Radiofrequency thermocoagulation is a potentially therapeutic focal intervention in patients undergoing invasive evaluation for epilepsy surgery, but for whom resective surgery is not considered a good first line treatment strategy. The same electrodes implanted for evaluation in these cases are usually still in place for a brief period of time after the intervention. Thus recordings from these patients offer a unique window into the changes of whole-brain dynamics following focal intervention.
Here we investigate brain-wide changes in functional brain connectivity following radiofrequency thermocoagulation in 14 patients. We show that this focal intervention is associated with wide-spread changes in connectivity - indeed, some of the biggest effects on node-to-node connections occurs in brain areas that are furtherst from the thermocoagulation target.
In a second step of the analysis we invert coupled networks of neural mass models to the recorded data, to infer the synaptic parameters that underly the observed functional connectivity effects. From this dynamic causal modelling approach, we identify a combination of changes in local intrinsic coupling within brain regions, as well as region-to-region synaptic connectivity.
Our provide important insights into the response of brain networks to node removal using a principled and neurobiologically plausible modelling approach. We hope that insights gained from this unique dataset will in future inform our 'virtual cortical resection' models that aim to improve our ability to predict outcomes from epilepsy surgery.