Binaural Interaction in Human Neonatal Auditory Brainstem

Abstract

Binaural interaction (BI) in brainstem auditory evoked response (BAER) were examined in normal term neonates. The BI components coincided consistently with the latency range of BAER wave IV through wave VII. Most BI components seen in the adults could be identified in the neonates, but the later components, i.e. those with longer latency, were underdeveloped in wave form. Wave DV was the most consistent and reproducible BI component. A marked difference between the neonatal and adult BI wave forms was that wave DVII was particularly small in the neonates. It appears that neuronal responses contributing to later BI components such as wave DVII are particularly immature at birth. Wave latencies and interpeak intervals were longer and amplitudes were smaller in the neonates than in the adults, which was associated with the differences between the neonates and adults in the BAER components. Changes in the BI components with stimulus intensity and rate in the neonates were fundamentally similar to but more significant compared with those in the adults. These findings suggest that neural connections in human auditory brainstem subserving the BI are established at birth but, particularly at higher levels of the brainstem, are immature.

Brainstem Auditory Evoked Response Recorded Using Maximum Length Sequences in Term Neonates

“…These general trends in the intensity-dependent changes in the MLS BAER are similar to those observed in conventional BAER [1,6,8,18].…”

Binaural Interactions Develop in the Auditory Brainstem of Children Who Are Deaf: Effects of Place and Level of Bilateral Electrical Stimulation

“…Although previous studies of normal human binaural processing have used magnetic resonance imaging of the inferior colliculus (Thompson et al, 2006), this technique is contraindicated for CI users (Majdani et al, 2008). Binaural interaction can also be studied using electrophysiology as shown in normal hearing individuals (Wada and Starr, 1989;Furst et al, 1990;Jiang and Tierney, 1996;Goksoy et al, 2005) as well as bilateral CI users (adults: He et al, 2010; children: Gordon et al, 2007a;cats: Smith and Delgutte, 2007). Using this technique, we demonstrate that binaural processing in the brainstem of children using bilateral CIs: (1) occurs regardless of bilateral or unilateral deafness, (2) is disrupted by large but not small mismatches in place of stimulation and (3) codes perceptible changes in level cues.…”

Processing of Horizontal Sound Localization Cues in Newborn Infants

“…Electrophysiological studies using auditory brainstem response (ABR) and middle latency response (MLR) techniques have revealed that although the neural mechanisms responsible for binaural processing are established at birth, they are immature (especially at higher stations of the brainstem) and require activity-based sensory experience for improved localization accuracy (Jiang and Tierney, 1996;Cone-Wesson, Ma and Fowler, 1997;King et al, 2001; for a review, see Fowler, 2004). Further, during the first months following birth, rapid change in head size takes place, which requires continuous recalibration of the auditory spatial 4 map of infants (Clifton et al 1988;King et al 2001).…”

“…By measuring short-latency electrophysiological responses, such as ABR and MLR, previous results have indicated that the auditory pathways responsible for sound localization are functional at 5 birth (Jiang and Tierney, 1996;Cone-Wesson, Ma and Fowler, 1997;Furst et al, 2004).…”

“…In each stimulus block, sounds appeared frequently at one side and infrequently at the other side. Starting from the results of the shortlatency electrophysiological measures on sound localization in young infants (Jiang and Tierney, 1996;Cone-Wesson, Ma and Fowler, 1997;Furst et al, 2004), we hypothesize that both the individual binaural cues of sound location as well as actual source location is further processed in the neonatal auditory cortex. This innate cortical sensitivity to sound source location would be reflected in significant differences between the ERP responses elicited by the rare and the frequent sounds (MMR elicitation) in all four stimulus conditions.…”