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Bringing learning and memory scientists from around the world to UCI

CNLM Colloquium Series

The CNLM Colloquium Series, supported by the Thomas Henry Curtis Fund, brings learning and memory scientists from around the world to UC Irvine. This lecture series is a great opportunity for faculty, students, trainees and research staff to learn about the latest in learning and memory research and gain feedback on their own work. Meeting with the speaker provides powerful network building opportunities for students and trainees and fosters future collaborations.

Location:
Herklotz Conference Facility
Building 506 on the campus map

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Upcoming Colloquia

Tuesday November 12, 2019 - 11:00 AM

Robert Hunt, Ph.D.
Assistant Professor
Anatomy & Neurobiology
University of California, Irvine

Interneurons and the control of memory precision.

Tuesday January 28, 2020 - 11:00 AM

Autumn S. Ivy, Ph.D.
Assistant Professor
Pediatrics, Physiology and Biophysics
University of California, Irvine

Exercise during early life enables memory and synaptic plasticity: role of the epigenome

Tuesday March 3, 2020 - 11:00 AM

Charan Ranganath, Ph.D.
Professor
Psychology
University of California, Davis

Colloquium Series 2018-2019

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Tuesday May 21, 2019 - 11:00 AM

Michael Bienkowski, Ph.D.
Assistant Professor of Research Neurology
Keck School of Medicine of USC

Gene expression and connectivity reveal the multiscale organization of mouse hippocampal networks

Description

Many studies have described structural and functional heterogeneity across the hippocampus, but different fields of neuroscience (behavioral, anatomical, and gene expression studies) have produced disparate views of hippocampal organization. To help bridge the gaps between these data, we analyzed and mapped mouse gene expression patterns across the entire hippocampus and subiculum to create a comprehensive Hippocampus Gene Expression Atlas (HGEA) with 20 distinct molecular subregions. Guided by the HGEA, we traced the anatomical inputs and outputs of each HGEA subregion to create the most detailed wiring diagram of the hippocampus to date. Finally, hippocampal network analysis revealed that the hippocampus is a multiscale hierarchical network that contributes to separate brain-wide networks hypothesized to influence spatial navigation, social, and homeostatic behaviors. Overall, the HGEA provides a foundational roadmap that integrates gene expression and connectivity for the future genetic dissection of hippocampal cell types in behavior and how these cell types are impacted by neurological diseases, like Alzheimer’s disease.

Friday May 17, 2019 - 11:00 AM

Nikolai Axmacher, Ph.D.
Faculty of Psychology
Institute of Cognitive Neuroscience
Ruhr-Universität, Bochum

Engram patterns: network codes for memory and navigation

Tuesday May 14, 2019 - 11:00 AM

Amar Sahay, Ph.D.
Associate Professor of Psychiatry
Massachusetts General Hospital
Harvard Medical School

Hippocampal Inhibition, Interference and Indexing

Description

We have previously demonstrated an important role for adult-born dentate granule cells in resolution of memory interference in adulthood and aging. These studies have motivated assessment of the neural circuit mechanisms by which dentate granule cells modulate memory interference to dictate discrimination and generalization. I will discuss ongoing efforts interrogating how dentate granule cells recruit inhibitory microcircuits to govern memory interference, indexing, discrimination and generalization.

Tuesday April 23, 2019 - 11:00 AM

Brad Aimone, Ph.D.
Scientist
Cognitive & Emerging Computing
Sandia National Laboratories

Computing as a Constraint to Understand the Hippocampus

Description

Research Summary: Neuroscience and computing researchers often allude to one other; but the two fields have rarely directly leveraged each other’s knowledge in advancing their theories. In this talk, I will show that strengthening this interaction has value for both disciplines: the realities of computer science can help constrain our understanding of the brain; and in turn, advances in neuroscience can help computing. I will describe specific examples of how combining neuroscience and computing research has advanced our insight into understanding the hippocampus. I will initially focus on adult neurogenesis, the process by which the dentate gyrus adds new neurons through life. The talk will then consider the broader computational implications of the overall hippocampus circuit. I will conclude by presenting a new theoretical framework through which experimental findings of the hippocampus can be considered.

Tuesday February 19, 2019 - 11:00 AM

Morgan Barense, Ph.D.
Associate Professor and Canada Research Chair
University of Toronto

Understanding Memory Disorders: At the level of Cognitive Process or Representational Content?

Description

How does the act of perceiving an object influence how one will subsequently remember it? A central assumption in most modern theories of memory is that memory and perception are functionally and anatomically segregated. For example, amnesia resulting from medial temporal lobe (MTL) lesions is traditionally considered to be a selective deficit in long-term declarative memory with no effect on perceptual processes. This view is consistent with a popular paradigm in cognitive neuroscience, in which the brain is understood in terms of a modular organization of cognitive function. The work I will present offers a new perspective. Guided by computational modelling complemented with neuropsychology and neuroimaging, I will provide support for the notion that memory and perception are inextricably intertwined, relying on shared neural representations and computational mechanisms. I will then describe how this new framework can improve basic understanding of cognitive impairments observed in Alzheimer’s disease, as well as guide development of new diagnostic procedures for those at risk for dementia.

Tuesday February 12, 2019 - 11:00 AM

Lisa Giocomo, Ph.D.
Assistant Professor, Neurobiology
Stanford University

Identifying the Algorithms for Calculating Spatial Maps

Description

Over the last several decades, the tractable response properties of parahippocampal neurons have provided a new access key to understanding the cognitive process of self-localization: the ability to know where you are currently located in space. Defined by functionally discrete response properties, neurons in the medial entorhinal cortex and hippocampus are proposed to provide the basis for an internal neural map of space, which enables animals to perform path-integration based spatial navigation and supports the formation of spatial memories. My lab focuses on understanding the mechanisms that generate this neural map of space and how this map is used to support behavior. In this talk, I’ll discuss new data and computational work that reveals the underlying algorithms for how landmark, self-motion and position codes combine to generate neural maps of space capable of supporting accurate navigation and memory.

Co-hosted with the Conte Center @ UCI
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Tuesday January 22, 2019 - 4:00PM *Note alternate time*
Event Location: Telemedicine Theater, Medical Education Building

Rebecca Shansky, Ph.D.
Associate Professor, Department of Psychology
Northeastern University

Sex differences in fear processing

Tuesday December 4, 2018 - 11:00 AM

Sara N. Burke, Ph.D.
Assistant Professor, Department of Neuroscience
University of Florida

Neural Network and Metabolic Mechanisms of Cognitive Aging

Description

By the year 2020 the number of Americans over the age of 65 is projected to reach 55 million, occupying a larger portion of our population aging demographics than ever recorded in history. It is therefore imperative that the ability of these individuals to live independently is preserved for reasons of personal dignity as well as the financial and public-health consequences that result from the necessity of long-term care. This talk will discuss recent behavioral, neurophysiological and imaging data from pre-clinical animal models that elucidates basic mechanisms of cognitive decline in old age. The focus will be on how functional connectivity is altered in aged animals and how these changes may be related to impaired glucose utilization.

Colloquium Series 2017-2018

Tuesday May 29, 2018 - 11:00 AM
Linda Levine, Ph.D.
Professor
Psychology and Social Behavior
University of California, Irvine

Bias in Predicted and Remembered Emotion

Description

To decide whether to pursue or avoid outcomes – be it traveling during the holidays, changing careers, or having children – people attempt to predict how happy or unhappy those outcomes will make them. These predictions are based, in turn, on people’s memories for how they felt in similar circumstances in the past. So predicted and remembered emotion play a major role in people’s decision making and wellbeing. But how accurate are these representations? It is widely-accepted that people have a robust and consistent tendency to overestimate the emotional impact of future and past events. I will present evidence that consistent overestimation is partly due to an artifact arising from common study procedures. When alternative procedures are used, overestimation is substantially reduced or reversed. My colleagues and I have assessed predicted, experienced, and remembered emotion in individuals with normal and extraordinary memory ability, and in response to high stakes events such as elections, trials, and exit exams. Our findings show that the magnitude and direction of bias depends on how people’s appraisals of events change over time and on the strategies they use to regulate emotion. We also find that predicted emotion serves as a particularly vivid and compelling guide for decisions even when inaccurate. The findings help explain when and why representations of emotion are biased and how bias affects people’s decisions and wellbeing.

Friday, April 13, 2018 - 11AM
Sumner Norman, Ph.D.
Postdoctoral Fellow, Caltech

Brain-Computer Interfacing: From Replacing Function to Enhancing Human Potential

Description

Brain-Computer Interfacing (BCI) is a technology that can facilitate direct communication between the brain and an external device. BCIs have been used to facilitate communication for the severely paralyzed and to control prostheses that replace lost motor function. They are also proving to be increasingly useful in enhancing motor performance and motor learning, particularly for people who have suffered a neurological injury. More specifically, BCI can guide activity-dependent plasticity in the brain to enhance function and learning. This functionality may be generalizable to all people, including those without impairment. As a result, BCI has seen an explosion in public interest, resulting in an urgent need for parallel development of fundamental neuroscience and BCI imaging technology.

Paul Rapp, Ph.D.
Director, Traumatic Injury Research Program, Department of Defense
Uniformed Services University

Are CNS synchronization abnormalities corrected in response to successful neuropsychiatric treatment? A direct test.

Description

It has been hypothesized since the 1970's that short lived coalitions in neural activity, commonly referred to as brain cell assemblies, are responsible for stimulus-response coupling and other cognitive processes. It has been further hypothesized that neural synchronization is a common mechanism for constructing these coalitions. A substantial literature has since reported task-related synchronization in brain electrical activity. Additionally, nonspecific abnormalities in synchronization have been observed in neuropsychiatric disease. The literature identifying changes in synchronization in response to treatment is, however, far smaller, and the literature correlating these changes with changes in clinical state is still smaller. The Traumatic Injury Research Program (TIRP) currently has two ongoing studies to investigate these phenomena. An ongoing clinical trial of repetitive transcranial magnetic stimulation in the treatment of persistent post-concussive symptoms following TBI in a military population includes the following objectives:

Determine if synchronization patterns change in response to treatment, and if changes do occur, determine if they are consistent with a convergence to normal activity,
Determine if changes in synchronization correlate with clinical assessments of treatment response.

In contrast with most investigations, this rTMS clinical trial includes measurement of pre- and post-treatment event related potentials in addition to free running EEGs. The ERP tasks include assessments of attention and of memory, two capabilities known to be compromised following traumatic brain injury. The introduction of ERPs, which produce nonstationary signals, introduces significant signal analysis challenges. These mathematical requirements are being addressed by the construction of new procedures for the time-dependent quantification of CNS activity. A second, observational, repeated measures study, in young healthy military academy volunteers will capture the same electrophysiological data as the clinical trial. In addition to determining reliability/stability of these measures over time, we will compare the synchronization patterns of the observational study population to those of the clinical trial population.

Tuesday February 20, 2018 - 11AM
Elisabeth Murray, Ph.D.
Chief, Section on Neurobiology of Learning and Memory
Laboratory of Neuropsychology
National Institute of Mental Health

Specializations for decision making in primate prefrontal cortex

Description

Some of the most sophisticated behaviors of primates, including humans, depend on the granular prefrontal cortex (PFC), yet there are few well defined and experimentally verified functional specializations within the primate PFC, especially at a causal level. Recent work from our laboratory has demonstrated contrasting specializations of the ventrolateral PFC (VLPFC) and the orbital PFC (also known as orbitofrontal cortex, OFC). We found that the OFC and the VLPFC play complementary roles in updating representations of value (i.e., valuations) that underlie decision making. Valuations represented in or accessed by the OFC depend on the dynamic internal state of an individual, what an object or action is worth at any given time based on current biological needs; valuations represented in or accessed by the VLPFC depend on dynamic external contingencies. In other words, the OFC updates valuations based on reward desirability whereas the VLPFC updates valuations based on reward availability. Additional studies have identified distinct functional subdivisions within the OFC. Its posterior part (area 13) is necessary for updating the valuations of objects and actions, while its anterior part (area 11) translates these valuations into choices and actions. According to comparative neuroanatomy, the granular parts of OFC and all of the VLPFC emerged during the evolution of primates, and it seems likely that their valuation-updating specializations elaborated on related functions performed by the agranular orbitofrontal areas that all mammals share.

Tuesday February 13, 2018 - 11AM
Mara Mather, Ph.D.
Professor of Gerontology and Psychology
Leonard Davis School of Gerontology
University of Southern California

How the locus coeruleus increases cognitive focus during high arousal moments

Description

Many of our most vivid memories arise from emotionally intense moments. But such memories also often have notable gaps and it can be hard to predict where the gaps will be. Our research indicates that the key thing that determines whether arousal will enhance or impair memory is the priority or salience of the information in question. Arousal enhances encoding high priority information while impairing encoding low priority information. Thus, arousal makes attention and memory more selective by favoring strong and inhibiting weak representations. This makes sense—during such moments it is especially important to focus on what matters most—but raises questions about how this can work in the brain. How can arousal have opposite effects on different stimuli representations depending on their priority? In our Glutamate Amplifies Noradrenergic Effects (GANE) model, we posit that the brain’s primary excitatory neurotransmitter, glutamate, provides a neural marker of priority and interacts locally with norepinephrine to create hot spots of high activity. Thus, via this GANE mechanism, the brain can flexibly mark what currently has high priority, allowing arousal to highlight what really matters and suppress other potentially distracting information. In a functional magnetic resonance imaging study, we found that the LC shows the strongest functional connectivity with cortical representations of a stimulus when two states co-occur: 1) the stimulus is highly salient; and 2) arousal was just induced. Both younger and older adults showed this arousal-by-salience functional connectivity interaction with the LC. However, whereas younger adults also showed enhanced frontoparietal activity and functional connectivity under arousal, the frontoparietal attentional control network was not as enhanced by arousal in older adults. In addition, for older adults, arousal increased processing of both low and high salience stimuli, generally increasing excitatory responses to visual stimuli. Thus, among older adults, arousal increases the potential for distraction from non-salient stimuli. Our findings suggest that older adults cannot rely on increases in selective attention during potentially high stake moments of high arousal.

Tuesday January 30, 2018 - 11AM
Majid Mohajerani, Ph.D.
Assistant Professor
Canadian Center for Behavioral Neuroscience
University of Lethbridge

Mapping the spatiotemporal dynamics of hippocampal-cortical dialogue in health and Alzheimer’s disease

Description

In my talk, I will provide new information regarding the interaction of hippocampus (HPC) and neocortex (NC) during sleep. Although evidence indicates that episodic memories are formed through a functional coupling between hippocampal sharp-wave (SPW) and cortical slow-wave oscillations (SO), how they interact to subserve a transfer of information is still unclear. To provide new insight regarding the interaction of HPC and NC during sleep, we have combined novel imaging technologies with the advanced genetic, molecular and electrophysiological technologies to interrogate the cortical circuits at the level of individual synapses and function with millisecond temporal resolution across the entire cortex with information from the hippocampus. Further, I will discuss our effort to monitor how HPC output to NC are altered in the mouse model of Alzheimer’s disease.

co-hosted with the MSTP and the Department of Anatomy and Neurobiology

Monday January 8, 2018 - 4PM (note alternate day/time)
Loren Frank, Ph.D.
Professor, Howard Hughes Medical Institute
Kavli Institute for Fundamental Neuroscience
University of California, San Francisco
Neural substrates of memories and decisions

Friday December 8, 2017 - 11AM (note alternate day/time)
Fabio Ferrarelli, M.D., Ph.D.
Assistant Professor in Psychiatry
University of Pittsburgh

Sleep spindle deficits in schizophrenia: when do they start?

Description

Sleep spindles are waxing and waning, 12-16 Hz oscillations, occurring during NREM sleep. Spindles are generated by the interplay of the Thalamic Reticular Nucleus (TRN) with the dorsal thalamus, and are then relayed to, and amplified within the cortex. While their functional role has yet to be fully elucidate, recent evidence indicates that spindles are associated with cognitive ability, schizotypal traits, and social functioning in healthy controls (HC), including adolescents and young adults. In previous work, by employing high density (hd)-EEG we established deficits in spindle amplitude, density, duration, and Integrated Spindle Activity (ISA) in centro-parietal and prefrontal regions of chronic patients with schizophrenia (SCZ) compared to both HC and non-schizophrenia psychiatric patients. A reduction in spindle amplitude and density was also recently reported in first episode SCZ, with EEG recordings performed on two central channels (C3, C4). Although promising, these findings leave a number of unanswered questions, including: 1) What is the spatial distribution of spindle deficits at illness onset? 2) Which are the most defective spindle parameters at that stage? 3) When do spindle deficits begin in relation to the development of SCZ and related disorders? Here, after reviewing previous findings on sleep spindle deficits in SCZ, I will present novel results of an ongoing study in first-break psychosis patients, as well as discuss a recently NIMH funded project investigating spindle activity in individuals at high risk for SCZ and other psychotic disorders, which should begin to answer some of these queries.

Wednesday November 1, 2017 - 10AM (note alternate day/time)
Mark Gluck, Ph.D.
Co-Director, African American Brain Health Initiative
Professor of Neuroscience
Center for Molecular & Behavioral Neuroscience
Rutgers University

Fitness and lifestyle affect neural and cognitive risk factors for Alzheimer's Disease in older African Americans

Description

In cross-sectional, longitudinal and interventional studies, we are examining how fitness and lifestyle affect neural and cognitive risk factors for Alzheimer’s Disease. Over the past 12 years, the African American Brain Health Initiative: A University-Community Partnership at Rutgers University-Newark has worked with local churches, senior centers, and low-income housing, along side city, county, and state agencies for aging and health, to promote improved brain health and reduce risk for Alzheimer’s Disease among older African Americans in Greater Newark, New Jersey. Our cross-sectional and longitudinal studies (funded by NIH/NIA) seek to understand how physical fitness affects both cognitive and neural markers for Alzheimer’s risk. Our interventional research (funded by the NJ Dept. of Health) examines how these markers change following five months of twice-weekly dance-based exercise. The cognitive assessments and brain imaging studies build on Gluck and colleagues prior animal, human, and neurocomputational studies of the role of the hippocampus and related medial temporal lobe structures in mediating stimulus representation and generalization in cognitive skill learning.

Tuesday October 24, 2017 - 11AM
Elly Nedivi, Ph.D.
Professor of Brain & Cognitive Sciences and Biology
The Picower Institute for Learning and Memory
Massachusetts Institute of Technology

Visualizing Synapse Structural Dynamics in vivo

Description

The introduction of two-photon microscopy for in vivo imaging has opened the door to chronic monitoring of individual neurons in the adult brain and the study of structural plasticity mechanisms at a very fine scale. Perhaps the biggest contribution of this modern anatomical method has been the discovery that even across the stable excitatory dendritic scaffold there is significant capacity for synaptic remodeling, and that synaptic structural rearrangements are a key mechanism mediating neural circuit adaptation and behavioral plasticity in the adult. To monitor the extent and nature of excitatory and inhibitory synapse dynamics on individual L2/3 pyramidal neurons in mouse visual cortex in vivo, we labeled these neurons with a fluorescent cell fill as well as the fluorescently tagged synaptic scaffolding molecules, Teal-Gephyrin to label inhibitory synapses, and mCherry-PSD-95 to label excitatory synapses. We simultaneously tracked the daily dynamics of both synapse types using spectrally resolved two-photon microscopy. We found that aside from the lower magnitude of excitatory synaptic changes in the adult, as compared to inhibitory ones, excitatory synapse dynamics appear to follow a different logic than inhibitory dynamics. While excitatory dynamics seem to follow a sampling strategy to search for and create connections with new presynaptic partners, inhibitory synapse dynamics likely serve to locally modulate gain at specific cellular locales.

Tuesday October 17, 2017 - 11AM
David Reinkensmeyer Ph.D.
Professor
Mechanical and Aerospace Engineering
Biomedical Engineering
University of California, Irvine

Robotic assistance during movement training after stroke: A Hebbian Model?

Description

In this talk I will first provide a brief overview of the evolution o the technology and science of robotic-assisted rehabilitation after stroke over the past twenty years. Then I will discuss a recent study in which we compared the therapeutic effects of high and low levels of robotic assistance during finger training. Participants (n = 30) with a chronic stroke and moderate hemiparesis actively moved their index and middle fingers to targets to play a musical game similar to GuitarHero three hours/week for three weeks. The FINGER exoskeleton robot provided assistance synchronized to the music; half of the participants were randomized to receive high assistance (causing 82% success at hitting targets), while the other half received low assistance (55% success). High levels of synchronized assistance boosted motivation, as well as secondary motor outcomes (Fugl-Meyer and Lateral Pinch Strength) – particularly for individuals with more severe finger motor deficits. Importantly, individuals with impaired finger proprioception at baseline benefited substantially less from the training. These results show that synchronized robotic assistance can promote psychological outcomes known to modulate motor learning and retention. Further, the therapeutic effectiveness of synchronized robotic assistance may derive at least in part from proprioceptive stimulation, consistent with a Hebbian plasticity model. I will conclude by presenting data showing extreme motor learning by people with very severe arm impairment after stroke, using a novel bimanual lever drive wheelchair.

Colloquium Series 2016-2017

Tuesday May 2, 2017 - 11AM
Elizabeth Buffalo, Ph.D.
Associate Professor, Department of Physiology and Biophysics
University of Washington School of Medicine

Bridging the gap between the spatial and mnemonic views of the hippocampus.

Description

While it has long been recognized that medial temporal lobe structures are important for memory formation, studies in rodents have also identified exquisite spatial representations in these regions in the form of place cells in the hippocampus and grid cells in the entorhinal cortex. Spatial representations entail neural activity that is observed when the rat is in a given physical location, and these representations are thought to form the basis of navigation via path integration. One striking difference between rodents and primates is the way in which information about the external world is gathered. Rodents typically gather information by moving to visit different locations in the environment, sniffing and whisking. By contrast, primates chiefly use eye movements to visually explore an environment, and our visual system allows for inspection of the environment at a distance. In this seminar, I will discuss recent work from my laboratory that has examined neural activity in the hippocampus and adjacent entorhinal cortex in monkeys performing behavioral tasks including free-viewing of complex natural scenes and navigation in a virtual environment. These data have suggested that spatial representations including place cells, grid cells, border cells, and direction-selective cells can be identified in the primate hippocampal formation even in the absence of physical movement through an environment. I will also discuss new research involving chronic, large-scale recordings throughout the primate brain and other areas of opportunity for future research to further our understanding of the function of the hippocampal formation and the nature of the cognitive map.

Tuesday April 25, 2017 - 11AM
Howard Eichenbaum, Ph.D.
Professor of Psychological and Brain Sciences
Director, Center for Memory and Brain
Boston University

The hippocampus: Mapping memories in space and time

Description

Many studies have identified neurons in the hippocampus and associated cortical areas as coding for locations in space (i.e., place cells and grid cells), leading some to view the hippocampus as dedicated to mapping space and supporting spatial navigation. Here I will argue an alternative view that populations of hippocampal neurons create a highly organized mapping of important events in the places and meaningful contexts in which they occur. Furthermore, I will describe recent evidence that hippocampal “time cells” in both the hippocampus and associated cortical areas encode specific moments in a temporally structured experience, much as place and grid cells encode locations in spatially structured environment. And I will describe how time cell ensembles encode the temporal organization of specific memories and predict memory success. These findings support of an emerging view that the hippocampus serves memory (and navigation) by mapping the organization of events within their spatial and temporal context.

Tuesday February 21, 2017 - 11AM
Robert Spitale, Ph.D.
Assistant Professor of Pharmaceutical Sciences and Chemistry
University of California, Irvine

Emerging Chemical Tools for Studying RNA: Applications to Neuroscience?

Description

Synopsis: RNA molecules play critical roles in nearly every cellular pathway. They have been demonstrated to be critical to the onset of many neurological disorders and diseases. Despite their importance there is a real lack of tools to study their biology at high precision. Within this presentation I will detail some of our labs ongoing work, and what we hope to achieve in the near future. I will also outline how what we are developing can be applied to some of the longest standing questions in neuroscience, on the molecular scale.

Tuesday, November 1, 2016 - 11AM
Jason Shepherd, Ph.D.
Assistant Professor of Neurobiology and Anatomy
Adjunct Professor of Ophthalmology and Visual Sciences
University of Utah, School of Medicine

Retroviral Origins of Synaptic Plasticity

Description

Co-hosted with Department of Psychiatry and Human Behavior
Tuesday, October 11, 2016 - 11AM
Bryce Mander, Ph.D.
University of California, Berkeley

Neural correlates of age-related disruption of sleep oscillation expression and sleep-dependent memory

Description

Sleep changes with age, becoming more fragmented, less organised, shorter in duration, and less densely-packed with the signature sleep oscillations, sleep spindles and slow waves, which causally promote memory consolidation. Despite the established role of sleep, and in particular slow waves and sleep spindles, in memory processing across the lifespan, how age-related changes in the brain ultimately impact slow wave and sleep spindle expression remains unclear. In this lecture, I will review our recent work examining how age-related changes in brain structure and neuropathology impacts slow wave and sleep spindle expression, ultimately impacting memory-related activation within the hippocampus. Embedded in a larger literature, these findings help to clarify how sleep changes with age may contribute to age-related memory decline, and offer novel treatment targets to preserve memory in later life.

Colloquium Series 2015-2016

Wednesday, April 20, 2016, 4 p.m.
Kei Igarashi, Ph.D.
Department of Anatomy and Neurobiology, University of California, Irvine

Dissecting sensory-hippocampal circuit interactions during associative learning

Description

Declarative memory is enabled by circuits in the entorhinal cortex (EC) that interface the hippocampus with the neocortex. During encoding and retrieval of declarative memories, entorhinal and hippocampal circuits are thought to interact via theta and gamma oscillations, which in awake rodents predominate frequency spectra in both regions. Using multisite recording at successive stages of associative learning, we found that the coherence of beta/gamma oscillations in directly-connected entorhinal-hippocampus circuits evolves as rats learn to use an odor cue to guide navigational behavior, and that such coherence is linked to the development of ensemble representations for unique trial outcomes in each area. These results point to 20-40 Hz oscillations as a mechanism for synchronizing evolving representations in dispersed neural circuits during encoding and retrieval of olfactory-spatial associative memory. Potential roles of 20-40 Hz oscillations for circuit plasticity, as well as future perspective on olfactory-hippocampal circuit analyses will be discussed.

Monday, March 28, 2016, 4 p.m.
Josef Parvizi, M.D., Ph.D.
Department of Neurology and Neurological Sciences, Stanford University

Numbers in the human brain: Eavesdropping on the activity of discrete populations of neurons in the human brain during arithmetic processing

Description

I will present a historical overview of localization of functions in the brain and review some of our most recent studies with intracranial electrocorticography (ECoG) and electrical brain stimulation (EBS) in patients implanted with intracranial electrodes to shed new light on some of the open questions in the field of cognitive neuroscience, especially when it comes to mathematical processing. For instance, which regions are at play when we put 2 and 2 together and how are they working together. I will present some of our most recent data from experimental as well as naturalistic conditions and will present videos of patients during ECoG and EBS procedures.

Tuesday, February 9, 2016, 4 p.m.
Jay McClelland, Ph.D.
Department of Psychology and Center for Mind, Brain, and Computation, Stanford University

Integrating Rapid Neocortical Consolidation into Complimentary Learning Systems Theory

Description

Since the 1950's, it has been known that the medial temporal lobes in the brain play a special role in learning and memory. These findings have led, through the work and thinking of David Marr and many others, to a theory of the roles of hippocampus and neocortex in memory called the complementary learning systems theory (McClelland, McNaughton, & O’Reilly, 1995). Our theory postulated two distinct learning systems, one in the medial temporal lobes that supports the rapid learning of arbitrary new information, and one in the neocortex and other structures that supports the gradual discovery of structured representations that encode knowledge of the natural and man-made world, as well as the knowledge underlying cognitive skills and the knowledge underlying language and communication. In this talk, I examine evidence from recent studies showing that new information can sometimes be integrated rapidly into the neocortex, challenging our theory as previously presented. I present new simulations based on our theory, showing that new information that is consistent with knowledge previously acquired by a cortex-like artificial neural network can be learned rapidly without interfering with existing knowledge. These results match the pattern observed in the recent studies, and provide a mechanism for understanding when and how rapid integration of new information can occur.

Thursday, December 10, 1 p.m.
Robert T. Knight, M.D.
University of California, Berkeley

Frontal Cortex Physiology and Human Behavior

Thursday, November 19, 4p.m.

Sheri J.Y. Mizumori, Ph.D.
University of Washington

Hippocampal neural activity reflects the economy of choices

Description

Hippocampal neural activity patterns are context-dependent, and this may aid in the formation of episodic memories. Distinguishing contexts requires an ability to recall features of a learned context, then compare the predicted features to those actually experienced. We studied how hippocampus represents predicted context information. Hippocampal place cells and theta activity were recorded during the performance of a maze-based probability discounting task in which predictive information about the probability of reward was systematically varied. Place fields redistributed (or remapped) around the goal location, but only during low probability trials that ended with reward delivery. Also around the goal location, theta power increased in proportion to the expected probability of reward, and not sensory or behavioral modulation. Theta power further dynamically varied as specific econometric information was obtained ‘on the fly’ during task performance. Behavioral economic information may define a ‘decision context’ that guides hippocampal context-dependent representations and learning during navigation.

Thursday, May 14, 4 p.m.
Warren H. Meck, Ph.D.
Duke University

Functional and Neural Mechanisms of Interval Timing

Description

The ability of the brain to process time in the seconds-to-minutes range is a fascinating problem given that the basic electrophysiological properties of neurons operate on a millisecond time scale. Neuropsychological studies of humans and other animals with damage to the basal ganglia have indicated that these structures play an important role in timing and time perception. Parkinson’s disease patients, for example, show evidence of a slowed internal clock and the “coupling” of durations stored in temporal memory when tested off of their dopaminergic medication. These studies have shown that the normal cognitive functions of the basal ganglia are heavily dependent upon dopamine-regulated neuronal firing in the cortex and striatum. Moreover, the electrophysiological properties of striatal medium spiny neurons within the basal ganglia suggest that these neurons may serve as a coincidence detectors of cortical and thalamic oscillatory input in order to provide the basis for duration discrimination in the seconds-to- minutes range. Recent findings obtained from ensemble recording in the prefrontal/cingulate cortex and the anterior dorsal striatum of rats performing in peak-interval timing procedures indicate that striatal neurons are able to encode specific durations in their firing rate in a “perceptron-like” manner. These findings correspond well with fMRI data obtained from human participants performing similar timing tasks and lend support to the striatal beat-frequency model of interval timing.

Colloquium Series 2014-2015

Thursday, January 16, 11am
Charles Limoli, Ph.D.
University of California, Irvine

Radiation- and chemotherapy-induced cognitive dysfunction: Causes, consequences and treatments

Description

Exposure of the CNS to treatments used to control the advance of cancer has been known to compromise cognitive function. Depending on disease state, treatments specifics and socioeconomic factors, cognitive outcomes vary in onset and severity. With increasing numbers of cancer patients surviving long-term, cognitive health is becoming an increasing concern, and to date, no satisfactory treatments exist for ameliorating the progressive and often debilitating cognitive side effects caused by radiotherapy and chemotherapy. This talk will cover the various mechanisms underlying treatment associated cognitive dysfunction and discuss the potential of using stem cell based strategies for the long-term treatment of this serious unmet medical need.

Thursday, March 13, 11am
Aryeh Routtenberg, Ph.D.
Northwestern University

Is mamallian NMDA-dependent long-lasting memory conserved in C. elegans?

Description

The N-methyl-D-aspartate receptor (NMDA-R) is associated with memory formation in both vertebrate and invertebrate nervous systems suggesting evolutionary conservation of this receptor mechanism. While considerable information exists concerning vertebrate NMDA-R and memory, evidence for its role in invertebrates is sparse; hence its linkage to mammalian mechanisms remains poorly understood. To begin to address this issue, we studied the formation of long-term associative memory as regulated by NMDAR and its subunit NMR-1 in the nematode, Caenorhabditis elegans (C. elegans).

Thursday, March 20, 11am
Loren Frank, Ph.D.
University of California, San Francisco

Neural substrates of memory retrieval and decision-making

Description

The hippocampus is a brain structure known to be critical for forming and retrieving memories for the experiences of daily life, but the specific patterns of neural activity that support memory formation and retrieval remain unclear. In this talk I will discuss work from my laboratory that links a specific pattern of hippocampal place cell activity to the ability to use past experience to guide behavior. We have shown that hippocampal replay events can reactivate patterns of brain activity from a previous experience in awake animals and that disrupting these events interferes with learning and memory-guided decision-making. Further, we have found that the intensity of replay activity is predictive of whether an upcoming choice will be correct or incorrect. Our results suggest that the awake replay of place cell sequences plays a role in deliberative proceeses that are important for memory-guided decision making.