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Biomedical subjects

O Lamm

Publications and source records attributed to O Lamm.

9 recordsLinked to original sources
PubMed1999

Left-handedness and achievements in foreign language studies.

Studies of brain lateralization lend support to the hypothesis that language-motor functions in left-handers are differently organized from those in right-handers. However, the implications of these differences regarding cognitive functioning are as yet subject to controversy. This concerns all hypotheses raised and empirical data collected over the years. Although it was suggested that left-handers are at higher risk of having language and reading deficits, empirical data from clinical and nonclinical populations are inconclusive at the present time. No effort, however, has been invested in examining possible differences in academic studies of foreign languages according to handedness. Here we report data indicating inferior achievements of left-handed native Hebrew speakers in studies of English as a foreign language. Left-handed pupils significantly more than right-handers were placed in lower level English classes and had more difficulties in applying orthographic-phonological mapping rules in reading English words and pseudowords. However, left-handers' difficulties in this task were not correlated with their performance in a word recognition task. It is thus suggested that the "common symptom" of poor word reading in left-handers indicates different processing failures in different left-handers, some of which impede the buildup of an internal representational system of mapping orthography to phonology and some of which concern mainly the precision of word production.

Achievement↗
PubMed1997

Dichotic listening in children: the reflection of verbal and attentional changes with age.

A sample of 290 kindergarten children (147 girls), all native Hebrew speakers, were tested by two dichotic listening tests: (a) a digits test (low verbal workload) and (b) a words test (high verbal workload). The same subjects were tested one year later (at the end of their first year at school) by the same tests. In both tests and both testing sessions the free recall procedure was used. It was found that the performance difference between ears significantly decreased and overall performance significantly increased in the digits test in the second testing session. Differences between sessions in ear difference in the words test were not significant, although overall performance in the second session increased. These data lend support to the hypothesis that the change with age in the between-ears difference is mainly related to an improvement in verbal processing efficiency, which in turn allows the allocation of more verbal resources to the inferior input channel, without a decrease in resources allocated to the preferred one. As expected, increase in available verbal resources was clearly manifested under low verbal workload conditions but not under high workload conditions, where task demands did not allow significant increase in verbal resources to be allocated to the inferior channel. This hypothesis also predicted highly consistent ear preference owing to its being solely determined by the verbal processors of the dominant-to-speech hemisphere. The inconsistent ear preference between tests found in more than a third of the subjects of this sample could not therefore be accounted for by the stated hypothesis. The analysis of performance in subjects who showed left-ear preference in only one test and right-ear advantage on the other occasions indicated that whenever the left ear was preferred it was accompanied by significantly smaller ear difference and lower overall performance compared with those manifested by the same subjects in the same test in the other testing session. These data are better accounted for by the hypothesis that two different pools of resources are involved in splitting attention between ears in the free recall of dichotically presented verbal stimuli: one which is controlled by verbal processors of the dominant-to-speech hemisphere and the other by a spatial attentional mechanism. However, it seems that changes in dichotic test performance within the first year at school can mainly be attributed to increase in verbal resources rather than to improvement in allocation of spatially controlled resources.

Age Factors↗
PubMed1994

Dichotic listening performance under high and low lexical work load in subtypes of developmental dyslexia.

This study examined dichotic listening performance in different subtypes of developmental dyslexia under high and low verbal work load conditions. Free recall tests of digits and words were administered to 320 dyslexic children from grade 3 to grade 10 and their matched controls. Results indicate significant differences within subtypes. Surface dyslexics manifested extreme ear neglect or total performance collapse but only under high verbal work load conditions. Phonological dyslexia was distinguished by poor total performance both under high and low work load levels. Visuo-motor dyslexics, however, did not differ in any measure from their controls. These results lend support to the contention that the main neuropsychological factor impeding reading acquisition varies according to dyslexia subtype.

Adolescent↗
PubMed1992

Are specific reading and writing difficulties causally connected with developmental spatial inability? Evidence from two cases of developmental agnosia and apraxia.

Two cases studies of subjects suffering from severe developmental constructional apraxia are presented. These two subjects demonstrated normal to high ability in reading, writing and arithmetical tests. The analysis of cognitive tests performed by them indicates that extreme developmental, perceptual, spatial and motor deficits may be dissociated from the acquisition of efficient reading ability.

Achievement↗
PubMed1992

Specific reading impairments--are they to be associated with emotional difficulties?

The assumption that specific learning disabilities are not causally related to emotional disturbances is crucial for the cognitive research approaches that endeavor to isolate specific malfunctioning cognitive-computational processes. Because there are conflicting data regarding the emotional status of subjects with learning difficulties, the purpose of this study was the evaluation of the emotional status of subjects with specific learning difficulties in comparison with that of subjects from several relevant control groups. The HSCL-90 profiles of 38 subjects suffering developmental dyslexia, 28 subjects with subjective complaints regarding general concentration and reading comprehension difficulties, and 23 psychiatric patients were compared with those of 44 skilled readers without any known emotional difficulties. All subjects were adolescents and young adults (age range = 15 to 23). A cluster analysis of subjects' HSCL-90 profiles did not reveal any significant differences between subjects with dyslexia and control subjects. Both groups, on the other hand, were easily differentiated from psychiatric patients. Subjects with severe deficits in their ability to remember details of a text, and with subjective complaints regarding concentration difficulties, tended to generate emotional profiles that testify to a high level of anxiety. Although these subjects, as well as individuals with dyslexia, may be regarded at the functional level as inefficient readers, the two groups seem to clearly differ regarding the failure factors that underlie their phenotypic difficulties.

Achievement↗
PubMed1985

Subclinical effects of exposure to inorganic mercury revealed by somatosensory-evoked potentials.

This study examined the validity of evoked somatosensory potentials as a measure of subclinical neurological damage to workers chronically exposed to nonorganic mercury. In this study potentials were recorded along the somatosensory pathway from the periphery to the primary cortex in response to electrical and mechanical stimuli. The findings of this study indicate that such workers exhibit subclinical damage which manifested in a delay in nerve ending conduction times at the periphery, and an acceleration of the conduction from brain stem to cortex. These findings support the suggestion that evoked potentials may be a sensitive and reliable measure in the detection of subclinical neuropathic phenomena. They may consequently be utilized as an efficient early warning system in the prevention of clinical symptoms.

Adolescent↗
PubMedDate not supplied

Brain potentials from dyslexic children recorded during short-term memory tasks.

Event Related Potentials (ERPs) from thirty children (9-13 years old); fourteen of whom were dyslexic and sixteen normal-reading controls, were recorded during the performance of a memory scanning task. Visually presented stimuli consisted of either digits (lexical) or unfamiliar (non-lexical) characters. The subjects had to indicate whether a probe stimulus was a member of a preceding memorized set, or not. The memorized sets included 1, 2 or 3 items. Performance accuracies were significantly lower and reaction times longer in the dyslexic group. The significant Group x Lexicality interaction demonstrated P3 amplitudes which were smaller to lexical compared to non-lexical stimuli in dyslexics compared to skilled readers. Brain activity in response to the probes was more prominent over the right scalp in dyslexics, in contrast to controls that had left side prominence. The results suggest that dyslexic children relate to the physical features of stimuli as opposed to skilled readers, who rely more on the linguistic features of the stimuli. We suggest that remembering visually presented items in dyslexics involves different cognitive strategies and brain structures compared to skilled readers.

Adolescent↗