Near‐infrared spectroscopy reveals neural perception of vocal emotions in human neonates

Abstract

Processing affective prosody, that is the emotional tone of a speaker, is fundamental to human communication and adaptive behaviors. Previous studies have mainly focused on adults and infants; thus the neural mechanisms underlying the processing of affective prosody in newborns remain unclear. Here, we used near‐infrared spectroscopy to examine the ability of 0‐to‐4‐day‐old neonates to discriminate emotions conveyed by speech prosody in their maternal language and a foreign language. Happy, fearful, and angry prosodies enhanced neural activation in the right superior temporal gyrus relative to neutral prosody in the maternal but not the foreign language. Happy prosody elicited greater activation than negative prosody in the left superior frontal gyrus and the left angular gyrus, regions that have not been associated with affective prosody processing in infants or adults. These findings suggest that sensitivity to affective prosody is formed through prenatal exposure to vocal stimuli of the maternal language. Furthermore, the sensitive neural correlates appeared more distributed in neonates than infants, indicating a high‐level of neural specialization between the neonatal stage and early infancy. Finally, neonates showed preferential neural responses to positive over negative prosody, which is contrary to the “negativity bias” phenomenon established in adult and infant studies.

The Neural Processing of Vocal Emotion After Hearing Reconstruction in Prelingual Deaf Children: A Functional Near-Infrared Spectroscopy Brain Imaging Study

“…After the hearing is reconstructed, the auditory cortex receives better auditory stimulation. Because emotion recognition and positive bias could be observed in neonates as early as 0–4 days after birth in previous studies ( Zhang et al, 2019 ), we expected that ITCIs would respond to the four vocal emotional stimuli in 0–7 days after the CI is activated, and a stronger neural response will be observed in the right temporal area, with a positive bias. That is, happiness will cause stronger activation of the cortex than other vocal emotions.…”

“…Many studies have examined the neural processing for vocal emotions in infants with normal hearing, which may provide a reference for the neural processing associated with hearing loss. Information regarding the neural processing mechanism of vocal emotion was also reported in neonates ( Zhang et al, 2017 , 2019 ; Zhao et al, 2019 ). The results showed that vocal emotions enhance the activation of the right superior temporal gyrus (STG), the left superior frontal gyrus (SFG), and the left angular gyrus, which may indicate the regions associated with the neural processing of vocal emotional perception during neonatal development.…”

“…Although we make hypotheses based on the results of studies performed in people with normal hearing, our research is exploratory due to the lack of existing brain imaging studies evaluating the effects of severe-to-profound hearing loss on vocal emotional processing patterns. We hypothesized that the neural responses to the four vocal emotions in the preoperative test results of prelingual deaf ITCIs would not differ significantly due to the impacts of hearing loss, whereas the neural processing will differ from that observed for normal-hearing infants ( Zhang et al, 2019 ). That is, the region and intensity of cortical activation should be different.…”

A systematic review of studies that used NIRS to measure neural activation during emotion processing in healthy individuals

“…Nonetheless, studies implementing emotion prosody tasks identified the temporal cortex as a key area of activation owing to its involvement in the auditory network ( Zhang et al. , 2017 , 2019 ; Zhao et al. , 2019 ).…”

Significance of the ability to differentiate emotional prosodies for the early diagnosis and prognostic prediction of mild hypoxic‐ischemic encephalopathy in neonates

“…It reflects cerebral blood flow by measuring changes in ΔHbO 2 and ΔHb (Ferrari & Quaresima, 2012; Scholkmann et al., 2014). Studies have shown that changes in cerebral blood flow can be observed in neonates when stimulated by different emotional prosodies (Zhang et al., 2017, 2019), by comparing the response between healthy neonates and HIE neonates using event‐related potentials (ERP), studies have found an impaired ability to differentiate emotional prosodies in neonates with brain injuries (Sun et al., 2019), but ERP lacks spatial resolution for determining the brain region that is impaired in function.…”