A new study performed by Dr. Richard James Addante, researcher at The University of Texas (UT) at Dallas, contests the long-accepted theory that the hippocampus is not involved with unconscious memory. The study was published in the journal NeuroImage and is entitled “A critical role of the human hippocampus in an electrophysiological measure of implicit memory.”
For decades it was thought that the hippocampus was important for conscious memory but did not play a role in processing unconscious memory, such as tasks a person performs without having to think about it such as buttoning a shirt. Now, research from Dr. Addante has raised some questions regarding this theory.
Research conducted on an amnesia patient at the Massachusetts Institute of Technology (MIT) has yielded most of the current knowledge concerning the hippocampus and how the brain organizes memories. This amnesia patient was known as “Patient H.M.,” later revealed to be Henry Molaison after his death in 2008. In 1957, in order to treat intractable epilepsy, the hippocampus and other tissues were removed from Molaison’s brain. Seizures were reduced after the surgery, but researchers were intrigued by the fact that Molaison could no longer generate new long-term memories, although he could remember events from his past prior to the surgery and had preserved his unconscious memory abilities.
Based on Molaison’s case, Dr. Addante hypothesized that amnesia patients should perform well in unconscious memory evaluations, as the hippocampus is apparently not required for unconscious memory. The UT Dallas researcher used electroencephalography (EEG) to analyze brain wave patterns of amnesia patients with injured hippocampuses while they were performing memory tests. The results were compared with control individuals.
Dr. Addante found that his hypothesis was wrong, as the amnesia patients’ EEGs showed major discrepancies compared to the controls, indicating a previously unknown fundamental role of the hippocampus in unconscious memory. The researcher was, however, careful with the idea of challenging an established scientific theory. “I didn’t know if the research would ever see the light of day,” said Dr. Addante in a news release. “But I was committed to solving a puzzle and have never quit anything thus far in life.” Dr. Addante has a positive attitude concerning the possibility that his findings could be proven wrong and he added, “If that happens, that’s awesome, too, because that’s science and progress.”
Dr. Addante believes that further studies are required in this field and that EEG should be used to analyze unconscious memory.