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Biomedical subjects

F R Manis

Publications and source records attributed to F R Manis.

11 recordsLinked to original sources
PubMed1997

Are speech perception deficits associated with developmental dyslexia?

Phonological awareness and phoneme identification tasks were administered to dyslexic children and both chronological age (CA) and reading-level (RL) comparison groups. Dyslexic children showed less sharply defined categorical perception of a bath-path continuum varying voice onset time when compared to the CA but not the RL group. The dyslexic children were divided into two subgroups based on phoneme awareness. Dyslexics with low phonemic awareness made poorer /b/-/p/ distinctions than both CA and RL groups, but dyslexics with normal phonemic awareness did not. Examination of individual profiles revealed that the majority of subjects in each group exhibited normal categorical perception. However, 7 of 25 dyslexics had abnormal identification functions, compared to 1 subject in the CA group and 3 in the RL group. The results suggest that some dyslexic children have a perceptual deficit that may interfere with processing of phonological information. Speech perception difficulties may also be partially related to reading experience.

Child↗
PubMed1997

A longitudinal study of cognitive functioning in patients with classical galactosaemia, including a cohort treated with oral uridine.

Existing longitudinal data on patients with classical galactosaemia suggests that neurocognitive functioning is impaired and, in isolated case reports, may show a decline in performance over time. The present study explored whether there are long-term changes in cognitive abilities in patients with galactosaemia and whether oral uridine can improve neurocognitive performance. Thirty-five patients (18 males, 17 females), 29 of whom received oral uridine powder at 150 mg/kg per day (divided dose, three times daily), were evaluated over a 2-5-year period with the Woodcock-Johnson Revised Cognitive Abilities Test, three academic achievement tests, and the Beery Test of Visual Motor Integration. Results showed that the uridine cohort and a comparison group that received only dietary restriction made small gains in cognitive performance over the treatment period and the size of the gains did not differ significantly. Seven subjects who started uridine prior to the age of 14 months did not differ significantly in their cognitive test scores at an average age of 3.5 years from a group of older children who had begun treatment at 4.5 years of age. These results provide no support for any developmental or uridine-treatment-related change in cognitive functioning for this sample of galactosaemic subjects.

Achievement↗
PubMed1996

On the bases of two subtypes of developmental [corrected] dyslexia.

This study examined whether there are different subtypes of developmental dyslexia. The subjects were 51 dyslexic children (reading below the 30th percentile in isolated word recognition), 51 age-matched normal readers, and 27 younger normal readers who scored in the same range as the dyslexics on word recognition. Using methods developed by Castles and Coltheart (1993), we identified two subgroups who fit the profiles commonly termed "surface" and "phonological" dyslexia. Surface subjects were relatively poorer in reading exception words compared to nonwords; phonological dyslexics showed the opposite pattern. However, most dyslexics were impaired on reading both exception words and nonwords compared to same-aged normal readers. Whereas the surface dyslexics' performance was very similar to that of younger normal readers, the phonological dyslexics' was not. The two dyslexic groups also exhibited a double dissociation on two validation tasks: surface subjects were impaired on a task involving orthographic knowledge but not one involving phonology; phonological dyslexics showed the opposite pattern. The data support the conclusion that there are at least two subtypes of developmental dyslexia. Although these patterns have been taken as evidence for the dual-route model, we provide an alternative account of them within the Seidenberg and McClelland (1989) connectionist model. The connectionist model accounts for why dyslexics tend to be impaired on both exception words and nonwords; it also suggests that the subtypes may arise from multiple underlying deficits. We conclude that performance on exception words and nonwords is not sufficient to identify the basis of dyslexic behavior; rather, information about children's performance on other tasks, their remediation experiences, and the computational mechanisms that give rise to impairments must be taken into account as well.

Child↗
PubMed1995

Cognitive functioning, neurologic status and brain imaging in classical galactosemia.

A historical group of 45 children (4-18 years) and adults (18-39 years) with classical galactosemia had deficits of cognitive function that were variable and not related to the age at diagnosis or to severity of illness at presentation. There was a trend for patients to score highest on visual processing tasks. The standardized tests of speech and memory skills fell within the same range as the Broad Cognitive Ability score, indicating that the speech and language deficits may be part of a more global set of cognitive impairments. Scores on the Beery Visual Motor Integration and Block Design Tests fell in approximately the same range as other cognitive abilities. In addition, there was a high incidence of abnormality detected on MRI and 12 patients had neurologic symptoms that included ataxia, tremor and dysmetria. These abnormalities did not correlate with the age at diagnosis, severity of illness at presentation or scores on cognitive testing. The pathophysiology of neurologic and neuropsychologic impairments remains unknown. Since these appear to be unrelated to the duration of galactose exposure, other factors impacting on outcome need to be understood so that strategies can be developed to improve what appears to be a global impairment of cognitive function.

Adolescent↗
PubMed1995

Abnormal somatosensory evoked potentials in patients with classic galactosemia: correlation with neurologic outcome.

In classic galactosemia, long-term neurologic sequelae can include low cognitive functioning and a curious neurologic syndrome with tremors, dysmetria, and ataxia. An abnormal white-matter signal on cerebral magnetic resonance imaging (MRI) is present in almost all patients; some have mild cerebral or cerebellar atrophy and focal white-matter lesions. The present study was undertaken to assess the integrity of myelinated pathways by recording somatosensory evoked potentials. Results were correlated with age at diagnosis, severity of illness, age at evoked potentials, neurologic examination, MRI studies and cognitive outcome as measured by the Woodcock-Johnson Revised Standard Cognitive Battery. Evoked potentials were abnormal in 17 (28%) of 60 patients who had median nerve, and 26 (77%) of 34 patients who had posterior tibial nerve studies. Abnormalities of the central rather than the peripheral nervous system were most common. Evoked potentials correlated with severity of presenting symptoms (P = .011), age at evoked potential testing (P = .029), and presence of focal white-matter lesions on MRI (P = .049). Results of neurophysiologic testing showed no correlation with the Woodcock-Johnson Battery. Patients with classic galactosemia may have abnormal conduction along myelinated pathways that is associated with other central deficits. Myelin, which contains galactose, may be adversely affected in this inborn error of metabolism.

Adolescent↗
PubMed1994

Correlation of cognitive, neurologic, and ovarian outcome with the Q188R mutation of the galactose-1-phosphate uridyltransferase gene.

This study was conducted to determine whether there is a genotype/phenotype correlation between aspects of cognitive, neurologic, and ovarian outcome in patients with galactosemia and the Q188R mutation of the galactose-1-phosphate uridyltransferase gene. The results showed that the Q188R mutation was found in 72% of alleles: 38 patients were homozygous and 21 were heterozygous for Q188R; eight patients did not have the mutation. The mean Broad Cognitive score for the group homozygous for Q188R was 75 (SD = 16), which was not statistically different from the outcome for the heterozygous group (mean score, 67; SD = 25) or the negative group (mean score, 88; SD = 21). Tremor, ataxia, and dysmetria were found in 12 subjects, and there was no association with Q188R status. Similarly, there was no association of this mutation with the development of primary amenorrhea (8 subjects) versus secondary amenorrhea (found in 14 women). Our findings suggests that the variability of outcome for patients with classic galactosemia cannot be explained by Q188R status alone, at least with regard to cognitive functioning, presence of neurologic symptoms, and timing of the onset of ovarian failure.

Adolescent↗
PubMed1993

Development of phonological and orthographic skill: a 2-year longitudinal study of dyslexic children.

Twenty-one dyslexic children, ages 9-15, were administered a battery of tests on two occasions separated by 2 years to assess the development of word recognition and spelling. The majority of the subjects were receiving intensive small-group instruction and one-on-one tutoring in reading and writing. Correlational and regression analyses supported the assumption that phonological and orthographic processing are distinct but reciprocally related components of word recognition and spelling. However, phonological skill appeared to capture most of the unique variance in word identification for dyslexics and younger normal readers matched on word identification skill. Although the dyslexic children made significant gains over 2 years in overall word identification skill and in aspects of phonological and orthographic processing, they failed to show significant "catch-up" in any component skills relative to age- and reading-level-matched normal readers. In addition, dyslexics made little or no progress on a measure of phonemic analysis, on a decoding task requiring processing at the level of the phoneme, and at spelling words with unusual and irregular orthography. The results are consistent with the hypothesis that dyslexic children have primary deficits in phonological processing of speech and print and secondary deficits in orthographic processing.

Child↗
PubMed1987

A comparison of word recognition processes in dyslexic and normal readers at two reading-age levels.

This study addressed the question of whether dyslexic children use qualitatively different word identification processes as compared to normal readers at the same stage of reading acquisition. Fifty-two dyslexic children and reading-age matched normal readers were required to pronounce words and pseudowords designed to tap several word recognition and decoding processes. Performance profiles were compared for the two reading groups at two reading ages. Although an invariant acquisition sequence was observed across reading groups, differences in level of performance between dyslexics and reading-age controls varied as a function of reading age. The performance of the more advanced dyslexics was virtually indistinguishable from normal readers on all measures. In contrast, the younger reading age dyslexics differed from normal readers on several measures of spelling-sound correspondences. However, no reading group differences were observed on measures of word recognition. The results indicated that dyslexics and normal readers at the same reading age use essentially the same processes to recognize words, but may differ in knowledge of correspondence rules.

Adolescent↗
PubMed1987

Paired associate learning in reading-disabled children: evidence for a rule-learning deficiency.

Two experiments examined whether normal and disabled readers differed in the utilization of rules in a paired associate learning task. Experiment 1 required children to learn symbol-word associates. Children were assigned to one of three conditions: nonrule, consistent rule, or inconsistent rule. When present, the rule was based on semantic opposites. Subjects benefited from having the rule, but disabled readers showed less improvement across four test blocks than both chronological age (CA) controls and reading age (RA) controls, particularly in the inconsistent condition. Experiment 2 required subjects to learn symbol-symbol associations in one of three conditions: nonrule, consistent rule, or inconsistent rule. When present, the rule specified the locations of a subsidiary figure in each symbol according to the pattern top-right, bottom-left. Disabled and normal readers did not differ in the nonrule condition where reliance on visual memory would be an effective strategy. Normal readers were superior to disabled readers in both rule conditions. In addition, disabled readers in the inconsistent rule condition were less able than normal readers to apply the rule in a generalization task where memory demands were reduced. Results supported the hypothesis that disabled readers have greater difficulty than normal readers inducing and/or using rules, particularly when they are inconsistent. It is suggested that difficulties in acquiring or using complex and inconsistent rules may be one important source of problems learning spelling-sound correspondence rules, which in English are complex and inconsistent.

Association Learning↗
PubMed1980

Development of the search-processing parameter.

A potentially important source of cognitive developmental variance is that associated with basic cognitive-processing efficiency. Discrepant findings from several studies have failed to establish convincingly whether developmental change exists in basic processing efficiency. Employing 2 different experimental tasks, memory and visual scanning, which permit the isolation of a theoretically similar process, that is, search, we examined age effects on the search-processing parameter after analyzing it for convergent and discriminant validity. Each of the 96 subjects at 4 ages (9, 11, 13, and 15 years) completed both experiments. Validity evidence was obtained through a comparison of process and task intercorrelations, which revealed the former to be significantly more related than the latter (p less than .001). Also, significant age effects (p less than .001) were obtained for the search-processing parameter in both tasks, which provides evidence for the development of basic cognitive-processing efficiency.

Adolescent↗