Auditory brainstem response in sheep. Part I: Fetal development

Abstract

The Auditory Brainstem Response (ABR) was recorded from fetal sheep in utero between gestational ages of 111 days and 136 days (Normal gestation is 145 days). The ABR was detected at 111 days gestation (dGA) and morphology of the waveform improved rapidly from 116 to 123 dGA. At 123 dGA, the four vertex-positive peaks were similar to those observed in adult ewes. Thresholds of the ABR to clicks and tone bursts improved rapidly between 111 and 123 dGA. From 123 to 136 dGA, ABR thresholds continued to improve, but at a much slower rate. Latencies for the peaks also decreased during development from 111 to 136 days, with latencies for Waves III and IV showing a greater decrease than latencies for Waves I and II.

Sound and the Developing Infant in the NICU: Conclusions and Recommendations for Care

“…Sound will produce physiologic effects by 23 to 25 weeks of gestation in the preterm infant. 1,2,16 Sudden intense bursts of sound >70 dB can cause a series of physiologic responses that includes changes in heart rate, blood pressure, oxygenation, respiration, intestinal peristalsis, and glucose consumption. Noise control may contribute to physiologic stability during critical care (Graven SN, unpublished data).…”

Functional impairment of the auditory pathway after perinatal asphyxia and the short-term effect of perinatal propofol anesthesia in lambs

“…Two independent blinded observers trained in ABR recording techniques completed the identification of all parameters visually. Peaks of waveforms that appeared consistently within and across subjects were serially numbered (I-V) based on the recording of vertex upward deflections (Figure 1) (38). The peak was graphically defined by the intersection of lines extended from the positive and negative slopes of the peaks.…”

Near‐term fetuses process temporal features of speech

“…Animal studies show that clicks delivered in air are processed in the womb. Cochlear, brainstem, and cortical auditory evoked potentials recorded in the chronically implanted fetal guinea‐pig (Scibetta & Rosen, 1969) and fetal sheep (Pierson, Gerhardt, Griffiths & Abrams, 1995; Woods & Plessinger, 1989) in utero have the same characteristics and same developmental course as the ones recorded in prematurely delivered animals.…”