Electrophysiological features of bioelectrical activity of the horse brain

Purpose: to study the bioelectrical activity of the brain and determine the parameters of electroencephalograms in sports and untrained horses.Materials and methods. The object of the study were horses aged from 2 to 20 years in the amount of 150 heads. The animals were in active training and were also used for rental training in horse riding; their average weight was 550.78 kg; the breeds were Oryol Trotter, Russian Trotter, American Trotter and Hanoverian. During EEG recording, horses were restrained using a halter at the junctions. Experiments were carried out in the morning or afternoon, 1 hour before feeding/training or 1 hour after. EEG registration was carried out with patch electrodes in 6 unipolar leads using a special patented Ippolitova / Gauss helmet for recording EEG in animals, the electrodes on which are located along the projections of different lobes of the brain, which allows non-invasively, without the use of sedatives and shaving hair, to record the electrical activity of the brain . EEG recording continued for 10-15 minutes. We assessed brain rhythms using the following indicators: Rhythm severity index (RSI) – the degree of manifestation of the rhythm, the percentage of time during which a given rhythm is recorded (%). Frequency – the number of complete oscillations performed per unit of time, sec. (Hz). Amplitude is the largest deviation (from the average) value of a quantity, the range of oscillations.Results. As a result of the research and analysis of the obtained EEG data, waves of bioelectrical activity of the brain in horses were established in the following ranges: alpha rhythm (α-rhythm) – 7.1 – 13 Hz, amplitude up to 100 µV; beta-1 rhythm (low-frequency β-1 rhythm) – 13.1 – 25 Hz, amplitude – 3-5 µV; beta-2 rhythm (high-frequency β-2 rhythm) – 25.1 – 40 Hz, amplitude – 3-5 µV; delta rhythm (δ rhythm) – 0.3 – 4 Hz, amplitude up to 40 µV; theta rhythm (Ѳ-rhythm) – 4.1 – 7 Hz, amplitude about 30 µV; gamma rhythm (γ rhythm) – above 40.1 µV. When analyzing EEG rhythms in animals, the most pronounced spontaneous brain activity at rest in the horses studied is the delta rhythm in all leads and hemispheres. We observe oscillations with a frequency of 0.3–4 Hz and an amplitude of up to 40 μV. The waveform is regular, sinus. Such oscillations represent the delta rhythm.