Sequential source of the M100 exhibits inter-hemispheric asymmetry

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Biophysics

Background:

• The M100 is a significant component of auditory evoked fields, reflecting neural activity in response to sound.
• Understanding the spatiotemporal dynamics of the M100 is crucial for interpreting auditory processing and identifying neurological differences.

Purpose of the Study:

• To model the neural generators of the M100 auditory evoked field.
• To investigate the latency and spatial distribution of M100 generators in both cerebral hemispheres.
• To explore the compound nature of the M100 and its implications for laterality differences.

Main Methods:

• Recording M100 data from 20 subjects across both left and right hemispheres.
• Employing equivalent current dipole modeling within a sliding window (10 ms) from 0 to 245 ms post-stimulus.
• Analyzing residual error curves to identify local minima corresponding to generator latencies.

Main Results:

• Two distinct generator latencies were identified at approximately 75 ms and 100 ms.
• In the left hemisphere, the early (75 ms) generator was located 6 mm superior to the later (100 ms) source.
• In the right hemisphere, the early source was 3 mm superior and 11 mm posterior to the later source.

Conclusions:

• The M100 auditory evoked field represents a compound neural source.
• The dipole modeling approach provides insights into the distinct spatial configurations of M100 generators.
• These findings may enhance the understanding of laterality differences in auditory processing.