Context effects on processing widely deviant sounds in newborn infants

Early maturation of neural auditory novelty detection - Typical development with no major effects of dyslexia risk or music intervention

OBJECTIVE

To determine the early development of novelty detection and the effect of familial dyslexia risk and infant music intervention on this development.

METHODS

In the longitudinal DyslexiaBaby study, we investigated the maturation of novelty-P3 and late-discriminative negativity (LDN) event-related potentials to novel sounds at birth (N = 177) and at the ages of 6 (N = 83) and 28 months (N = 131).

RESULTS

Novelty-P3 was elicited at all ages, whereas LDN was elicited at 6 and 28 months. Novelty-P3 amplitude was largest at 6 months, and its latency decreased with age. LDN amplitude decreased and latency increased between 6 to 28 months. Dyslexia risk or intervention had no effects, apart from a longer LDN latency in the high-risk than no-risk group.

CONCLUSIONS

Already neonates respond to novel environmental sounds, indicating prerequisites for detecting potentially relevant events at birth. Maturation influences neural novelty detection.

SIGNIFICANCE

Novelty detection is crucial for perceiving important events, but its early development has been scarcely studied. We found, with a large sample, that neonates detect novel events, and showed the developmental pattern of its neural signature. The results serve as a reference for studies on typical and atypical novelty-detection development in infancy when behavioral testing is challenging.

Brain and Emotion

Progress in understanding the relation between brain profiles and emotions is being slowed by the belief in a collection of basic emotional states, with the names: fear, anger, joy, disgust, and sadness, that do not specify the species or age of the experiencing agent, the origin of the state, or the evidence used to infer it. This article evaluates critically the premise that decontextualized emotional words refer to natural kinds. It also suggests that investigators set aside the currently popular words and search for relations, in humans and animals, between patterns of measures to varied incentives presented in distinctive contexts.

Processing of Horizontal Sound Localization Cues in Newborn Infants

OBJECTIVES

By measuring event-related brain potentials (ERPs), the authors tested the sensitivity of the newborn auditory cortex to sound lateralization and to the most common cues of horizontal sound localization.

DESIGN

Sixty-eight healthy full-term newborn infants were presented with auditory oddball sequences composed of frequent and rare noise segments in four experimental conditions. The authors tested in them the detection of deviations in the primary cues of sound lateralization (interaural time and level difference) and in actual sound source location (free-field and monaural sound presentation). ERP correlates of deviance detection were measured in two time windows.

RESULTS

Deviations in both primary sound localization cues and the ear of stimulation elicited a significant ERP difference in the early (90 to 140 msec) time window. Deviance in actual sound source location (the free-field condition) elicited a significant response in the late (290 to 340 msec) time window.

CONCLUSIONS

The early differential response may indicate the detection of a change in the respective auditory features. The authors suggest that the late differential response, which was only elicited by actual sound source location deviation, reflects the detection of location deviance integrating the various cues of sound source location. Although the results suggest that all of the tested binaural cues are processed by the neonatal auditory cortex, utilizing the cues for locating sound sources of these cues may require maturation and learning.

Detecting the temporal structure of sound sequences in newborn infants

Most high-level auditory functions require one to detect the onset and offset of sound sequences as well as registering the rate at which sounds are presented within the sound trains. By recording event-related brain potentials to onsets and offsets of tone trains as well as to changes in the presentation rate, we tested whether these fundamental auditory capabilities are functional at birth. Each of these events elicited significant event-related potential components in sleeping healthy neonates. The data thus demonstrate that the newborn brain is sensitive to these acoustic features suggesting that infants are geared towards the temporal aspects of segregating sound sources, speech and music perception already at birth.