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

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

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

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

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 of 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.

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