Functional anatomy of human speech

Area of Science:

• Neuroanatomy
• Human brain anatomy
• Lateralization of brain function

Background:

• The Planum temporale, also known as the Geschwind-Levitzky areas, is a region in the temporal lobe.
• Previous research suggests potential asymmetries in this brain region.
• Understanding these asymmetries is crucial for comprehending brain lateralization.

Purpose of the Study:

• To investigate and quantify side differences in the human Planum temporale.
• To compare the volume and cell numbers between the left and right Planum temporale.
• To analyze cell density in relation to volume differences.

Main Methods:

• Examination of ten human brains.
• Measurement of the volume of the Planum temporale on both sides.
• Counting of cell numbers within the Planum temporale for each hemisphere.
• Calculation of cell density (cell number per unit volume).

Main Results:

• Significant asymmetry was observed in both the volume and cell numbers of the Planum temporale.
• The left Planum temporale was found to be larger than the right side by 38-34%.
• Cell density was found to be consistent between the left and right sides, indicating volume is the primary factor in cell number differences.

Conclusions:

• The human Planum temporale exhibits significant lateralization, with the left side being larger.
• These findings contribute to the understanding of structural asymmetries in the human brain.
• The data suggests that volume differences, not cell density, account for the observed asymmetry in cell numbers.