MRS & EEG Study

What is the purpose of this study?

The purpose of this study is to investigate learning and impulsivity through brain activity, i.e. how these are reflected in your brain. The results of the study will enable us to better understand how a healthy brain reacts to specific tasks and may also help us understand how this is different in OCD.

What does this study involve?

You will be asked to complete psychological questionnaires to collect measures of differences in personality or mental states. Our goal is then to correlate the outcome of these questionnaires with computer task performance or specific activity in the brain as measured by functional Magnetic Resonance Imaging (fMRI) and EEG (Electroencephalography), or different ratios of neurometabolites important for OCD symptoms using Magnetic Resonance Spectroscopy (MRS). There are two sessions completed 4-weeks apart:

Session 1: a few computer tasks, some questionnaires (which you can also do at home), one hour MRS scan and one EEG session of about 2 hours. The whole testing will take around 4-5 hours.

Session 2: a few computer tasks, some questionnaires (which you can also do at home), one hour fMRI scan and one EEG session of about 2.5 hours. The whole testing will take around 4-5 hours.

Between the two sessions, you may or may not be asked to practise an app on your phone on a daily basis. This is to measure how your brain acquires new habits, an important feature of OCD symptomatology.

We would prefer if you did both the EEG and scans as it will allow us to have a more complete picture of the problems we are trying to solve. However, you can also choose to participate in only the EEG or MRS study. If you prefer not to do any neuroimaging, then you can also choose to participate in our behavioural study which consists of computer tasks and questionnaires. 

What is EEG?

It is a neuroimaging technique to measure the electrical potential at different points of your scalp, which is generated by the activity of large group of neurons in your brain. The signals are picked up by 128 electrodes that are positioned in your head. This technique is considered non-invasive, safe, causing no discomfort or harm. You will NOT receive any shocks or feel any discomfort. The electrodes are to fixed to your head with a net (Geodesic Sensor Net) that is non-allergenic and washable. In order to improve the conductance of the signal from the scalp to the sensors, the electrodes are filled with a water-soluble gel that is safe for humans, does not provoke physical reactions and is easily removed.

Participant wearing the net with 128 electrodes.

Lastly, we will also ask you to complete a set of questionnaires so that we may associate performance in the computerised tests to physiological changes, emotional states and personality traits.

What is MRS?

You will also undertake 2 Magnetic Resonance Spectroscopy (MRS) scans, one in each visit. You will be provided with ear plugs to block the noise from the device and the entire procedure will be conducted by specialised and trained radiographers, at the Wolfson Brain Imaging Centre (WBIC), Addenbrookes, Cambridge. A safety form prior to undertaking the scan will also be required, to ensure there will be no hazards with the magnetic field.

What is an MRS device?

The Siemens Terra 7T MRI Scanner at the WBIC


We can learn a great deal about how the brain works by looking at the flow of chemicals to different parts of the brain while the brain performs different tasks or when it is at rest. We need to obtain this information to understand both the working of the healthy brain, but also the problems of patients with neurological or psychiatric disease. We measure the changes in chemical flow due to brain function using ‘images’ taken with a magnetic resonance spectroscopy scanner (MRS). The MRS is a non-invasive, ionizing- and radiation-free analytical technique. This scanner uses a strong magnetic field to create detailed images of brain. By analysing the concentration of different metabolites in the brain, we can understand possible chemical imbalances and acquire information for novel treatments. This is quite similar to a Magnetic Resonance Imaging (MRI) scan and does not involve injections or X-rays. The only difference is that instead of looking at blood flow (fMRI), it measures the concentration of different brain metabolites, important for brain function.

You will be compensated £120 for your participation in our study and will be reimbursed for any travel expenses. 

If you would like to know more about this study, please message mrs.eeg.cambridge@gmail.com

This study is conducted at the Herchel Smith Building for Brain and Mind Sciences (HSB) and the Wolfson Brain Imaging Centre (WBIC), both buildings situated at the Cambridge Biomedical Campus also hosting Addenbrooke’s Hospital.