Selective memory for the good things in life may signal early memory loss

By Jessie Yaros, Graduate Student in the Translational Neurobiology Laboratory

“Those were the good old days”. Chances are you’ve expressed this statement yourself, or heard a parent or grandparent share the sentiment. Nostalgia is almost second nature for us, and seems like a healthy way to reflect on the past. Who wouldn’t want to reminisce about childhood, college, or that first job, when life was wonderfully uncomplicated. Viewing life through rose-tinted glasses, however, may not be such a good thing. New research from UC Irvine suggests that this selective remembering of positive experiences can be a marker for memory loss in the elderly.

In a study that appears in the August edition of Learning and Memory, Michael Yassa, associate professor of neurobiology & behavior and neurology, and colleagues designed and employed a test that uses participants’ recall of stories with differing emotional content to identify memory deficits and decline. The findings suggest that older adults with minor memory deficits are more likely to learn and retain positive information, relative to negative or neutral information.

Participants who were administered the new test, coined the Emotional Logical Memory Test (ELMT) , listened to various stories, and immediately afterwards were asked to recite all the details they could remember. They reported the events from memory again after 20 minutes, and at a subsequent visit one week later. This allowed the neurobiologists to observe how recall varied with the emotional tone of stories as time passed.

The research was overseen by Stephanie Leal, who recently earned a doctorate at UCI, and Jessica Noche, a clinical research specialist in the Yassa lab.

“We were interested in seeing how emotional memory changes over time, so we developed a test to detect the subtle changes that occur with different types of emotional memory in older adults,” Noche said. “We specifically compared responses to positive, negative and neutral stories to learn whether emotional valence had a role in the way stories were remembered over time.”

Study participants also took a verbal learning exam to gauge general memory performance. This served to distinguish between individuals who were high performers and those who were low performers (i.e., showing subtle memory deficits). Importantly, none of them suffered from overt memory problems severe enough for a clinical diagnosis.

Analyzing the results, researchers found that low-performing older adults exhibited a large “positivity effect,” or propensity to remember positive information. However, this came at the expense of retaining neutral material. On the other hand, high-performing older adults could recall more from neutral stories at the expense of retaining positive details.

Past studies have generated contradictory results on the existence of the positivity effect in aging populations. Yassa’s research suggests that prior inconsistent detection of the emotional preference may be caused by grouping older adults together, irrespective of high and low memory performance.

It is likely that this observed preference for positive information in older adults is connected to changes in the brain associated with aging. “We suggest that this bias toward positive retention in low-performing adults may be a compensatory mechanism that masks the effects of memory loss in the elderly, although this remains speculative,” Yassa said. “It’s possible that selectively remembering positive information may be related to changes in the brain networks supporting memory, emotional valence and reward value. Future studies using brain imaging techniques will be essential in understanding the mechanisms underlying this effect.”

Since all study participants at the time of testing had no memory complaints, researchers believe that the ELMT may tap into subtle changes in emotional memory abilities prior to obvious symptoms of cognitive decline. Further work will be necessary to establish whether participants expressing the positivity effect are more likely to develop Alzheimer’s disease. If so, the test could prove to be a valuable tool in the early detection of Alzheimer’s susceptibility.

Elizabeth Murray, a research specialist in Yassa’s lab at UCI, also contributed to the study, which received support from the National Institutes of Health (grants R01 MH102392, R21 AG049220 and P50 AG 16573). UCI’s Center for the Neurobiology of Learning & Memory and the Institute for Memory Impairments & Neurological Disorders also provided support.

 

Jessica (Jessie) Yaros received her Bachelors in Science in Cognitive Neuroscience from the University of California, San Diego. After graduating, she joined the Laboratory of Neuro Imaging (LONI) at UCLA, and later USC, to provide support in managing the Image & Data Archive (IDA) database, and dissemination of ADNI Whole Genome Sequence data. Jessie joined the Translational Neurobiology lab in 2015. Her current research explores the neural basis of the Other Race Effect- the tendency to best recognize individuals within one’s own race. She is interested in communicating science to the lay audience and appeared recently on Friends of Joe’s Big Ideas on NPR. Click here to find out more about Jessie. 

New review in Trends in Neurosciences

Our TiNS review “Neurocognitive aging and the hippocampus across species” is now online. Here are some of the trends we discuss in the article:

  1. The role of neurogenesis in the dentate gyrus in the context of neurocognitive aging has been recently revisited, given data suggesting that neurogenesis continues into older adulthood.
  2. The lateral entorhinal and perirhinal cortices represent early sites of vulnerability in aging and age-related decline. Designing tasks and approaches to examine these extrahippocampal pathways is crucial
  3. Hyperexcitability in the hippocampal network is a key pathological state in the aging brain that confers risk for Alzheimer’s disease (AD), potentially linking AD and subclinical epilepsy.
  4. Epigenetic imaging (e.g., HDAC PET) is an emerging technology that will allow more detailed examinations of epigenetic changes related to memory decline in the aging human brain.

2014 Walk to end Alzheimer’s – Huntington Beach Sat Nov 1, 2014 @ 10AM

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SoCal Alzheimer’s Research Conference coming soon – 9/12/14

The time is almost here. The 25th annual Southern California Alzheimer’s Disease Research Conference is on 9/12/2014. All information about it is here. You can still register for the program!

Of particular note is Howard Federoff who is joining us from Georgetown to discuss the use of new blood lipid biomarkers for early/preclinical diagnosis and Ken Kosik who will discuss the Colombian cohort of familial inherited autosomal dominant AD and what we can learn from them. For my talk in the afternoon, I will be discussing the use of neuroimaging biomarkers as a research tool in Alzheimer’s disease, in particular as tools for early detection, tracking, and clinical trial enrichment.

If you’re interested in hearing us talk about this work and discuss the conference in more detail, KUCI did an hour-long interview with us (Andrea Tenner, Howard Federoff, and I) on the air on August 26th. Here is a link to the podcast.

Registration2014

Hosted by the UCI Institute for Memory Impairments and Neurological Disorders (UCI MIND) and the Alzheimer’s Association, Orange County Chapter, this conference convenes nationally and internationally recognized experts to address the progress our nation is making in the fight against Alzheimer’s disease. The 25th Annual Research Conference’s theme is “The Future of Alzheimer’s Research”, and will focus on exciting new developments that will take us into the next generation of Alzheimer’s research. 

Schedule

Program

Zach Reagh awarded Holcomb Scholarship

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Congratulations to Zach Reagh for being awarded the coveted Dr. William F. Holcomb Scholarship by the School of Biological Sciences! This award supports a graduate student in biomedical sciences and is in the amount of $2000. Zach is pictured here at the award ceremony with Dr. Mike Mulligan, Associate Dean for Graduate Studies, on the left and Dr. Frank LaFerla, Dean of the School of Biological Sciences, on the right.

New paper: Temporal discrimination in older adults

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New paper by graduate student Jared Roberts. Here he is with the paper pony!

Roberts J.M., Ly, M., Murray, E., Yassa, M.A. (2014) Temporal discrimination deficits as a function of lag interference in older adultsHippocampus DOI:10.1002/hipo.22303

Abstract

A vital component of episodic memory is the ability to determine the temporal order of remembered events. Although it has been demonstrated that the hippocampus plays a crucial role in this ability, the details of its contributions are not yet fully understood. One proposed contribution of the hippocampus is the reduction of mnemonic interference through pattern separation. Prior studies have used behavioral paradigms designed to assess this function in the temporal domain by evaluating the ability to determine the order of remembered events as a function of proximity in time. Results from these paradigms in older adults (OA) have been mixed, possibly due to limitations in controlling elapsed time and narrow range of temporal lags. Here, we introduce a novel behavioral paradigm designed to overcome these limitations. We report that OAs are impaired relative to younger adults at moderate and high temporal lags but not at low lags (where performance approached floor). We evaluated OAs’ ability to benefit from primacy (enhanced order judgment on the first few items of any given sequence) and found two distinct subgroups: one group was on par with young adults [aged-unimpaired (AU)] and the other group was two standard deviations below the mean of young adults [aged-impaired (AI)]. Temporal discrimination performance in AU adults was consistent with a pattern separation deficit, while performance in AI adults was consistent with a generalized temporal processing deficit. We propose that the task introduced is a sensitive marker for episodic memory deficits with age, and may have diagnostic value for early detection of age-related pathology.

New paper: Pattern separation and emotional information

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New paper by graduate student Stephanie Leal. Here she is holding the paper pony!

Leal, S.L., Tighe, S.K., Jones, C.K., Yassa, M.A. (2014) Pattern separation of emotional information in  hippocampal dentate and CA3.Hippocampus DOI:10.1002/hipo.22298.

Abstract:

Emotional arousal, mediated by the amygdala, is known to modulate episodic memories stored by the hippocampus, a region involved in pattern separation (the process by which similar representations are independently stored). While emotional modulation and pattern separation have been examined independently, this study attempts to link the two areas of research to propose an alternative account for how emotion modulates episodic memory. We used an emotional discrimination task designed to tax pattern separation of emotional information by concurrently varying emotional valence and similarity of stimuli. To examine emotional modulation of memory at the level of hippocampal subfields, we used high-resolution fMRI (1.5 mm isotropic) of the medial temporal lobe. Consistent with prior reports, we observed engagement of the hippocampal dentate gyrus (DG) and CA3 during accurate discrimination of highly similar items (behavioral correlate of pattern separation). Furthermore, we observed an emotional modulation of this signal (negative > neutral) specific to trials on which participants accurately discriminated similar emotional items. The amygdala was also modulated by emotion, regardless of the accuracy of discrimination. Additionally, we found aberrant amygdala-hippocampal network activity in a sample of adults with depressive symptoms. In this sample, amygdala activation was enhanced and DG/CA3 activation was diminished during emotional discrimination compared to those without depressive symptoms. Depressive symptom severity was also negatively correlated with DG/CA3 activity. This study suggests a novel mechanistic account for how emotional information is processed by hippocampal subfields as well as how this network may be altered in mood disorders.

Jared Roberts awarded Haycock Memorial Travel Award

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Congratulations to Jared Roberts who was just awarded the John Haycock Memorial Travel Award. The award was established to honor John W. Haycock; friend and mentor to many, and an influential scientist.

John’s family has established a memorial graduate student award named for John in the Center for the Neurobiology of Learning and Memory at UC Irvine. John was a graduate student and received his Ph.D. from UC Irvine before going on to do research and teach at several universities, including The Rockefeller University. The purpose of the John W. Haycock Memorial Graduate Student Travel Award is to provide funding to outstanding graduate students in neuroscience to travel to the annual Society for Neuroscience meeting. This is the most important and informative annual meeting for neuroscientists world-wide, and one that John, himself, greatly enjoyed attending.

Jared will be able to use the award to cover expenses for travel to Washington DC to present his research at the Society for Neuroscience meeting this year. Congrats Jared!

 

Zach Reagh presents his research to Congress!

zach_capitolhillGraduate student Zach Reagh presented his NSF-supported research on Alzheimer’s disease biomarkers to members of Congress at Capitol Hill as part of an effort to increase awareness of the science supported by the National Science Foundation.

New paper: emotion and interference

New paper by Stephanie Leal just published in Neurobiology of Learning and Memory.

Leal, S.L., Tighe, S.K., Yassa, M.A. (2014) Asymmetric effects of emotion on mnemonic interference. Neurobiology of Learning and Memory DOI:10.1016/j.nlm.2014.02.013

Abstract

Emotional experiences can strengthen memories so that they can be used to guide future behavior. Emotional arousal, mediated by the amygdala, is thought to modulate storage by the hippocampus, which may encode unique episodic memories via pattern separation – the process by which similar memories are stored using non-overlapping representations. While prior work has examined mnemonic interference due to similarity and emotional modulation of memory independently, examining the mechanisms by which emotion influences mnemonic interference has not been previously accomplished in humans. To this end, we developed an emotional memory task where emotional content and stimulus similarity were varied to examine the effect of emotion on fine mnemonic discrimination (a putative behavioral correlate of hippocampal pattern separation). When tested immediately after encoding, discrimination was reduced for similar emotional items compared to similar neutral items, consistent with a reduced bias towards pattern separation. After 24 hours, recognition of emotional target items was preserved compared to neutral items, whereas similar emotional item discrimination was further diminished. This suggests a potential mechanism for the emotional modulation of memory with a selective remembering of gist, as well as a selective forgetting of detail, indicating an emotion-induced reduction in pattern separation. This can potentially increase the effective signal-to-noise ratio in any given situation to promote survival. Furthermore, we found that individuals with depressive symptoms hyper-discriminate negative items, which correlated with their symptom severity. This suggests that utilizing mnemonic discrimination paradigms allows us to tease apart the nuances of disorders with aberrant emotional mnemonic processing.