Auditory evoked delta brushes involve stimulus-specific cortical networks in preterm infants

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Auditory Neuroscience

Background:

• The human auditory cortex exhibits spontaneous and evoked electroencephalogram (EEG) patterns during the third trimester.
• Delta brushes (DBs) are intermittent local oscillatory activities nested in delta waves observed in the developing auditory cortex.

Purpose of the Study:

• To investigate if the spatiotemporal dynamics of evoked delta brushes (DBs) differ based on auditory stimulus type.
• To explore the characteristics of auditory evoked responses (AERs) and evoked DBs in neonates.

Main Methods:

• Utilized 32-electrode EEG to record auditory evoked responses (AERs) in 30 healthy neonates (30-38 post-menstrual weeks).
• Presented auditory stimuli including "voice" and "click" sounds to assess evoked DBs and AERs.

Main Results:

• Both "voice" and "click" stimuli evoked two main peaks in AERs around 250 ms and 600 ms.
• Evoked DBs demonstrated stimulus-specific topographical distributions and contained theta to gamma oscillations.
• Gamma oscillations showed an increase with post-menstrual age, and AERs shifted from right to left predominance for voice responses with age.

Conclusions:

• Auditory evoked delta brushes exhibit stimulus-specific patterns, indicating specialized auditory processing in the fetal brain.
• The findings suggest that evoked DBs play a role in specific auditory information processing during human fetal development.