May 14, 2007

The Cerebellum-Part2

start menu of Windows XPQuite a few of us are acquainted with the fact that in Windows XP, the start menu items that display, when we click the start button, organize themselves continuously (dynamically), as we use them. The programs we use most frequently, are placed on the top; while the least used items settle down at the bottom. A similar hierarchy is followed by the brain too. The tasks we have inherited from our ancestors, phyllogenetically, are kept at the bottom of our memory/program cache while more recent skills are placed at the top. As we go on acquiring new knowledge, they first locate in the cortical areas;- once the task have been mastered, they settle down deeper, into the cerebellum and so on. It seems we have our own stack registers. For example, much of our basic and posture maintenance algorithms are kept in lower brain areas such as the spinal cord, medulla, the midbrain rather than the cerebral cortex. They are old programs, evolution wise, and hence kept in the lower shelves. In early neonates, and in diseases of neuronal pathways e.g. in upper motor neuron lesion, midbrain lesions, spinal cord lesions the functional architecture/hierarchy is lost, as the higher centers are not yet or no longer active.That is, now, the sophisticated programs of the cerebral cortex are no longer working, the phylogenetically/ evolutionarily old programs resurface. Babinski reflex in UMN lesions, Moro's reflex are two examples.

In addition to the above mentioned address lines, there is this real time integration and differentiation that goes on constantly within the brain. The much awed calculus is their regular cup of tea!

To be contd.
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