weighs three pounds
uses 20 watts of power
100,000 miles of blood vessels
100 billion neurons
1,000 – 10,000 synapses per neuron
survival time 4-6 minutes without oxygen
Sunday 28 November 2010
Saturday 27 November 2010
The ability to select what you will look at is vital to cognitive growth. It introduces a sense of order and structure to a child’s understanding of the world. How visual functioning is affected depends very much on what specific part of the brain has been damaged. My experience points to a frequent problem in this area of the brain that handles and processes visual attention. This is the ability to choose what you look at and focus on. We take this so much for granted yet it is a highly complex skill. The region I am talking about is a part of the cerebral cortex called the parietal lobes. The cerebral cortex is the outer shell of the brain and is in two halves. The parietal lobes form two halves of the cortex. What is the function of this section of the cortex? This part of the brain brings information together from all the senses and presents a child with a unified understanding of his world. It acts as a centre for all sensory information. It helps to coordinate what a child sees with what the upper and lower limbs are doing and is profoundly involved with the body’s motor skills. The parietal lobes contain the centre for giving selective visual attention to something in the environment. For example it is concerned with using vision to reach out for an object such as a bottle or cup, or to see a hand and an object well enough to locate something with precision . Threading, playing with Lego bricks, reaching for and holding food are everyday tasks for a child that employ skills which are all centred in the parietal lobes. And this region of the brain is sometimes damaged when there is a sudden interruption of the flow of oxygen during birth.
Thursday 25 November 2010
Hi. Are you a parent of a child who has poor vision as well as brain damage and or do you work with such a child? Then you want to know as much as you can about your child, the ways that your child perceives the world and how different that may be from the way you perceive it.
This is not a medical blog nor will I overwhelm you with technical terms. Hopefully it will be accessible to all regardless of background and education. Nevertheless technical terms will be introduced and explained for without them the account will otherwise make no sense.
This site is dedicated to all those parents, teachers, and countless other professionals who are committed to work tirelessly helping babies and youngsters with complex needs who also happen to have difficulty perceiving, seeing and understanding the world they live in. It is intended to be a resource where information can be offered or exchanged to empower and enable all those who work with some of the most challenging children of all.
How is a visual impairment in the brain (CVI) different from other forms of visual impairment (VI)?
Visual impairment affects the eyes and the optic nerve. There at least 80 known specific impairments of vision that are caused by something within the eye itself. These range from problems with visual fields, focusing, problems seeing detail up close or far away and sensitivity to light (to name but a few). Some conditions (squint, short-sight, long-sight, astigmatism) are relatively easily corrected with optical aids such as spectacles. But many other visual disorders cannot be corrected. A person has to learn to live with the condition and manage it himself (‘he’ is used for the sake of brevity). In addition the child’s school may have to make various modifications to the child’s learning materials and environment in order to make it easier for the child to learn.
However CVI (cerebral visual impairment or cortical visual impairment) is different. CVI is an impairment of vision that is rooted in the brain or caused by damage to the brain tissues. In fact seeing is done in the brain; 40% of the brain is concerned with some aspect of seeing. The eyes are like a camera that receives the input but the real seeing goes on inside a person’s brain. Often in these cases there is absolutely nothing wrong with the mechanism of the eye itself. Whereas a visual impairment can be measured fairly accurately, CVI is less easy to quantify precisely. It is also quite difficult to manage compared with a ‘malfunction’ of the eye mechanism.
Sometimes a child has a combination of visual impairment and CVI. This is when there is a problem with the eye itself and also a problem caused by damage to the brain. In this scenario the impact of the two conditions needs to be carefully understood and separated. In the following days I will be looking what it really means to the child to be in this situation.