Investigating the Neural Correlates of Percepts Using Magnetoencephalography and Magnetic Source Imaging

Abstract

Magnetoencephalography (MEG) has become an important tool for neu-roscientists. The high temporal resolution and the low signal-to-noise ratio of MEG provide advantages that other neuroscientific methods do not. Owing to recent find-ings concerning the relationship between perception and neuronal oscillations, more attention is being drawn to the importance of MEG. This chapter provides an intro-duction to oscillatory brain dynamics and outlines the fundamental and recent re-search on this topic. It also includes an overview of the basic principles of MEG and compares MEG with other neuroscientific methods such as imaging techniques like functional magnetic resonance imaging, positron emission tomography and elec-troencephalography. Finally, as an example of the application of MEG in current research, a short review of our work on tinnitus is provided, including links to cur-rent research on general perception. 1 Perception in Relation to Oscillatory Brain Dynamics Imagine for a moment a barking dog. It is easy to conjure up an image of the dog in our mind and to vividly add sensory and emotional content to this image. The im-age is a percept reconstructed from memory and it may be so vivid that we might perceive changes in peripheral physiological response such as sweating or a racing heart beat. Elements of the underlying complex network of this cognitive process have been formed by our own unique experiences in life and are modified each time we retrieve the information and each time we re-experience similar situations. Multiple complex components of the brain are involved in this process and vari-ous pieces of sensory information related to this memory are utilized. For instance, the barking dog may be perceived acoustically at first, i.e., processed by the auditory