Poster #: 39
Topic: Development (infancy, childhood, adolescence, and aging)
Friday, Sep 11, 2015
Large auditory evoked potentials to rare emotional stimuli in pre-term infants at term age
In this study, we evaluated the pre-attentive processing of linguistic and emotional information in preterm and term-born infants by recording auditory evoked potentials (aERP). Preterm (n=9; mean birthweight 1395 g, range 930–1950 g; mean gestational weeks 30.4, range 26.7–33.3) and healthy, term-born control (n=20; gestational weeks 38–42) infants were assessed at term age. The stimuli were presented in a multi-feature mismatch negativity (MMN) paradigm with a standard tone (50 %) and five different deviant stimuli (~9%, each). In addition, three emotionally valenced rare stimuli (~1%, each) were occasionally presented. The standard stimulus was a naturally recorded pseudo-word /ta-ta/, and the deviants were linguistically relevant variations (e.g., frequency and vowel change) whereas the rare stimuli were happy, angry, and sad utterances of the standard.
Statistically significant discriminatory responses (rare-minus-standard aERPs) were recorded in both groups for all rare emotional sounds at 250– 350 ms and at 450– 550 ms post stimulus onset. The responses to the standard stimulus did not differ between groups. The discriminatory responses for all three emotional rare sounds were significantly (p < 0.05) larger in the preterm than in the control group at both time windows.
Large aERPs to rare stimuli in preterm infants show that they discriminate between the emotional and the standard stimuli. That the responses were larger in the preterm than in the control group may result from postnatal learning and therefore enhanced sensory processing. On-going follow-up studies will clarify the behavioural significance of these findings.