Contemporary data on the structural and functional organization of the insular lobe of cerebral hemispheres

Abstract

The article presents an analysis of contemporary literature data on the structural and functional organization of the insular lobe of cerebral hemispheres. In adults, the insular lobe is located deep in the lateral sulcus under the frontoparietal and temporal opercula and is divided by the central sulcus of insula into two lobes – anterior and posterior. The relief of the sulci and gyri of the insula has individual variability. The insula receives blood supply from the M2 segment of the middle cerebral artery. The description of the cytoarchitectonics of the insular cortex according to different authors has significant differences. It is believed that the insular cortex is a transitional area from the paleocortex to the neocortex. In the domestic literature, two main cytoarchitectonic fields are described – 13, corresponding to the posterior parts of the insula and 14, occupying the anterior central gyrus of the insula, its short gyri, as well as a number of subregions. In foreign literature, seven cytoarchitectonic zones are distinguished: Ia1, Ig3, Id2, Id3, Id4, Id5, Id6. The insular lobe receives afferent projections from the thalamic nuclei and a number of parts of the cerebral cortex responsible for the perception of sensory stimuli. There are connections with the amygdala and some structures of the limbic system, the associative cortex. Efferent projections of the insular cortex diverge both to the structures of the brainstem and to the subcortical formations: the lateral hypothalamus, amygdala, pontine nuclei, bed nuclei of the stria terminalis, the nucleus of the solitary tract and a number of other formations associated with the control of autonomic functions. In functional terms, four sections are distinguished in the insula: sensorimotor, socioemotional, cognitive, chemosensory. The sensorimotor department ensures a number of visceral reactions, which indicates its participation in the regulation of the autonomic functions of the body. It ensures the perception of somatically sensitive impulses from the face and upper limbs. The role of the insula in thermo- and nociception is described. It is known about the participation of the insular cortex in functioning of the auditory analyzer, processing of taste sensations, vestibular signals, and olfaction. It is believed that the anterior-ventral part of the insula plays a key role in the formation of emotions and subjective sensations, as well as in making decisions associated with risk. The anterior-dorsal department is responsible for the integration of sensory stimuli from the external environment with internal data on the state of the body and the emotional state in order to coordinate the work of brain networks and initiate switching between the network of the passive mode of brain operation and the network of operational problem solving.