Quantitative Electroencephalography (qEEG) or 'Brain Mapping' with source localisation is a technique in which the electrical brain activity is measured digitally. Using this technique, researchers are able to interpret how and which areas of the brain work together. The qEEG procedure involves the use of a 19 or more electrode EEG cap. Electrode gel is used to ensure that each electrode has optimal contact with the skin. But recently dry (gel-less) electrodes are being developed. The placement of the cap and electrode takes approximately 10 minutes followed by 10 minutes recording, as to obtain a minimum of 5 minutes of qualitatively good data. Before the procedure, patients are asked not to use hair gel, spray or conditioner. They are also asked not to consume alcohol, coffee or other stimulants.

The qEEG provides critical information about the electrical activity and connectivity in the brain and can be compared to a normative database, i.e it can tell whether the activity and connectivity of your brain is normal or deviates from the norm. this can signal pathological activity or a compensation mechanism. The qEEG is essential to determine where to apply the stimulation and what technique to use. Therefore, everybody who participates in a study in BRAI3N will undergo a qEEG before treatments are initialised and also at the end of the treatment so we can evaluate whether the treatment delivers what it should do, i.e. normalise brain activity.

qEEG showing brain activity in the parahippocampus in people who respond better to auditory cortex stimulation as a treatment for tinnitus

HRV is a measurement of the heart rhythm by means of 2 electrodes that are placed on the chest. This happens during the qEEG recording allowing researchers to track the influence of brain activity on the autonomic nervous system and vice versa. The autonomic nervous system is responsible for control of a large number of unconsciously directed functions such as breathing, digestion and heart rate. it consists of two components, a sympathetic (fight or flight) component and a parasympathetic (rest, digest, restore) component, which should be in balance.

When someone is stressed, his/her sympathetic nervous system becomes more active. The body is getting ready to "fight or flee". The breathing and the heart rate are faster, the pupils dilate. This is an evolutionary system and it protects us from danger. For example, how you would react when you are being chased by a hungry bear? The chance that you will encounter a bear today is quite small, but our body does not distinguish between seeing a bear or be overloaded with work, and noise.

Sometimes we are unable to 'relax' because the stress 'network' in our brain remains hyperactivate. A HRV measurement gives us an idea about the parasympathetic nervous system (rest, digest and restore) and indirectly about the sympathetic (fight, flight) system. As such it gives an idea about the balance between the sympathetic and parasympathetic activity at rest.

Functional Magnetic Resonance Imaging (fMRI) is an imaging method for brain activity based on oxygen levels in the brain (BOLD activity). There are two forms of fMRI, evoked fMRI and resting state fMRI.
During the evoked fMRI procedure the researcher may ask you to complete a task, such as counting, listening to sound, music or watching a show or stimulating a painful area. This allows the researchers to associate brain activity with a related task or sensory stimulus.

During resting state fMRI no specific task needs to be done. The fMRI will be performed while you are quietly lying in the MRI machine.

Magnetic Resonance Imaging (MRI) is an imaging method that is more sensitive than RX or CT scans to take a picture of your brain. The patient lays on a table which moves slowly into a “tunnel” or "tube". During the investigation, the MR-unit makes a loud noise but is completely painless and harmless. MR brain research sometimes utilises a contrast dye to obtain a better understanding of the region of interest. Depending on the body part, an MR-research session takes approximately 15 to 45 minutes.

Structural MRI, in contrast to routine MRI, quantifies structure of your brain. The brain consists of grey matter (= cells) and white matter (= fibres). Both grey and white matter can be quantified to see whether they are normal in size and volume. This can correlate with specific brain functions.

The technique is complementary to qEEG and fMRI, both techniques which look at function in contrast to structure.

VBM (voxel based morphometry) , demonstrating decrease in grey matter in different regions of the brain associated with hearing loss

Tractography showing the white matter bundles