Can bipolar disorder have recognizable symptoms in a person's eeg?

Supposedly, yes: There is an experimental technique utilizing an eeg during electric shock convulsion. Patients with bipolar disorder show a high occurrence of high frequency activity in the gamma brainwave range on the eeg reading. Patients will reach a maximum peak, followed by two minor peaks ranging from 47 hz to 51 hz. These frequencies are located in the postictal-suppression phase of the patient's seizure.

Could be: One small [18 patient] study has shown that bipolar patients -- even when not in a mood episode -- have decreased Alpha activity in their eeg's. http://www.ncbi.nlm.nih.gov/pmc/articles/pmc3253163/ they were also free of medications for at least 2 weeks for the study. The authors feel it may differentiate bipolar from schizophrenia eeg's, but it's not diagnostically definitive on its own.