This study of the maturation of prestimulation‐induced modulation of startle in 3 to 8 year old children and adults demonstrated significant effects of age on both startle magnitude and onset latency. Startle was evoked by 104dB(SPL) 50‐ms bursts of white noise, and the amplitude and onset latency of the blink reflex were measured after integration of the obicularis oculi EMG. Prestimulation with 75dB 1000 Hz tones resulted in severe inhibition of both amplitude and latency in adults when 20‐ms tones preceded the startling stimuli by 120 ms or 250 ms. Following sustained prestimulation for 2000 ms, the adults showed modest nonsignificant response facilitation. Eight‐year‐old children showed mature inhibitory and facilitatory startle amplitude modulation, but significantly less inhibition and more facilitation of onset latency compared to adults. Preschool children showed significantly less amplitude and latency inhibition and more facilitation than 8‐year‐olds and adults. In response to prestimulation 120 ms before startling stimuli, the preschool children actually showed latency facilitation. Modulation of startle by prestimulation is mediated by brainstem neuronal networks. These findings suggest that brainstem mechanisms which mediate startle response modulation undergo development during early childhood and do not mature until about 8 years of age.
These results confirm that mild depressive symptoms are related to subjective memory loss, but for some forms of memory complaint, the relationship holds true only for people without the major known genetic risk for Alzheimer's disease.
The time constants and gains of the vestibulo-ocular reflex were computed from the primary nystagmus evoked by constant angular acceleration in 79 normal infants and children, ranging in age from 2 months to 11 years old, and 10 normal adults. There were significant changes in both time constant and gain in respect to development. The time constants increased while the gains decreased as a function of the logarithm of age. The time constants of the youngest infants were close to the cupular time constant. The lengthening of the time constant with increasing age was discussed in respect to maturation of inhibitory brainstem reticular formation mechanisms.
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