Abstract
Purpose: This paper will examine different neurocognitive theories which conclude that the brain is able to restore or redress lost or damaged processing systems by reorganising remaining neuronal resources.
Method: The blood oxygenation level dependent or BOLD-signal is the most frequently used method for imaging brain activity in healthy, young adults, children, the elderly, or subjects with a neurodegenerative condition. The BOLD-signal reflects the balance between oxygen metabolism and vascular blood supply. The effect of neuronal discharge activity and neuronal recruitment on oxygen metabolism and vascular blood supply will be described.
Result: Maturation, senescence or degenerative illness alter the balance of oxygen metabolism and vascular blood supply on a regional level. This changes the ability to detect brain activity using the BOLD-signal and accounts for the activation pattern observed in the young, the old and the ill.
Conclusions: The change in activation pattern observed in the young, the old and the ill is not the result of a compensatory mechanism but the result of a disparity in the neuronal process which can not be compensated for.
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