I was told by a famous neurosurgeon more damage is done to the brain than just the substantia nigra...

I was told as people aged - it was fairly normal for the black matter -aka substantia nigra to loose pigmantation?

what about the
Neuropsychological correlates of amygdala activity
Early research on primates provided explanations as to the functions of the amygdala, as well as a basis for further research. As early as 1888, rhesus monkeys with a lesioned temporal cortex (including the amygdala) were observed to have significant social and emotional deficits.[4] Heinrich Klüver and Paul Bucy later expanded upon this same observation by showing that large lesions to the anterior temporal lobe produced noticable changes, including overreaction to all objects, hypoemotionality, loss of fear, hypersexuality, hyperorality. Some monkeys also displayed an inability to recognize familiar objects and would approach animate and inanimate objects indiscriminately, exhibiting a loss of fear towards the experimenters. This behavior disorder was later named Klüver-Bucy syndrome accordingly.[5] Later studies served to focus on the amygdala specifically, as the temporal cortex encompasses a broad set of brain structures, making it difficult to find which ones specifically may have correlated with certain symptoms. Monkey mothers who had amygdala damage showed a reduction in maternal behaviors towards their infants, oftentimes physically abusing or neglecting them.[6] In 1981, researchers found that selective radio frequency lesions of the whole amygdala caused Klüver-Bucy Syndrome.[7]

Studies on the amygdala in the human brain have produced similar findings. In 2006, researchers observed hyperactivity in the amygdala when patients were shown threatening faces or confronted with frightening situations, and that patients with more severe social phobia showed a correlation with the increased response in the amygdala. Recently, researchers have paid close attention to the amygdala, as its hyperactivity has been shown to have a role in certain anxiety disorders.[8]

Two preliminary small-scale studies also have linked lower neuron density in the amygdala with autism, though it's unclear whether this is a cause or an effect of the condition. [9]

look up amygdala at www.answers.com