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Biomedical subjects

A Salamy

Publications and source records attributed to A Salamy.

At least 37 records · Page 2Linked to original sources
PubMed1981

Maturational effects on the middle components of the averaged electroencephalic response.

Middle component AERs to brief click stimuli were recorded from 60 subjects in four age groups to assess age effects on waveform, latency, and amplitude. Replicable responses similar in waveform to those recorded in adults were observed in 3 - 4-year-old children, full-term newborns, and premature infants tested as early as the 31st postconceptional week. Latencies and amplitudes were compared across ages and significant age effects were evident for amplitude but not latency. Amplitudes of components Po, Pa and Pb were found to increase until 3 - 4 years of age and decline in adulthood. Response amplitudes for premature infants differed significantly from those of adults, but newborns' responses did not differ from either group. Only the responses of 3 - 4-year-old children were clearly differentiated from those of all other groups in this respect. Significant age effects on latency were found only for Po, which is postulated to be synonymous with Wave V of the brainstem response. The absence of a trend for decreasing latency as a function of age in the middle components is surprising in that both early (brainstem) and late (cortical) responses demonstrate this effect. This finding raises questions about the generator sources for middle components.

Adult↗
PubMed1981

Binaural interactions in the short-latency evoked potentials of neonates.

Short-latency evoked potentials to monaural and binaural clicks were recorded from scalp electrodes on healthy full-term neonates and on normally hearing adults. Binaural interaction (BI) was measured by summing the average monaural responses obtained from each ear (L+R) and subtracting the binaural response (B) from the monaural sum (BI=L+R-B). Consistent BI was apparent following stimulation with moderate level clicks in all cooperative infants. As in the adult, BI occurred during waves IV, V and VI, where there were systematic amplitude differences between the L+R and B waveforms. Peak latencies of the waves were not significantly affected. However, peak latencies were longer in neonates than in adults, reflecting maturational changes in the response. Similarly, peak latencies in the BI waveforms were also prolonged for the neonates. These results indicate that: (1) BI is present at or soon after birth; (2) the gross response properties of BI are similar in infants and adults; (3) BI occurs during specific waves in the response, independent of age, and (4) the assessment of BI may prove useful in estimating the functional integrity of brain stem structures in infants.

Audiometry, Evoked Response↗
PubMed1981

The theoretical distribution of evoked brainstem activity in preterm, high-risk, and healthy infants.

The observed scores for a number of parameters (amplitude, latency, interwave differences, and ratios) of the brainstem auditory evoked potential (BAEP) were plotted in order to ascertain the sampling distribution at selected ages. Comparisons between preterm and high-risk infants and healthy controls were also made. The cumulative frequency histograms for all but one BAEP variable were found to be normally distributed. Although this finding held across the age and diagnostic category, healthy and risk populations revealed distinct curves due primarily to the dispersion of scores rather than to the shape of the distributions. Only the amplitude ratio of waves 1 and 5 did not match the normal curve. The assumption of normality which underlies most "standard" statistical analyses can therefore be met for many BAEP measures.

Brain Stem↗
PubMed1980

Differential development of brainstem potentials in healty and high-risk infants.

Maturation along the brainstem acoustic pathway, as well as the integrity of these structures, has been shown to be reflected in brainstem evoked potential recordings. Trajectories formed from repeated sequential measurements of several brainstem response variables reveal distinct developmental curves for healthy and high-risk infants. Longitudinal analysis offers a means of determining temporary or permanent maturational effects on the central nervous system in early life.

Age Factors↗
PubMed1980

Contrasts in brainstem function between normal and high-risk infants in early postnatal life.

Brainstem auditory evoked potentials (BAEPs) were recorded from healthy and high-risk infants at selected ages throughout their first year of life. Amplitude and latency measurements of peaks I, III and V were treated in a series of multivariate analyses of variance. Significant main effects for age (newborn, 3 wk, 6 wk, 3 mth, 6 mth and 1 yr), group (healthy, risk) and peaks (amplitude and latency of BAEP waves I, III and V) were observed. In addition, the interaction between these factors proved statistically significant. As expected, the pattern of response amplitude and latency for the various peaks differed as a function of age. Moreover, healthy and risk infants revealed different maturational trends. These results indicate that infants born 'at risk' but free of severe auditory deficits and major neurological difficulties can be distinguished from healthy (age-matched) controls in terms of the BAEP throughout the first postnatal year.

Brain Stem↗
PubMed1979

Brain stem evoked potential findings in children with otitis media.

Sixty-three children from 2 to 12 years of age were studied by means of brain stem evoked potentials (BEP) and otoscopic evaluation in a preliminary assessment of the sensitivity of BEP latency measures to middle ear abnormality. Wave I proved to be the most sensitive component; 81.25% of subjects with acute suppurative otitis media and 62.50% of subjects with secretory otitis media demonstrated latencies prolonged by more than 1 SD beyond the values observed in normal control subjects. Of the same subject groups, 86.21% and 93.31% demonstrated wave I latencies within normal limits upon retesting after the otitis had resolved. The BEP technique permitted identification of several subjects with abnormal audiometric findings despite normal otoscopy. There are implications for use of the BEP as a clinical adjunct to traditional methods of auditory assessment.

Acute Disease↗
PubMed1979

Ontogenesis of human brainstem evoked potential amplitude.

Brainstem evoked potentials (BEP's) were studied in human subjects ranging in age from birth to adulthood. The BEP's were recorded from the surface of the scalp referenced to either ear while brief clicks were delivered binaurally through earphones. Separate analyses of variance were computed for the peak-to-peak amplitude of each component of the BEP. Significant age effects were observed documenting the strong relationship between human brainstem development and amplitude changes in the BEP. The independent maturation of these structures was reflected by the significant interaction between age and peaks. Despite small fluctuations in the maturational curve of each peak, strong linear and quadratic trends were apparent. The research presented here provides evidence of significant amplitude changes in the BEP accompanying human development. These findings indicate that brainstem maturation is not yet complete at birth and that the components believed to represent spatially separate generators in the auditory system show distinct maturational stages.

Acoustic Stimulation↗
PubMed1978

Commissural transmission: maturational changes in humans.

Latency differences between ipsilateral and contralateral somatosensory evoked potentials show maturational trends in keeing with the myelogenic timetable and development of the corpus callosum. The distribution and modality-specific projection of early ipsilateral activity suggests an origin in the contralateral posterior-parietal area.

Adolescent↗
PubMed1976

Postnatal development of human brainstem potentials during the first year of life.

Average brainstem potentials evoked by auditory stimuli were recorded from the scalp's surface of human newborns and infants, 6 weeks, 3 months, 6 months and 1 year of age as well as from normal adults. The auditory processes related to peripheral transmission (PT) and central transmission (CT) were shown to mature at differential rates during the first year of life. By the 6th week PT had reached the adult latency. In contrast, CT through the brainstem did not match that of the adult until approximately 1 year of age. In addition, the waveform of the brainstem evoked potential (BEP) displayed an independent time course for development. The adult configuration replaced the infantile response by 3--6 months. Despite considerable inter-subject variability in the BEP amplitude during the neonatal period, a general wave-form pattern could easily be delineated. Preliminary results revealed the BEP to be quite resistant to habituation following continuous stimulus presentation. Longitudinal follow-ups on several babies paralleled the transverse data.

Adult↗