Brain metabolic differences as a function of hemisphere, writing hand preference, and gender

Area of Science:

• Neuroimaging
• Neurochemistry
• Human Brain Anatomy

Background:

• Previous research suggests sex and handedness influence brain structure and function.
• Proton magnetic resonance spectroscopy (MRS) allows non-invasive in vivo measurement of brain metabolites.

Purpose of the Study:

• To investigate sex and handedness differences in brain metabolite concentrations.
• To explore hemispheric and regional variations in N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) levels.

Main Methods:

• Proton magnetic resonance spectroscopy (MRS) was performed on 35 men and 36 women.
• Seven brain regions were examined: frontal lobe tips, mid-temporal lobes, thalami, and hypothalamus.
• Metabolite ratios (NAA/H2O, Cho/H2O, Cr/H2O) were quantified.

Main Results:

• Thalamic gray matter showed higher NAA ratios than telencephalic regions.
• Right thalamus had a higher Cr/H2O ratio, while the left temporal lobe showed the opposite asymmetry.
• Women had higher left frontal NAA/H2O; men had higher hypothalamic NAA/H2O.
• Right-handers exhibited higher temporal lobe NAA/H2O, especially in the left hemisphere.
• Significant interactions between handedness, sex, and hemisphere were found in the frontal lobe.

Conclusions:

• Brain metabolite concentrations vary significantly based on sex and hand preference.
• Hemispheric and regional differences in NAA, Cho, and Cr highlight neurochemical asymmetries.
• These findings contribute to understanding the neurobiological underpinnings of sex and handedness differences.