The development of the relationship between auditory and visual neural sensitivity and autonomic arousal from 6 m to 12 m.

The differential sensitivity hypothesis argues that environmental sensitivity has the bivalent effect of predisposing individuals to both the risk-inducing and development-enhancing influences of early social environments. However, the hypothesis requires that this variation in environmental sensitivity be general across domains. In this study, we focused on neural sensitivity and autonomic arousal to test domain generality. Neural sensitivity can be assessed by correlating measures of perceptual sensitivity, as indexed by event-related potentials (ERP) in electrophysiology. The sensitivity of autonomic arousal can be tested via heart rate changes. Domain generality was tested by comparing associations in perceptual sensitivity across auditory and visual domains, and associations between sensitivity in sensory domains and heart rate. We contrasted ERP components in auditory (P3) and visual (P1, N290 and P4) detection-of-difference tasks for N = 68 infants longitudinally at 6 and 12 months of age. Domain generality should produce correlated individual differences in sensitivity across the two modalities, with higher levels of autonomic arousal associating with increased perceptual sensitivity. Having controlled for multiple comparisons, at 6 months of age, the difference in amplitude of the P3 component evoked in response to standard and deviant tones correlated with the difference in amplitude of the P1 N290 and P4 face-sensitive components evoked in response to fearful and neutral faces. However, this correlation was not found at 12 months of age. Similarly, autonomic arousal correlated with neural sensitivity at 6 months but not at 12 months. The results suggest bottom-up neural perceptual sensitivity is domain-general across auditory and visual domains and is related to autonomic arousal at 6 months but not at 12 months of age. We interpret the development of the association of these markers of ES within a neuroconstructivist framework and with respect to the concept of interactive specialisation. By 12 months of age, more experience of visual processing may have led to top-down endogenous attention mechanisms that process visual information in a way that no longer associates with automatic auditory perceptual sensitivity.

Elevated physiological arousal is associated with larger but more variable neural responses to small acoustic change in children during a passive auditory attention task.

Little is known of how autonomic arousal relates to neural responsiveness during auditory attention. We presented N = 21 5-7-year-old children with an oddball auditory mismatch paradigm, whilst concurrently measuring heart rate fluctuations. Children with higher mean autonomic arousal, as indexed by higher heart rate (HR) and decreased high-frequency (0.15-0.8 Hz) variability in HR, showed smaller amplitude N250 responses to frequently presented (70%), 500 Hz standard tones. Follow-up analyses showed that the modal evoked response was in fact similar, but accompanied by more large and small amplitude responses and greater variability in peak latency in the high HR group, causing lower averaged responses. Similar patterns were also observed when examining heart rate fluctuations within a testing session, in an analysis that controlled for between-participant differences in mean HR. In addition, we observed larger P150/P3a amplitudes in response to small acoustic contrasts (750 Hz tones) in the high HR group. Responses to large acoustic contrasts (bursts of white noise), however, evoked strong early P3a phase in all children and did not differ by high/low HR. Our findings suggest that elevated physiological arousal may be associated with high variability in auditory ERP responses in young children, along with increased responsiveness to small acoustic changes.

Event-related potential correlates of sound duration: similar pattern from birth to adulthood.

The effects of sound duration on event-related potentials (ERP) were studied in newborns and adults. Increasing tone duration from 200 to 300 ms led to the enhancement of the N2 peak amplitude, whereas two peaks became distinguishable in the N2 response elicited by 400 ms long tones. The sound-duration related ERP changes most likely reflect contribution from the sustained potential, although the observed results can also be explained by assuming the elicitation of a sound-duration sensitive frontocentrally negative ERP component (duration-sensitive N2; DN2). The pattern of duration-related changes observed in newborn infants was very similar to that in adults, regardless of the structural differences between adult and infant ERPs. The results suggest that sound duration is processed already at birth in a similar way as in adulthood.

Central auditory processing of durational changes in complex speech patterns by newborns: an event-related brain potential study.

In this study, newborns' ability to discriminate durational changes in the fricative /s/ within a nonsense word was investigated. The results showed that infrequent increments and decrements of a speech sound duration elicit a mismatch negativity kind of response in sleeping human newborns. In the auditory event-related potential to these deviant stimuli two negative waves of this response were revealed. The first negative wave peaked at about 150 msec and the second at about 350 msec after the change onset. At least one negative deflection, which was interpreted as evidence for stimulus change-detection, was observed in every infant.