Is Human Auditory Cortex Organization Compatible With the Monkey Model? Contrary Evidence From Ultra-High-Field...

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Comparative Neuroanatomy

Background:

• The human auditory cortex organization is often assumed to mirror that of macaque monkeys.
• This includes a core region elongated parallel to the tonotopic axis with distinct subdivisions.

Purpose of the Study:

• To investigate the actual organization of the human auditory cortex core.
• To test the long-standing assumption of similarity with macaque auditory cortex organization.

Main Methods:

• Utilized high-resolution ultra-high-field (7 Tesla) magnetic resonance imaging (MRI).
• Mapped tonotopy and delineated the auditory cortex core in 24 individual human hemispheres.
• Employed quantitative analysis for tonotopic gradients and dual MRI criteria for core delineation.

Main Results:

• The human auditory cortex core is elongated perpendicular, not parallel, to the main tonotopic axis.
• The core region contains a maximum of two mirror-reversed tonotopic gradients.
• Previously proposed homologies with macaque auditory areas (A1, R) were not supported.

Conclusions:

• Human and macaque auditory cortex organization exhibit fundamental differences.
• The assumed similarity in auditory cortex structure between humans and macaques is incorrect.
• This study provides new insights into the unique organization of the human auditory system.