Biomedical subjects
Publications and source records attributed to P Tallal.
The mechanisms by which human speech is processed in the brain are reviewed from both behavioral and neurobiological perspectives. Special consideration is given to the separation of speech processing as a complex acoustic-processing task versus a linguistic task. Relevant animal research is reviewed, insofar as these data provide insight into the neurobiological basis of complex acoustic processing in the brain.
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Children with language-based learning impairments (LLIs) have major deficits in their recognition of some rapidly successive phonetic elements and nonspeech sound stimuli. In the current study, LLI children were engaged in adaptive training exercises mounted as computer "games" designed to drive improvements in their "temporal processing" skills. With 8 to 16 hours of training during a 20-day period, LLI children improved markedly in their abilities to recognize brief and fast sequences of nonspeech and speech stimuli.
A speech processing algorithm was developed to create more salient versions of the rapidly changing elements in the acoustic waveform of speech that have been shown to be deficiently processed by language-learning impaired (LLI) children. LLI children received extensive daily training, over a 4-week period, with listening exercises in which all speech was translated into this synthetic form. They also received daily training with computer "games" designed to adaptively drive improvements in temporal processing thresholds. Significant improvements in speech discrimination and language comprehension abilities were demonstrated in two independent groups of LLI children.
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Recent advances in cognitive neuroscience, particularly studies utilizing functional neural imaging and animal models, are providing unique insights into the neural substrates of speech and other central auditory processes. In particular, the acoustic-phonetic aspects of speech appear to provide an important organizing principle for linking systems neuroscience research to cognitive and linguistic theories.
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Explore the source record for details and available documents.
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Eight children with developmental language impairment (LI) and eight age-, sex-, socioeconomic-status-, and I.Q.-matched controls were given tests of comprehension and expression of affective intent in spoken language and through facial expression. The LI children performed significantly more poorly than did controls in both comprehension and spontaneous expression of vocal affect. On tasks involving emotional facial expression, the opposite results were observed: The LI children were more dramatic in their expression of facial affect than were the controls. Children with language impairment appear to have a deficit in affective comprehension and expression that is modality-specific, i.e., limited to vocal affect. The heightened range of affective facial expression that they demonstrate may be a compensatory mechanism to offset their difficulties with vocal affect.
In 3 studies adult male rats showed significantly better discrimination of tone sequences with the right ear than with the left ear. This result parallels similar findings of left-hemisphere specialization for auditory temporal processing in humans and nonhuman primates. Furthermore, because clinical evidence supports a link between specialization of the left hemisphere for auditory temporal processing and for speech processing, these results may reflect evolutionary precursors to left-hemisphere language specialization. Because male rats showed a stronger ear advantage than female rats, the findings may relate to evidence of a stronger right ear advantage in men than in women. Finally, results suggest that neonatal handling enhances lateralization for auditory temporal processing in both sexes. Combined results implicate neuroendocrine mechanisms as important factors in the development of lateralization for auditory temporal processing.
Samples of conversational language were elicited with a standardized interview protocol from 24 children, aged 2:6 to 7:8, half with specific language impairment (SLI), half with normally developing language (LN), matched for language level. Samples were analyzed to determine whether there were associations between adult questioning and children's use of ellipsis. For the SLI children, but not the LN children, increased proportions of questions were significantly correlated to increased proportions of ellipsis. This finding has implications for the use of MLU measures in clinical and research practice.
OBJECTIVE: Investigate longitudinally the course of development of preschool learning impaired (LI) children to better understand the interaction between neurodevelopmental delay, behavioral/emotional disorders, and language development and disorders. METHOD: Relationships between developmental language disorders and emotional problems were investigated in 99 8-year-old specifically language impaired and control children originally assessed at age 4 years using the Achenbach Child Behavior Checklist and the Conners' Parents Questionnaire. RESULTS: LI children received higher behavior problem scores and were more likely to score in the clinical range than were control children. Neither degree of early language impairment nor amount of language improvement predicted 8-year behavioral/emotional status. LI children with the largest drop in IQ between ages 4 and 8 received the highest behavior problem scores. No significant comorbid relationship was seen between LI and attention-deficit hyperactivity disorder. CONCLUSIONS: The enhanced incidence of behavior problems reported heretofore may be related more to lower IQ than to linguistic deficit per se. Care must be taken to differentiate the symptoms of neurodevelopmental delay and emotional disturbance, however, preschool children with scores in the clinical range on such measures should be referred for additional evaluation.
Although there is still some disagreement whether developmental reading and language disorders are neurologically based, recent research provides increasing evidence that these disorders may be due to both abnormal cerebral lateralization patterns and neurological pathology at the cellular level. Technological advances in the field of neuroscience have led to increasing knowledge about brain-behavior relationships, particularly in the area of higher cognitive functions. Hypotheses about the underlying causes of the functional deficits characterizing developmental language and reading disorders are now focusing on specific neurological processing mechanisms, the disruption of which may be at the heart of these disorders.
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.
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.
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