Early Specialization for Voice and Emotion Processing in the Infant Brain

Abstract

Human voices play a fundamental role in social communication, and areas of the adult "social brain" show specialization for processing voices and their emotional content (superior temporal sulcus, inferior prefrontal cortex, premotor cortical regions, amygdala, and insula). However, it is unclear when this specialization develops. Functional magnetic resonance (fMRI) studies suggest that the infant temporal cortex does not differentiate speech from music or backward speech, but a prior study with functional near-infrared spectroscopy revealed preferential activation for human voices in 7-month-olds, in a more posterior location of the temporal cortex than in adults. However, the brain networks involved in processing nonspeech human vocalizations in early development are still unknown. To address this issue, in the present fMRI study, 3- to 7-month-olds were presented with adult nonspeech vocalizations (emotionally neutral, emotionally positive, and emotionally negative) and nonvocal environmental sounds. Infants displayed significant differential activation in the anterior portion of the temporal cortex, similarly to adults. Moreover, sad vocalizations modulated the activity of brain regions involved in processing affective stimuli such as the orbitofrontal cortex and insula. These results suggest remarkably early functional specialization for processing human voice and negative emotions.

Affective and non-affective touch evoke differential brain responses in 2-month-old infants

“…Infants are known to process sensory information in both active and quiet sleep (Desmedt and Manil, 1970;Kotilahti et al, 2005;Pihko, 2004). Since we found activation in areas that coincide with the results from other studies with socially relevant stimuli both in sleeping and awake infants (Lloyd-Fox et al, 2009;Blasi et al, 2011), we conclude that emotional or social information in the infant brain are processed also during sleep.…”

Sleep and Emotional Functions

“…Recent imaging data in 3-to 7-month olds infants also revealed specific brain responses to emotional human vocalizations during sleep, involving the orbitofrontal cortex and insula (Blasi et al 2011). Furthermore, it is noteworthy that active (or REM) sleep occupies the biggest portion of a child's sleep and occurs much earlier in human development than proper dreaming (Foulkes 1993).…”

“…The recruitment of emotional and reward circuits during sleep might reflect the affective and motivational components of the dreaming experience. While a link with dreaming is plausible, this proposal may not fully account for the fact that activation of these networks is present across many different species (e.g., rats, humans), and can also be elicited in sleeping babies from 3-to 7-month old of age (Blasi et al 2011), that is, before the emergence of dream consciousness (Hobson 2009). Here, we review a series of recent studies supporting the hypothesis that the processing of emotional and reward-related information is preserved during sleep, and may offer a major evolutionary advantage for neurophysiological adjustments underlying waking behavioral fitness and emotional well-being.…”

Characteristics of the Understanding and Expression of Emotional Prosody among Children with Autism Spectrum Disorder

“…The children performed similar to adults [41]. In contrast, functional magnetic resonance studies [42] find that 3 to 7 month old infants are able to discriminate emotional vocalizations (positive, neutral and negative). These results together may indicate that following language acquisition children tend to vacillate between emotional prosody and linguistic meaning.…”