirror-like increase in surface EMG of the tonically abducting thumb was significantly larger in PD patients than in age-matched or young healthy volunteers. Off therapy, mirroring was slightly greater than on medication, although this difference was not significant. Our findings suggest that dysfunction of unimanual motor control is a general feature of PD. It is likely that this deficient movement lateralization contributes to an impairment of nonsymmetrical bimanual movements in PD.

Aged↗
PubMed1988

[Temporary mirror writing and mirror reading as disinhibition phenomena? A case study].

After removal of a left parietal meningioma a 74-year-old right-handed woman developed temporary mirror writing and mirror reading. Further analysis of the mirror phenomena came from tachistoscopic hemifield stimulation showing a right hemisphere superiority for the recognition of words presented in mirror fashion. These neuropsychological results are discussed in the context of common concepts. Finally the hypothesis of bihemispheral mirror-image engrams according to Orton will be suggested as a comprehensive explanation and supported by evidence from the literature.

Aged↗
PubMed2004

Mirror writing ability is genetic and probably transmitted as a sex-linked dominant trait: it is hypothesised that mirror writers have bilateral language centres with a callosal interconnection.

Mirror writing is the ability to write from right to left, reversing each letter so that when held to a mirror the script appears normal. There is no information on the prevalence of this trait but a suggestion was received that it may be hereditary. A newspaper survey was carried out to discover the approximate prevalence and whether a hereditary factor is involved. The results indicated a prevalence of 1 in 6500. There is strong evidence that the trait is hereditary and is associated with non-right-handedness'. It is hypothesised that mirror writers may comprise a very small group of people who not only have bilateral language centres but also have an interconnecting pathway between these centres via the corpus callosum. The surprising genetic nature of a trait with no obvious evolutionary consequences is discussed. The data can best be explained on the basis of the trait being the phenotypic expression of an X-linked dominant gene, which does have evolutionary consequences. Similarities are noted between the proposed genetics of mirror writing and those of synaesthesia and of a few pathological X-linked dominant syndromes such as Rett syndrome. Other similarities and contrasts between mirror writing and synaesthesia are noted.

Adult↗
PubMed1998

Mirror, mirror on the wall, who's the thinnest one of all? Effects of self-awareness on consumption of full-fat, reduced-fat, and no-fat products.

Two studies tested whether self-focusing situations influence people to avoid fatty food. In Study 1, college students tasted full-, reduced-, and no-fat cream cheese spreads on bagelettes. A large mirror was present in the room for some students and was absent for the remaining students. In Study 2, shoppers at large supermarkets tasted full-, reduced-, and no-fat margarine spread on bread. A large mirror was present on the table top for some shoppers and was absent for the remaining shoppers. In both studies, individuals in the mirror group ate less of the full-fat product than did those in the no-mirror group. The presence of a mirror did not influence consumption of reduced- and no-fat products, perhaps because people thought these products were not unhealthy. These findings support self-awareness theory and suggest that individuals on weight reduction programs may benefit from making food choices in self-focusing situations.

Adolescent↗
PubMed1991

Social responding to mirrors in rhesus monkeys (Macaca mulatta): effects of temporary mirror removal.

As a result of a long-term, longitudinal project initiated in 1978, a pair of rhesus macaques (Macaca mulatta) housed together in front of a mirror all their lives now exhibit relatively little interest in their reflection. Previous work has shown, however, that simply moving the mirror to a new location produces a short-term reinstatement of social responding to their images. As an extension of these findings, in this study the mirror was left in the same position but turned away from the cage. On turning the mirror back to face the cage 5 days later, both animals reacted as if confronted with another pair of monkeys and directed a burst of social responses at the mirror.

Animals↗
PubMed1979

Mirror, mirror on the wall...?

This study was designed to determine the value of using a mirror for speech teaching. Data derived from manner, place, voicing, and blend errors produced by 27 hearing-impaired children while imitating consonant-vowel syllables under three conditions (audition alone, audition plus direct vision, audition plus vision using a mirror) were analyzed to determine whether the use of a mirror enhances or detracted from the accuracy of their responses relative to the other two conditions; whether different types of errors were made under any of the conditions; and whether error types under each condition were related to age or hearing level. Although more place errors occurred under the auditory condition, the difference between the numbers of errors made under the two auditory-visual conditions was not significant. The use of a mirror neither enhanced nor detracted from the accuracy of responses of subjects in this study. This finding cast doubt upon the value of using a mirror as a general aid in speech teaching.

Adolescent↗