A cross-sectional, observational, and descriptive exploratory study will be conducted.
The target population is active medical students in 2023 at the Technological University of Pereira.
A sample of 20 medical students will be selected through non-probabilistic convenience sampling, taking into account their availability and willingness to participate in the study. Participants will be divided into two groups, one control (n=10) and one intervention (n=10).
The unit of analysis will be the records of the cardiac variability and electroencephalographic tracing of the participants.
The inclusion criteria are: being a medical student at the Technological University of Pereira, aged between 18 and 30 years, having given written informed consent, having a normal body mass index (BMI) within the range of 18.5-24.9, and being right-handed.
The exclusion criteria are: having a history or current diagnosis of any mental disorder listed in the DSM-5R, having a history or current diagnosis of neurological or cardiovascular diseases, having a history or current diagnosis of any chronic disease regardless of the compromised system, having consumed psychoactive substances in the last 48 hours, having received medications that affect the central nervous system in the last 48 hours (corticosteroids, beta-blockers, calcium channel blockers, anti-seizure medications), being pregnant or lactating.
Variables and Operationalization:
Socio-demographic characteristics of the participants: age, gender, socioeconomic status, marital status, occupation, educational level, among others.
Cardiac coherence: Independent variable. HRV with a range of 0.1-0.14 Hz.
Frontal alpha asymmetry: Difference between alpha power measurements obtained at electrodes located at F3 and F4. The reference value is: -0.3-0.3.
Relative theta power: Proportion of power in the theta frequency range divided by total power in the spectrum. The reference value is: 20-30.
Relative beta power: Proportion of power in the beta frequency range divided by total power in the spectrum. The reference value is: 10-20%.
Frontal beta asymmetry: Difference between beta power measurements obtained at electrodes located at F3 and F4. The reference value is: -1.5-1.5.
Delta coherence: Phase coherence coefficient between electrodes located at F3 and F4 in the delta frequency range. The reference value is: 0.5-0.8.
Theta/beta ratio: Proportion of power in the theta frequency range divided by power in the beta frequency range. The reference value is: 2.5-3.5, (Ortiz, 2020).
Source type: Primary sources will be used through direct contact with the study subjects.
Information collection techniques:
A prior interview will be conducted to explore disorders included in the DSM-5R, as well as the Matlab software and different subscribed toolboxes for processing the information collected through a VFC sensor and cutaneous electrodes for measuring electroencephalographic activity.
Biological variable measurement process: Once participants have given their informed consent, they will be invited to the laboratory of the Faculty of Medicine at the Technological University of Pereira (UTP). EEG measurements will be taken before and during the application of the heart coherence technique, with participants comfortably seated in a chair with their eyes closed. During the measurement, a mobile application designed for this purpose will provide instructions for breathing, following a specific pattern. The intervention will last between 5-15 minutes and will be performed in an individual session in a quiet and distraction-free environment. Heart coherence will be measured using a portable heart rate sensor. The control group will remain in the same space for the same amount of time, without being exposed to the strategy. Electrodes will be placed on specific points on the participant's head using the international 10/20 system manual, measuring activity in the central, parietal, temporal, occipital, and ocular signals. An electrooculogram (EOG) and ground electrode will be applied to the forehead, and exfoliating gel will be used to reduce skin resistance. All electrodes will be fixed with conductive paste, ensuring that impedances do not exceed 5 kΩ. An initial EEG measurement will be recorded in the absence of heart coherence at the start of the session (measuring VFC). Then, participants will be asked to sit in front of a monitor displaying a visual feedback signal (heart rate variability) based on real-time analysis of their electrofisiological data. Participants will follow the breathing and cursor on screen until obtaining a sinusoidal pattern registration, considered to have achieved heart coherence. At this point, they will be asked to close their eyes and maintain heart coherence for a second measurement. Data collection will be performed using a computer with an EEG amplifier. The signal will be processed and analyzed using the EEGLAB toolkit of MATLAB, defining four frequency bands for subsequent analysis: delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-30 Hz), and gamma (30-50 Hz). The spectral power of EEG data will be calculated using the fast Fourier transformation, using the "spectrogram" function of EEGLAB, and absolute power will be averaged over all time windows and frequency bands for subsequent analysis.