Jeffrey M. Zacks - US grants

Normal cognition is characterized by the ability to flexibly learn new procedures and to perform previously learned procedures. When this ability is disturbed, as in frontal apraxia, consequences are profound. Normal procedural learning may depend in part on hierarchically organized representations of the temporal structure of activity. Motivated by a theoretical account of event representations and recent work on the perception of goal-directed tasks, I hypothesize that such representations are shared across perception and skill acquisition. The studies proposed here test this hypothesis using a procedural learning program. Participants will learn a novel everyday procedural task, using a computer-based training system. Varying the layout of the computer interface allows a direct test of the role of the proposed event representations: Layouts that directly represent the temporal organization of the activity are hypothesized to lead to better performance. Varying the medium in which the information is presented (still pictures or video) allows a test of the specificity of these representations. In addition to testing the basic hypothesis, each of the two proposed experiments will examine a secondary theoretical issue. In the first experiment, a test of explicit memory for the task instructions will indicate the degree to which explicit memory mediates understanding of event structure. In the second experiment, a test of task transfer will indicate the degree to which representations of task structure are internalized and flexibly re-used. By taking advantage of a paradigm derived from recent theoretical and empirical work, these experiments will clarify the role of structured representations of events in normal cognition. They also provide a basis to develop systems to help patients cope with impaired procedural knowledge, as well as a basis for systems to assist in skill instruction.

In talking about the past or about a movie, we often describe things in terms of discrete events, breaking continuous activity into meaningful parts. A child asked about a day at school might first describe reading, then recess, and maybe lunch. If asked further about recess, the child might divide it into smaller parts like soccer or tag or talking to friends. Psychological studies show that events and their sub-events play discernable roles in how we understand stories, for example, or remember them later. However, little is known about how this way of structuring of experience guides ongoing perception and comprehension. In research supported by the National Science Foundation, Dr. Jeffrey M. Zacks studies how events and sub-events drive ongoing perceptions and later memories. His work incorporates perceptual judgments, tests of memory, reading, and he constructs computer models to make his hypotheses explicit. Dr. Zacks's research uses novel methods for the real-time study of perception of dynamic events. The broader impacts of this work include training graduate and undergraduate students in these methods and the tools used to implement them. These results also contribute to the ongoing development of tools for procedural learning and for navigating video.

[unreadable] DESCRIPTION (provided by applicant): Much of the text we read or hear has a narrative component. Examples include stories, novels, biographies, instructions for putting things together, and recipes. Narratives may be segmented into meaningful units called events, and the structure of events is critical for narrative comprehension. To adequately comprehend a narrative, readers must delineate successive events and assemble them into a meaningful whole. The broad goal of the proposed research is to investigate the neurocognitive mechanisms by which narratives are segmented into meaningful events during comprehension. Research on narrative comprehension shows that changes in dimensions such as space and time affect long term memory representations. These same changes can affect the updating of working memory during reading or listening, and affect reading rate. Research on event perception shows how an ongoing stream of activity can be segmented into meaningful units. Our hypothesis is that the mechanisms readers and listeners use when identifying events in narratives are similar to those they use when identifying events in real life. The proposed research brings methods and theory from event perception to bear on narrative comprehension. One series of experiments aims to characterize how readers and listeners use features of narrative texts to identify event boundaries. A second series tests the hypothesis that perceptual event structure guides reading by modulating the contents of working memory. In both sets of experiments, converging behavioral and neurophysiological techniques will be used. We believe that an integrated cognitive neuroscience approach has the potential for significant progress on these questions--particularly because there have been very few neuroscientific studies of the larger structure of narrative thus far. [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Older adults arrive in the neurological clinic with a variety of complaints about their changing cognitive profile. These include reduced interest in hobbies and activities, repeating stories and statements, trouble learning how to use new tools and appliances, difficulty keeping track of what day it is, and difficulty remembering appointments. Such complaints have a striking feature in common: They all appear to be related to one's mental representation of "what is happening now." Recent research in cognitive psychology and neuroscience has begun to explain how people construct such representations and update them to facilitate perception and memory. This research suggests that the segmentation of ongoing activity into meaningful events is crucial to later memory for those events. However, little is known about how these mechanisms change with aging and dementia. The specific aims of this research address this lacuna: Specific Aim 1: Identify cognitive mechanisms of effective event segmentation. What distinguishes those individuals who segment events effectively from those who do not? Does this change across the lifespan? The proposed research will address these questions using psychometric and functional and structural neuroimaging methods. Specific Aim 2: Assess the contribution of effective event segmentation to memory in older adults. In younger adults event segmentation is associated with updating the current contents of short-term memory and with long-term memory retention. The proposed research will investigate how the relations between event segmentation, online memory updating and long-term memory change with age using behavioral and neuroimaging methods. Specific Aim 3: Test interventions to facilitate effective encoding of events. To the extent that effective event segmentation helps memory, improving event segmentation may improve memory. The proposed research will test interventions intended to improve memory by facilitating effective event segmentation. This research proposed here is all based on tasks in which observers comprehend and remember movies and stories that are closer to real-life activity than typical laboratory materials. The tasks are not too different from everyday comprehension of ongoing activities and conversations. These features improve the chances that this approach to event perception and memory may generalize to the memory complaints common to older adults. PUBLIC HEALTH RELEVANCE: Declines in memory for everyday events are one of the common complaints of aging. Recent research with younger adults suggests that "chunking" ongoing activity into meaningful events is important for later memory. The proposed research investigates how the mind and brain do this chunking, how it changes as people age, and what interventions might improve its effectiveness. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Project Summary The fields of biology, psychology, and biomedical engineering have generated exciting new advances in the study of neural systems underlying behavior. Individually, these disciplines have individually provided novel insights into brain function and provide opportunities for improved understanding of disorders of the nervous system, healthy and disordered development, and communication. However, the rapid advancement of scientific progress has been limited by the boundaries surrounding the disciplines. Moreover, neuroscientists that are firmly grounded in an array of approaches used by biologists, psychologists, and engineers will best advance new research technologies such as non-invasive functional imaging and neural prosthetics. A training model that is thoroughly interdisciplinary is needed. At Washington University, we have developed such a model: The Cognitive, Computational, and Systems Neuroscience (CCSN) Pathway produces rigorously trained independent investigators that will lead a new generation of scientists who study the brain in truly integrated interdisciplinary investigations. CCSN serves students from the PhD programs in Biomedical Engineering, Psychology, and Neuroscience. The core of CCSN is a two-year curriculum that emphasizes interdisciplinarity, collaboration, and project-based instruction. In the first year, students take courses that bring them up to speed on the core concepts and methods in Cognitive Psychology, Biological Neural Computation, and Neural Systems. In the second year, students participate in two unique courses that have been specially designed as the capstone to the CCSN pathway Advanced CCSN and Project Building in CCSN. Advanced CCSN consists of a series of interdisciplinary case studies in cutting-edge brain science topics. Each topic is presented as a module by a faculty team drawn from the three home programs. Modules include team-based projects and peer review as well as primary source readings and classroom lectures and discussions. Project Building in CCSN is a fully student-driven course. In collaboration with the faculty leader, each student designs an independent interdisciplinary research project. The faculty leader helps them to assemble an interdisciplinary faculty advising team, to whom they present their project multiple times throughout the semester. Faculty advising is complemented by peer advising including written peer review, culminating in a research grant-style project proposal. Surrounding the core CCSN curriculum is a rich penumbra of activities. These are designed to provide intellectual training and to build a cohort of scientists with the identification and social skills necessary to conduct research in interdisciplinary teams. Formal coursework is provided in Mathematics and Statistics of Experimental Neuroscience, and by an intensive mini- course preceding Advanced CCSN. Immersive Encounters with distinguished visiting scientists provide high-intensity exposure to cutting-edge research. In collaboration with the Saint Louis Science Center, CCSN trains students to communicate with the public and helps them build programs and presentations to teach children and adults about the brain and mind. In its initial phases, CCSN has produced cohorts of young brain scientists on the fast track to new discoveries. Evaluations from students, faculty, and an outside advisory team indicate the pathway is on track for continued growth. PUBLIC HEALTH RELEVANCE: Project)Narrative) Cutting edge research in brain science is increasingly interdisciplinary, and traditional discipline-based graduate training programs strain to accommodate this development. The Cognitive, Computational & Systems Neuroscience pathway at Washington University represents a unique new model for training 21st century brain scientists. Such training will produce a generation of scientists effectively equipped to produce breakthroughs in neurological disease, mental illness, and neural engineering.

DESCRIPTION (provided by applicant): Reduced navigation ability has been associated with advanced age in general and particularly with Alzheimer's disease (AD). Navigation difficulties can be devastating to an individual's self-reliance, and such problems can even be dangerous, particularly while driving. Research suggests that such age related difficulties arise specifically from deficits in the ability to create structured cognitive maps of environments from traveling around in them. Theories of how these mental maps are constructed during navigation are sorely needed to design responses to older adults' difficulties with getting lost. Here we test a novel proposal constraining how mental maps are built up from navigation experience and how mental map construction changes with age. Research suggests that spatial representations and spatial memory in general, are organized into chunks; certain locations are grouped together in memory. Several factors, such as temporal and spatial proximity and salient physical features of the environment have been identified as important in determining what locations get chunked together. However, little work has been done to identify specific cognitive and neural mechanisms by which spatial memory is organized. We propose that temporal segmentation of experience into episodes, or events, is an important factor in determining the structure of spatial memory. Therefore, improving temporal encoding could improve spatial memory. In these experiments, participants will view short first person movies of actors navigating through particular environments (e.g., buildings). In some cases, participants will segment the movies into spatial regions or events, and in others functional magnetic imaging (fMRI) will be used to monitor brain activity during movie viewing. After movie viewing, spatial memory for the navigated environments will be measured to test the following hypotheses: 1) Spatial and temporal segmentation during navigation affects later memory for the navigated space. 2) Age related declines in spatial and temporal segmentation mechanisms are associated with poorer spatial memory. 3) Phasic activity in spatially sensitive brain regions is disrupted in older adult, and this disruption is associated with spatial memory impairment. Successful completion of this research will open up a new set of cognitive and neural mechanisms as targets for researchers and clinicians working to address the important problem of age related navigation difficulty. Theoretically motivated measures of structure in spatial memory may prove particularly valuable for diagnosing navigation difficulties associated with early-stage dementia. If age-related navigating difficulties are mediated by temporal segmentation impairments, this will provide a novel target for intervention. PUBLIC HEALTH RELEVANCE: Navigation difficulties associated with normal aging, and especially with age-related dementia, can be devastating to an individual's self-reliance, and such problems can even be dangerous, particularly while driving. This work will examine how the structure of spatial memory is determined and how important aspects of that structure change as we age. Successful completion of this research will open up a new set of cognitive and neural mechanisms as targets for researchers and clinicians working to address the important problem of age related navigation difficulty.

Negotiating one's environment requires flexible adaptation to changing circumstances. For example, suppose you were to visit an office building once and park in its underground garage. On your second visit, you come upon a sign informing you that the garage is being renovated and directing you to a surface lot. If you successfully integrate the previous experience with the new information, you will be able to use that information to know which way not to turn, and to better able to find your way. However, if you fail to adaptively process the changed feature, you may find yourself following your previous path and stuck in a construction zone? particularly if you are under cognitive load. People's ability to comprehend changes has been examined is very basic laboratory tasks, but little is known about the mechanisms that underlie the comprehension of changes in naturalistic activities. Central to this proposal, even less is known about how healthy aging and early Alzheimer's disease (AD) affect people's comprehension of the rapidly changing environment. Here, three aims will address the overarching issue of how younger adults, healthy older adults, and older adults with early AD comprehend changes in dynamic everyday activities. The first aim tests a new proposal for how the brain changes in healthy aging and AD affect people's ability to comprehend and remember changes in events. The second aim directly investigates the neural mechanism of change comprehension using an advanced pattern analysis based functional MRI technique. The final aim tests an intervention designed to remediate negative effects on change comprehension and memory by cuing people to the relationship of a new event to a previously encountered event. These experiments will provide critical insights into the mechanisms that can be targeted by clinical interventions aimed at improving everyday cognition.

PROJECT SUMMARY/ABSTRACT Memory for events in the recent past is crucial for effective functioning in everyday environments. Imagine someone is retiring and moving to a new city to be with family. Event memory will allow them to remember how to get to the grocery store and in which aisle to look for cereal, which neighbor's child to ask about mowing the lawn, and whether it is late enough to check if the mail has arrived. Failures of event memory are exactly the problems that bring elders into the neurological clinic and raise concerns that they may be developing Alzheimer's disease (AD)?both major epidemiological concerns, given that the population of older adults and the number of people with AD are growing dramatically. However, there is a large gap between this kind of memory and memory as it is usually studied in the psychological and neuroscientific laboratory, by presenting people with disconnected words, pictures, or sentences. Recent empirical and theoretical results have identified specialized neural and computational mechanisms that segment ongoing activity into meaningful events and have shown that these mechanisms are important for memory formation. In this proposal, we describe a novel synthesis and extension of previous approaches to the effects of age and AD on memory, based on these innovations. This synthesis opens up an opportunity to better understand how the mechanisms of human memory encoding change with age and AD, and at the same time to test the potential of novel interventions for potential clinical application to memory improvement. This project will capitalize on this opportunity, achieving three specific aims: Specific Aim 1 will test whether and how attention to event segmentation improves elders' memory for everyday activity at delays from minutes to week. Two well-powered experiments will extend a promising intervention that has been shown to improve event memory in young adults to older adult samples, testing memory at delays up to one month. Specific Aim 2 will test the hypothesis that effective event segmentation improves the resolution of elders' posterior/medial memory representations. Structures in the medial temporal lobes and posterior medial parietal cortex have been shown to be important for event memory and are affected by healthy aging and early AD. Two studies will test whether improving event segmentation improves the resolution of memory representations in these regions. Specific Aim 3 will test whether the mechanisms and consequences of segmentation improvement are maintained or impaired by early symptomatic Alzheimer's disease. Early AD selectively impairs the very systems that are proposed to be important for representing event memories. Two studies will test the possibility that improving event segmentation improves event memory in people with early symptomatic AD.