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At least 289 records · Page 16Linked to original sources
PubMed2007

Another gorilla (Gorilla gorilla gorilla) recognizes himself in a mirror.

Various attempts have been made to explain why gorillas (Gorilla gorilla gorilla) find it difficult to recognize their mirror image. One of the most oft-cited reasons is aversion to eye contact, which stops gorillas from looking into a mirror and thus prevents them from carrying out a suitable exploration that could lead to self-recognition. In the experimental design used here the subject was first habituated both to observers and to the mirror as an object before being exposed to the latter. The study was performed with a single subject who was well adapted to captivity and exhibited no aberrant behavior or signs of stress. The results revealed that the subject had no aversion to eye contact. He showed considerable interest in the mirror and appeared relaxed when faced with his image. He gave a positive response to the mark test.

Animals↗
PubMed2003

Separate ipsilateral and contralateral corticospinal projections in congenital mirror movements: Neurophysiological evidence and significance for motor rehabilitation.

The neurophysiological hallmark of congenital mirror movements (MM) are fast-conducting corticospinal projections from the hand area of one primary motor cortex to both sides of the spinal cord. It is still unclear whether the abnormal ipsilateral projection originates through branching fibres from the normal contralateral projection or constitutes a separate ipsilateral projection. To clarify this question, we used focal paired-pulse transcranial magnetic stimulation to test task-related modulation of short-interval intracortical inhibition (SICI) in the abductor pollicis brevis (APB) muscles of a 15-year-old girl (Patient 1) and a 40-year-old woman (Patient 2) with congenital MM. In both patients, during intended unilateral APB contraction, SICI decreased markedly in the "task" APB but remained unchanged in the "mirror" APB when compared to muscle rest. In contrast, spinal excitability as tested with H reflexes increased similarly in the task and mirror flexor carpi radialis muscles. This dissociation of task-related SICI modulation strongly supports the existence of a separate ipsilateral fast-conducting corticospinal projection. In Patient 1, we tested the functional significance of this separate ipsilateral projection during 7 months of motor rehabilitation training, which was designed to facilitate unilateral finger movements. A marked reduction of MM was observed after training, suggesting that unwanted mirror activity in the ipsilateral pathway can be suppressed by learning.

Adolescent↗
PubMed1999

Factors affecting mirror behaviour in western lowland gorillas, Gorilla gorilla.

To date, it has proven difficult to demonstrate mirror self-recognition in gorillas. However, gorillas display pronounced gaze aversion that may prevent them from spending a sufficient amount of time exploring their mirror images to understand that they are the source of their reflections. It has also been suggested that the presence of observers may inhibit gorillas from engaging in mark-directed behaviours. To overcome the problem of gaze aversion, we used an angled-mirror apparatus developed by Anderson & Roeder (1989, Primates, 30, 581-587) that prevented two gorillas at the National Zoological Park from making direct eye contact with their reflections. To counter the observer inhibition hypothesis, we conducted mark tests on these animals using video cameras. Despite addressing these and other concerns in a series of four experiments, the gorillas did not show compelling evidence of self-recognition, even after over 4 years of mirror exposure. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2002

Is human imitation based on a mirror-neurone system? Some behavioural evidence.

Recently, a population of neurones was discovered in the monkey's ( Macaca nemestrina) ventrolateral part of the pre-motor cortex (area F5). It is specialised for recognising object-oriented actions, regardless of whether these actions are performed or observed by the monkey. The latter observation led to the term mirror-neurones, and because these cells respond to both observed and executed actions, it seems likely that neurones of that type became co-opted during hominid evolution to serve the imitative behaviours that are so prevalent in our species. There is recent physiological evidence that Broca's area, the human ( Homo sapiens) homologue of monkey's area F5, is involved in the imitation of finger movements. However, concluding that human imitation is based on a mirror-neurone system is premature, because: (1) imitation in monkeys does not reach the same level as in humans or apes and (2) monkeys' mirror-neurones are specialised for object-oriented actions. This specialisation has not yet been demonstrated in adult humans. We investigated the role of objects in human imitation behaviour in a response time experiment. Subjects had to imitate downward movements of an index finger. In one condition, the observed finger touched one of two dots either ipsi- or contralaterally. In the other condition, the very same movements had to be imitated. However, there were no dots on the table. The presence of dots had a decisive influence on error patterns and on response times, but did not influence the movement proper. Dots specifically reduced the onset latency of ipsilateral finger movements and they specifically increased the use of the wrong finger, when contralateral movements were required. In general, results showed that objects also drive human imitation behaviour. Hence, it is very likely that imitation emerged from the mirror-neurone system of the common ancestor of monkeys and humans.

Adult↗
PubMed2006

Extending the mirror neuron system model, I. Audible actions and invisible grasps.

The paper introduces mirror neuron system II (MNS2), a new version of the MNS model (Oztop and Arbib in Biol Cybern 87 (2):116-140, 2002) of action recognition learning by mirror neurons of the macaque brain. The new model uses a recurrent architecture that is biologically more plausible than that of the original model. Moreover, MNS2 extends the capacity of the model to address data on audio-visual mirror neurons and on the response of mirror neurons when the target object was recently visible but is currently hidden.

Animals↗
PubMed1997

Molecular mapping of a translocation breakpoint at 14q13 in a patient with mirror-image polydactyly of hands and feet.

Mirror hands and feet (MIM, 135750) is a rare congenital anomaly, and mirror-image polydactyly is considered to be a variant of mirror hands and feet. To our knowledge, seven patients with the disorder have been reported in the literature. Parent-to-child transmission was reported in two families, which may indicate a single-gene defect inherited in an autosomal dominant fashion. We had previously encountered a boy with mirror-image polydactyly whose karyotype showed 46,XY,t(2;14) (p23.3;q13) de novo. We hypothesized that at least one of the putative genes responsible for the determination of an anterior-posterior limb pattern is disrupted by a translocation breakpoint. In this study, we identified a yeast artificial chromosome clone spanning a translocation breakpoint at 14q13, and the breakpoint was confirmed to be located between two loci, AFM200ZH4 and D14S306, within a genetic distance of 0.6 cM.

Chromosome Mapping↗
PubMed1992

Reversal of peptide backbone direction may result in the mirroring of protein structure.

In linear polypeptides, inversion of amino acid chirality (all-L to all-D) achieves a mirroring of side chain positions and interactions in conformational space. A similar mirroring of side chain positions is independently achieved by a reversal of the direction of the peptide backbone (retro modification). Thus, while an all-D chain could be expected to adopt a perfect 'mirror image' of the three-dimensional structure of its parent all-L protein, the retro-all-L chain could be expected to adopt a topological equivalent of such a mirror image, through the symmetry transformations of side chain interactions. These notions, supported by sequence analyses, modelling studies, and evidence relating to the activity of 'retro-inverso' peptides, are extended towards the proposal, that the backbone reversed chain of a large globular protein might recognize the chiral opposite of the parent protein's substrate(s).

Amino Acid Sequence↗
PubMed1983

Mirror writing in right-handers and in left-handers.

To determine whether normal left-handers were more adept than were normal right-handers at mirror writing, we tested right-handers and left-handers for their ability to mirror write. Independent of hand used, left-handers wrote mirror words (but not normal words) faster than did right-handers, which suggest that left-handers may be better able to reverse directions (left leads to right to right leads to left). Although when using their preferred hand, left-handers made fewer errors than did right-handers (using their preferred hand), the left hand both in right- and in left-handers was superior to the right hand. That the left hand was superior to the right is compatible with the hypothesis either that the right hemisphere contains mirror engrams or that movements away from the body are more accurate than movements toward the body or both.

Adolescent↗
PubMed1989

Mirror writing: an advantage for the left-handed?

It has been claimed that left-handed individuals are better than right-handers at writing in a mirror script (R. Tankle & K. Heilman, 1983, Brain and Language, 19, 115-123). We tested this claim by comparing the mirror writing ability of normal right- and left-handed adults as a function of hand used and hand use order. Our results do not support the notion of a left-hander superiority in mirror writing since, in two different experiments, right-handed individuals were found to be as good as left-handers. Instead, we obtained evidence for an order effect such that in both experiments, mirror writing was faster in those who started the task with their right hand.

Adult↗
PubMed2006

Double-mirror goniolens with dual viewing system for goniosurgery.

PURPOSE: To compare the performance of the double-mirror goniolens with dual viewing system in goniosurgery, goniosynechialysis, and trabeculotomy ab externo with that of the conventional Swan-Jacob gonioprism (SJG). DESIGN: Prospective interventional case series. METHODS: We treated 10 patients (10 eyes) with medically uncontrollable chronic angle-closure glaucoma by goniosynechialysis and another 10 eyes with open-angle glaucoma by trabeculotomy ab externo (TLO). The 20 patients were divided randomly into two equal groups and underwent operation with the double-mirror goniolens or SJG instrument. RESULTS: There were no intraoperative complications, irrespective of the procedure or instrument that was used. Patients in the SJG group were required to tilt the head at a >30-degree angle to facilitate observation and manipulation of the quadrants. On the other hand, all structures could be observed and manipulated without head-tilting in the double-mirror goniolens group. CONCLUSION: The double-mirror goniolens with dual viewing system is more suitable than the conventional SJG for goniosurgery.

Glaucoma, Angle-Closure↗
PubMed2004

The human premotor cortex is 'mirror' only for biological actions.

Previous work has shown that both human adults and children attend to grasping actions performed by another person but not necessarily to those made by a mechanical device. According to recent neurophysiological data, the monkey premotor cortex contains "mirror" neurons that discharge both when the monkey performs specific manual grasping actions and when it observes another individual performing the same or similar actions. However, when a human model uses tools to perform grasping actions, the mirror neurons are not activated. A similar "mirror" system has been described in humans, but whether or not it is also tuned specifically to biological actions has never been tested. Here we show that when subjects observed manual grasping actions performed by a human model a significant neural response was elicited in the left premotor cortex. This activation was not evident for the observation of grasping actions performed by a robot model commanded by an experimenter. This result indicates for the first time that in humans the mirror system is biologically tuned. This system appears to be the neural substrate for biological preference during action coding.

Adult↗
PubMed2006

Posturographic stabilisation of healthy subjects exposed to full-length mirror image is inversely related to body-image preoccupations.

Affective states, anxiety in particular, have been shown to negatively influence human postural control efficiency as measured by posturographic means, while exposure to a full-length mirror image of one's body exerts a stabilizing effect. We tested the hypothesis that body image concerns and preoccupations would relate negatively to this stabilising effect. Sixty-six healthy students, who screened negative for psychiatric disorders, completed rating scales for anxiety, depression and body image concerns. Posturography recordings of body sway were taken under three conditions: with eyes closed, looking at a vertical bar and looking at a full-length mirror. The Eyes Open/Mirror Stabilometric Quotient [EOMQ=(sway path with eyes closed/sway path looking at the mirror)x100], an index of how much postural control is stabilized by mirror feedback in comparison to the visual vertical bar condition, was significantly inversely related to body image concerns and preoccupations, and to trait anxiety. This finding confirms the impact of emotional factors on human postural control, which warrant further studies. If confirmed in clinical populations characterized by high levels of body image disturbances, e.g. eating disorders, it could lead to developments in the assessment and monitoring of these patients.

Adult↗
PubMed2000

The functional role of oriented spatial filters in the perception of mirror symmetry--psychophysics and modeling.

We investigated human sensitivity to vertical mirror symmetry in noise patterns filtered for narrow bands of variable orientations. Sensitivity is defined here as the amount of spatial phase randomization corresponding to 75% correct performance in a 2AFC detection task. In Experiment 1, sensitivity was found to be high for tests patterns of all orientations except those parallel to the axis of symmetry. This implies that corresponding mirror-orientations (e.g. -45 and +45 degrees ) are combined prior to symmetry detection. In Experiment 2, observers detected symmetry in tests of variable orientation in the presence of either non-symmetric or symmetric masks filtered for orientations either parallel or perpendicular to the axis. Observers were found to be primarily affected by masks of the same orientation as the test, thus suggesting that symmetry is computed separately in distinct mirror-orientation channels. In Experiment 3, observers detected a symmetric test of variable height and width embedded in random noise. Data revealed that mirror symmetry is computed over a spatial integration region (IR) that remains approximately constant in area but whose height-to-width aspect ratio changes from 20:1 to 2:1 as orientation is varied from parallel to perpendicular to the axis. We compare human data against that of an ideal observer to identify key factors that limit visual performance and discuss the implications for the functional architecture of symmetry perception. We also propose a multi-channel model of symmetry detection that combines the output of oriented spatial filters in a simple and physiologically plausible manner. Particular emphasis is placed on the notion that changes in the shape of the IR with orientation compensate for changes in information density and partially equate performance across orientations.

Humans↗
PubMed2002

Procedural memory in schizophrenia assessed using a mirror reading task.

The preservation of procedural memory in individuals with schizophrenia has been confirmed by methods such as the Tower of Hanoi, pursuit rotor and mirror reading tests. However, the cognitive procedural memory of Japanese subjects with schizophrenia has never been assessed using mirror reading. To better determine the characteristics of cognitive procedural memory in schizophrenia, a Japanese version of the mirror reading task, consisting of cards with words written in Japanese katakana characters in mirror image, was administered to 18 Japanese patients with schizophrenia and 21 normal controls. The results indicated that the patients indeed learned the skill despite exhibiting lower overall performances in reading time than the controls, their scores displaying correlation with the severity of schizophrenic negative symptoms. This suggests that procedural memory for this task is retained in individuals with schizophrenia. It is important for them to use their preserved procedural memory for efficient rehabilitative efforts.

Adult↗
PubMed2002

Frogs and toads in front of a mirror: lateralisation of response to social stimuli in tadpoles of five anuran species.

Tadpoles of five anuran species were tested for preferences in the use of the eyes during inspection of their own visual image in a mirror. When tested in a tank with several small mirrors, tadpoles of five different species (Bufo bufo, Bufo viridis, Rana temporaria, Rana esculenta, Bombina variegata) preferentially approached and positioned themselves with the mirror located on their left side, thus looking at the image with the monocular field of their left eye. Similar results were obtained with tadpoles of R. temporaria tested in a simple task in which they had to choose approaching one or other of two large mirrors located on their left and right side. Control experiment showed that the behavioural asymmetry was not due to motor preferences and that it was independent of morphological asymmetries in the positions of the spiracles. This is the first demonstration of a functional visual lateralisation among juvenile amphibia before metamorphosis.

Animals↗
PubMed2000

Simple geometry gridless ion mirror.

A gridless variation of the cylindrical ion mirror has been designed to create an electric field that is nonlinear in the axial direction and nearly homogeneous in the radial direction. The designs may include one or two chambers that consist of truncated cones. This new design concept yields ion mirrors with improved energy focusing over conventional single-field and multiple-field mirrors. Conventionally, ion mirrors with nonlinear field gradient use multiple diaphragm electrodes to which distinct voltages are applied. In this work, optimized nonlinear field distributions are achieved through shaping only two or three electrodes and applying only one or two voltages on the electrodes. The designs presented here offer high resolving power and low ion dispersion. SIMION simulations of performance from the ion source to the detector demonstrate resolving powers of 11,000 and 1,750 for ions with kinetic energy variations of 7.5% and 23.6%, respectively.

Chemical Phenomena↗
PubMed2002

Congenital mirror movement: a study of functional MRI and transcranial magnetic stimulation.

Two male patients (a child and an adult) with congenital mirror movement were studied using functional MRI (fMRI) and transcranial magnetic stimulation (TMS). Bilateral primary sensorimotor cortices were activated during unilateral hand gripping on fMRI when the child patient was 8 years old andthe adult was 37 years old. Bilateral motor evoked potentials were induced from the hand and forearm muscles after TMS of each hemisphere. Bilateral motor responses were also induced from the arm muscles in the adult patient. Bilateral motor responses had short and similar latencies. Contralateral motor responses to TMS were smaller than ipsilateral ones in the hand muscles, while contralateral responses were larger than ipsilateral ones in the arm muscles. Contralateral hand motor responses reduced in amplitude or disappeared with increasing age while in the child patient, mirror movements decreased gradually. Our results suggest that bilateral activation of the primary sensorimotor cortices during intended unilateral hand movement and bilateral motor responses to TMS account, at least in part, for the pathophysiology of congenital mirror movement. Reduction of contralateral hand motor responses may be related to the decrease in mirror movements during development.

Adult↗
PubMed1984

Winding one's ps and qs: mental rotation and mirror-image discrimination.

Subjects were timed as they made judgments about ps and qs (also interpretable as ds and bs) in different angular orientations. Whether these judgments were left-right mirror-image discriminations (b vs. d or p vs. q) or up-down mirror-image discriminations (b vs. p or d vs. q), the subjects' reaction times increased sharply with the angular departure of each letter from its designated normal upright orientation, a fact implying mental rotation. This was so whether the subjects responded with the letter labels themselves (e.g., b vs. d) or with the labels left versus right or top versus bottom. It was again the case when the letters were replaced by nonletter forms, in which event there was also a left visual-field advantage in reaction time. This study is therefore the first to demonstrate a mental-rotation strategy when the canonical forms to be discriminated are up-down mirror images as well as when they are left-right mirror images. In both cases, however, the task requires the ability to tell left from right, and we suggest that this is the critical ingredient that induces mental rotation.

Adult↗