Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MIRRORS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2004

The role of mirror focus in the surgical outcome of patients with indolent temporal lobe tumors.

PURPOSE: To review the clinical and neurophysiological data of 21 patients with epilepsy due to temporal lobe tumors and who had undergone evaluation and surgery at the Hospital das Clínicas da Universidade de São Paulo. The aim of this study was to investigate whether the occurrence of a mirror focus was influenced either by certain clinical factors or if the surgical outcome was influenced by the presence of a mirror focus. METHOD: We included these 21 patients who had undergone at least one interictal electroencephalogram in the pre- and post-surgical periods. They had had a minimum follow-up of one year. RESULTS: Eight patients had mirror focus (Group 1) and 13 did not (Group 2). The mean age at seizure onset, duration of epilepsy disorder and total number of seizures did not vary statistically between the two groups of patients. Generalized tonic-clonic seizures occurred more frequently in the mirror focus group. All, but one patient, with a mirror focus were seizure free at follow- up. The mirror focus disappeared in all eight patients in the post-surgical electroencephalogram. In this group, the patient who was not seizure - free had a seizure recorded in his post-surgical electroencephalogram with seizure onset ipsilateral to the resected tumor. The patients who were not seizure-free had either been submitted to an incomplete resection of the tumor or showed evidence of associated cortical dysplasia. CONCLUSION: The occurrence of mirror focus is not a contraindication to surgery even when interictal epileptiform activity predominates contralaterally to the tumor and neither when seizures appear to arise from the mirror focus on scalp EEG. Good surgical outcome is expected despite EEG findings that may conflict with tumor location.

Adolescent↗
PubMed2002

Investigations into the association between cervicomedullary neuroschisis and mirror movements in patients with Klippel-Feil syndrome.

BACKGROUND AND PURPOSE: Our purpose was to investigate the association between cervicomedullary neuroschisis and mirror movements in patients with Klippel-Feil syndrome (KFS). METHODS: We conducted a retrospective analysis of 23 patients with KFS who were seen at our institution during a 10-year period. Sixteen of the 23 patients had undergone adequate axial view cross-sectional imaging of the upper cervical spine. The degree of neuroschisis was assessed for each patient, using an objective scoring system. Twelve patients were evaluated for the presence or absence of mirror movements. RESULTS: A high percentage of female patients with KFS was noted (17 [74%] of 23 patients). Adequate cross-sectional images were available for 16 of the 23 patients, six (38%) of whom had some form of cervicomedullary neuroschisis. Five of the six patients had been clinically evaluated, and all were shown to have mirror movements. One patient with Chiari II malformation, which obscured evaluation for neuroschisis, also had mirror movements. Of the remaining nine patients without cervicomedullary neuroschisis, six were evaluated, and none of the six had mirror movements. A review of the theoretical neuroanatomic basis of mirror movements is presented herein, and neurosurgical management concerns for patients with KFS are discussed. CONCLUSION: A strong association exists between cervicomedullary neuroschisis and mirror movements in cases of KFS. Screening of patients with mirror movements may help identify clinically unsuspected KFS and may also help stratify risk within this patient population, identifying patients who might benefit from early neurosurgical intervention.

Adolescent↗
PubMed2006

Comparison of muscle activity associated with structural differences in dental hygiene mirrors.

PURPOSE: Ergonomic studies suggest that the commonly used pinch grasp, held in a static position, is a contributing factor for dental Hygienists' development of work-related musculoskeletal disorders (WMSDs) such as carpal tunnel syndrome (CTS), Trigger Thumb, de Quervain's stenosing tenosynovitis, and carpometacarpal (CMC) osteoarthritis. The pinch grasp is commonly used by the dental hygienist while holding the dental mirror in the non-dominant hand. In response to this concern, manufacturers are redesigning dental mirror handles. The value of these re-designed products is based solely on anecdotal evidence. To date, minimal research has been done to examine the non-dominant mirror hand. The purpose of this study was to objectively evaluate dental mirror handle design using surface electromyography (sEMG) to compare muscle activity associated with grasping the mirror. METHODS: This randomized controlled clinical trial utilized a two-by-two repeated measures statistical design. Data was collected on a convenience sample of 19 (N=19) healthy dental hygiene students in their last year of study. Data collection was divided into two phases to maintain a balanced study. The independent variables in phase I were diameter and weight. The independent variables in phase II were weight and padding. Muscle activity was measured while grasping various dental hygiene mirrors in 30-second increments using sEMG. Following data collection subjects designated which mirror felt most and least comfortable to compare subjective data with objective data. RESULTS: Three statistically significant results occurred. In phase II, padding (p=.01) demonstrated the largest reduction of muscle activity in the flexor pollicis brevis, by decreasing mean muscle activity by 3.7 microv. The interaction of diameter and weight (p=.01) in phase I reduced the mean muscle activity in the extensor digitorum by .8 microV and weight (p=.02) in phase II decreased the muscle activity in the extensor digitorum by .62 microV. Self-reports of comfort reported by the subjects in this study were not consistent with the measurements of muscle activity using sEMG. CONCLUSION: Ergonomic adaptations to dental hygiene mirror handles were associated with increases and decreases in muscle activity. The clinical impact of this is amplified as force is exerted. Furthermore, it may be possible to reduce WMSDs for dental hygienists by using instrument designs during the workday. Self-reports of comfort by the subjects in this study did not calibrate with the measurements of muscle activity using sEMG. Additional research is needed to further isolate the external variables of the study and to determine what actual reduction in muscle activity is significant for maintaining musculoskeletal health.

Adult↗
PubMed2001

Cotton-top tamarins (Saguinus oedipus) fail to show mirror-guided self-exploration.

To investigate the problem of inter- and intraspecific differences on the mirror test, we conducted two experiments on cotton-top tamarins. Experiment 1 employed a technique similar to one used recently on chimpanzees, and provided no evidence of mirror-mediated touching of the marked area. In a control condition, involving colored dye applied to one arm, two subjects also failed to show self-directed touching, even though they clearly looked at their newly dyed arm. Under these test conditions, cotton-top tamarins fail to show mirror-guided self-exploration. Experiment 2 examined whether this failure was due to insufficient mirror exposure, as well as other details of the testing conditions. In particular, we replicated the design of a previously successful experiment on mirror-mediated recognition in tamarins [Hauser et al., 1995], providing four new animals with a protracted period (three weeks) of mirror exposure prior to dying their hair. In parallel with results from Experiment 1, we observed no evidence of mirror-mediated behavior (recognition) in Experiment 2.

Animals↗
PubMed2005

Visual bias of unseen hand position with a mirror: spatial and temporal factors.

Two experiments examined the integration of visual and proprioceptive information concerning the location of an unseen hand, using a mirror positioned along the midsagittal plane. In experiment 1, participants tapped the fingers of both hands in synchrony, while viewing the mirror-reflection of their left hand. After 6 s, participants made reaching movements to a target with their unseen right hand behind the mirror. Reaches were accurate when visually and proprioceptively specified hand positions were congruent prior to the reach, but significantly biased by vision when the visual location conflicted with the real location. This effect was independent of the target location and depended strongly upon the relative position of the mirror-reflected hand. In experiment 2, participants made reaching movements following 4, 8, or 12 s active visuomotor or passive visual exposure to the mirror, or following passive exposure without the mirror. Reaching was biased more by the visual location following active visuomotor compared to passive visual exposure, and this bias increased with the duration of visual exposure. These results suggest that the felt position of the hand depends upon an integrated, weighted sum of visual and proprioceptive information. Visual information is weighted more strongly under active visuomotor than passive visual exposure, and with increasing exposure duration to the mirror reflected hand.

Adolescent↗
PubMed2006

The mirror antisaccade task: direction-amplitude interaction and spatial accuracy characteristics.

In this study we examined the performance of human subjects in three oculomotor tasks: a visually guided saccade task (VST), a simple antisaccade task (SAT) and a mirror antisaccade task (MAT). The stimulus presentation was identical for all three tasks, and the differentiation of the tasks was based on the instruction given to the subjects. Subjects were instructed to either look at a visually presented target location (visually triggered saccade task), or to look at the opposite direction of the visually presented target (simple antisaccade task) or finally to look at the mirror location opposite to the location of the visually presented target (mirror antisaccade task). The loading of the simple antisaccade task with the addition of the amplitude requirement did not affect the percentage of directional errors but slowed down the onset of antisaccade execution by 19 ms. The amplitude of the directionally correct antisaccade in the mirror antisaccade task showed a significant distortion of the true mirror target location. This dysmetria followed the same qualitative pattern to that observed for the visually guided saccades, i.e., a near-target hypermetria together with a far-target hypometria, but both these features were exaggerated in the mirror antisaccade task. This distorted amplitude modulation of mirror antisaccade amplitude was completely lost in corrected antisaccades that followed a directional error.

Brain↗
PubMed2006

Role of the right dorsal premotor cortex in "physiological" mirror EMG activity.

A distributed cortical network enables the lateralization of intended unimanual movements, i.e., the transformation from a default mirror movement to a unimanual movement. Little is known about the exact functional organization of this "non-mirror transformation" network. Involvement of the right dorsal premotor cortex (dPMC) was suggested because its virtual lesion by high-frequency repetitive transcranial magnetic stimulation (rTMS) increased the excitability of the left primary motor cortex (M1) during unilateral isometric contraction of a left hand muscle (Cincotta et al., Neurosci Lett 367: 189-93, 2004). However, no behavioural effects were observed in that experimental protocol. Here we tested behaviourally twelve healthy volunteers to find out whether focal disruption of the right dPMC by "off-line" One Hz rTMS (900 pulses, 115% of resting motor threshold) enhances "physiological" mirroring. This was measured by an established protocol (Mayston et al., Ann Neurol 45: 583-94, 1999) that quantifies the mirror increase in the electromyographic (EMG) level in the isometrically contracting abductor pollicis brevis (APB) muscle of one hand during brief phasic contractions performed with the APB of the other hand. Mirroring in the right APB significantly increased after real rTMS of the right dPMC. In contrast, no change in mirroring was seen with sham rTMS of the right dPMC, real rTMS of the right M1, or real rTMS of the left dPMC. These findings strongly support the hypothesis that the right dPMC is part of the non-mirror transformation cortical network.

Action Potentials↗
PubMed2006

Evidence for stronger visuo-motor than visuo-proprioceptive conflict during mirror drawing performed by a deafferented subject and control subjects.

It has been proposed that mirror drawing is difficult because of the conflict between visual and proprioceptive signals from the arm. However, even without proprioception, there should be difficulties in planning movements to visual targets observed in a mirror, as the mirror-reversed spatial information must be translated into appropriate hand actions. Mirror drawing tasks suggest these planning conflicts are likely to be most obvious at corners, when encountering sharp changes in direction. We have therefore tested the speed of mirror drawing in a chronically deafferented man and in a control group of normal subjects, and hypothesized that increases in template complexity (number of corners) would result in reduced drawing speeds in all subjects. Indeed, all subjects, including the deafferented man, showed movement durations that increased linearly as the complexity of the drawings increased. However, the deafferented man was significantly faster than the control subjects at tracing curved templates. We suggest that the major difficulty in mirror tracking is in the visuo-motor planning of actions based on mirror-reversed visual information, and is not a conflict between visual and proprioceptive signals about arm motion.

Adult↗
PubMed1990

Latency to enter a mirrored chamber: a novel behavioral assay for anxiolytic agents.

Many animal species exhibit approach-avoidance responses upon the novel placement of a mirror into an individual animal's environment. With a view toward identifying new behavioral measures with qualitatively or quantitatively different responses to anxiolytic agents, we developed a mirrored chamber apparatus for which adult male BALB/cByJ mice showed an extended latency to enter. Administration of diazepam significantly reduced this latency to enter a mirrored chamber in a dosage-dependent manner. The psychomotor stimulant, methylphenidate, had no effect on latency to enter the mirrored chamber at a dose which stimulated locomotor activity to the same extent as diazepam. Thus, the decreased latency to enter the mirrored chamber brought about by diazepam seems unlikely to reflect the motor effects of this benzodiazepine. The potency of diazepam was significantly lower in the mirrored chamber assay than it was on three other measures of exploratory activity--"head-dipping" performance, plus-maze performance and locomotor activity stimulation. The findings of our study indicate that the mirrored chamber method is simple to carry out, nonpunishing, rapid and quantitative and that it possesses pharmacological attributes which distinguish its response to anxiolytics from other assays of exploratory behavior.

Animals↗
PubMed2002

Preference for mirror images and video image in Java sparrows (Padda oryzivora).

Java sparrows were exposed to a mirror and a frosted mirror, a mirror and a live bird, a mirror and a live bird with frosted screen, a closed circuit TV monitor and a TV program or the closed circuit monitor and an upside down monitor. The birds showed strong preference for the self-image on the mirror, the live bird and the self-image on the monitor. They preferred almost equally to the mirror and the frosted live bird. These results suggest that the Java sparrows saw the self-image on the mirror as conspecific image.

Journal Article↗
PubMed1993

Mirror imaging in twins: biological polarization--an evolving hypothesis.

This study examined sleep patterns in twins, paying special attention to the mirroring phenomenon. Concordance and discordance of sleep related patterns (parasomnias) in a group of 27 monozygotic (MZ) mirror image twins were compared to sleep patterns in a group of 53 MZ non-mirror image twins and a group of 24 dizygotic (DZ) twin pairs. Sleep patterns had the lowest concordance among MZ mirror twins. "Mirroring" was observed not only in facial features but also in some physiological patterns such as sleep and sleep deviations. These facts suggest that mirroring in MZ twins is not merely a superficial epiphenomenon, but a reflection of a biological polarization. Biological polarization in this context is a descriptive term emphasizing the role of biological (physiological, biochemical or even genetic) versus psychological or environmental factors causing not only mirror body image but opposite tendencies in the development of personality, professional and sex orientation and, most importantly, the opposite presentation of pathology.

Adolescent↗
PubMed2003

Naive optics: Predicting and perceiving reflections in mirrors.

Undergraduate students predicted what would be made visible by a planar mirror. A paper-and-pencil task confirmed previous findings that when approaching a mirror from the side, participants expected to see their reflection in the mirror earlier than they actually would. This early response was found for all mirrors when the observer moved horizontally--even when the mirror was placed on the floor or the ceiling--but not when the observer moved vertically (in a lift). The data support the hypothesis that many people imagine the world in the mirror as rotated around the vertical axis. When participants had to judge manipulated mirror reflections according to their naturalness, a high degree of tolerance was found. In contrast to the prediction task, a rotation around the vertical axis was judged to be less natural than other distortions. The authors conclude that perceptual knowledge and predictive knowledge lead to different patterns of errors. ((c) 2003 APA, all rights reserved)

Adult↗
PubMed2005

Naive optics: acting on mirror reflections.

It is known that naive observers have striking misconceptions about mirror reflections. In 5 experiments, this article systematically extends the findings to graphic stimuli, to interactive visual tasks, and finally to tasks involving real mirrors. The results show that the perceptual knowledge of nonexpert adults is far superior to their conceptual knowledge. Whereas conceptual errors include the assumption of left-right reversals in mirror images and often blatant extensions of the boundary of mirror space, the perceptual context prevents most such errors. However, a consistent bias to misjudge objects in mirrors too far to the outside is demonstrable in all cases including tasks with real mirrors. The authors present a 2-stage hypothesis consisting of an implicit bias of judging the mirror surface to be turned toward the observer's line of sight followed by a normalization that becomes explicit.

Adult↗
PubMed2005

The monkey in the mirror: hardly a stranger.

It is widely assumed that monkeys see a stranger in the mirror, whereas apes and humans recognize themselves. In this study, we question the former assumption by using a detailed comparison of how monkeys respond to mirrors versus live individuals. Eight adult female and six adult male brown capuchin monkeys (Cebus apella) were exposed twice to three conditions: (i) a familiar same-sex partner, (ii) an unfamiliar same-sex partner, and (iii) a mirror. Females showed more eye contact and friendly behavior and fewer signs of anxiety in front of a mirror than they did when exposed to an unfamiliar partner. Males showed greater ambiguity, but they too reacted differently to mirrors and strangers. Discrimination between conditions was immediate, and blind coders were able to tell the difference between monkeys under the three conditions. Capuchins thus seem to recognize their reflection in the mirror as special, and they may not confuse it with an actual conspecific. Possibly, they reach a level of self-other distinction intermediate between seeing their mirror image as other and recognizing it as self.

Analysis of Variance↗
PubMed1994

Mirror movements in normal adult subjects.

Intensity of mirror movements occurring under specific task conditions in normal adults was investigated using a finger flexion task. Subjects were asked to sustain target pressures using different fingers. Greater pressures of mirror movement were recorded when the weaker, small finger of either hand performed the task. The target pressure which subjects were asked to sustain did not influence the amount of mirror movement exhibited by either males or females, even though higher target forces required a significantly greater percentage of total finger strength. On average, males exhibited the same quantity of mirror movements as female subjects, despite the force requirements of the task representing for them a significantly smaller percentage of total finger strength. Moreover, when the right hand performed the experimental tasks, less mirror movement was exhibited than when the left hand was active. Thus, the left hand showed stronger mirror movements. The findings were consistent with previous research using children as subjects, although the nonsignificant effects of gender and pressure were unexpected and need to be examined further. It appears that, while the force requirement of the task does influence the magnitude of mirror movement, it is not the principle determinant.

Adult↗
PubMed2003

Bilateral primary sensori-motor cortex activation of post-stroke mirror movements: an fMRI study.

This fMRI study was undertaken to test whether the pathophysiological mechanism of mirror movements in hemiparetic stroke patients involves activation of the unaffected motor cortex. We studied 16 control subjects and 51 stroke patients. fMRI was performed at 1.5 T using a finger flexion-extension movement paradigm. The incidence of bilateral primary sensorimotor cortex activation was significantly increased during movements of the affected hand of stroke patients who showed mirror movements. Moreover, the incidence of bilateral primary sensorimotor cortex activation increased with the severity of mirror movements and primary sensorimotor cortex was activated bilaterally in all patients who showed sustained mirror movements. We conclude that the motor cortex activation on the non-stroke side is associated with mirror movements and is correlated with the severity of mirror movements. It seems that the pathophysiological mechanism of sustained mirror movements in stroke patients involves the unaffected motor cortex.

Adult↗
PubMed2005

Dominance of ipsilateral corticospinal pathway in congenital mirror movements.

OBJECTIVE: To clarify the mechanism of congenital mirror movements. DESIGN: The triple stimulation technique (TST) and the silent period were used to investigate a patient with congenital mirror movements. The TST was used to calculate the ratio of ipsilateral to contralateral corticospinal tracts from the two hemispheres to the spinal motor neurones. RESULTS: Transcranial magnetic stimulation over unilateral M1 induced larger ipsilateral than contralateral motor evoked potentials on both sides. Only 9% of spinal motor neurones innervating the abductor digitorum minimi were excited by contralateral primary motor cortex (M1) stimulation, while 94% were excited by the ipsilateral M1 stimulation. The silent period was examined during mirror movements and with voluntary contraction of the right first dorsal interosseus mimicking mirror movements. Left M1 stimulation (through the crossed corticospinal tract) did not show any difference in silent period between the two conditions, while right M1 stimulation (through the uncrossed tract) caused a longer silent period during mirror movements than during voluntary contractions. CONCLUSIONS: The results suggest that mirror movements may be caused by a strong connection between ipsilateral M1 and the mirror movements conveyed through a dominant ipsilateral corticospinal pathway.

Adult↗
PubMed1980

Mirror-reading and writing in association with right-left spatial disorientation.

A left-handed patient suddenly developed a right hemiparesis, mirror-reading, and mirror-writing. Although he could discriminate between right and left on himself, he demonstrated right/left spatial disorientation. We propose that his right/left spatial disorientation was induced by a scanning defect. It has been demonstrated that mirror-image engrams are normally available. We believe that a reversal of the learned left-to-right scanning process with the availability of mirror engrams induced mirror-reading. Similarly, reversal of the normal left-to-right writing pattern, with the availability of mirror engrams, induced mirror-writing.

Dominance, Cerebral↗