Assistant Professor, Department of Psychology
Ph.D. University of Texas at Austin
M.A. Charles University in Prague
Research Interests: Cognitive-Neuroscience, Memory
Overview: Memory allows us to use past experiences to navigate novel situations and inform future decisions. Because every event is unique, we need to use memory flexibly, drawing upon multiple relevant experiences to anticipate future judgments. Brain and Memory Lab studies how memories are formed and how they are linked to each other to create internal representations of the world that can guide our behavior. We investigate how different memory systems are implemented in the brain, how they represent information, and how they interact. In the quest for discovery, we rely on computer-based experiments, cognitive models of behavior, and advanced functional MRI methods.
My research focuses on how we build complex knowledge representations—such as schemas, cognitive maps or concepts—from simple learning experiences. Stacking memories as building blocks, we form knowledge that transcend direct experience, allowing us to use the memory for the past to guide behavior in the future. I am especially interested how the hippocampus—a brain structure critical for memory for individual events in our lives—interacts with the prefrontal cortex and other memory systems to support the flexible use of experience. My primary research tools include computer-based experiments, formal models of behavior, and advanced functional MRI methods.
Ventromedial prefrontal cortex is necessary for normal associative inference and memory integration.
J Neurosci. 2018 Mar 19;:
Authors: Spalding KN, Schlichting ML, Zeithamova D, Preston AR, Tranel D, Duff MC, Warren DE
The ability to flexibly combine existing knowledge in response to novel circumstances is highly adaptive. However, the neural correlates of flexible associative inference are not well-characterized. Laboratory tests of associative inference have measured memory for overlapping pairs of studied items (e.g., AB, BC) and for non-studied pairs with common associates (i.e., AC). Findings from functional neuroimaging and neuropsychology suggest the ventromedial prefrontal cortex (vmPFC) may be necessary for associative inference. Here, we used a neuropsychological approach to test the necessity of vmPFC for successful memory-guided associative inference in humans using an overlapping pairs associative memory task. We predicted that individuals with focal vmPFC damage (N=5; 3F, 2M) would show impaired inferential memory but intact non-inferential memory. Performance was compared to normal comparison participants (N=10; 6F, 4M). Participants studied pairs of visually-presented objects including overlapping pairs (AB, BC) and non-overlapping pairs (XY). Participants later completed a three-alternative forced-choice recognition task for studied pairs (AB, BC, XY) and inference pairs (AC). As predicted, the vmPFC group had intact memory for studied pairs but significantly impaired memory for inferential pairs. These results are consistent with the perspective that the vmPFC is necessary for memory-guided associative inference, indicating that the vmPFC is critical for adaptive abilities that require application of existing knowledge to novel circumstances. Additionally, vmPFC damage was associated with unexpectedly reduced memory for AB pairs post-inference, which could potentially reflect retroactive interference. Together, these results reinforce an emerging understanding of a role for the vmPFC in brain networks supporting associative memory processes.SIGNIFICANCE STATEMENTWe live in a constantly changing environment, so the ability to adapt our knowledge to support understanding of new circumstances is essential. One important adaptive ability is associative inference - it allows us to extract shared features from distinct experiences and relate them. For example, if we see a woman holding a baby, and later see a man holding the same baby, then we might infer that the two adults are a couple. Despite the importance of associative inference, the brain systems necessary for this ability are not known. Here, we report that damage to human ventromedial prefrontal cortex (vmPFC) disproportionately impairs associative inference. Our findings show the necessity of the vmPFC for normal associative inference and memory integration.
PMID: 29555854 [PubMed - as supplied by publisher]
Decreased Prefrontal Activation during Matrix Reasoning in Predementia Progranulin Mutation Carriers.
J Alzheimers Dis. 2018;62(2):583-589
Authors: Alexander C, Zeithamova D, Hsiung GR, Mackenzie IR, Jacova C
We tested the potential of task-based functional neuroimaging as a biomarker of emerging prefrontal brain changes in progranulin (GRN) mutations carriers. Five GRN mutation carriers free of frontotemporal dementia (FTD) and 11 non-carriers from families with FTD-GRN underwent functional MRI while solving matrix-reasoning problems. Mutation carriers displayed slower responses for more difficult problems and lower lateral prefrontal activation across all problems. Overall task-evoked posterior ventrolateral prefrontal activation predicted mutation status with 100% sensitivity and 91% specificity. Volumetric differences did not account for activation differences. Prefrontal activation may have utility as a biomarker in GRN mutation.
PMID: 29480174 [PubMed - in process]