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Advanced Neurology MNS in patients with anxiety and depressive symptoms

associated with stress and mood swings lead to changes present. Electroencephalograms show rhythmicity in the
in an individual’s normal rhythm of life and relationships electrical activity of the brain. A number of rhythms are
and loss of professional skills. Such disturbances are often associated with various brain activities that have different
2
accompanied by an inability to recognize changes in the areas of registration, shape, amplitude, and frequency of
facial expressions and body language of other individuals, oscillations. The mu rhythm, or sensorimotor rhythm, of
as well as reduced interest in social contacts, ultimately the EEG, is associated with human motor functions. 17
leading to social maladaptation. 3 The mu rhythm (μ rhythm) is a rhythm of the brain, the

One of the physiological substrates of social interaction oscillation frequency of which lies in the range of 8 – 13 Hz
is the mirror neuron system (MNS). A special class of nerve with an amplitude of ≤50 μV. It should be noted that while
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cells called “mirror neurons” was discovered in the 1990s the frequency ranges of mu and alpha rhythms are the
by a group of researchers led by Giacomo Rizzolatti. This same, their images/shapes on the encephalogram, the areas
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group studied the premotor cortex in monkeys (Macaca of the brain in which the bioelectrical activity is recorded,
nemestrina) using implanted electrodes to monitor the and the state corresponding to the maximum amplitude
activity of neurons from Brodmann’s cytoarchitectonic of the rhythm differ. The alpha rhythm is characterized
area 6 in core area F5. The results revealed that the neurons by a “spindle-shaped” image, while the mu rhythm image
responded similarly to both observation and execution is “arch-shaped.” The mu rhythm is registered in the
of motor movement, leading to the naming of these cells sensorimotor cortex of the brain, in contrast to the alpha
as “mirror neurons.” Further studies of the MNS have rhythm, which is recorded primarily in the occipital region
6,7
shown its participation in recognizing and experiencing above the visual cortex. Unlike the alpha rhythm, whose
primary emotions, 6,8,9 and emotional coloring of gestures amplitude increases and reaches its maximum value in a
or facial expressions seen through the connection with the state of quiet wakefulness with eyes closed and decreases
insula. 10 during the arrival of visual information, the maximum
The main methods for studying mirror neurons are amplitude of the mu rhythm corresponds to the state
functional magnetic resonance imaging (fMRI), positron of quiet wakefulness, and desynchronization of the mu
emission tomography, transcranial magnetic stimulation rhythm is observed during observation, presentation, and
(TMS), and electroencephalography (EEG). EEG does not performance of motor tasks, that is, exactly when the MNS
directly record the spiking activity of neurons but rather is presumably activated.
evaluates the activation of any area of the MNS during Several studies indicate that the mu rhythm and
mirror tasks. Thus, mirror properties have been identified MNS are related to each other. Simultaneous recording
in various parts of the cerebral cortex, such as the motor of the EEG signal and fMRI in the resting state showed
cortex, sensorimotor cortex, inferior frontal gyrus, and important results: the amplitude of mu rhythm
anterior parietal cortex. 11-14 According to the first invasive components was negatively correlated with the blood
human study, MNS revealed activity that goes beyond oxygen level-dependent response in attention networks,
the cerebral cortex to subcortical structures such as the sensorimotor areas, and networks thought to be mirror
hippocampus and the amygdala. 15 system networks. EEG of the mu rhythm in patients who
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The MNS is clearly a complex system divided into a set had suffered a stroke and had damage to the MNS area
of subsystems involved in recognizing and experiencing also confirmed the connection between the suppression
emotions and movements. However, if a disorder affects of the mu rhythm and the functioning of the mirror
social behavior and interaction with individuals or system. Another unconditional argument for using mu
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causes problems in everyday life, the functioning of rhythm desynchronization as a measure of MNS activity
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the MNS may be impaired. As mentioned earlier, EEG was made by Bimbi et al. Simultaneous registration of
allows a detailed study of the properties of MNS. EEG multiple unit activity, local field potentials (LFP), and EEG
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is based on the recording of the bioelectrical activity from the ventral premotor cortex in monkeys revealed
of the brain. Its advantages include accessibility and that the activity of mirror neurons in the premotor cortex
high temporal resolution. A high temporal resolution significantly correlates with an increase in the gamma range
allows the recording of brain activity signals in real- power of the LFP, as well as with a decrease in the upper
time. The disadvantages of this method are its low spatial mu and lower beta powers of the EEG of the central leads.
resolution (i.e., difficulty in determining the exact source Moreover, researchers discovered that an increase in LFP
of the signal) and low signal-to-noise ratio. In addition to gamma activity precedes mu desynchronization, which
electromagnetic noise, noise associated with human muscle means that the activation of mirror neurons in the premotor
activity (artifacts), such as blinking or twitching, may be cortex modulates the mu rhythm. Thus, desynchronization

Volume 3 Issue 1 (2024) 2 https://doi.org/10.36922/an.2009