Читать книгу Abnormal Psychology - William J. Ray - Страница 86

It is also possible to use the MRI magnet to measure cortical connections in the brain, which is referred to as diffusion tensor imaging (DTI). DTI is available with most MRI imaging systems (see Thomason & Thompson, 2011, for an overview of DTI and psychopathology). It is a procedure for showing fiber tracts (white matter) in the brain. This information can then be visualized by color coding it as shown in Figures 2.18 and 2.19. This allows one to map the white matter connections in the brain. In these figures, the connections between different parts of the brain can be seen.

Figure 2.16 Functional Magnetic Resonance Imaging (fMRI)

Source: © Zephry/Science Source.

Developmentally, after-infancy measures of white matter suggest a linear development until a person is in her thirties. Following a plateau, these gradually decline with age. Using DTI, it is possible to map the mild cognitive impairment seen in dementia and the more severe impairment seen in Alzheimer’s disease. Disconnections are seen between the major areas involved in memory such as the hippocampus and the temporal lobes (Stebbins & Murphy, 2009). As would be expected, this loss of connectivity is greater in Alzheimer’s than in mild cognitive impairment. Individuals with schizophrenia also exhibit problems with cortical connections (Phillips et al., 2011). It is also possible to compare the structure of pathways in the brain between humans and other primate species (Wedeen et al., 2012).