SEPTAL AREA [septum pellucidum (PNA, JNA, BNA); synonym transparent partition] — the formation of a brain located in a triangle between the arch of a brain and a corpus collosum. Anatomically (fig.) also functionally is a part limbic system (see). S.'s role of the lake in activity of a brain, as well as all limbic system, consists in implementation of the modulating influences connected with an affective behavior and its motor and vegetative manifestations. The island leads disturbance of activity of S. to changes in motivatsionnoemotsionalny and emotional spheres.
At animal S. of the lake is formed by indistinctly delimited kernels and nerve fibrils. At the person upper part C. of the lake is presented by two thinned plates (laminae septi pellucidi), in to-rykh yarns and glial elements are located; between plates there is a narrow cavity (cavum septi pellucidi). Basal part C. of the lake, or a true partition (septum verum), consists of an indistinct basal layer and a cortical plate, in a cut kernels are located. Only the true partition of the person is homologous S. of the lake of animals. For the first time kernels of a partition were investigated by Young (M. W. Young, 1936); the nomenclature offered them kept the practical value.
On topography of a kernel of S. of the lake divide into medial and lateral groups. Kernels and kernels of a diagonal bunch enter into medial group medial, septogippokampalny (dorsal, or premordium a hippocampus), triangular. Lateral, fimbrialny, adjacent kernels, and also kernels of front commissure and a terminal stria concern to lateral group.
On the neural organization of a kernel of a partition combine in 3 groups: the reticular kernels (a diagonal bunch, front commissure and a terminal stria) constructed of dlinnoaksonny reticular redkovetvisty neurons; the striatal kernels (medial, lateral, fim-brialny and septogippokampalny) consisting of cells with a large number short gyrose silnovetvya-gtsikhsya dendrites; the trrgangulyarny kernel differing on the neural organization from other kernels of S. of the lake
of S. of the lake (see. Very tectonics of a cerebral cortex ) treats ancient bark, or a paleocortex (on I. N. Filimonov's classification, 1957). In the course of S.'s phylogenesis by the lake progressive increase in the size of its kernels among primacies is observed.
The village of the lake has the numerous bonds which are carrying out impulses in both directions. Afferent influences take place on the ascending fibers of a medial perednemozgovy bunch going from nonspecific structures of a trunk. A part of fibers of periventri-kulyarny system joins them. The fundamental relay unit of the ascending ways from nonspecific structures of a trunk is the medial kernel. Afferent influences go to S. of the lake also from hippocampus (see): in medial and septofimbrialny kernels, and also in a medial part of a lateral kernel of S. of the lake axons of pyramidal cells of the field CA2 of a hippocampus, and in a lateral kernel — axons of pyramidal cells of the fields CA3_4 of a hippocampus terminate. S.'s bonds by the lake with amigdaloidny area (see) are not found. From a partition (from its medial kernel) the impulsation through a small fringe of a hippocampus comes to a hippocampus (fields CA3_4) and to a gear fascia. From a lateral kernel of communication go only to a medial kernel. Thus, the lateral kernel of S. of the lake is an internal relay kernel of septogippokampalny system. From this kernel of fiber are connected to the descending part of a medial perednemozgovy bunch and reach the central gray matter, a reticular formation of a mesencephalon and the bridge. Preferential from a septofimbrialny kernel of fiber go through a medullary strip to a medial kernel of a bridle. Bonds of a partition with a medial cranked body are traced (see. Diencephalon ) and lower dvukholmiy (see. Mesencephalon ). Indirect bonds of S. of the lake are even more extensive.
Electrostimulation of separate structures of S. of the lake causes characteristic changes of bioelectric activity in various departments of a brain. So, at irritation of a medial kernel bioelectric activity of a symmetric zone of a partition, dorsal hippocampus changes, and in them slow theta-like activity (so-called septal reaction) appears. Activation of a kernel of a diagonal bunch causes synchronization of a rhythm in new bark that is followed by decrease in reactivity, an adynamia, backfilling. Assume that in this kernel the brake system of the fibers going to a neocortex begins. However at development of septal reaction of tension bioelectric activity changes and the effect of long desynchronization is observed that testifies to bigger extent of excitement of the activating system of a brain. The medial kernel of S. of the lake is pacemaker (see) theta rythm of a hippocampus. At anodic polarization of S. of the lake there is a reduction of amplitude and stage of latency of the hypertensia caused by stimulation of a ventromedialny kernel of a hypothalamus. Therefore, the partition activates the hypertensive reaction caused by the excitement which arose initially in the emotsiogenny center of a hypothalamus.
The page the island participates in the organization of different types of motivatsionnoemotsionalny behavior and processes of training. An important role is played by S. about in feeding and drinking behavior. It is shown, in particular, that destruction of dorsolateral departments of a partition causes a hyperphagia, and damage of its ventral areas — an aphagia with the subsequent death of animals. Concerning drinking behavior opposite effects are observed: the irritation causes reduction of drink of water, damage — a polydipsia. Apparently, the lake determines by S. also nuances of appetite. Difficult mekhanizkhm S.'s participations by the lake in the organization of a motivational feeding behavior it is still insufficiently studied. The large number of experimental data indicates a role of kernels of a partition in sexual motivation. Bilateral damage of a partition brakes a sexual behavior at females, and at males at the same time perversions are observed — there is a female form of a sexual behavior. At females the instinct of motherhood and nesting disappears, tendency to a kannibalrkhzm appears. Administration of oestradiol and progesterone in a lateral septal kernel activates the bioelectric activity registered in this area. S.'s stimulation by the lake changes also gonadotropic function of a hypophysis. The person has S.'s irritation of the lake (on X. Delgado, 1971) was followed by erotic experiences. At patients with epilepsy direct introduction to this area of acetylcholine with to lay down. the purpose caused transition from the suppressed mood to feeling of satisfaction and euphoria. S.'s role is installed to the lake in mechanisms of motivational and emotional reactions of defensive type (see. Defensive reactions ). After S.'s damage by the lake at rats and mice ferocity, and at cats — hyper emotionality develops; the similar effect was not found in monkeys. Thus, this so-called septal syndrome is characteristic only of the lowest ml ekopitayushchy.
The village of the lake plays also important role in processes of training. The island leads S.'s damage to deterioration in training. Such animals badly cope with reversal learning. Damage of a partition considerably slows down fading of conditioned reflexes. Besides, S. the island participates in mechanisms of nervous control of a muscle tone, vegetative and endocrine functions.
In biochemical sense of S. of the lake is a difficult heterogeneous education. Lakes in a hippocampus pass the ascending monoaminergichesky ways from the corresponding systems of neurons of the bridge and a mesencephalon through S. (a livor, kernels of a seam, a tire of a mesencephalon). Lakes as a part of a medial perednemozgovy bunch pass the ascending and descending cholinergic ways, and also serotonin through S. - dopamine - and noradrenergichesky fibers. At S.'s damage by the lake to a hippocampus levels fall serotonin (see) and noradrenaline (see). A part of septal afferent structures forms cholinergic neyropil and terminal synapses in a hippocampus. A source of cholinergic system of a hippocampus are medial and diagonal kernels of S. of the lake
Methods of a research
S.'s Morphology islands study by means of methods light and a submicroscopy (see. Microscopic methods of a research , Submicroscopy ). Islands conduct a research of physiology of S. by registration of bioelectric activity of its separate structures or separate neurons, stimulation by electric impulses, influences (through a cannula or by means of a microionophoresis) various mediators, neuropeptids, etc. «Switching off» of a partition is carried out by method of anodic polarization, administration of novocaine, electrolytic destruction, etc.
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F. P. Vedyaev, O. Yu. Mayorov.