Patients with depression are evaluated using functional magnetic resonance imaging ( fMRI ). With depression, there are functional and structural abnormalities in the structures of the brain.
Also in recent years, neuroimaging has been carried out to study the specifics of brain diseases. Structural interactions in mental illness are investigated using MRI with diffusion tensor imaging (DTI) and fractional anisotropy. The methods determine the integrity of the white matter and anatomical damage to the structural bonds of the white matter.
Functional MRI allows you to study the organization of the cortex in space. The disadvantage of this method is the time interval and indirect assessment of neural activity. fMRI is unable to detect brain activity at higher frequencies. Therefore, studies are carried out using EEG (electroencephalography), magnetoencephalography (MEG), intracranial electroencephalography ( iEEG ). When synchronizing the processes of excitation of neurons in individual areas of the brain, distant areas and regions of the brain are involved. Synchronization of neurons occurs in a short period of time and is detected on the EEG.
Neural network connections can be studied by measuring two areas of the brain using three methods: EEG, iEEG , MEG. Magnetoencephalography (MEG) is a non-invasive procedure for assessing regional and distant modulation of synchronous neural activity.
Electroencephalography can determine the functioning of large networks of neurons with high temporal resolution. But MEG is superior to EEG, since the magnetic signal of the apparatus is less distorted by the bones of the skull and brain tissue than the electric field. In practical psychiatry, the ease of use of the MEG is an advantage as it takes less time.
In the study of patients with depression using MRI, PET, EEG, MEG, fundamental disorganization of the cerebral cortex is monitored. The activity of several networks is determined:
- sensomotor ;
- laterally fronto- parietal;
- central executive.
The use of instrumental research methods for mental illnesses, including depression, will make it possible to establish the causes of diseases at the level of defects in neural networks and structures of the white matter of the brain. This will open the way for new treatments for depression.