Background

Although we have learned much about the brain by studying brain tissue donated at the time of death (autopsy), having a way to study the brain of living people would be much better. A small number of patients with drug-resistant epilepsy undergo a surgical operation to remove the part of the brain that is causing their seizures. Occasionally, electrodes are implanted deep inside the brain before the operation to localize where the seizure starts or spreads. We had the idea that the surface of these electrodes – accessible after they are removed from the patient – would carry traces of the genes that were active in the living brain. These chemical signatures, in the form of ribonucleic acids (RNA), could then be compared to electrical recordings and brain scans to learn which genes are most (or least) active in the zones of the living brain that trigger seizures.

Research

We were able to recover trace RNA from depth electrodes from epilepsy patients. We used this to measure the activity of hundreds of genes and found molecular ‘fingerprints’ that related to the firing patterns of brain cells where the electrodes were placed. We were also able to use information on which genes were active to establish the types of brain cells from which the signal arose. This indicated that both neurons and supporting cells called glia contribute to the gene activity signal we found on the surface of the electrodes.

Potential Impact

The research provides a new method to study the activity of genes in the living human brain in health and disease and could see the development of new diagnostic technologies to assist with optimising neurosurgery for drug-resistant epilepsy.