Jodi Arias’ attorneys called their expert witness, clinical and forensic psychologist Dr. Richard Samuels, to the stand Thursday.

Among the many different topics he brought up about memory loss was a condition known as transient global amnesia (TGA).

According to the Mayo Clinic, TGA is a “sudden, temporary episode of memory loss that can't be attributed to a more common neurological condition, such as epilepsy or stroke… episodes are usually short-lived, and afterward one’s memory is fine.”

Dr. Samuels explained to the jury that TGA is rare, noting, “Between three and eight people per 100,000 people each year experience transient global amnesia.”

He continued, “The amazing thing is, here are the things that can cause that -- sudden immersion in cold or hot water, physical exertion, emotional or psychological stress, pain, medical procedures, sexual intercourse and similar events have been observed in 50 to 90% of these documented attacks of transient global amnesia.”

When HLN’s Dr. Drew heard that testimony, he strongly reacted, saying, “[TGA] is a confusional state and it’s medical and it’s caused by medication.  I’ve seen it a dozen times," adding, "It's not just [like] your memory vanishes … I don’t know how much clinical experience he has with [TGA].”

Arias claims she had to kill Alexander in self-defense in June of 2008 at his Mesa, Arizona home, even though she had given authorities other stories about the circumstances of his death.

The 32 year-old defendant also says she simply can’t remember many details of the day she killed Alexander. Most of it, in her words, was a “fog.”

She faces the death penalty if convicted in her trial.

Dr. Drew On Call airs Monday through Thursday on HLN at 9 p.m. ET.  Follow the show on Facebook and Twitter @DrDrewHLN.

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