Short-term memory impairment and unilateral dichotic listening extinction in a child with Landau-Kleffner syndrome: auditory or phonological disorder?

The neuropsychological profile of a child with a Landau-Kleffner syndrome is presented here. The observed cognitive difficulties included verbal short-term memory and seemed partially compensated for when the experimental assessments bypassed the auditory channel. This case study is especially challenging since the child, whose phonological skills were quite efficient and who exhibited a dichotic listening unilateral extinction, had developed average reading and spelling abilities. The fact that B.E.'s performance on memory tasks was quite poor when the stimuli were presented auditorily and more efficient when the stimuli were presented visually, strongly suggests that the observed memory impairment was due to a deficit at the level of cortical auditory processing. B.E.'s phonological skills were efficient, suggesting a neuropsychological dissociation between phonological ability and auditory processing. The fact that B.E. dramatically recovered language and easily acquired reading and spelling accounts for the hypothesis that compensatory strategies allowed him to develop phonological skills from predominantly visual input.

Language development in a child with left hemispherectomy.

A longitudinal study of a left hemispherectomized boy (AB) was conducted to document linguistic evolution and maturation and determine the extent to which right hemisphere processes allow development of language. Resection of the left hemisphere occurred at age 5 years 6 months, following intractable epilepsy. Tests of language comprehension (pointing, understanding of prepositions, understanding of narratives) and production (naming, repetition, lexical diversity, grammatical production) were administered at ages 6:2, 6:4, 6:6, and 6 years 9 months. Observations showed little progress, if any, in most aspects of linguistic performance. In contrast to studies with left-hemispherectomized children, AB showed only a modest expansion of the semantic lexicon and the phonological repertoire more than a year after the surgical intervention. These observations indirectly suggest (1) poor functional involvement of the right hemisphere in the development of adequate linguistic abilities, (2) the necessary integrity of the LH for adequate development of language, or (3) that variations in individual brain maturation rates may account for AB's linguistic progress.

Child speech and language assessment and measurement.

The necessity of using standardized and norm-referenced tests in assessing speech and language of impaired children has now been recognized. Thus it seems useful to summarize based on the literature principles for founding such testing methods. These include: a) the necessity for a neuropsycholinguistic model that allows the speech-language pathologist to relate the observed linguistic behavior to underlying language processes, b) the knowledge of the psychometric characteristics required for language tests, and c) a discussion of some of the difficulties or controversed points from clinical practice. Among these latter the following are discussed: 1) measurement versus clinical observation, 2) screening versus exhaustive assessment, 3) language linguistic aspects versus pragmatic dimension, 4) formal tasks versus spontaneous language analysis, 5) linguistic versus metalinguistic assessment, 6) "knowledge-dependent" versus "processing-dependent" tests, 7) early detection of at risk children versus diagnosis of developmental language disorders. Diagnosticians are advised to be aware of the principles to respect when assessing child language.

Developmental changes in the clustering pattern of sleep rapid eye movement activity during the first year of life: a Markov-process approach.

Findings are presented in support of the hypothesis that the tendency of sleep rapid eye movement (REM) activity to group into burst structures changes with age during the first year of life in normal infants. Specifically, by assuming a markovian model for the generation of 1 sec long units of REM activity, it is shown that the propensity of those units to develop a sustained clustering pattern may increase during the first 2 months, possibly reaching a plateau at about 4 months. On the other hand, the overall density of REM activity units may continue to increase beyond that point in time.

Spontaneous non-nutritive sucking in continuously fed infants.

In order to investigate the effects of a deprivation of the nutritive sucking (NS) on the activity of non-nutritive sucking (NNS), we examined 8 infants (ages 1-13 months) continuously fed by intracaval catheter. They had no NS experience at all from birth. Eight age-matched normally fed infants served as controls. The infants were examined for a full 24-h period by polygraphic recordings and behavioural observation. The amount of NNS was computed for the whole 24-h period and separately for each behavioural state (waking, quiet sleep, paradoxical sleep and ambiguous sleep). All the continuously fed infants showed a typical pattern of NNS. There were no differences in amount of NNS between continuously fed and control infants in any behavioural state. These results suggest that NS does not contribute to the long term maintenance of the NNS activity.

Sleep patterns in infants under continuous feeding from birth.

Continuous parenteral or enteral feeding of infants with major gastrointestinal problems (prolonged diarrhoeas, inflammatory digestive illnesses, anatomical anomalies necessitating surgical intervention, etc.) brings about a prolonged modification in nutritional and environmental conditions. The consequence of eliminating the feeding rhythms of the waking-sleeping rhythm in 16 infants between 1 and 8 months old were studied. In most of the infants the duration of sleep was close to that given by Kleitman in normals. Slightly decreased in 4 of the infants, these durations never showed significant differences from normative values. No delay was observed in the maturation of sleep patterns. The percentage and mean length of periods of quiet sleep were practically identical for all infants but a number of them showed large amounts of ambiguous sleep. The fact that none of these values evolved with age should be stressed. Paradoxical sleep periodicity was similar to that of normal infants, while the quiet sleep-paradoxical sleep cycles were shorter. In conclusion, the absence of feeding rhythms appeared not to modify greatly the sleep maturation and organization.