High frequency activity in epilepsy patients
Research type
Research Study
Full title
High frequency oscillations in epilepsy patients: an intracranial electroencephalography and single unit recording multi-case study at the National Hospital for Neurology and Neurosurgey
IRAS ID
135085
Contact name
Matthew Walker
Contact email
Sponsor organisation
UCLH
Clinicaltrials.gov Identifier
15/0353, R&D Number
Duration of Study in the UK
5 years, 0 months, 1 days
Research summary
Our proposed study aims to record local high-frequency electrical signals and single cell activity (neurons) during intracranial monitoring of brain activity in epilepsy patients. The two primary objectives are i) to investigate whether high frequency signals are indicative of seizure location; ii) to investigate how observed high frequency signals and the activity of single cells relate to memory function.
We will recruit epilepsy patients undergoing intracranial monitoring of brain activity at the Telemetry Unit in the National Hospital for Neurology and Neurosurgery to identify the region of brain tissue responsible for causing epileptic seizures. This clinical procedure is undertaken in approximately 30-40 patients per year prior to removal of abnormal tissue to treat drug-resistant epilepsy. It involves implanting recording electrodes with a series of large contacts along the shaft (“macro-electrodes”) into the brains of patients. These remain in place until a sufficient number of seizures have been recorded to allow precise localization of the epileptogenic zone (~10-14 days). A large proportion of these patients have electrodes implanted in regions of the brain critical for memory function.
During the time that the electrodes are implanted, ongoing neural activity is recorded for clinical inspection to identify the seizure onset zone. Through the use of specialised electrodes, “micro-wires” placed down the central bore of the electrode enable the continuous recording of changes in local high frequency signals near the tip of the electrode. These signals may help indicate seizure location (which we wish to investigate), and also allows the activity of individual neurons to be detected (which we wish to analyse with respect to memory function). Patients are fully aware during their time on the Telemetry Unit for pre-surgical monitoring and are able to perform tests of memory normally, except during seizure episodes. During behavioural tests of memory, local high frequency signals and the activity of single brain cells can be related to successful and unsuccessful memory formation. This clinical population offers a unique opportunity to study both how information is represented by brain activity within regions of interest and how such processes might be affected by epilepsy.
The findings will be important for (a) examining the relationship between neuronal signals and epileptogenicity and (b) understanding memory processes in the human brain and the related consequences of epilepsy.
REC name
London - Queen Square Research Ethics Committee
REC reference
15/LO/1783
Date of REC Opinion
23 Dec 2015
REC opinion
Further Information Favourable Opinion