18 Декабрь 2016

The desires and aspirations of the human heart are endless. It is foolish to attribute them all to a single brain system. But they all come to a standstill if certain brain systems, such as the dopamine (DA) circuits arising from midbrain nuclei, are destroyed. Such was the tragedy that overtook Leonard L. in his childhood, and it was not until he was a grown man that he was able to partake again of worldly delights. What allowed him to achieve the feelings of success described by Sacks was L-DOPA, the precursor of DA. This medicine had already alleviated the psychomotor problems of ordinary parkinsonian patients, who had weaker forms of deterioration in their ascending DA systems. In such individuals L-DOPA can dramatically alleviate the inability to initiate movements, allowing them to enjoy everyday pleasures. Now we know that ascending DA tracts lie at the heart of powerful, affectively valenced neural systems that allow people and animals to operate smoothly and efficiently in all of their day-to-day pursuits.