In our everyday life, we sense and accordingly react to changes in our environment. Sensory information is sent to the central nervous system by the neurons, when an external stimulus is detected. The sensory information is processed based on which a motor response may be initiated involving muscle contraction or movement of body parts. For instance, when something flies close or we hear a big sound, near our eyes, our eyes blink. The working of visual and auditory attention systems is not a simple process that can be demonstrated as a single stand-alone system.
Visual attention may be classified into pre-attentive processing and attentive processing. These two processes are mostly parallel and sometimes sequential. The external sensory stimuli are converted to electrical impulses by special nerve cells or sensory receptors. The conversion of all external stimuli like sight, feel, taste, sound etc. , are carried out by a similar method. The sensory receptors or neurons convey their information to the brain through nerve cells. Cross-sensory interactions and their dynamics in the human brain is learnt by advanced multisensory processing (Thesen et al. ).
The nerve cells are formed in parallely arranged pathways, and simultaneously convey individual aspects of the stimulus to the brain. Man has about 1010 neurons formed around 104 connections. Neurons have dendrites for receiving inputs and axons for output. Inputs from the dendrites accumulate and once a threshold is reached, an output is activated. The brain splits an image into several portions, which are then assigned to specific regions of the brain’s visual center, where a neural representation of the image is created (Lois Baker). The presence of a large amount of sugar in urine is called Diabetes Mellitus.
Nerve conduction aspects generally deteriorate with age, but is however more pronounced in diabetic people. The performance of sensory nerve conduction tends to become inferior although it would remain in the normal range, at the initial stages (Albers et. al. ). Generally blood sugar levels rise after eating, which induces the pancreas to release insulin. Diabetes is one of the important cause for visual loss, resulting from retina damages. It is estimated that about 30% of all diabetic people have retinopathy. Diabetic retinopathy is caused to blood vessels in the retina.
When the smaller blood vessels get blocked, other vessels expand to compensate, leading to leakage of several substances (Perlstein). These produce blurring of vision. Blockage also causes newer vessels to grow on the near side of vitreous, producing vision distortion. Damage to the body’s hearing system due to diabetic mechanism is not well established. However, there is now increased evidence of damage when blood supply to cochlea and nerve centers of the hearing system are affected (McDermott and Vaughan).
REFERENCES
Helder Araujo. An interdisciplinary approach to the problem of visual and auditory attention. University of Coimbra [Electronic Version] retrieved on 8th February 2008 from http://www. socsci. ru. nl/CogSys2/PDFs/Araujo_COGSYS2-POP-version1. pdf Paul Spong. Selective Attentiveness and Cortical Evoked Responses to Visual and Auditory Stimuli. Departments of Psychology and Physiology, University of California Los Angeles [Electronic Version] retrieved on 8th February 2008 from http://www. sciencemag. org/cgi/content/abstract/148/3668/395 Robyn Perlstein. Diabetes and Visual Impairment. The British Journal of Visual Impairment Vol. VIII No. 2 Summer 1990 Daniel McDermott and Nancy Vaughan.
Diabetes and Hearing Loss: Exploring Connections Hearing Health, Volume 19:3, Fall 2003 James W. Albers et. al. Subclinical Neuropathy Among Diabetes Control and Complications. Diabetes Care 30:2613-2618, 2007. [Electronic Version] retrieved on 8th February 2008 from http://care. diabetesjournals. org/cgi/content/full/30/10/2613? ck=nck Thomas Thesen et al. Neuroimaging of multisensory processing in vision, audition, touch, and olfaction Cognitive Processing; Springer Berlin / Heidelberg Volume 5, Number 2 / June, 2004 Lois Baker . Studying how the senses are perceived. University of Buffola Reporter Volume 34, Number 5