Is an alpha frequency of 9 Hz in O1 and 11.5 Hz in O2 considered abnormal in an adult?

The presence of an alpha frequency of 9 Hz in O1 and 11.5 Hz in O2 can be considered abnormal in an adult for several reasons. In a typical adult EEG, the alpha rhythm is usually observed in the range of 8 to 13 Hz, with a frequency around 10 Hz being most common.

An alpha frequency of 9 Hz in O1 is at the lower end of the normal range, which may suggest a deviation from the expected frequency for that area, while 11.5 Hz in O2 is approaching the upper limit. The asymmetry between the two electrodes, where one exhibits an alpha frequency that is noticeably different from the other, can indicate potential underlying neurological issues or abnormalities.

Specifically, the lower alpha frequency in O1 (9 Hz) might suggest reduced cognitive or attentional resources, which can correlate with various conditions such as depression, attention deficits, or other neurophysiological problems. Abnormalities in alpha frequency and asymmetry can also be an indicator of lesions or localized brain dysfunction.

Therefore, the answer is based on the interpretation of these frequencies concerning the expected normative data for adult EEG readings, affirming that the observed rates are indeed considered abnormal.