Quantitative estimation of the primary auditory cortex in human brains

• Published in: Brain research Vol. 1008; no. 1; pp. 20 - 28
• Main Authors: Artacho-Pérula, Emilio, Arbizu, Javier, Arroyo-Jimenez, Maria del Mar, Marcos, Pilar, Martinez-Marcos, Alino, Blaizot, Xavier, Insausti, Ricardo
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 15-05-2004; Amsterdam Elsevier; New York, NY
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Auditory Cortex - anatomy & histology; Auditory Cortex - physiology; Biological and medical sciences; Brain Mapping; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Female; Functional Laterality; Fundamental and applied biological sciences. Psychology; Human; Humans; Male; Middle Aged; Parvalbumin; Postmortem Changes; Primary auditory cortex; Staining and Labeling; Stereology; Stereotaxic Techniques; Vertebrates: nervous system and sense organs; Volume; Human; Sensory systems; Primary auditory cortex; Stereology; Parvalbumin; Volume; Binding protein; Calcium; Central nervous system; Auditory pathway; Auditory cortex; Encephalon
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2004.01.081

Functional neuroimaging studies in humans are common worldwide. In order to determine with more accuracy both morphometric parameters and volume of the primary auditory cortex (PAC), we studied both right and left hemispheres in human control brains. Twelve hemispheres were systematically sectioned orthogonal to the anterior–posterior commissures (ac–pc line). Serial sections of the complete temporal lobe at 50 μm were obtained and stained with thionin (12 hemispheres) for cytoarchitectonic analysis. Four hemispheres were stained with the neuronal marker parvalbumin, a marker of primary sensory cortices. Morphometric analysis of the thionin-stained sections included size and shape factors as well as volume estimation using the Cavalieri method. Primary auditory areas extended for an average of 24 mm (twelve 2 mm apart sections); volume estimates determined by the Cavalieri method was 857±213 mm
3 with a range of 658 mm
3. The left primary auditory cortex was 7% greater than the right auditory cortex, without significant differences between hemispheres. The size and form of morphometric parameters obtained from each sampled section also revealed scarce differences between hemispheres, and the tendency to irregularity and ellipsoidity was more marked in the left hemisphere. No differences in size and form between right and left hemispheres were determined in our study. Morphometric analysis are of value in functional studies, specially those using non-invasive and lower resolution techniques such as Single Photon Emission Computed Tomography (SPECT).