Roberts L

Bio: Roberts L is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 41 citations.

Syndrome of Acquired Aphasia with Convulsive Disorder in Children

Abstract: Certain of the children who are evaluated and taught at the Central Institute for the Deaf are classified as aphasic because they present a specific deficit in the ability to use speech and language.1 For most of these children the deficit seems to be congenital, since they have failed to acquire the ability to use speech and language normally.2 Some of them, however, have acquired the ability to use language in an apparently normal fashion and have subsequently lost it. Six such children have been seen in the last two years. One of the six became aphasic and hemiplegic after a severe head injury; the remaining five developed aphasia in relation to a convulsive disorder. These five cases are reported here. Case 1 . A white male, third of four children, was born in April 1948. Pregnancy and birth history were unremarkable. He was a healthy infant, sat at about six months, and walked before he was a year old. He learned to talk normally at 15 to 18 months. Further behavioral development was also unremarkable. In 1952 when the boy was four, he had one nocturnal generalized seizure. When he was five (July 1953), he developed several furuncles over his face. A few days later he fell in the yard and was found in a semiconscious condition. He staggered into the house and vomited several times. Following treatment with penicillin, it became apparent to the family that the child was having difficulty understanding what was said to him, a defect interpreted as "plain stubbornness." His speech also became garbled. He was hospitalized in August 1953. His electroencephalogram (figure 1A) showed a generalized spike dysrhythmia, most prominent in the temporal leads bilaterally. Neurologic examination was not remarkable except for the deficit in speech. He was considered to have …

Cerebral lateralization of language in normal left-handed people studied by functional MRI.

Abstract: Objective: To use functional MRI (fMRI) to further define the occurrence of left-hemisphere, bilateral, and right-hemisphere language in a normal left-handed population. Methods: A total of 100 healthy volunteers, consisting of 50 left-handed subjects and a reference group of 50 right-handed subjects, were studied by fMRI of the frontal cortex during silent word generation. Results: Ninety-six percent of right-handed subjects showed fMRI changes lateralized to the left hemisphere, whereas 4% showed a bilateral activation pattern. In contrast, left-hemisphere lateralization occurred in 76% of left-handers, bilateral activation in 14%, and right-hemisphere lateralization in the remaining 10%. The predominance of right-hemisphere activation, however, was weak in these cases; only a single left-handed subject (2%) showed complete right-hemisphere lateralization. Conclusions: Silent word generation lateralizes to the left cerebral hemisphere in both handedness groups, but right-hemisphere participation is frequent in normal left-handed subjects. Exclusive right-hemisphere activation rarely occurred in the frontal lobe region studied.

Morphological cerebral asymmetries of modern man, fossil man, and nonhuman primate

Abstract: Cerebral asymmetries are common in modern and fossil man and the great apes. Those occurring most often are listed here: 1. The left sylvian fissure in man is longer than the right and in both fetal and adult brains the posterior end of the right sylvian fissure is commonly higher than the left. Associated with these findings, the left planum temporale is usually longer than the right. 2. The left occipital pole is often wider and usually protrudes more posteriorly than the right. 3. The left lateral ventricle, and especially the occipital horn, is usually larger than the right. 4. If one frontal pole extends beyond the other it is usually the right. 5. On X-ray computerized axial tomograms (CT) of the brain the right frontal lobe and the central portion of the right hemisphere more often measure wider than the left. 6. The CT studies commonly show a Yakovlevian anticlockwise torque (taking the nose as 12 o'clock), with the left occipital pole longer and often extending across the midline toward the right and a wider right hemisphere in its central and frontal portions and frequent forward protrusion of the right frontal pole. This is found also in newborns. 7. The posterior end of the sagittal sinus usually lies to the right of the midline and the sinus flows more directly into the right transverse sinus than into the left. 8. The right transverse sinus is usually higher than the left. 9. In left-handed and ambidextrous individuals the posterior ends of the sylvian fissures are more often nearly equal in height and the occipital regions are more often equal in width or the right may be wider. 10. The torque of the pyramidal tract and the hemispheral torque cannot at present be related to right- or left-handedness. Statistics concerning left-handedness are somewhat confounded, because it is likely that not a few individuals are left-handed because of an early injury of the left hemisphere in a normally right-handed individual. 11. Cerebral asymmetries are found in fossil man similar to those in modern man. 12. Asymmetries of the sylvian fissures similar to those of modern man have been found in the great apes and are particularly common in the orangutan. 13. The most striking and consistently present cerebral asymmetries found in adult and fetal brains are in the region of the posterior end of the sylvian fissures-- the areas generally regarded as a major importance in language function.

Handedness, language dominance and aphasia: a genetic model.

Abstract: A simple two-allele Mendelian model of the genetics of handedness is described and fitted to data in the literature. The model proposes that there are two alleles, D (dextral) and C (chance), the homozygous DD genotype producing only right-handers (directional asymmetry), the homozygous CC genotype producing a racemic mixture of 50% right-handers and 50% left-handers (fluctuating asymmetry), and the heterozygote, DC, being intermediate between the homozygotes and producing 25% left-handers, and 75% right-handers. It is also suggested that the true population incidence of left-handedness is 7.75%, deviations from this figure being due to either criterion shifts or selection biases. The same model is then fitted, by means of a number of minor conceptual extensions, to data from the literature on the relationship of handedness to language dominance, acute and permanent aphasia, and visual processing dominance.