Effect of Age on in Vivo Human Brain Tissue Electrical Conductivity

This study aimed to investigate the dependency on age of in vivo human grey and white matter electrical conductivities. Most of the related previous studies were conducted using in vitro animal tissue samples, and it has been assumed that these measurements could indicate age-related dependencies of living human gray and white matter. Electrical conductivity measurements were taken from the surgical channel during 13 brain surgeries from patients aged from 4 to 87 years using a needle electrode with a measurement frequency of 50 kHz. Our results indicated that there was no significant linear correlation between age and gray matter electrical conductivity (R2 was 0.1095) or white matter electrical conductivity (R2 was 0.0149) within the patient age range and used measurement frequency. The collated results indicate that age dependency of gray matter conductivity can be observed at a very young age (near newborn age) and that white matter conductivity dependency can be observed at higher frequencies. The conductivity information may have implications for specific absorption rate (SAR) and source localization calculations and simulations with subjects of different ages and with different frequencies.