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Advanced Neurology MNS in patients with anxiety and depressive symptoms

(mixed anxiety and depressive disorder) or F41.2 (panic the researcher demonstrated left-handed clenching (in
disorder) according to the International Classification a mirror manner for the participant’s right hand) to the
of Diseases, 10 revision (ICD-10), and duration of the participant. Then, during the pauses, the participant was
th
disorder ranging from 6 months to 5 years. given the assignment to imagine and then execute the same
Two self-report symptom scales, the Beck Depression movement independently. During the joint execution task,
Inventory (BDI) and the State-Trait Anxiety Inventory the participant and researcher simultaneously squeezed
46
45
(STAI), were used for screening purposes. We included their hands while observing each other’s movements. The
patients with an anxiety level of 45 or higher on the STAI total duration of each session was 30 – 45 min, including
preparation. Before starting the study, the experimenter
scale and a depression level of 10 or higher on the BDI met the participants, communicated, and established
scale. The psychiatric consultations were carried out by an social contact. Before the start of the session, it took
experienced psychiatrist whose diagnosis was based on the approximately 30 min for the participant to get used to the
ICD-10 criteria.
experimenter.
The exclusion criteria for patients were as follows:
initial occurrence of a depressive episode due to the 2.5. Data collection
loss of loved ones or severe traumatic experiences, such EEG data were acquired for each participant during
as traffic accidents; STAI level <45; BDI level <10; left- the active tasks and at the baseline. EEG was recorded
handedness; low-amplitude resting-state EEG (<15 μV) to using a 19-channel EEG-analyzer EEGA-21/26
detect changes in EEG rhythms, moderate or severe head “Encephalan-131-03.” Data were sampled at 256 Hz with
injury, alcohol or drug addiction, diabetes, and chronic filter settings of 0.5 – 60 Hz in the DC acquisition mode
neurological diseases. with impedances kept below 10 kΩ. The electrodes were

The exclusion criteria for the control group were positioned using a 10 – 20 international system. We also used
as follows: STAI level > 35 and BDI level > 8. The other four electrodes to record the electrooculogram (horizontal
inclusion and exclusion criteria were matched to those of and vertical), electrocardiogram, and electromyogram data.
the patient groups. This study was conducted before any All electrodes were referenced to A1 and A2, which were
prescribed pharmacotherapy. All the patients were enrolled located on the left and right mastoids, respectively.
at the Scientific and Practical Psychoneurological Center. 2.6. Data processing and analysis
Additional demographic characteristics of the sample are
presented in the Supplementary file. Processing (including filtering, artifact minimization,
epoch division, fast Fourier transform, spectral analysis,
2.3. Experimental design and data export) was performed using the embedded
We used a sequence of five trials: the baseline task and commercial software “Encephalan-EEGA-pro” (Medicom-
four active tasks aimed at activating the MNS. The active MTD) and LORETA software. EEG records for each
tasks included observation, imagination, execution, and subject were divided into five groups according to the
joint execution with the experimenter. We chose one of the stimuli: baseline, observation, imagination, execution, and
simplest and most common natural movements usually execution+observation. The registered fragments were
used in MNS studies: hand clenching. The time schemes cleared of artifacts and then processed with a fast Fourier
were as follows: baseline (10 s), observation (10 s), pause transform in three frequency bands: alpha1 (8 – 10.5 Hz),
(10 s), imagination (10 s), pause (10 s), execution (10 s), alpha2 (10.5 – 13 Hz), and beta1 (13 – 24 Hz).
pause (10 s), and joint execution with the experimenter The calculated spectral power density values of each
(10 s). frequency band in the active tasks were compared with
the baseline values. Desynchronization or synchronization
2.4. Procedure was computed in dB units, that is, 10 × log (Stimulus EEG
10
Participants sat in a calm atmosphere in a familiar room power)/(Baseline EEG power). Negative values indicate
at a distance of 1.5 m from the researcher so that they desynchronization (i.e., a decrease in power relative to the
could observe his actions. After placing the electrodes, baseline), and positive values indicate synchronization.
the EEG recording began along with the task sequence. This computation was performed for each channel.
The baseline was recorded for 10 s immediately before Subsequently, relative power densities in dB were averaged
the active tasks, which followed each other in the separately for the three analyzed frequency bands and
described sequence. The sequence of tasks was chosen over three clusters of electrodes: frontal (F)—(F3, F4, F7,
to enhance the effect of “projecting” the observed action F8, and Fz), central (C)—(C3, C4, and Cz), and occipital
and to activate the MNS. During the observation task, [O]—(O1 and O2).

Volume 3 Issue 1 (2024) 4 https://doi.org/10.36922/an.2009