Mirror, mirror on the wall. What will medicine be like in 10 years?
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Mirrors as enrichment for captive chimpanzees (Pan troglodytes).
At many facilities, limitations of the physical environment have reduced the opportunity for captive chimpanzees to live in large, naturalistic social groups. Convex mirrors used to increase visual access of neighboring groups may improve the social environment. This was tested in a study of 28 chimpanzees (Pan troglodytes) group-housed in conventional indoor/outdoor runs. A total of 47.8 hours of behavioral observations were conducted and comparisons made across three conditions: no mirror present, a mirror present with visual access to neighboring conspecifics, or a mirror present with visual access to the neighbors' empty run. When the mirror gave subjects visual access to neighboring animals, facial expressions, sexual, and agonistic behaviors increased, whereas affiliative behavior decreased compared with when no mirror was present. When the mirror gave subjects visual access to a neighbors' empty run, facial expressions and sexual behavior increased compared with when no mirror was present. When the mirror gave subjects visual access to a neighbor's empty run, agonism decreased compared with when a mirror gave subjects visual access to neighboring animals. When subjects had visual access to neighbors, they used the mirror 30% of the total data points; while they had visual access to the neighbors' empty run, they looked during 24% of the total data points. Juveniles' use of the mirror increased over time while adults' use remained stable. Adult males used the mirror less than did the other subjects. These findings indicate that a mirror allowing visual access to neighboring conspecifics has potential as an enrichment device that affects social behavior.
Age Factors↗
Mirrors as environmental enrichment for African green monkeys.
Stainless steel circular mirrors were employed in an enrichment plan for 105 singly housed male African green monkeys. We observed 25 randomly selected males to measure mirror use and to assess the mirrors' effectiveness as an enrichment item. We conducted additional mirror-use surveys on all 105 males using fingerprint accumulation as an indicator (rated on a scale of 0 to 4). Use was defined as either being in contact with the mirror (contact use (CU)) or looking directly into the mirror without contact (non-contact use (NC)). Mirror-use data were collected 10 months after the initial introduction of the mirrors and again at 16 months. The two time points were compared by paired t-tests. No significant difference in use was found between the two data collection points. On average, the monkeys used the mirrors 5.2% of the total time intervals recorded (approximately 3 min/hr). Results from the five fingerprint-accumulation surveys showed that 102 of 105 males (97%) had CU with their mirrors over the survey points. Based on the sustained use of the mirrors over a 6-month period, we concluded that the mirrors were an effective enrichment tool that the vast majority of our monkeys routinely used. Habituation did not appear to occur even a year after the mirrors were introduced.
Animals↗
[Effects of central acting drugs on the mirror staircase test].
A mirror-covered staircase was erected to study screening methods, and several basic experiments were carried out using it. The staircase consisted of 5 steps each measuring 15 cm long by 20 cm wide by 6 cm high, fabricated in a wooden device measuring 95 cm by 20 cm by 30 cm high. The inner surfaces were all mirrored, including steps, floors and walls. At the foot of the stairs, a rat weighing about 200 g was placed quietly with the back toward the stairs. The frequencies of rearing and climbing on the stairs were recorded for the subsequent 3 and 10 min. The recordings were also performed using 2 rats placed simultaneously and in a non-mirrored device of the same structure. When mirrored, the frequencies of rearing and climbing were much higher, and the average duration lasted also longer than when non-mirrored. To compare the results among the following 3 qualifications: i) a rat in the mirrored device, ii) 2 rats in the mirrored device, and iii) 2 rats in the non-mirrored device, the highest frequency of rearing for the first 3 min was observed in i). Effects of nitrazepam, phenobarbital and morphine were compared between mirrored and non-mirrored qualifications. No significant differences between them were observed in the drug-induced changes in the behaviors. Although the mirrored-staircase test as a screening method was almost identical to the non-mirrored test, it was superior in the point of continuation of augmented frequencies. As a fact arousing interest, the subject received more potent stimulation from its self image exposed on the mirrors than the image of another individual of the same species (within the same device).
Animals↗
mirror controls planar polarity and equator formation through repression of fringe expression and through control of cell affinities.
The Drosophila eye is divided into dorsal and ventral mirror image fields that are separated by a sharp boundary known as the equator. We have previously demonstrated that Mirror, a homeodomain-containing putative transcription factor with a dorsal-specific expression pattern in the eye, induces the formation of the equator at the boundary between mirror-expressing and non-expressing cells. Here, we provide evidence that suggests mirror regulates equator formation by two mechanisms. First, mirror defines the location of the equator by creating a boundary of fringe expression at the mid-point of the eye. We show that mirror creates this boundary by repressing fringe expression in the dorsal half of the eye. Significantly, a boundary of mirror expression cannot induce the formation of an equator unless a boundary of fringe expression is formed simultaneously. Second, mirror acts to sharpen the equator by reducing the mixing of dorsal and ventral cells at the equator. In support of this model, we show that clones of cells lacking mirror function tend not to mix with surrounding mirror-expressing cells. The tendency of mirror-expressing and non-expressing cells to avoid mixing with each other is not determined by their differences in fringe expression. Thus mirror acts to regulate equator formation by both physically separating the dorsal cells from ventral cells, and restricting the formation of a fng expression boundary to the border where the dorsal and ventral cells meet.
Animals↗
[Mirror-writing in the aged].
Mirror-writing is script that runs in the direction opposite to normal, with the individual letters also reversed. Although mirror-writing is well recognized as occurring in the presence of central nervous system damage, and is especially seen in association with hemiplegia, its mechanism has not yet been elucidated. The purpose of the present study is to document a high incidence of mirror-writing among patients aged 65 years or more, and to investigate the relationship of mirror-writing with brain damage and the degree of cognitive dysfunction. The subjects analyzed in this study were 112 patients (44 males and 68 females) and their average age was 73.8 years. Hasegawa's Dementia Scale (HDS) was used to evaluate their cognitive function. We could find no cases of mirror-writing with the right hand. A high incidence of mirror-writing was found in patients who could use their left hand. Mirror-writing was seen in 67% of patients with cerebral lesions on CT scan. However, we could not observe any relationship between the incidence of mirror-writing and damage to a given circumscribed area of the brain. More than 90% of demented patients, whose HDS scores were less than 20, showed mirror-writing with their left hand. The mean score on the HDS for those with a high incidence of mirror-writing was significantly lower than the score for those without mirror-writing. These results indicate that a high incidence of mirror-writing among aged patients is related to cerebral damage and cognitive dysfunction.
Aged↗
Mirroring in the analysis of an artist.
A patient, a young woman artist, once remarked, 'I am always looking in the mirror and that's why I can't paint'. Miranda in W. H. Auden's The Sea and the Mirror said, 'My dear one is mine as mirrors are lonely'. Both these quotations refer to the wish to be free from the residual derivations of infantile mirroring which Winnicott defined by saying that the mother's face is the child's natural mirror; a young girl, when she has recourse to the glass mirror, is reassuring herself that the mother-image is there. The paper traces the connexions between mirroring and a painter's stated personal dilemma of knowing that looking in the mirror was an alternative to being able to paint and yet of needing to look in the mirror to reassure herself. To have framed that dilemma had involved work to effect a shift from narcissism to reflective self-awareness. The theme of mirroring, as previously described by other clinicians, is enlarged upon to show how the painter's dilemma could be reconstructed in terms of the early mother-child-mirror dissonances. The patient's experience of her self-image through painting began to become more accessible as an accompaniment to a move 'through the looking glass' into the mirror dialogue with her infantile mother-image.
Adult↗
Design and validation of mirror skills instruction.
Students contorted to achieve direct vision indicate that training of mirror skills is absent or ineffective. Training referenced in the literature is not described or amounts to practice using a mirror to perform a psychomotor task often marginally related to dental procedures. No complete task analysis of mirror use is reported. In this study, the authors applied instructional engineering principles to 1) analyze the task and design instruction, 2) validate instruction, and 3) foster mirror use. First-year students (experimentals) completed the new mirror instruction as well as the regular course instruction. A randomly selected group of second-year students who had not completed the mirror instruction but had completed a similar course comprised the control group for the validation. Sets of randomly grouped experimental subjects evaluated a maxillary preparation using mirror vision at three times during the semester and one time a year later. The controls evaluated the same preparation the first time only. Accuracy in describing the critical features of the preparation was used as an indicator of mirror skill. All subjects were observed for mirror use during a practical examination involving maxillary preparations. All groups were equivalent on entering GPA, DAT-A, and DAT-P. Experimental groups made significant improvement in measures of mirror vision skill over time. Experimental groups 2, 3, and 4 significantly outperformed controls on the same measures and demonstrated significantly higher rate of mirror use during the practical exam. The mirror skills instruction appears valid.
Chi-Square Distribution↗
Schema design and implementation of the grasp-related mirror neuron system.
Mirror neurons within a monkey's premotor area F5 fire not only when the monkey performs a certain class of actions but also when the monkey observes another monkey (or the experimenter) perform a similar action. It has thus been argued that these neurons are crucial for understanding of actions by others. We offer the hand-state hypothesis as a new explanation of the evolution of this capability: the basic functionality of the F5 mirror system is to elaborate the appropriate feedback - what we call the hand state - for opposition-space based control of manual grasping of an object. Given this functionality, the social role of the F5 mirror system in understanding the actions of others may be seen as an exaptation gained by generalizing from one's own hand to an other's hand. In other words, mirror neurons first evolved to augment the "canonical" F5 neurons (active during self-movement based on observation of an object) by providing visual feedback on "hand state," relating the shape of the hand to the shape of the object. We then introduce the MNS1 (mirror neuron system 1) model of F5 and related brain regions. The existing Fagg-Arbib-Rizzolatti-Sakata model represents circuitry for visually guided grasping of objects, linking the anterior intraparietal area (AIP) with F5 canonical neurons. The MNS1 model extends the AIP visual pathway by also modeling pathways, directed toward F5 mirror neurons, which match arm-hand trajectories to the affordances and location of a potential target object. We present the basic schemas for the MNS1 model, then aggregate them into three "grand schemas" - visual analysis of hand state, reach and grasp, and the core mirror circuit - for each of which we present a useful implementation (a non-neural visual processing system, a multijoint 3-D kinematics simulator, and a learning neural network, respectively). With this implementation we show how the mirror system may learn to recognize actions already in the repertoire of the F5 canonical neurons. We show that the connectivity pattern of mirror neuron circuitry can be established through training, and that the resultant network can exhibit a range of novel, physiologically interesting behaviors during the process of action recognition. We train the system on the basis of final grasp but then observe the whole time course of mirror neuron activity, yielding predictions for neurophysiological experiments under conditions of spatial perturbation, altered kinematics, and ambiguous grasp execution which highlight the importance of the timing of mirror neuron activity.
Animals↗
Mirror asomatognosia in right lesions stroke victims.
The objectives of this prospective study were: to search for mirror-induced disorders of the body image in right hemisphere stroke victims using a description task of the contralateral upper limb, to analyze their clinical features, and to discuss possible mechanisms. Sixteen consecutive patients with documented unilateral right hemisphere stroke were examined for asomatognosia at the acute phase of stroke, then at least 2 months after stroke under three test conditions: without a mirror, with a conventional mirror, with an inverted mirror. Video recordings of the tests were analyzed to assess performance. The diagnosis of asomatognosia was retained if the subject reported at least one of three sensations: limb transformation, limb strangeness, and/or limb alienation. During the acute phase, 14/16 patients presented manifestations of asomatognosia. All of these spontaneous manifestations had disappeared 2 months later, but were reactivated in 12 patients when exposed to mirror images. The mirror tests revealed four situations: no disorder (n = 4), asomatognosia with both mirrors (n = 5), asomatognosia with the conventional or inverted mirrors (n = 1 and 5), and asomatognosia with the inverted mirror (n = 1). These manifestations were designated as mirror-asomatognosia, a disorder resulting from adaptations of the procedures leading to reorganization of the internal representations of the body image. These findings suggest there are several such internal representations of the body image and that direct body image and mirror body image would be two specific ones. These clinical manifestations and their evolution over time are an expression of the progressive nature of the underlying compensatory mechanisms made possible by brain plasticity.
Adult↗
Mirror images and unilateral spatial neglect.
Responding correctly to a mirror image requires the creation of a rather peculiar form of dual representation. Mirror agnosia and mirror ataxia, i.e. a deficit in reaching an object reflected in a mirror, have been reported to be associated with parietal lobe lesions. This prospective study was conducted to investigate the capacity of subjects with neglect to identify the mirror image nature of visual information. Four consecutive brain-damaged patients with neglect, selected on the basis of specific criteria, and four control subjects performed grasping and object displacement tests under two response conditions (normal mirror and inverted mirror). Video recordings of the tests were analyzed to assess performance using the following criteria: (i) direction of the arm movement during the initial phase of movement, (ii) number of corrections of the hand position before grasping. The control subjects successfully grasped the objects in both experimental conditions. The patients (1) neglected the contralesional space, grasping objects correctly in the ipsilesional space (normal mirror condition) and (2) neglected the ipsilesional space, grasping correctly objects in the contralesional space (inverted mirror). Controls used real object-centered correction clues to modify the position and direction of their hand movement. The patients only produced horizontal displacements of the upper limb in the "healthy" and neglected space. These results suggest that patients with neglect do not use the same clues and do not modify their procedures as they cannot recalibrate their spatial representations. These differences concerned non-mirror-image clues and directional and positional as well as attentional vectors. Theoretical and rehabilitative implications are discussed.
Adult↗
Acquired mirror writing and reading: evidence for reflected graphemic representations.
Mirror writing occurs when individual letters and whole word strings are produced in reverse direction. By analogy, mirror reading refers to the preference to read mirror reversed over normally written words. These phenomena appear rarely after brain damage and offer insight into the nervous system's organization of visual-spatial and visual-motor representations. We present the case of a 51-year-old patient with persistent mirror writing and reading following traumatic brain injury. She preferred to write in the mirror direction with either hand. She drew asymmetric pictures with the same directional bias as normal right-handed subjects, and she did not exhibit left-right confusion regarding other pictures. By contrast, on picture-word matching and lexical decision tasks, she was faster and more accurate with mirrored than normally written words. This pattern of performance suggests that her behavior was not accounted for by reflected motor programs, or by the mirroring of visual-spatial representations in general. Rather, we suggest that her behavior was produced by privileged access to mirrored graphemes. Furthermore, because she seemed better able to read irregular words in mirrored than in normal formats, we suggest that mirrored representations may exist at the whole word level and not simply at the letter level.
Brain Injuries↗
Mirror agnosia.
Normal people rarely confuse the mirror image of an object with a real object so long as they realize they are looking into a mirror. We report a new neurological sign, 'mirror agnosia', following right parietal lesions in which this ability is severely compromised. We studied four right hemisphere stroke patients who had left visual field 'neglect'. i.e. they were indifferent to objects in their left visual field even though they were not blind. We then placed a vertical parasagittal mirror on each patients' right so that they could clearly see the reflection of objects placed in the (neglected) visual field. When shown a candy or pen on their left, the patients kept banging their hand into the mirror or groped behind it attempting to grab the reflection; they did not reach for the real object on the left, even though they were mentally quite lucid and knew they were looking into a mirror. Remarkably, all four patients kept complaining that the object was 'in the mirror', 'outside my reach' or 'behind the mirror'. Thus, even the patients' ability to make simple logical inferences about mirrors has been selectively warped to accommodate the strange new sensory world that they now inhabit. The finding may have implications for understanding how the brain creates representations of mirror reflections.
Aged↗
Fabrication of compact turning mirrors in silicon-on-insulator materials.
A turning mirror is a key component in compact optical waveguide devices and high-density integrated optics. An improved two-step method for fabrication of high-quality, compact turning mirrors in silicon-on-insulator materials is proposed. First, inductively coupled plasma etching is applied to produce the turning mirror, which keeps the turning mirror compact; then silicon wet anisotropic etching is applied to enhance the quality of the turning mirror by of its polishing surface, correcting its orientation, and improving the verticality. The shape of the turning mirror fabricated by the two-step method is hexagonal or octagonal, matching the optical field of the rib waveguide well. A large effective mirror size to reflect light waves and reduced shrinkage of the mirror size during etching guarantee that a mirror produced by this two-step method will be more compact than previously designed mirrors.
Journal Article↗
Three-dimensional trajectory analysis of congenital mirror movements in a single subject.
Mirror movements are involuntary movements executed by one side of the body that occur with voluntary activation of homologous muscles of the other side. Although such movements have been described qualitatively and with surface EMG recordings, the spatial and temporal characteristics of these movements remain relatively unexplored. We studied selected simple and complex upper limb movements in a 20-yr.-old woman with congenital mirror movements and no other neurological disorder. Movements were digitized in three-dimensional space, reconstructed computergraphically, and analyzed numerically and graphically. Mirror movements had smaller amplitudes than did the corresponding voluntary movements, and there was, in general, temporal coupling between mirror and voluntary movements. Nonetheless, mirror movements were not always a perfect mirror image of the corresponding voluntary movements and sometimes differed in timing and trajectory shape from the original movement. Substantially larger mirror movements were elicited by distal than by proximal movements, and mirror movements were enhanced when loads were applied to the hand executing the voluntary movement. These data support the proposal that congenital mirror movements are produced by a partial failure of decussation of the pyramidal tract. We suggest that the variability in the extent to which mirror movements correspond to the voluntary movements is due to propriospinal and descending extrapyramidal input.
Adult↗
Self-recognition: a study of a population without mirrors.
The study of the influence of familiarity with mirrors on children's capacity to identify their reflected images permitted differentiation between two problems that confront the child in the mirror situation: (a) the identity of the image and (b) the capacity to relate mirror space to real space. Sixty children, 6 to 26 months old, without previous experience with mirrors, were observed systematically while discovering their mirror image and a reflected object. Their behavior was compared to a control group with habitual mirror familiarity. The results suggest that (a) self-recognition in the mirror is independent of the child's familiarity with reflecting surfaces and (b) the capacity to relate mirror to real space seems to be strongly influenced by previous experience with mirrors.
Affect↗
Learning-related changes of brain activation in the visual ventral stream: an fMRI study of mirror reading skill.
A previous neuroimaging study has indicated that the visual dorsal stream may contribute to accurate reading of mirror-reversed words. However, the role of the visual ventral stream in the learning of mirror reading skill remains ambiguous. In the present fMRI study, we investigated learning-related changes in brain activation in the visual ventral stream in a mirror reading task. Subjects participated in three successive runs of the mirror reading task, in each of which they were asked to read mirror-reversed words and normal words as accurately and as quickly as possible. The behavioral data for the mirror reading condition showed significant improvement in reaction time but not in performance accuracy across the three runs. The activation data showed different learning-associated patterns related to the right and left visual ventral streams. On the right side, activity related to the reading of mirror stimuli was significantly greater than that related to normal stimuli in the first run only, whereas on the left side it was greater in all runs. Additional correlation analysis between response time data and percentage signal changes only in the mirror reading condition showed significant correlation on the right visual ventral stream in the first run only, whereas that on the left visual ventral stream was found only in the third run. The dissociable response between the right and left visual ventral streams may reflect learning-related changes in reading strategy and may be critical in improving the speed of reading mirror-reversed words.
Adult↗
Mirror writing in right-handers and in left-handers: a study using Chinese characters.
The mechanism of mirror writing was investigated using legal Chinese characters and illegal pseudocharacters. It was found from the results of right-handers in experiment 1 that the performance of normal writing and mirror writing for legal characters was better than that of normal writing and mirror writing for pseudocharacters. A reasonable explanation for this character-superiority effect is that normal engrams and mirror engrams exist only for legal characters but not for pseudocharacters. Further analysis revealed that the character-superiority effect took place in normal writing only when the right hand was used and the same effect was observed in mirror writing only when the left hand was used. It seemed that the normal engrams used in normal writing were stored in the left hemisphere while the mirror engrams used in mirror writing were stored in the right hemisphere. The results in experiment 2 from the left-handers showed the similar pattern as that of the right-handers. The mirror-engram hypothesis seems to be the best mechanism to account for the performance difference of right hand and left hand in mirror writing.
Adult↗