Nav: Home

Researchers discover neural patterns key to understanding disorders such as PTSD

April 09, 2019

Researchers at the University of California, Irvine have identified for the first time an imbalance in a key neural pathway that explains how some people reactivate negative emotional memories. The finding could help scientists unlock new ways to treat psychiatric disorders such as post-traumatic stress disorder.

The study, "Multiplexing of Theta and Alpha Rhythms in the Amygdala-Hippocampal Circuit Supports Pattern Separation of Emotional Information," is published today in the journal Neuron.

For decades, scientists have viewed emotional memory as a double-edged sword: while the entire emotional event is highly memorable, details of the event are often fuzzy. This lack of detailed recollection may lead to faulty reactivation of negative memories. For example, if someone is bitten by a dog, he or she may become anxious around dogs of all breeds and sizes. Understanding the nature of emotional memory could have implications for the treatment of PTSD and other mental disorders.

"Emotion exerts a powerful influence on how vividly we can remember experiences," said co-senior author Michael Yassa, professor of neurobiology & behavior, UCI School of Biological Sciences; professor of neurology and psychiatry, UCI School of Medicine; and director of UCI's Center for the Neurobiology of Learning & Memory. "However, studies in humans have shown that the impact of emotion on memory is not always positive. In many cases, emotional arousal can impair a person' ability to differentiate among similar experiences."

This neural computation is critical for episodic memory and is vulnerable in neuropsychiatric disorders, Yassa said.

According to this new study from UCI, an imbalanced communication between the brain's emotional center, the amygdala, and its memory hub, the hippocampus, may lead to the failure to differentiate negative experiences that have overlapping features. On the other hand, a balanced dialogue between the amygdala and the hippocampus allows one to separate overlapping emotional experiences and make distinct memories.

Further, two types of brain rhythms - a faster (8 cycles per second) alpha oscillation and a slower (4 cycles per second) theta rhythm - diametrically regulate communications between the amygdala and the hippocampus. Overamplified alpha rhythms from the amygdala to the hippocampus lead to faulty extrapolation of memories among similar experiences while balanced theta rhythms between the two brain regions promote correct discrimination and accurate recall.

"The teamwork between the amygdala and hippocampus is like a yin and yang and may be the key to disentangle overlapping emotional experiences and to overcome overreactions in a similar situation," said Jie Zheng, a UCI alumnus and the study's first author.

"Our findings provide a neural mechanism underlying this phenomenon and propose a circuit-level framework for possible neuropsychiatric therapy, such as deep brain stimulation, transcranial alternating current stimulation, and transcranial magnetic stimulation," said Dr. Jack J. Lin, co-senior author and professor of neurology, UCI School of Medicine, and professor of biomedical engineering, UCI Henry Samueli School of Engineering.

Measurements were collected from electrodes implanted by UCI Health neurosurgeons in seven patients with medication-resistant epilepsy as part of an assessment of their seizure activity. Electrode placement was guided exclusively by these patients' clinical needs, Lin said.
-end-
This work was supported by several grants from the National Institutes of Health: NINDS R37NS21135, NIMH R01MH102392, NINDS T32NS45540, as well as support from the UCI School of Medicine and the Roneet Carmell Memorial Fund. The authors wish to express their appreciation to these patients and the staff of the UCI Health Epilepsy Monitoring Unit.

About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 36,000 students and offers 222 degree programs. It's located in one of the world's safest and most economically vibrant communities and is Orange County's second-largest employer, contributing $5 billion annually to the local economy. For more on UCI, visit http://www.uci.edu.

Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.

University of California - Irvine

Related Memory Articles:

How long does memory last? For shape memory alloys, the longer the better
Scientists captured live action details of the phase transitions of shape memory alloys, giving them a better idea how to improve their properties for applications.
Seeing it both ways: Visual perspective in memory
Think of a memory from your childhood. Are you seeing the memory through your own eyes, or can you see yourself, while viewing that child as if you were an observer?
A NEAT discovery about memory
UAB researchers say over expression of NEAT1, an noncoding RNA, appears to diminish the ability of older brains to form memories.
Molecular memory can be used to increase the memory capacity of hard disks
Researchers at the University of Jyväskylä have taken part in an international British-Finnish-Chinese collaboration where the first molecule capable of remembering the direction of a magnetic above liquid nitrogen temperatures has been prepared and characterized.
Memory transferred between snails
Memories can be transferred between organisms by extracting ribonucleic acid (RNA) from a trained animal and injecting it into an untrained animal, as demonstrated in a study of sea snails published in eNeuro.
More Memory News and Memory Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...