The perception of structure in vectorpatterns by 4-month-old infants.
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Attention↗
Biomedical subjects
D W Muir
Publications and source records attributed to D W Muir.
Can blind infants and children use sonar sensory aids?
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Auditory Perception↗
Maternal, fetal, and newborn complications associated with newborn intracranial hemorrhage.
Two hundred twenty newborn infants with one or more fetal or newborn complications and 54 newborn infants without fetal or newborn complications were prospectively studied to assess the relationship between maternal, obstetric, fetal, and newborn complications and intracranial hemorrhage. Intracranial hemorrhage occurred in 47 newborn infants with fetal or newborn complications (21%) and in one infant with no fetal or newborn complications (2%). Maternal and obstetric complications, duration of labor, and mode of delivery were not associated with intracranial hemorrhage. Newborn immaturity at delivery is an important factor in the occurrence of intracranial hemorrhage. There is little evidence that fetal hypoxia is a contributing factor. Severe respiratory complications and major infections are newborn complications associated with intracranial hemorrhage.
Cerebral Hemorrhage↗
Pattern perception in infants: effects of structure and transformation.
Four experiments on pattern perception in 4-month-old infants are reported. The first two experiments examined the perception of pattern structure as defined by Garner (1974). Although the infants did not show an immediate preference for well-structured patterns (Experiment 1), during habituation they showed a reliable decrement in looking only to well-structured patterns (Experiment 2). On recovery trials in Experiment 2 infants were presented with two types of pattern change: a new configuration of the habituation pattern and a change in the orientation of the habituation pattern. The infants recovered looking to the orientation change, but generally not to the changes in configuration. It is argued that the results of Experiment 2 highlight the role of symmetry, especially vertical symmetry, in infant pattern perception. Recovery of looking to changes in the orientation, size, and position of the habituation pattern was examined in Experiments 3 and 4 where it was demonstrated that such changes are salient to the infant, arguably because of the presence of a surrounding, external frame.
Attention↗
Motor and cognitive development of infants with intraventricular hemorrhage, ventriculomegaly, or periventricular parenchymal lesions.
Two hundred twenty-six moderate- or high-risk newborn infants were studied to examine the relationship between ultrasound findings in the newborn period and at 6 months and motor and cognitive deficits at 1 year. A three-part classification of abnormal ultrasound findings was used to grade intraventricular hemorrhage, ventriculomegaly, and parenchymal lesions. Abnormal ultrasound findings were observed in 48 infants, of whom 21 had intraventricular hemorrhage, 18 persistent ventriculomegaly, and nine parenchymal lesions. The incidence of deficits was as follows: normal ultrasound examination, 20%; intraventricular hemorrhage, 33%; persistent ventriculomegaly, 67%; and parenchymal lesions, 89%. The present study indicates that serial ultrasound examinations are indicated in preterm newborn infants less than 1500 gm and in selected newborn infants at risk and greater than 1500 gm at birth. The three-part classification of abnormal ultrasound findings should be used because of the predictive significance of persistent ventriculomegaly and parenchymal lesions for motor and cognitive deficits at 1 year of age.
Cerebral Hemorrhage↗
The relationship between perinatal hypoxia and newborn encephalopathy.
Newborn encephalopathy was observed in 30% of 303 selected high-risk preterm and term newborn infants. The newborn encephalopathy was mild or moderate in 65 children and severe in 27. The predictive significance of newborn encephalopathy to motor and cognitive deficits at 1 year was evident from the incidence of deficits in the children with no encephalopathy (17%), in children with mild or moderate encephalopathy (25%), and in children with severe encephalopathy (55%). The biologic risk factors with a significant association with newborn encephalopathy included severe intrapartum fetal hypoxia, moderate and severe newborn respiratory complications, and major infections. Perinatal hypoxia was associated with, and may have contributed to, 26% of the cases of mild and moderate newborn encephalopathy and 66% of the cases of severe newborn encephalopathy. Fetal and newborn hypoxia occurred with equal frequencies in cases of mild and moderate encephalopathy; however, newborn hypoxia was twice as frequent as fetal hypoxia in cases of severe newborn encephalopathy.
Brain Diseases↗
The contribution of fetal-newborn complications to motor and cognitive deficits.
A total of 364 selected high-risk premature and mature infants were studied prospectively to assess the relationship between fetal-newborn complications and motor and cognitive deficits identified during the first year of life. Deficits occurred in 24 per cent of the children: 14 per cent had one or more major deficit and the other 10 per cent had one or more minor deficit. Prematurity was one of the fetal-newborn complications not associated with deficits at one year. Complications that were associated with deficits included fetal hypoxia, respiratory difficulties, infection and newborn encephalopathy. There was also a significant association between fetal hypoxia, newborn respiratory complications, infection and newborn encephalopathy, which is in keeping with the concept that the first three may be mechanisms in CNS injury and subsequent deficits, while newborn encephalopathy reflects the injury and is an important predictor of such deficits.
Aging↗
Factors associated with motor and cognitive deficits in children after intrapartum fetal hypoxia.
Sixty children with biochemical evidence of intrapartum fetal hypoxia were studied to define the factors which distinguish the children with deficits from those without deficits of motor and cognitive development. Follow-up assessment included growth measures, neurological examination, Bayley Scales of Infant Development, and a modified Uzgiris and Hunt Scale. Eight children (13%) had a major deficit and 10 children (16%) had a minor deficit at 1 year. Children with deficits had an episode of hypoxia that was more severe and prolonged and, subsequent to delivery, a greater incidence of severe respiratory complications, apnea, and newborn encephalopathy. No other significant risk factors were identified. It is concluded that an episode of hypoxia less than one hour may occur without subsequent deficits. However, an episode of hypoxia in excess of 1 hour resulting in a metabolic acidosis of the order of 25 mEq/L will be followed by motor and cognitive deficits in approximately 50% of children.
Acidosis↗
The predictive significance of biologic risk factors for deficits in children of a high-risk population.
Two hundred forty-two high-risk children and 47 low-risk children were prospectively studied to assess the relationship between biologic risk factors that occurred during the perinatal period and the motor and cognitive deficits that were identified during the first year of life. Multiple risk factors were present in 80% of the children of the high-risk group. Provisional deficits were classified on the degree of abnormality found in a clinical and behavioral assessment that included neurological examinations, Bayley Physical and Mental Development Scales, and the Uzgiris and Hunt Scale. Provisional deficits occurred in 10% of the children of the low-risk group. High-risk children had a significantly greater incidence of provisional deficits, particularly in respect to positive deficits. In high-risk children, the probability of a deficit was 17% in those without infection or encephalopathy, 30% in those with infection, and 40% in those with encephalopathy.
Cognition Disorders↗
Intrapartum fetal hypoxia: a study of long-term morbidity.
Reported is the second phase of a prospective follow-up study of 37 children who had episodes of intrapartum fetal hypoxia at delivery identified by an acid-base assessment and of a control group of 59 children who had no evidence of intrapartum fetal hypoxia. The newborn infants were normally grown and mature at delivery. Follow-up assessments of motor, cognitive, and language development were made between 1 and 6 years of age. There was no significant difference in the pattern of physical growth and the incidences of motor and cognitive handicap or developmental delay, language developmental delay, and tests of vision and hearing in the children of the hypoxia group and the children of the control group. These findings suggest that acid-base measures of metabolic acidosis can be used as a method of assessment of the mature normally grown fetus during labor without compromising the long-term outcome of the child.
Acid-Base Imbalance↗
Reaching in very young infants.
It has been claimed that reaching to visually presented targets is a valid indicator of perceptual capacity in very young infants. In a previous report we failed to replicate the findings on which that claim is based. Here we reanalyze some of the tapes of the first report, using a less restricted criterion for what constitutes a reach, and a much more detailed analysis of the various components of reaching behaviour. A number of components are readily distinguished and reliably observed. Infants of seven to twenty-one days show great individual variation in their reaching, from no such behaviour to a great deal. Certain clusters of the components of reaching can be used to define different reaching "styles". The infants who reached most frequently in our sample all showed a dominant pattern of reaching, which in certain respects appears to be more mature than that of other babies. The finer analysis revealed no differences in the reaching behaviour to objects and pictures of objects, even among the most active reachers.
Arm↗
A physiological and behavioural study in cats of the effect of early visual experience with contours of a single orientation.
1. Three kittens were reared in visual environments that consisted of stripes at one of three orientations - horizontal, right oblique, or left oblique. Two additional cats were reared as controls. One of these matured viewing right and left oblique stripes on alternate days. The other experienced a normal visual environment. 2. Following the completion of rearing, and after several weeks of normal visual experience, behavioural testing of the stripe-reared animals demonstrated a deficit in visual acuity for orientations which were not present in the early visual environment. No comparable deficit emerged for either of the control cats. 3. Following 1-3 years of further, normal, visual experience, each of the cats was shipped separately to California where single units were recorded from area 17 of the visual cortex and an effort made to guess the early visual history of each animal which was unknown to the experimenters. Cell samples from each experimental cat and the normal control cat allowed the physiologist to guess their early visual experience correctly. The control cat which matured viewing orthogonal sets of oblique stripes on alternate days demonstrated a bias for horizontal contours in his cell sample. In contrast to units recorded from normal cats, about 80% of which are binocular, only about 30% of the cells recorded from the stripe-reared animals could be influenced by both eyes.
Animals↗
Orientation anisotropy: incidence and magnitude in Caucasian and Chinese subjects.
Cutoff spatial frequencies for sine-wave gratings were measured at four orientations for 100 Caucasian and 24 Chinese subjects, all of whom were raised in carpentered enviornments. For the Caucasian subjects, average acuity for horizontal and vertical gratings was superior to that for obliques by about one-quarter of an octive. However, about 10 percent of subjects showed an anisotropy of about one-eight of an ovtave. The carpentered enviornment explanation of orientation anisotropy cannot, in its present form, account for the wide variety of response patterns obtained, nor the differences between Chinese and Caucasian subjects.
Asian People↗
Does the tilt after-effect occur in the oblique meridian?
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Adaptation, Ocular↗
Behavioral deficits in cats following early selected visual exposure to contours of a single orientation.
The ability of adult cats, whose early visual experience was confined to contours of a single orientation (either vertical or horizontal), to resolve gratings of different orientations was studied by operant methods. Following selective visual exposure during part or all of the first 4 months of life, the cats were trained on a simultaneous discrimination between gratings of various orientations and blank fields of the same mean luminance. The spatial frequency of the gratings was systematically altered in order to obtain an estimate of acuity based upon extrapolation to chance levels of performance. Selectively deprived cats performed as well as normally reared cats on gratings having the same orientation as that of the stripes they saw as kittens, but their performance on gratings orthogonal to these was poorer. The deficits in acuity for gratings perpendicular to the experienced orientation varied between 0.26 and 0.87 of an octave. On the other hand, control cats whose early visual experience alternated between vertical and horizontal stripes, or who were reared in an environment containing randomly oriented contours, failed to show any difference in their acuity for vertical and horizontal gratings. The acuity deficits shown by the selectively deprived animals are long-standing since they remain unchanged even after 30 months of normal visual exposure. It is argued that these perceptual deficits are a consequence of the changes in cortical physiology that other investigators have described in cats who had undergone similar early visual deprivation. Taken together, these findings provide a basis for explaining a number of human perceptual disorders.
Animals↗
Interocular transfer of the motion after-effect in normal and stereoblind observers.
The extent of interocular transfer of the motion after-effect was measured in 4 stereoblind subjects and in 19 subjects having varying degrees of stereopsis. Stereoblind individuals failed completely to show any interocular transfer of this after-effect, while subjects with good stereopsis exhibited between 55 and 82 percent transfer (mean 73 percent). Furthermore, normal subjects who manifested a clear eye dominance tended to show greater transfer from the dominant to the nondominant eye than vice versa. Individuals who either had a history of a strabismus or possessed some other early impediment to clear binocular vision tended to show less transfer. Overall there was a significant positive correlation of 0.75 between the extent of interocular transfer and the subject's stereoacuity. It is argued that the extent of interocular transfer of this after-effect provides a measure of the proportion of the total number of visual cortical neurons that are binocular. Thus stereoblind humans, who show no transfer whatsoever may, like cats and monkeys deprived of concordant binocular visual input early in life, suffer from a lack of binocular neurons.
Depth Perception↗
Visual resolution and experience: acuity deficits in cats following early selective visual deprivation.
Cats reared during the first 5 months of life in environments that contain contours of a single orientation show a diminished ability to resolve gratings of the orthogonal orientation in later life. It is argued that these perceptual deficits result from changes in the organization of the visual cortex induced by the selected early visual input.
Animals↗