Search PubMed⌕ Search

Biomedical subjects

P Tallal

Publications and source records attributed to P Tallal.

At least 19 recordsLinked to original sources
PubMed1992

Cerebral brain metabolism in adult dyslexic subjects assessed with positron emission tomography during performance of an auditory task.

Ten dyslexic adults (aged 33.5 +/- 7.3 years, nine men, one woman) and 10 age-, sex- and handedness-matched control subjects (aged 33.6 +/- 5.8 years) performed an auditory syllable discrimination task during 18-fluoro-2-deoxyglucose uptake, and then underwent positron emission tomographic scans. A second normal control group performed an analogous visual discrimination task. Dyslexic subjects experienced greater difficulty and made significantly more errors in performing the auditory task. There were no differences in brain metabolic rates in lateral cortical areas (frontal, parietal, temporal, and occipital lobes). A significant difference emerged in the medial temporal lobe, with dyslexic subjects having significantly higher absolute and relative brain metabolism along an anterior-posterior gradient than normal adults. These data support the hypothesis of altered cerebral processing of auditory stimuli in patients with dyslexia.

Adult↗
PubMed1992

Verbal learning and memory in language impaired children.

The present study investigated patterns of verbal learning and memory in Language Impaired (LI) and normal children, using the California Verbal Learning Test--Children's Version. The LI children showed a normal immediate memory span; however, they were impaired in the total number of correct responses that they generated across repeated trials. They reported significantly more perseverations, but not intrusions, relative to the controls. The LI children were not impaired on a delayed free recall task, but they were significantly impaired relative to the controls on semantically cued recall. The implications of these findings for future research and for remediation are discussed.

Child↗
PubMed1992

Rapid automatized naming and gesture by normal and language-impaired children.

This study investigates whether language-impaired (LI) children show deficits in rapid automatized naming and whether RAN performance is specific to verbal output (or to rapid motor output in general). A total of 67 LI and 54 age-matched control children were tested with the Rapid Automatized Naming (RAN) test (Denckla & Rudel, 1976) and with a manual version of the RAN (RAN-manual) in which subjects were required to provide a nonverbal, pantomime response. Subjects also completed tests of rapid oral and manual sequencing skills and standardized tests of reading ability. Each subject was tested at 4, 6, and 8 years old. The results showed that LI children perform significantly poorer on both versions of the RAN than age-matched controls. Correlations between RAN scores and tests of reading ability were significant for normal and LI subjects and were particularly high for 8-year-old LI children. RAN-manual scores also correlated with 8-year-old LI children's reading scores. Further, RAN and RAN-manual scores for the LI children correlated significantly with these children's manual sequencing abilities, whereas this was not the case for the control subjects. These findings suggest that LI children's rapid sequential processing deficits are not limited to verbal output, but also generalize to other motoric domains.

Child↗
PubMed1992

Delay versus deviance in the language acquisition of language-impaired children.

To investigate the issue of delay versus deviance in the language acquisition of language-impaired (LI) children, the order of acquisition of a set of linguistic structures and the relationship obtaining between one structure and another were examined in comprehension and production over a 5-year period in a group of LI and language-matched normal children. The results demonstrated a marked similarity between groups, both in the point at which mastery of individual structures was achieved and in the overall patterns of acquisition demonstrated. These data suggest that LI children are constructing grammars based on the same rules and principles as those of linguistically normal control subjects, and that their linguistic impairments may be principally processing, not representational, in nature.

Child, Preschool↗
PubMed1991

Phenotypic profiles of language-impaired children based on genetic/family history.

Although etiological influences in developmental language impairment (dysphasia) are not well defined, a significant increase of family aggregation for the disorder has been reported. We report data from a large cohort of language-impaired (LI) children participating in the San Diego longitudinal study in which we examined whether children with or without positive family histories show different phenotypic profiles. Due to the longitudinal design of the study, questions pertaining to change over time are also addressed. Second, a subgroup of the most impaired children were reevaluated to obtain additional information pertaining to family history and phenotypic outcome. Approximately 70% of the LI children met criteria for inclusion as family history positive, with fathers reporting a history of language or learning problems one and a half to two times as frequently as mothers. LI children with or without a positive family history were not significantly different on language skills or IQ. However, subjects having a positive family history for developmental language/learning problems were significantly lower in socioeconomic status and were rated by parents and teachers as having more attention-related behavior problems than their family history negative counterparts. Similarly, family history positive LI children performed more poorly on standardized academic tests as well as on tests of auditory processing and attention.

Child↗
PubMed1991

Hormonal influences in developmental learning disabilities.

Developmental language and learning disabilities in children can take many different forms and can result from a variety of causes. Research to date has focused primarily on specific disabilities in learning, which are characterized by a significant delay or disorder in one aspect of learning against a background of otherwise normal development. Learning disabilities affecting language and/or reading acquisition (developmental dysphasia and dyslexia) have been studied most thoroughly. Verbal learning disabilities occur more frequently in boys than in girls, and there is a higher than expected incidence of left-handedness among affected children. Although there are many reasons why a child may have delayed or disordered language development, differential diagnosis of specific developmental language or reading disorders calls for ruling out mental retardation, peripheral auditory or visual dysfunction, autism, frank neurological impairments such as hemiplegia or seizure disorder, and severe social deprivation or lack of educational opportunity. The typical profile of a developmentally dysphasic or dyslexic child is one who shows a marked discrepancy between nonverbal (performance) IQ and verbal IQ, with a history of delayed or disordered speech, language and/or reading development. Such a child usually performs quite normally on visual spatial tasks, while demonstrating severe deficits in tasks of auditory temporal processing, motor sequencing, phonological processing and memory, language, reading and spelling. This characteristic neuropsychological profile may suggest left hemisphere dysfunction or a failure to develop normal cerebral lateralization. The etiology of these developmental learning disorders is unknown, but there is evidence of familial aggregation, indicating a potential genetic basis. Although these children respond to remediation, longitudinal studies have shown that the symptoms often persist into adulthood (see Tallal, 1988, for a more detailed discussion).

Female↗
PubMed1991

Anticipatory coarticulation in the speech of adults and young children: acoustic, perceptual, and video data.

Three experiments investigated anticipatory lingual and labial coarticulation in the [sV] productions of children and adults. Acoustic, perceptual, and video data were used to trace the development of intrasyllabic coarticulation in the speech of adults and children (ages 3, 5, and 8 years). Although children show greater variability in their articulatory patterns than adults, the data do not support claims that young children produce a greater degree of intrasyllabic coarticulation than older children or adults. Rather, the acoustic and video data suggest that young children and adults produce similar patterns of anticipatory coarticulation, and the perceptual data indicate that coarticulatory cues in the speech of 3-year-old children are less perceptible than those of the other age groups.

Adult↗
PubMed1990

A developmental, interactive activation model of the word superiority effect.

Parallel distributed processing (PDP) models of reading developed out of an appreciation of the role that context plays in letter and word perception. Adult readers can more accurately identify letters in a word than alone or in other random display contexts, a phenomenon known as the Word Superiority Effect (WSE). We examined the effects of orthographic context on the letter recognition skills of dyslexic children, comparing their performance to adults, and chronological- and reading-age matched groups. Consistent with previous studies, results showed adults better able to identify letters in the context of words and pseudowords than in random letter strings. Young normal readers demonstrated the WSE, but their pseudoword advantage was less than adults. The dyslexic children showed no WSE at all. PDP computer simulations for the experimental data using the Interactive Activation model (IA) suggested that the orthographic components of the lexical system of normal children are interactive and distributed as they are in adults but provide less bottom-up activation. In addition, top-down processing increases with age and reading skill, but may be absent for dyslexic readers.

Adult↗
PubMed1990

Late childhood changes in brain morphology observable with MRI.

Quantitative studies of brain morphology in groups of normal children aged eight to 10 years and of young adults aged 25 to 39 years revealed continuing maturation of the brain over this age-range. There was some evidence of slightly increasing brain volume, but the most striking changes occurred in the gray matter to white matter ratio, and especially in the cortical mantle, which becomes substantially thinner on MRI between the age of eight and adulthood. An increase in the volume of the cerebral ventricles occurred in close association with the decrease in cortical gray matter. Analyses of the morphology of the cerebellar vermis suggest that significant increases occur in the neocerebellar vermal area over this age-range, and that the ratio of neocerebellar to paleocerebellar vermal areas may also increase.

Adult↗
PubMed1990

Selecting language-impaired children for research studies: insights from the San Diego Longitudinal Study.

The need for a standardized approach to the selection of research subjects for studies on language impairment has long been an area of controversy in the literature. The data obtained from the selection of language-impaired and control subjects for the San Diego Longitudinal Study allows one to evaluate the effects a two-stage subject-selection procedure has on the characteristics of the language-impaired and normal subjects selected for research studies. Specifically, what effect do quantitative measures, as compared to clinical judgements and referrals, have on the characteristics of subjects selected for research studies? Explicit and detailed oral and written descriptions of subjects sought for both a language-impaired group and a control group were given to teachers and clinicians. However, only 39 of the first 100 children referred as language-impaired and 29 of the first 60 referred as normal controls were found on standardized testing to meet the study criteria and to be matched on important variables, such as IQ and socioeconomic status. These results demonstrate the importance of establishing quantitative inclusionary as well as exclusionary criteria for selecting and matching subjects in clinical research studies.

Child, Preschool↗
PubMed1989

Unexpected sex-ratios in families of language/learning-impaired children.

There is a well-documented propensity of males affected with developmental language/learning impairment. Results from this study demonstrate, unexpectedly, that this sex-ratio difference of males to females with developmental language/learning disorders was found to occur significantly only in families with a language/learning-impaired mother. In addition, a remarkably aberrant offspring sex-ratio was found in families of language/learning-impaired children who had an affected mother, but not father. Mothers who were developmentally language/learning-impaired had three times as many sons as daughters, and five times as many language/learning-impaired sons as daughters. Genetic and hormonal influences that might affect both sex-ratio and neuroanatomical development and disorders are discussed.

Child, Preschool↗
PubMed1989

Familial aggregation in specific language impairment.

Self-report data from the families of children participating in the San Diego Longitudinal Study of specific developmental language impairment were used to assess familial aggregation in the disorder. Families of impaired children reported higher rates of affected first-degree relatives than did families of matched controls. Significantly higher incidence of maternal and paternal childhood language and/or learning disabilities, as well as sibling disability rates, were reported. The extent to which familial aggregation reflects genetic or environmental influences in specific language disorders remains to be determined.

Adult↗
PubMed1989

Metabolic correlates of learning disability.

To summarize, the neuropsychologic findings in MSUD and MMA children in both groups demonstrated deficits in cognitive/language areas, but interesting individual differences existed. For example, a marked contrast in abilities existed between NT and GV, even taking into account the age difference between these children with MSUD. While NT's general intellectual functioning was within the low-average range, GV was severely impaired. In more specific areas of cognitive functioning, NT had an uneven performance profile with areas of strengths and weaknesses, while GV evidenced a flat profile with significant impairment in all areas. NT demonstrated mild delay in visual-spatial processing, articulation development, motor-speech abilities, and selective attention and concentration; however, his language and psychosocial development were within the broad range of normality. In contrast, GV exhibited severe dysfunction in speech, language, and perceptual/conceptual development. The three children with MMA also exhibited a range of disabilities in cognitive functioning. TJ and SH contrasted in the degree of developmental delay across language and cognitive domains. Both were distractible and exhibited very short attention spans but there was a measurable difference in the extent of their speech, language, visual-spatial development. CH was markedly delayed in all areas of cognitive development, which is consistent with global retardation. The severity of her disease and its probable impact on brain development were undoubtedly related to her intellectual impairment. These datasets illustrate the challenges we face, because within each group we see a range of impairment. Nevertheless, we are optimistic that our efforts to relate metabolic, anatomic and neuropsychologic findings for such children will lead to a better understanding of these disorders. We are hopeful that this will result in new advances in diagnosis and intervention, which will ultimately improve the prognosis for cognitive development. In summary, a multidisciplinary center has been established at UCSD to study the neurologic basis of disorders of language, learning and behavior in infants and children. The center draws together a group of researchers from many fields including neurology, biochemistry, pediatrics, cognitive and developmental neuropsychology, psycholinguistics, neurophysiology and communicative disorders. Because of the diverse interests and expertise of our group, it is hoped to forge a synthesis of the behavioral and neurosciences to study populations of children with a variety of neurologic, metabolic, and language/learning disorders. Disorders currently under study include Lesch-Nyhan disease, oculocutaneous tyrosinemia, propionic acidemia, carnitine palmityl transferase deficiency, Schwachman-Diamond syndrome, histidinemia, Hartnup disease, citrullinemia, galactosemia, maple syrup urine disease, and methylmalonic acidemia.(ABSTRACT TRUNCATED AT 400 WORDS)

Child↗
PubMed1985

The relationship between auditory temporal analysis and receptive language development: evidence from studies of developmental language disorder.

The relationship between sensory, perceptual and motor abilities and receptive language abilities was studied in developmental dysphasic children. The tests administered included experimental auditory, visual and cross-modal perceptual tests. In addition, a battery of neurodevelopmental "soft sign" sensory, perceptual and motor tests were also given. Demographic and case history data were collected. Receptive language was derived based upon a battery of standardized language tests. Multivariate analyses were employed to examine the relationship between receptive language and sensory, perceptual and motor abilities. Results demonstrated that auditory perceptual variables, specifically those requiring rapid temporal analysis, were most highly correlated with the degree of receptive language deficit of the dysphasic children.

Aphasia↗
PubMed1985

Identification of language-impaired children on the basis of rapid perception and production skills.

Discriminant function analysis was used to determine whether performance on temporal perception and production tasks alone could correctly classify children as language-impaired or normal. The analysis identified six variables, all of which assessed temporal perceptual and production abilities, which taken in combination correctly classified 98% of participating subjects. None of these variables assess the higher-level linguistic abilities (semantic, syntactic, pragmatic) that have classically been considered to be deficient in language-impaired children, or have been used to diagnose them clinically.

Aphasia↗