Navigation Links
Penn researchers find neural signature of 'mental time travel'
Date:7/18/2011

PHILADELPHIA Almost everyone has experienced one memory triggering another, but explanations for that phenomenon have proved elusive. Now, University of Pennsylvania researchers have provided the first neurobiological evidence that memories formed in the same context become linked, the foundation of the theory of episodic memory.

The research was conducted by professor Michael Kahana of the Department of Psychology in the School of Arts and Sciences and graduate student Jeremy R. Manning, of the Neuroscience Graduate Group in Penn's Perelman School of Medicine. They collaborated with Gordon Baltuch and Brian Litt of the departments of Neurology and Psychology at the medical school and Sean M. Polyn of Vanderbilt University.

Their research was published in the journal Proceedings of the National Academy of Sciences.

"Theories of episodic memory suggest that when I remember an event, I retrieve its earlier context and make it part of my present context," Kahana said. "When I remember my grandmother, for example, I pull back all sorts of associations of a different time and place in my life; I'm also remembering living in Detroit and her Hungarian cooking. It's like mental time travel. I jump back in time to the past, but I'm still grounded in the present."

To investigate the neurobiological evidence for this theory, the Penn team combined a centuries-old psychological research technique having subjects memorize and recall a list of unrelated words with precise brain activity data that can only be acquired via neurosurgery.

The study's participants were all epilepsy patients who had between 50 and 150 electrodes implanted throughout their brains. This was in an effort to pinpoint the region of the brain where their seizures originated. Because doctors had to wait for seizures to naturally occur in order to study them, the patients lived with the implanted electrodes for a period of weeks.

"We can do direct brain recordings in monkeys or rats, but with humans one can only obtain these recordings when neurosurgical patients, who require implanted electrodes for seizure mapping, volunteer to participate in memory experiments," Kahana said. "With these recordings, we can relate what happens in the memory experiment on a millisecond-by-millisecond basis to what's changing in the brain."

The memory experiment consisted of patients memorizing lists of 15 unrelated words. After seeing a list of the words in sequence, the subjects were distracted by doing simple arithmetic problems. They were then asked to recall as many words as they could in any order. Their implanted electrodes measured their brain activity at each step, and each subject read and recalled dozens of lists to ensure reliable data.

"By examining the patterns of brain activity recorded from the implanted electrodes," Manning said, "we can measure when the brain's activity is similar to a previously recorded pattern. When a patient recalls a word, their brain activity is similar to when they studied the same word. In addition, the patterns at recall contained traces of other words that were studied prior to the recalled word."

"What seems to be happening is that when patients recall a word, they bring back not only the thoughts associated with the word itself but also remnants of thoughts associated with other words they studied nearby in time," he said.

The findings provide a brain-based explanation of a memory phenomenon that people experience every day.

"This is why two friends you met at different points in your life can become linked in your memory," Kahana said. "Along your autobiographical timeline, contextual associations will exist at every time scale, from experiences that take place over the course of years to experiences that take place over the course of minutes, like studying words on a list."


'/>"/>

Contact: Evan Lerner
elerner@upenn.edu
215-573-6604
University of Pennsylvania
Source:Eurekalert

Related medicine news :

1. Researchers identify how a gene linked to both Alzheimers disease and type 2 diabetes works
2. NYU researchers develop compound to block signaling of cancer-causing protein
3. Mayo researchers: Genetic mutation linked to Parkinsons disease
4. Researchers Closer to Developing Universal Meningitis B Vaccine
5. Novel Virus Jumped From Monkeys to Humans, Researchers Find
6. Dentists can identify people with undiagnosed diabetes, Columbia researchers show
7. UAB researchers present a study on the psychological adaptation of adopted children
8. Researchers identify key role of microRNAs in melanoma metastasis
9. A change of heart: Penn researchers reprogram brain cells to become heart cells
10. Researchers identify early biomarker for future atopy in asymptomatic children
11. Berkeley Lab researchers apply NMR/MRI to microfluidic chromatography
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/13/2017)... ... October 13, 2017 , ... ... that offers insurance and financial preparation services, is providing an update on a ... organization. , Rock City Rescue is a locally recognized nonprofit that provides shelter ...
(Date:10/13/2017)... ... October 13, 2017 , ... The International Association of Eating ... excellence for the field of eating disorders, announces the opening of early registration ... Orlando, Florida at the Omni Resort at ChampionsGate. , The annual ...
(Date:10/13/2017)... ... 2017 , ... Apple Rehab Shelton Lakes , which specializes in the ... facility as part of a disaster drill on October 3rd. , Apple Rehab participated ... Emergency Manager, as well as the Connecticut Long Term Care Mutual Aid Plan ...
(Date:10/13/2017)... , ... October 13, 2017 , ... Global Healthcare Management’s ... Alexandria Park in Milford, NJ. This free event, sponsored by Global Healthcare Management’s ... The fun run is geared towards children of all ages; it is a ...
(Date:10/13/2017)... ... October 13, 2017 , ... “The Journey: From the Mountains to the ... save lost souls in the Philippines. “The Journey: From the Mountains to the Mission ... of the Bible. She has taught all ages and currently teaches a class of ...
Breaking Medicine News(10 mins):
(Date:10/4/2017)... South Korea , Oct. 4, 2017  South ... its next-generation CPR training aide "cprCUBE" on Kickstarter. The ... chest compression during cardiac arrests with better efficiency compared ... It also offers real-time feedback on efficacy of the ... The crowdfunding campaign has a goal to raise $5,000. ...
(Date:10/2/2017)... -- Eli Lilly and Company (NYSE: LLY ) ... of 2017 on Tuesday, October 24, 2017. Lilly will ... the investment community and media to further detail the ... begin at 9 a.m. Eastern time. Investors, media and ... the conference call through a link that will be ...
(Date:9/28/2017)... -- Hill-Rom Holdings, Inc. (NYSE: HRC), will host its ... on Friday, November 3, 2017, beginning at 7:00 a.m. ... 8:30 a.m. (CDT) / 9:30 a.m. (EDT). ... and guidance for 2018, Hill-Rom executives will also highlight ... and long-range financial outlook through 2020. ...
Breaking Medicine Technology: