Chapter 13: Electrophysiology and Imaging

Electroencephalography represents a continuous recording of electrical brain activity captured through scalp electrodes positioned according to the standardized ten-twenty system, with analysis typically organized into frequency bands including delta, theta, alpha, and beta waves, while clinical applications focus on detecting pathological conditions such as seizures and research applications investigate patterns of normal cognition. Evoked potentials and event-related potentials measure the brain's consistent response to specific sensory or cognitive stimuli through computer averaging of multiple trials to isolate signal from background noise, with early exogenous components reflecting sensory processing and later endogenous components including the P300 relating to higher-order cognitive evaluation. Coherence analysis provides a sophisticated approach to identifying shared activity between brain regions independent of overall power changes. Much electrophysiological research has pursued investigation of hemispheric differences, though critics question whether some reported asymmetries represent genuine functional lateralization or constitute artifacts arising from methodological factors such as eye movement patterns. The chapter surveys structural and functional neuroimaging advances beginning with computerized tomography and progressing through magnetic resonance imaging, which provides detailed anatomical visualization through magnetic field manipulation, followed by functional approaches including functional magnetic resonance imaging that identifies active regions through blood flow changes detected via subtraction methodology comparing task states to baseline conditions. Positron emission tomography employs radioactive tracers to study complex behavioral phenomena, while magnetoencephalography detects magnetic fields generated by neural activity with exceptional spatial and temporal precision despite significant equipment costs. Tractography extends magnetic resonance capability to visualize white matter organization in three dimensions. The chapter emphasizes that despite their substantial contributions to understanding the neural basis of cognition, these techniques face considerable methodological challenges including replication difficulties and risks of overinterpretation, advocating for future advancement through integrated approaches combining imaging findings with traditional lesion study methods to strengthen the connection between brain structure, physiological mechanisms, and observable cognitive performance.