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Flat ảnh hưởng đến thay đổi tối thiểu trong tâm trạng, cảm xúc phản ứng không thích hợp, chẳng hạn như tiếng cười với những sự kiện buồn, không thể đoán trước tâm trạng sự lung lay. Thông thường nhất, thính giác (nghe tiếng nói và bằng lời nói với họ), | 190 Part III Clinical and Medicinal Use of Drugs Figure 13.1. The brain in Alzheimer s disease. The figure on the left is a static MRI scan where marked cortical atrophy is evident. The right-hand figure is a SPECT scan showing impoverished metabolism in the Alzheimer brain. Reproduced by permission of Professor John O Brien Wolfson Research Centre Newcastle-upon-Tyne UK. views of the brain of an Alzheimer s disease sufferer. The atrophy and lack of cortical activity in the cortex can be clearly observed in the living brain. However more subtle damage precedes this large-scale cortical demolition. As has been emphasised throughout this book the optimal working of the brain requires a fully integrated neural network Chapters 2 3 10 and 14 . The disease process adversely affects neurons in a number of specific ways. The main features contributing to this degeneration include cholinergic nerve degeneration and the widespread presence of neurofibrillary plaques and tangles see later . The next section will focus on acetylcholine nerves as the prime target for drug treatments. The role of plaques and tangles in Alzheimer s disease will be explored later. Cholinergic degeneration in Alzheimer s disease Neuronal loss in Alzheimer s disease is most evident in several regions which are rich in cholinergic neurons Isacson et al. 2002 these include the medial septal area which impinges on the hippocampus a crucial area for learning and memory the anterior cingulate which subserves attention and motivation and the hypothalamus which controls appetitive behaviours Perry et al. 1998 Chapter 2 . Marked degeneration is also observed in the nucleus basalis of Meynert NBM - an area containing around 1 million neurons. This relatively modest number of cells has a widespread influence on the cortex innervating a cortical sheet that would measure around half a square metre if fully stretched out. The NBM represents the major cholinergic projection to the cortex Mesulam 1995 and thus .
