In the works devoted to the study of electrophysiological correlates of depression, it was shown that in patients with “melancholy depression” electrophysiological signs of increased tone of the parasympathetic system are observed. When the parasympathetic tone dominates, the pupil expands, the cardiovascular system decreases, the bronchi narrow, the intestinal wall shrinks, and red dermographism and watery sweat appear. According to many authors, parasympathicotonia suggests that “melancholy depression” may be associated with the predominance of the activity of serotonergic structures.
In a group of patients with anxious depression, the nature of electrophysiological indicators indicates the opposite effect — an increase in the tone of the sympathetic section of the vegetative system, although signs of its functional insufficiency were noted. This type of depression was associated with a deficiency of both serotonin (to a greater extent) and noradrenaline, and was manifested by an imbalance of their interaction.
In patients with signs of apathy, judging by the electrophysiological activity and vegetative indices, the nature of the response was close to normal, but with a decrease in intensity.
T. Itil et al. (1994), using the methods of topographic mapping of the bioelectric activity of the brain, identified three types of quantitative EEG patterns in depression. Patients with severe depression showed higher alpha rhythm indices than normal. Decreased mood with signs of irritability corresponded to mismatched bioelectric activity, with an atypical EEG pattern, affective disorder of organic nature could be more often diagnosed.
E. Helgorn, J. Loughborrow (1966), P.V. Simonov (1981), TS Melnikova, A.I. Nikiforov (1992) noted inhibition deficit during the depression.
Numerous electrophysiological studies during depression revealed hemispheric balance disorders, studying the effects of local brain lesions, noted that in patients with selective lesions of the right hemisphere of the right hemisphere, patients experienced “depressing depression”, sleep disturbances, periodic changes of hypomania and depression; with the defeat of the left hemisphere, anxious depression was observed, the decrease or disappearance of dreams.
With depression, the duration of total sleep time is reduced, its latent phase is increased, the latent phase of fast eye movements is reduced, the frequency of fast eye movements is increased, and the fourth phase of sleep is reduced.
Biological rhythms
One of the popular models of the origin of depression involves a change in natural biological rhythms, the so-called. circadian or “near-day”: rhythm “sleep wakefulness”, rhythm of body temperature change (fluctuates during the day, reaching the highest point in the second half of the day, and the lowest – during sleep), blood pressure, hormone secretion, etc. This circumstance may indicate the involvement in the pathological process of nuclei that are in the reticular formation of the brain stem (together with the hippocampus, these structures form the limbico-reticular complex).
Within the framework of the theory of biological rhythms, sleep disorders observed in depression are a decrease in its overall duration and a significant reduction in the duration of slow-wave stages (Wehr T., 1982; E., Belougou J. et al., 1989; Linkowski P., van Cauter E. , Kerkhofs M., 1994; Souetre E.) are interpreted as a manifestation of the desynchronization of physiological functions (Y. Aschoff, 1984).
According to the monoaminergic theory of regulation of the sleep and wakefulness cycle (Jouvet M. 1961), this ratio of sleep phases indicates a decrease in the activity of the serotonergic system regulating slow-wave sleep phases while maintaining the functions of the noradrenergic system, controlling the “fast” sleep phase. The last remark is especially important against the background that the morpho-functional basis for the regulation of biorhythms are the structures of the anterior hypothalamus, which are closely related to the serotonergic nuclei of the brain stem (Helghorn E., Lufborrow J., 1966). The positive effect of the normalization of the sleep-wake cycle to reduce the severity of depression is well known. It is interesting to emphasize that social daily stimulants, such as periodic meals, also contribute to the restoration of disturbed sleep.