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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

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↗
PubMed1979

Analysis of stop consonant production errors in developmentally dysphasic children.

The speech production skills of 12 dysphasic children and of 12 normal children were compared. The dysphasic children were found to have significantly greater difficulty than the normal children in producing stop consonants. In addition, it was found that seven of the dysphasic children, who had difficulty in perceiving initial stop consonants, had greater difficulty in producing stop consonants than the remaining five dysphasic children who showed no such perceptual difficulty. A detailed phonetic analysis indicated that the dysphasic children seldom omitted stops or substituted nonstop for stop consonants. Instead, their errors were predominantly of voicing or place of articulation. Acoustic analyses suggested that the voicing errors were related to lack of precise control over the timing of speech events, specifically, voice onset time for initial stops and vowel duration preceding final stops. The number of voicing errors on final stops, however, was greater than expected on the basis of lack of differentiation of vowel duration alone. They appeared also to be related to a tendency in the dysphasic children to produce final stops with exaggerated aspiration. The possible relationship of poor timing control in speech production in these children and auditory temporal processing deficits in speech perception is discussed.

Aphasia↗
PubMed1976

Rapid auditory processing in normal and disordered language development.

Four-and-one-half- to eight-and-one-half-year-old children with normal language development, normal adults, and dysphasic children were tested for their ability to perceive binary sequences of nonverbal auditory stimuli. Performance was studied in relation to the rate of presentation of stimulus sequence, as measured by the time interval between stimulus elements. Of the normal children studied, only the eight-and-one-half-year-old group responded as well as the adult group to auditory patterns composed of complex tones presented in rapid succession (8-305 msec intervals). Normal children six-and-one-half years and older were able to respond to these same auditory patterns when they were presented more slowly (947-4026 msec intervals). The overall pattern of performance of the dysphasic children was not similar to that of any age group of children with normal language development. The dysphasics' performance was significantly poorer than that of even the four-and-one-half-year-old normal group on rapidly presented auditory sequences, but not significantly different from normal children their own age or adults on the same patterns which were presented more slowly. The interrelation of normal development of rapid auditory processing and normal language development is discussed.

Adult↗