Touch sensation
Even if we close our eyes we can touch our body parts correctly. How is it possible?
K. KARTHICK
Tiruchi, Tamil Nadu
The basic mechanism is called proprioreception. This is a neurological phenomenon like thoughts. We neurologists found out that the various aspects of physiology like origin of thoughts, movements etc., are still an enigma to Neuroscience.
The receptors in the skin are called Pacinian carpuscles, and End bulbs of Krouse. Apart from this there are many receptors which are called Tendon Organ of Golgi, which are situated in the muscles, called muscle spindle, which constantly fires impulses to the brain, about the various degrees of contraction of the muscle, and on what we rest our feet.
These impulses are co-ordinated with brain stem, cerebellum, vetibular nucleus, (which also receive impulses from the middle ear, from vestibular apparatus, which alter according to the body and head positions), ultimately co ordinating with the ‘Greater Brain’ the cerebral cortex which is ultimate processing unit.
In the parietal cortex, all the templates are available to understand the movement of hand, position, the nature of objects which we touch, the range of movements required to touch that body parts, etc, which is a neurological phenomenon called Steroagnosis.
It is true otherwise also, that people who had a tumour or death of this parietal cortex due to occlusion of blood supply cannot identify their body parts correctly, or unable to understand what they are touching, whether it is cloth or paper etc.
Not only this, the sense of direction, spatial orientations (for example, where the wall ends in the room, and which is the direction to go) are all determined in this part of the brain. The parietal cortex, on both sides, performs this function, but may vary inside depending on the handedness of the individual.
This is the mechanism by which one can understand their own body parts or outside materials, which even blind people observe.
The Braille method of learning for blind is based on this mechanism of brain. The timbre, tone, quality, who sings the song are all determined by this Parietal cortex of the brain, which compares with the engram templates, which are already imprinted . But all are based on the impulses from perpheral receptors which feed the brain.
Dr. V. NAGARAJAN
Professor Emeritus in Neurosciences
Tamil Nadu Dr. MGR Medical University
Madurai, Tamil Nadu
Printer friendly
page
Send this article to Friends by
E-Mail
Sci Tech
