Why does vivid memory 'feel so real?'

Scientists find evidence that real perceptual experience and mental replay share similar brain activation patterns

2012-07-24

(Press-News.org) Toronto, Canada – Neuroscientists have found strong evidence that vivid memory and directly experiencing the real moment can trigger similar brain activation patterns.

The study, led by Baycrest's Rotman Research Institute (RRI), in collaboration with the University of Texas at Dallas, is one of the most ambitious and complex yet for elucidating the brain's ability to evoke a memory by reactivating the parts of the brain that were engaged during the original perceptual experience. Researchers found that vivid memory and real perceptual experience share "striking" similarities at the neural level, although they are not "pixel-perfect" brain pattern replications.

The study appears online this month in the Journal of Cognitive Neuroscience, ahead of print publication.

"When we mentally replay an episode we've experienced, it can feel like we are transported back in time and re-living that moment again," said Dr. Brad Buchsbaum, lead investigator and scientist with Baycrest's RRI. "Our study has confirmed that complex, multi-featured memory involves a partial reinstatement of the whole pattern of brain activity that is evoked during initial perception of the experience. This helps to explain why vivid memory can feel so real."

But vivid memory rarely fools us into believing we are in the real, external world – and that in itself offers a very powerful clue that the two cognitive operations don't work exactly the same way in the brain, he explained.

In the study, Dr. Buchsbaum's team used functional magnetic resonance imaging (fMRI), a powerful brain scanning technology that constructs computerized images of brain areas that are active when a person is performing a specific cognitive task. A group of 20 healthy adults (aged 18 to 36) were scanned while they watched 12 video clips, each nine seconds long, sourced from YouTube.com and Vimeo.com. The clips contained a diversity of content – such as music, faces, human emotion, animals, and outdoor scenery. Participants were instructed to pay close attention to each of the videos (which were repeated 27 times) and informed they would be tested on the content of the videos after the scan.

A subset of nine participants from the original group were then selected to complete intensive and structured memory training over several weeks that required practicing over and over again the mental replaying of videos they had watched from the first session. After the training, this group was scanned again as they mentally replayed each video clip. To trigger their memory for a particular clip, they were trained to associate a particular symbolic cue with each one. Following each mental replay, participants would push a button indicating on a scale of 1 to 4 (1 = poor memory, 4 = excellent memory) how well they thought they had recalled a particular clip.

Dr. Buchsbaum's team found "clear evidence" that patterns of distributed brain activation during vivid memory mimicked the patterns evoked during sensory perception when the videos were viewed – by a correspondence of 91% after a principal components analysis of all the fMRI imaging data.

The so-called "hot spots", or largest pattern similarity, occurred in sensory and motor association areas of the cerebral cortex – a region that plays a key role in memory, attention, perceptual awareness, thought, language and consciousness.

Dr. Buchsbaum suggested the imaging analysis used in his study could potentially add to the current battery of memory assessment tools available to clinicians. Brain activation patterns from fMRI data could offer an objective way of quantifying whether a patient's self-report of their memory as "being good or vivid" is accurate or not.

###The study was funded with grants from the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada.

ELSE PRESS RELEASES FROM THIS DATE:

Mice have distinct subsystem to handle smell associated with fear

2012-07-24

PROVIDENCE, R.I. [Brown University] — A new study finds that mice have a distinct neural subsystem that links the nose to the brain and is associated with instinctually important smells such as those emitted by predators. That insight, published online this week in Proceedings of the National Academy of Sciences, prompts the question whether mice and other mammals have specially hardwired neural circuitry to trigger instinctive behavior in response to certain smells. In the series of experiments and observations described in the paper, the authors found that nerve cells ...

Survival rates for premature babies in high-level NICUs are better than previously reported

2012-07-24

Premature babies are more likely to survive when they are born in high-level neonatal intensive care units (NICUs) than in hospitals without such facilities, and this benefit is considerably larger than previously reported. The likelihood that an extremely premature baby will survive if born in a high-technology, high-volume hospital unit was already known, but the current study, the largest to date, revealed a stronger effect. Pediatric researchers who analyzed more than 1.3 million premature births over a 10-year span found that the survival benefits applied not only ...

Study finds non-disclosure of HIV serostatus common among India female sex workers

2012-07-24

(Boston) - Researchers from Boston University School of Medicine (BUSM) in partnership with Indian researchers and HIV positive networks groups, have found that in India, non-disclosure of HIV serostatus to sex partners among both HIV-infected female sex workers (FSWs) and HIV-infected clients of FSWs is exceedingly common. These findings currently appear online in the journal AIDS and Behavior. No previous studies in India specifically, and few internationally, have assessed FSWs' and male clients' disclosure of HIV status to sex partners. Disclosure of HIV serostatus ...

New species of ancient rodents hint at what could be world's oldest grasslands

2012-07-24

A paleontological team that includes scientists from the American Museum of Natural History; University of California, Santa Barbara; and Case Western Reserve University has described two ancient species of South American rodents, including the oldest chinchilla, a discovery that substantiates what might be the earliest grasslands in the world. The two new species lived near a chain of volcanoes about 32.5 million years ago in what are now the steep slopes of a river valley in the Chilean Andes. Studies of the teeth of the ancient chinchilla support evidence from other ...

New findings by GW researcher break tanning misconceptions: 'There is no such thing as a safe tan'

2012-07-24

WASHINGTON (July 23, 2012) – A new study conducted by GW School of Medicine and Health Sciences (SMHS) researchers Edward C. De Fabo, Ph.D., Frances P. Noonan, Ph.D., and Anastas Popratiloff, M.D., Ph.D., has been published in the journal Nature Communications. Their paper, entitled "Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment," was published in June 2012. "This is the first time that UV-induced melanin formation (tanning), traditionally thought to protect against skin cancer, is shown to be directly involved in melanoma ...

Clemson plant breeders roll out new oat variety

2012-07-24

CLEMSON, S.C. — Clemson University plant breeders announced a new high-yielding variety of oats. Named Graham, the new variety grows to medium height, withstands falling over (lodging), matures earlier and produces more seed than comparable varieties. "Graham has excellent seed yield potential, exceeding the Rodgers variety by 20 bushels per acre at some locations and produces a 32.2-pound bushel compared to 31.9-pound bushel for Rodgers," said Chris Ray, director of the S.C. Crop Improvement Association, which grows certified seed for sale to the public. The new ...

Research shows potential of microneedles to target therapeutics to the back of the eye

2012-07-24

Thanks to tiny microneedles, eye doctors may soon have a better way to treat diseases such as macular degeneration that affect tissues in the back of the eye. That could be important as the population ages and develops more eye-related illnesses – and as pharmaceutical companies develop new drugs that otherwise could only be administered by injecting into the eye with a hypodermic needle. For the first time, researchers from the Georgia Institute of Technology and Emory University have demonstrated that microneedles less than a millimeter in length can deliver drug molecules ...

Bloodstream scavenger inhibits clotting without increased bleeding

2012-07-24

DURHAM, N.C. – A compound that mops up debris of damaged cells from the bloodstream may be the first in a new class of drugs designed to address one of medicine's most difficult challenges -- stopping the formation of blood clots without triggering equally threatening bleeding. In a mouse study published online July 23, 2012, in the journal Proceedings of the National Academy of Sciences, Duke University Medical Center scientists report that the experimental compound called PAMAM G-3 actually prevents activation of the process that leads to the formation of dangerous blood ...

Synthetic stimulants called 'bath salts' act in the brain like cocaine

2012-07-24

CHAPEL HILL, NC – The use of the synthetic stimulants collectively known as "bath salts" have gained popularity among recreational drug users over the last five years, largely because they were readily available and unrestricted via the Internet and at convenience stores, and were virtually unregulated. Recent studies point to compulsive drug taking among bath salts users, and several deaths have been blamed on the bath salt mephedrone (4-methylmethcathinone or "meow-meow"). This has led several countries to ban the production, possession, and sale of mephedrone and ...

Public health expert David Dausey calls BPA ban 'hollow victory'

2012-07-24

The FDA says baby bottles and sippy cups can no longer contain Bisphenol-A (BPA), an endocrine disruptor that mimics estrogen. But what about the hundreds of other plastic items, from water bottles to dental sealants, containing BPA? The FDA didn't go far enough, said Mercyhurst University Public Health Department Chair Dr. David Dausey. Dausey addresses the FDA's recent BPA ban in his latest vlog, The Dausey File: Public Health News Today. BPA has been associated with a wide range of health problems from metabolic disease to reproductive health defects. Dausey said ...

LAST 30 PRESS RELEASES:

The Lancet Obstetrics, Gynecology, & Women’s Health: Taking paracetamol during pregnancy does not increase risk of autism, ADHD or intellectual disabilities, confirms new gold-standard evidence review