Quantitative Electroencephalography (QEEG)

Most of our studies involve quantitative electroencephalography (QEEG).  These digital recordings of  brain electrical activity employ six to 36 electrodes focused either on a limited brain region (such as the frontal cortex), or distributed to record activity from all major brain regions.  We utilize several QEEG measures including cordance, a measure developed in our Laboratory.  Cordance has been studied in adult and elderly subjects with major depression.  Cordance is calculated utilizing:  1) a new reference electrode method for calculating absolute and relative QEEG power, and 2) a method for integrating absolute and relative power measures into a single measurement.  As a means of validating the cordance algorithm, we studied subjects with simultaneous ¹⁵O PET and QEEG measurements.  These studies examined the association between QEEG measurements at each electrode and perfusion underlying the electrode, and determined that cordance shows stronger associations with cerebral perfusion than traditional power measurements.  Cordance values can be calculated for any frequency band, and our pilot data and prior reports from others indicate that alterations related to depression might be best detected in the theta band (4-8 Hz).  Because of these prior studies, most of our work focuses on cordance values in the theta band.