The human insula (or island of Reil) is an evolutionary old (paleocortex) and entirely hidden brain structure, a polymodal integrative zone, implicated in a large number of different functions and dysfunctions. E.g. insular cortex is intensely activated by painful stimuli or foul stimuli such as rotting fish and is responsible for the processing of social emotions related to the current motivational state. In the mature brain the insular cortex is situated in the depths of the lateral sulcus and revealed only when the banks of the lateral sulcus are partially separated or when the brain is dissected. The insula passed through a progressive differentiation during terrestrial vertebrata evolution, and is greatly expanded in humans playing an important role in the extended integrated action cycle (that starts in Integration, Information, Motivation, Intention and Volition, and culminates in Action and Reflection).
Fishes use a special sensory system to obtain information about minute water movements: the lateral line system. The lateral line system decodes the information in the water surrounding the fish to enable the fish to identify and localize the source of the perturbation. From the lateral-line system of fishes evolved the vestibular system of terrestrial vertebrata which deals with equilibrium and position in space and ascending thalamocortical projection from the vestibular nuclei to the insular cortex which is important in the conscious awareness of head motion, balance, orientation, appropriate actions and integration/memorization of the paths taken. Likely, the insula is one of the most changed regions of the human brain. This
CEREBRART work illustrates an evolutionary trend in the island of Reil development.
I suppose fish really haven't got any brain insula at all, have they?
ReplyDeletethis rather special cerebrart style is loaded with silent messages and some esoteric symbolism
ReplyDeletePerhaps the human insula might serve as a key node in extended integrated action cycle subserving cognition–emotion integration?
ReplyDeleteThank you Alex and two Anonymi. I think there is no fish insula in sensu stricto but some locus of chemical-mechanical integration exists without any doubt. E.g. some sharks are able to detect as little as one part per million of blood in seawater, to determine the direction of a given scent and move accordingly at speeds up to 50 kilometres per hour - an example of the most effective information–motion integration! Shark brain isn't chaotic and has been found to share several features with those of humans, new research shows...
ReplyDeletebrain integration seems to begin with the island of Reil. The brain insula is made up of two separate structures, one on each side of the brain, and is part of a circuit, receiving and dispersing information. The brain insula receives information, and then uses this information to determine the body’s needs. Once the body’s needs have been determined, the brain insula produces feelings which bring on motivation
ReplyDeleteThe island of Reil (the brain insula) works in accord with the cingulate and parahippocampal cortices and they all serve as a key node of information circuits.
ReplyDeleteOf course, the brain insula is instrumental in integrating different functional
Deletesystems of the human brain and is well suited to provide an interface between information, motivation and action.