Читать книгу Abnormal Psychology - William J. Ray - Страница 80

With 86 billion neurons and 50 to 200 trillion connections between neurons in the human brain, understanding these connections on a neuronal level would be an impossible task. However, scientists have been able to use the manner in which neurons work as a window into their function. A variety of techniques for observing activity in the brain have been developed.

Currently, the major types of brain imaging techniques are electroencephalography (EEG), magnetoencephalography (MEG), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). EEG is a technique for recording electrical activity from the scalp related to cortical activity. MEG measures the small magnetic field gradients exiting and entering the surface of the head that are produced when neurons are active. PET is a measure related to blood flow in the brain, which reflects cognitive processing. fMRI is based on the fact that blood flow increases in active areas of the cortex. It is also possible to use the magnetic resonance imaging (MRI) magnet to measure cortical connections in the brain, which is referred to as diffusion tensor imaging (DTI). Let’s take a look at each of these techniques, and consider the strengths and weaknesses of each type.

Figure 2.9 Spike Trains Produced by Different Levels of Firing of Neurons

Source: Spencer, W. (2011). The Physiology of Supraspinal Neurons in Mammals. Supplement 1: Handbook of Physiology, The Nervous System, Cellular Biology of Neurons, pp. 969–1021. First published in print, 1977.