Colloquia are located in:
Dale Melbourne Herklotz Conference Center
Center for the Neurobiology of Learning and Memory
(building 506 on the campus map)
The CNLM Colloquium Series is supported by the Thomas Henry Curtis Fund.
Coming up next:
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.
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 environme
nt, 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
Director, Cognitive Neurobiology Laboratory
The hippocampus: Mapping memories in space and time
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 organi
zation 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.
CNLM Colloquium Series 2016
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?
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 nueroscience, 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
Memories are stored in specific patterns of synaptic connections that occur through changes in synaptic strength, which rely on the addition or removal of AMPA-type glutamate receptors (AMPARs) from postsynaptic membranes. The immediate early gene Arc plays a critical role in multiple forms of synaptic plasticity, but the underlying molecular mechanisms remain unclear. Here we describe novel findings that Arc protein acts like the GAG retrovirus poly-peptide to control synaptic plasticity. Using cryo-electron microscopy we show that Arc forms viral capsid-like oligomers, which bind lipid membranes and RNA. Our studies elucidate the processes that underlie protein-synthesis dependent synaptic plasticity and may have uncovered a specialized neuronal trafficking pathway that has unique biochemistry similar to viral infection and replication.
Special Colloquium co-hosted by the CNLM and the 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
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.
Dissecting sensory-hippocampal circuit interactions during associative learning
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.
Numbers in the human brain: Eavesdropping on the activity of discrete populations of neurons in the human brain during arithmetic processing
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
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.
CNLM Colloquium Series 2015
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
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.
Functional and Neural Mechanisms of Interval Timing
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.
CNLM Colloquium Series 2014
Thursday, January 16, 11am
Charles Limoli, Ph.D.
University of California, Irvine
Radiation- and chemotherapy-induced cognitive dysfunction: Causes, consequences and treatments
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.
Is mamallian NMDA-dependent long-lasting memory conserved in C. elegans?
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
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.