Sleep and Cognition Lab

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Research

The Sleep and Cognition (SaC) Lab is interested in understanding who we are as humans by investigating how we form memories. Memories are at the core of our personal and social histories, our perceptions, and our beliefs. By understanding how memories are formed, processed and retained, we can understand how they can be improved, as well as how memory abilities can falter due to aging or disease. We are specifically interested in translational research questions that lead to improving the lives of people with cognitive impairments. To accomplish this work, we utilize electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to measure brain activity during sleep and wake. We also use pharmacology and brain stimulation during sleep to improve waking performance. In addition, we use signal processing and computational modeling to reveal patterns in the data not available to the naked eye.

Questions we are exploring include:

Why do some memories tend to become stronger after a period of sleep?

How do brain areas communicate during sleep-dependent memory consolidation?

Do different types of memory (explicit/declarative vs implicit/non-declarative) require different features of sleep for consolidation?

Can we enhance individual sleep features with pharmacology or electrical brain stimulation to enhance memory performance?

Can these interventions be used in populations with memory dysfunction, e.g., elderly, mild cognitive impairment, Alzheimer’s disease, post-traumatic stress disorder, and other mental illnesses?

People

Sara Mednick, PhD

sara mednick, sleep scientist, napping, sleep research, sleep expert, sleep professor, nap expertDr. Sara Mednick is a Professor in the Department of Cognitive Science at the University of California, Irvine and author of the book, Take a Nap! Change your Life (Workman), and forthcoming book The Hidden Power of the Downstate, The New Science to Ignite Energy, Enhance Sharpness, and Reclaim Balance (Hachette Go). For her PhD in the Department of Psychology at Harvard University, she pioneered studies nap studies, which provided methodological advancements from nocturnal sleep studies and are now the dominant research method to understand the role of sleep in memory formation. During her post-doc at the Salk Institute and UCSD, she was awarded an NIH NRSA fellowship to use functional magnetic resonance imaging (fMRI) to understand the neural mechanisms supporting sleep-dependent memory consolidation. In 2011, she moved to UCR Psychology Department (2011-2015), tenured to Associate Professor in 2015, then moved to UC Irvine Department of Cognitive Sciences in 2018, and advanced to Professor in 2020. Dr. Mednick has conducted studies in conjunction with numerous academic institutions, the U.S. Navy, V.A. Medical Center and private businesses. Her articles have been published in such leading scientific journals as Nature Neuroscience and The Proceedings from the National Academy of Science. Her napping research has been covered by CNN, Reuters TV, NPR, The Economist, The Wall Street Journal, Consumer Reports Health Journal, Reader’s Digest, The New York Times and many other major media outlets. Dr. Mednick resides in San Diego, CA. A list of her peer-reviewed manuscripts and abstracts can be found here. If you would like more information about Dr. Mednick’s research, please visit her website. Her CV can be found here.

Sara Mednick, PhD

sara mednick
Dr. Sara Mednick is a Professor in the Department of Cognitive Science at the University of California, Irvine and author of the book, Take a Nap! Change your Life (Workman), and forthcoming book The Hidden Power of the Downstate, The New Science to Ignite Energy, Enhance Sharpness, and Reclaim Balance (Hachette Go). For her PhD in the Department of Psychology at Harvard University, she pioneered studies nap studies, which provided methodological advancements from nocturnal sleep studies and are now the dominant research method to understand the role of sleep in memory formation. During her post-doc at the Salk Institute and UCSD, she was awarded an NIH NRSA fellowship to use functional magnetic resonance imaging (fMRI) to understand the neural mechanisms supporting sleep-dependent memory consolidation. In 2011, she moved to UCR Psychology Department (2011-2015), tenured to Associate Professor in 2015, then moved to UC Irvine Department of Cognitive Sciences in 2018, and advanced to Professor in 2020. Dr. Mednick has conducted studies in conjunction with numerous academic institutions, the U.S. Navy, V.A. Medical Center and private businesses. Her articles have been published in such leading scientific journals as Nature Neuroscience and The Proceedings from the National Academy of Science. Her napping research has been covered by CNN, Reuters TV, NPR, The Economist, The Wall Street Journal, Consumer Reports Health Journal, Reader’s Digest, The New York Times and many other major media outlets. Dr. Mednick resides in San Diego, CA. A list of her peer-reviewed manuscripts and abstracts can be found here. If you would like more information about Dr. Mednick’s research, please visit her website. Her CV can be found here.

Graduate Students

Alessandra Shuster

Alessandra is a doctoral student in Cognitive Neuroscience at UC Irvine. She received her B.A. in Psychology from Cornell University in 2015. After graduating, she spent 5 years in the healthcare-tech sector before joining the Sleep and Cognition Lab.  Alessandra’s primary research interests include identifying neural biomarkers and mechanisms of learning and memory in REM sleep. She is also interested in the role of sex hormones on sleep-related cognition and the effect of aging. A list of Alessandra’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar).

Allison Morehouse

Allison is a doctoral student in Cognitive Neuroscience at UC Irvine. She received her B.A. in Cognitive Science from UC Berkeley in 2020. Before graduate school, she worked with Dr. Andrea Goldstein-Piekarski as the lab manager for the Computational Psychiatry, Neuroscience, and Sleep Laboratory (CoPsyN Sleep Lab) at Stanford University. Allison is interested in how sleep and heart rate variability play a role in consolidating and processing emotional memories and spatial navigation.  A list of Allison’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar).

Tracy Uzoigwe

Tracy is a doctoral student in Cognitive Neuroscience at UC Irvine. She received her B.A. in Anatomy from Igbinedion University, Nigeria. Tracy is interested broadly in understanding the neural infrastructure through which sleep transforms the brain’s memory integration system.

Post-Doctoral Researcher

Ali Ekhlasi

Ali Ekhlasi joined the Sleep and Cognition Lab at UC Irvine in September 2023 as a postdoctoral researcher. He holds a PhD in biomedical engineering from Azad University of Science and Research in Iran, which he obtained in 2021. During his doctoral studies, Ali focused on utilizing the transfer entropy measure as a criterion for identifying causal relationships among EEG signals. Ali’s research involved enhancing the transfer entropy measure and introducing novel criteria based on it. His work aimed to explore the distinctions in EEG brain connectivity and brain information transmission between healthy individuals and children with ADHD. Furthermore, Ali has published articles in the field of EEG processing, specifically in the comparison of EEG signals between healthy individuals and those with color vision deficit, as well as in recognizing robot movement commands using EEG signals and in lie detection through a combination of EEG and psychophysiological signals.

His primary research interests lie in computational neuroscience, signal processing, determining connectivity among brain regions, and machine learning. Currently, Ali is investigating the effective and functional connectivity during sleep and its impact on the formation of short- and long-term memories. For more information on his recent research and publications, please visit his profile on Google Scholar.

Alumni

 Kate Simon, PhD

Kate Simon was a postdoctoral researcher in the Sleep and Cognition Lab at UC Irvine and licensed clinical psychologist. Kate now is an Assistant Professor in the Department of Pediatrics, School of Medicine, at UC Irvine and the Assistant Director of Research in Pediatric Sleep at the Children’s Hospital of Orange County. Prior to joining the SaC Lab, Kate received her B.A. at UC Berkeley where her interest in the science of sleep and development was sparked while working as a research assistant for Drs. Matt Walker, Allison Harvey, and Joseph Campos. She obtained her clinical psychology doctorate at the University of Arizona under the guidance of Drs. Lynn Nadel, Rebecca Gomez, and Richard Bootzin. Her graduate work focused on sleep and memory in early development, memory reconsolidation, and targeted memory reactivation for forgetting. She then completed her clinical psychology internship and postdoctoral fellowship in Pediatric Consultation-Liaison at the Children’s Hospital of Orange County (CHOC). Kate’s current primary research interests are the mechanisms underlying sleep and memory formation, the effect of sex hormones on long-term memory, developmental sleep, and targeted memory reactivation. For recent research and publications, visit her Google Scholar page. You can find her lab website at: https://sleepinpediatrics.com 

Jing Zhang

Jing Zhang, cognition, sleep, sleep science, napping, research, sleep researchJing is a doctoral student in Cognitive Neuroscience at UC Irvine. She received her B.S. in Psychology with a minor in gender studies at Furman University. After graduation, she spent two years working as a research assistant at Seminowicz Pain Imaging lab at University of Maryland Baltimore (https://www.daslab.org).

Her research interests include the role of autonomic nervous system in sleep and cognitive functioning as well as biomarkers of cognitive processing during sleep. Ultimately, she hopes to gain a deeper understanding in how sleep physiology influence our cognition and ways to enhance it.

Hamid Niknazar, PhD

Hamid Niknazar joined the Sleep and Cognition Lab at UC Irvine as a postdoctoral researcher in March 2020. He received his PhD in Biomedical Engineering at the Science and Research Azad University, Iran, in 2018. There, the focus of his research was on developing new methods for nonlinear dynamics quantification and their different applications in EEG signal processing such as epileptic seizure prediction and EEG patterns in sleep. His main research interest includes intersection of computational neuroscience, signal processing, nonlinear dynamics, and machine learning. For recent research and publications, visit his Google Scholar page.

Tenzin Tselha

TenzinTselha, memory reactivation, sleep, glymphatic system, sleep science, sleep, psychostimulants, sleep researchTenzin Tselha is a doctoral student in the Cognitive Sciences department at UC Irvine. Tenzin is Tibetan and grew up in Chauntra(H.P.), India. He completed his M.S. in Neuroscience from Stony Brook University, New Yorkce.. His primary research interests are in the field of learning and memory. Since joining the lab he has been working on memory reactivation during sleep using functional magnetic resonance imaging (fMRI). He is also interested in studying the glymphatic system in humans using fMRI (i.e., the brain waste disposal system). In a recent project, he has examined the effects of psychostimulants on working memory and sleep.

Besides research activities, he considers himself an activist for human rights in Tibet, student of Buddhist philosophy of emptiness, and lastly a Barcelona football club fan. A list of Tenzin’s peer-reviewed manuscripts and abstracts can be found here.

PinChun Chen

PinChun Chen, brain stimulation, memory consolidation, aging, autonomic activity, sleep science, sleepPinChun is a doctoral student in Cognitive Neuroscience at UC Irvine. She received her B.S. in Psychology and B.Ed. in Education with 1st Class Honors from National Chengchi University, Taiwan in 2017. PinChun’s research interests include the effect of aging, autonomic activity, and brain stimulation on memory consolidation. A list of PinChun’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar and ORC-ID).

Frida Corona

Frida Corona, sleep science, sleep, cognition research, napping, circadian rhythm, role of ethnicity and stress on sleepFrida is a doctoral student in the Cognitive Sciences department at UC Irvine. She completed her undergraduate degree at the University of Illinois at Urbana-Champaign, where she worked in a honeybee lab. Afterwards, she spent a year doing an NIH post-bac at Rebecca Spencer’s Sleep and Cognition Lab at the University of Massachusetts, Amherst.

Her primary research interests are the impact of health disparities on sleep, and disrupted circadian rhythms and the use of light to shift circadian rhythms. She is currently working on analyzing sleep and stress information to determine the role of ethnicity and stress on sleep, cognition, and overall health. A list of Frida’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar and ORC-ID)..

Negin Sattari

NeginSattari, computer science, sex hormones, sleep science, sleep research, napping, memory and againNegin is a doctoral student in the Cognitive Sciences department at UC Irvine. She received her B.S. in Computer Science from Sadjad University of Higher Education in Mashhad, Iran and her M.A. in Psychology from University of California, Riverside. Negin’s research interests entail the effect of sex hormones on sleep-related memory consolidation and learning. Negin has also investigated the effect of napping on memory formation in older adults. A list of Negin’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar and ORC-ID).

Benjamin Yetton

Benjamin Yetton, machine learning, sleep science, sleep research, signal processing, REMBen is a doctoral student in the Cognitive Sciences department at UC Irvine. Coming from an engineering background, Ben’s work blends Bayesian modeling and machine learning techniques with memory and sleep data.

His initial foray in the sleep field involved applying machine learning and signal processing techniques on EOG data to detect the presence of Rapid Eye Movements.

More recently, his work on sleep dynamics and big data has quantified the influence of individual differences on the sequence of sleep states. Other projects of note include developing an online sleep data collection tool (www.modasleepscoring.com) and investigating how memories encoded close in time might become integrated, such that layer manipulations of one effect the other.
Current interests include examining trait-level individual differences of sleep electrophysiological markers as predictors of cognitive outcomes. For example, are there sleep features that more stable within an individual than across people, and can they be used to predict workplace performance? A list of Ben’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar, ORC-ID, and OSF).

When not working on analysis code for the sleep and cognition lab, Ben likes to snowboard and cook. He also enjoys traveling, especially back to his home country of New Zealand.

Paola Malerba, PhD

PaolaMalerbaPaola obtained a PhD in Mathematics at Boston University in 2010 and she applies mathematical analysis and modeling to the understanding of brain rhythms. Within SaC Lab, she has studied the spatio-temporal patterns of slow oscillations on the electrode manifold. Using k-clustering and relative detection probability we have found that slow oscillations were clustered in three types: Global, Local or Frontal depending on their footprint on the electrode manifold during a time window. Global slow oscillations showed the strongest relationship with sleep spindles, both in amplitude and probability of detection. This research is laying the foundation for modeling work on the spatio-temporal occurrence of slow oscillations and spindles on the electrode manifold, to study how closed-loop stimulation during sleep changes sleep waves and possibly memory performance. A list of Paola’s peer-reviewed manuscripts and abstracts can be found here (Google Scholar and ORC-ID).

Lauren Whitehurst, PhD

Lauren-WhitehurstLauren Whitehurst received her. B.S. in Psychology and M.A. in Experimental Psychology from James Madison University in 2011 and 2013, respectively and her PhD in Psychology from the University of California, Riverside in 2018. She is currently a T32 and Chancellor’s Postdoctoral Fellow at the University of California, San Francisco in the Department of Psychiatry. Lauren’s research interests broadly entail the processes during sleep that are important for health and cognitive function including how external stressors (e.g. exposure to discrimination, illicit drug use) may impact sleep physiology and result in notable health consequences. Additionally, her work investigates how autonomic and central nervous system factors interact to produce regulatory effects on sleep-dependent health and cognitive outcomes. Further, by harnessing physiological biomarkers during sleep, her work aims to develop a greater understanding of both typical functioning and maladaptive health states. For recent research and publications, visit her Google Scholar page.

Mohsen Naji, PhD

MohsenNajiMohsen joined the Sleep and Cognition lab in December 2015. He obtained a PhD in Biomedical Engineering (Bioelectrics) at the Science and Research Azad University, Iran, in 2014 working on designing an emotion recognition system via fusion of heart and brain signals. His work in the Sleep and Cognition lab included study of cardiac-brain interactions during sleep and its role in memory consolidation, as well as developing techniques for investigating neural events during rapid-eye movement (REM) and non-REM sleep. He is currently an Algorithm Scientist with Sotera Wireless, Inc., San Diego. For recent research and publications, visit his Google Scholar page.

Elizabeth McDevitt, PhD

Elizabeth McDevittElizabeth McDevitt (PhD, Cognitive Psychology, UC Riverside, 2017) is currently a Postdoctoral Researcher in the Computational Memory Lab at Princeton Neuroscience Institute. Her graduate work in the SaC Lab focused on understanding mechanisms of memory consolidation during sleep, with an emphasis on the memory function of REM sleep. She also investigated individual differences in napping behavior and how they might impact sleep-dependent memory benefits from napping. Her current research utilizes functional MRI to look at multivariate patterns of brain activity to investigate how sleep might drive changes in memory representations in the brain. For recent research and publications, visit her Google Scholar page.

Katherine Duggan, PhD

Katherine DugganKatherine Duggan (PhD, Social/Personality Psychology, UC Riverside, 2016) is currently a Postdoctoral Fellow in the Department of Psychiatry at the University of Pittsburgh. While with the lab, her work focused on developing models linking conscientiousness and neuroticism with healthy self-reported sleep habits. She also adopted statistical methods common in other fields (e.g., personality, aging) to experimental work on sleep and memory consolidation. Her current research is focused on developing prospective, causal models linking conscientiousness with health biomarkers (e.g., metabolic syndrome) and outcomes (e.g., mortality risk) via self-reported and objectively-assessed sleep. For recent research and publications, visit her Google Scholar page.

Mohammad Niknazar, PhD

Mohammad NiknazarMohammad received his B.Sc. degree in electrical-electronic engineering in 2007, and M.Sc. degree in electrical-biomedical engineering in 2010 from Sharif University of Technology. There, the focus of his research was on detection and prediction of epileptic seizures using EEG recordings in rats as well as humans. He received his Ph.D. in signal, image and speech processing and telecommunication from Joseph Fourier University, Grenoble I, France. He worked on separation of fetal and maternal electrocardiogram (ECG) signals.
Mohammad completed his postdoctoral research at the University of California, Riverside from 2014 to 2016 where he focused on the effects of sleep on memory consolidation. Most recently, Mohammad held the title as Data Scientist for Phosphorous, a biotechnology company. For recent research and publications, visit his Google Scholar page.

Jennifer Kanady, PhD

Jennifer KanadyJennifer Kanady received her Ph.D. in Clinical Science from the University of California, Berkeley in 2016. She completed her psychology internship at the Puget Sound VA Health Care System, Seattle. Before she began her doctoral studies at UC Berkeley, she was a lab coordinator for Dr. Mednick at UC San Diego from 2005 to 2009. She is currently a Research Postdoctoral Fellow as part of the Mental Illness, Education, and Clinical Center (MIRECC) program at the San Francisco VA Health Care System and the University of California, San Francisco. Broadly, her research focuses on examining associations between sleep and circadian disruptions and cognitive and emotional symptoms across mental health conditions and the life span. For recent research and publications, please visit her Google Scholar page.

Denise Cai, PhD

Denise CaiDenise Cai is an Assistant Professor in the Neuroscience Department at the Icahn School of Medicine at Mount Sinai. Her lab investigates the temporal dynamics of how memories are formed, integrated and separated. In addition, her team studies how aging contributes to cognitive decline. During her doctoral studies with Sara Mednick at UCSD, she characterized how REM sleep enhanced creative problem solving by integrating recently learned information with prior experience. As a postdoctoral fellow with Alcino Silva at UCLA, she discovered that memories encoded close in time are linked by sharing an overlapping neural ensemble, such that recalling one memory triggers another temporally-related memory through the overlapping ensemble. She also found there are disruptions in temporally linking memories with aging. She was also a key developer in the Miniscope project, which aims to advance development of imaging tools and techniques via an open-source platform and open-sharing of all developments through an online Wiki resource as well as hands-on workshops. For recent research and publications, please visit her Google Scholar page.

Publications

      News and Video

      Research Participation

      We are currently recruiting participants for our ongoing sleep studies!

      Individuals aged 18 and over and who speak English can participate, and responses are completely anonymous. You will not be compensated for taking the survey, but you will learn whether you are eligible to participate in any of our ongoing research studies. Although there are no other direct benefits to you for taking the survey, our research has helped society learn more about the relations between sleep, memory, and health. The survey takes approximately 30 minutes to complete, and your responses are completely anonymous.

      If you would like to participate in the survey, you can do so in three ways: (1) click the link below and take the survey online; (2) call or email us and you can take the survey over the phone; (3) call or email us and you can take the survey in-person. You can take the survey in the format you prefer. We will inform you of your eligibility within 4-6 weeks.

      If you know anyone who might be interested in participating in this survey, please forward them this message. If you have any questions about the study, do not hesitate to contact us at (949)824-2684. If you have any questions about your rights as a research subject you can contact the UCI Office of Research, Human Research Protections, at (949)824-7295.

      Currently recruiting studies are listed below:

      Study Title: Sleep Cycles
      Study Description: The research we are conducting aims to investigate the relationship between sex hormones and sleep related memory consolidation among young adults. This is a research study because we are monitoring sleeping behavior, recording nighttime sleep in the lab, and administering cognitive tasks in order to investigate our hypotheses about sleep architecture and memory.  The experiment will involve cognitive testing and EEG-recorded sleep over five visits at the Sleep and Cognition Lab at UC Irvine. 
      Time commitment: Two-three months.
      Instructions: Please complete this recruitment survey to determine eligibility, the study team will follow up with you in 2-3 weeks: https://cutt.ly/SleepCycles
      Contact: sleepcyclesuci@gmail.com or 949-824-2684

      JOIN OUR LAB!

      Post-Doctoral Candidates

      The Sleep and Cognition (SaC) Lab of the Department of Cognitive Science at the University of California, Irvine is soliciting applications from psychologists and neuroscientists for a postdoctoral research position on sleep, learning and memory and aging. The researcher will work with existing and ongoing data sets related to the effect of pharmacology and sleep on memory consolidation in young and older populations. Successful candidates should have experience in sleep, pharmacology or aging research and possess a doctoral degree. Minority candidates are especially encouraged to apply. The University of California offers excellent benefits. Salary is based on research experience. The initial appointment is for 1 year with a possibility of extension. The candidate will be expected to apply for extramural funding at the appropriate time. Please send your CV, statement of research interests and the names of three references or make inquires to Sara C. Mednick (mednicks@uci.edu).

      Prospective Graduate Students

      The Sleep and Cognition (SaC) Lab of the Department of Cognitive Science at the University of California, Irvine is accepting applications for graduate students to start in the Fall of 2019. Our lab is interested in a wide range of topics, including the effect of sleep on memory, mechanisms of memory processing, pharmacological effects on memory, aging, psychosocial and social network effects on health behaviors. Minority candidates are especially encouraged to apply. Please make inquires to Sara C. Mednick (mednicks@uci.edu).

      Research Assistants

      The Sleep and Cognition (SaC) Lab is currently accepting applications for research assistants. Research Assistants in the lab may be involved in any aspects of experiments, including recruiting and screening potential subjects, running human subjects in experimental procedures (informed consent, psychophysics, polysomnography), data coding and analysis, and helping with other needed tasks. The minimum time commitment is 12 hours/week for at least 1 year (4 quarters). You must be willing to occasionally work overnight and weekends in the lab. As a Research Assistant in our lab, you can register for 2-4 credits per quarter, P/NP. After working in the lab for 1 quarter, research assistants can register for 2-4 credits per quarter for a letter grade. If you are interested, please use the link below and email your application and your resume as attachments to Andres Peña (aapena3@uci.edu). We will contact you in the near future if we think you are a good candidate for our lab.

      Research Assistant Application 

       

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