The cerebral hemodynamic response to phonetic changes of speech in preterm and term infants: The impact of postmenstrual age

Abstract

Higher brain dysfunction, such as language delay, is a major concern among preterm infants. Cerebral substrates of cognitive development in preterm infants remain elusive, partly because of limited methods. The present study focuses on hemodynamic response patterns for brain function by using near-infrared spectroscopy. Specifically, the study investigates gestational differences in the hemodynamic response pattern evoked in response to phonetic changes of speech and cerebral hemispheric specialization of the auditory area in preterm infants (n = 60) and term infants (n = 20). Eighty neonates born between 26 and 41 weeks of gestational age (GA) were tested from 33 to 41 weeks of postmenstrual age (PMA). We analyzed the hemodynamic response pattern to phonemic and prosodic contrasts for multiple channels on temporal regions and the laterality index of the auditory area. Preterm infants younger than 39 weeks of PMA showed significantly atypical hemodynamic patterns, with an inverted response shape. Partial correlation analysis of the typicality score of hemodynamic response revealed a significant positive correlation with PMA. The laterality index of preterm infants from 39 weeks of PMA demonstrated a tendency rightward dominance for prosodic changes similar to term infants. We provide new evidence that alterations in hemodynamic regulation and the functional system for phonemic and prosodic processing in preterm infants catch up by their projected due dates.

Cerebral hemodynamic responses in preterm-born neonates to visual stimulation: classification according to subgroups and analysis of frontotemporal–occipital functional connectivity

“…This finding is in contrast to other studies. 22,23 In our results, weight at measurement was more important. Unfortunately, previous fNIRS studies of preterm-born neonates did not analyze a possible association between the weight and the HR shapes/signs.…”

“…A recent fNIRS study examining the phase relationship of spontaneous oscillations of Δ½O 2 Hb and Δ½HHb 23 further revealed rapid changes in neurovascular regulation from neonates with a PMA of 34 to term, which was similarly seen in response to phonetic changes of speech in preterm-born and term-born infants. 22 Watanabe et al 23 showed that the phase relationship of spontaneous oscillations of Δ½O 2 Hb and Δ½HHb in very preterm-born infants was lower than term-born infants and had a slower development compared with late preterm-born and term-born infants at later PNA, suggesting that (1) early preterm-born infants may have an advanced development of their circulatory process after birth and that (2) the structural and/or functional aspects of the development of the neurovascular system may be altered during the first month of life.…”

“…[18][19][20] However, the development of the HRF pattern in the human brain remained unclear; some fNIRS studies reported an inverted HRF pattern (i.e., a decrease in blood flow or [O 2 Hb]) in young infants in response to perceptual stimuli, whereas some studies did not. 2,21,22 This has been a controversial issue, and investigations about this aspect in preterm-born neonates are particularly sparse, partly because the investigation of HRFs of these neonates using fNIRS is a relatively new subject. [22][23][24] Notably, a recent fNIRS study 23 reported developmental changes in phase differences of spontaneous low-frequency oscillations of [O 2 Hb] and [HHb] in pretermborn infants.…”

“…2,21,22 This has been a controversial issue, and investigations about this aspect in preterm-born neonates are particularly sparse, partly because the investigation of HRFs of these neonates using fNIRS is a relatively new subject. [22][23][24] Notably, a recent fNIRS study 23 reported developmental changes in phase differences of spontaneous low-frequency oscillations of [O 2 Hb] and [HHb] in pretermborn infants. Although such developmental changes in neurovascular regulation are very intriguing, these results come only from resting-state (rs) measurements.…”

fNIRS for Tracking Brain Development in the Context of Global Health Projects

“…As the number of fNIRS publications on neurodevelopment continues to grow, so does the range of topics it is being used to investigate. For example, the past year has seen the publication of fNIRS infant studies focusing on speech processing [4,5], social perception and interaction [6], and face perception [7,8], alongside studies investigating more complex processing networks such as mimicry and self-perception [9,10], touch [11][12][13][14] and live interaction [15,16].…”