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MEM Lab (Measurement of Episodic Memory)

http://www.memlab.psyc.vt.edu/index.html

The MEM Lab uses cognitive neuroscience methodology to examine the cognitive and neural processes underlying human memory.

To better understand how memory works, we investigate:


  • Encoding strategies to determine the most effective ways to remember words/pictures/events
  • Retrieval procedures designed to show the processes that bring memories to mind
  • Instructions that give participants different perspectives on the memory task and may affect the way a memory is stored
  • Physiological correlates of memory processes using electrical recordings on the scalp (event-related potentials or ERP)
  • Blood flow in the brain during a memory task using functional magnetic resonance imaging (fMRI)


The goal of this research is to develop and test theories of memory that explain our cognitive experiences related to memory and how those cognitive experiences are produced by the brain.

 

MEM Lab Research

Episodic Memory: Episodic memory is the personal record of events and experiences across a lifetime. What did you eat for breakfast yesterday? Where are your car keys? Who was getting married at the last wedding you attended? As you can imagine, episodic memories are central to our sense of self. Much of what we know about episodic memory and the brain regions that support it was discovered based on a single case study. Patient HM's hippocampus (in both hemispheres) was surgically removed to treat severe epilepsy in 1953. From that point forward, he could not remember new events or experiences. The MEM lab studies episodic memory and the brain regions, including the hippocampus and surrounding cortices, that allow us to encode and retrieve episodic memory.



Active Research

Adaptation in the medial temporal lobes during memory encoding: The medial temporal lobes (MTL) play an essential role in episodic memory, and accumulating evidence indicates that two MTL subregions - the perirhinal (PRc) and parahippocampal (PHc) cortices - might have different functions. According to the binding of item and context theory (Eichenbaum et al., 2007; Diana et al., 2007), PRc is involved in processing item information, the target of memory encoding, whereas PHc is involved in processing context information, peripheral information that identifies the circumstances of the episode. Here, we used functional magnetic resonance imaging (fMRI) adaptation to test the roles of different MTL subregions in the processing of item and context information. Participants were scanned while viewing a series of objects. Each object was presented with a unique semantic encoding question that elicited a salient cognitive context. The object picture, the encoding question, both, or neither were immediately repeated. We found that PRc activity was sensitive to repetition of the object but not the encoding question whereas PHc activity was sensitive to repetition of the encoding question but not the object. These data are consistent with the idea that the PRc and PHc are differentially involved in the representation of item and context information and additionally suggest that the role of the PHc extends to nonspatial, cognitive context information.


Parahippocampal cortex function in episodic memory: A central feature of episodic memories is that each item to be remembered is associated with a specific context - a time, place, and situation. Indeed, most research in psychology and neuroscience has conceptualized episodic recollection as the retrieval of an association between an item and the context in which the item was encountered. According to the BIC (binding of items and contexts) theory of medial temporal lobe function (Eichenbaum, Yonelinas, & Ranganath, 2007; Diana, Ranganath, & Yonelinas, 2007), three regions in the medial temporal lobes (MTL) - the perirhinal cortex (PRc), parahippocampal cortex (PHc), and the hippocampus - make qualitatively different contributions to the encoding of item information, context information, and the binding of item information to episodic context, respectively. PHc function is the least well understood of the MTL subregions and our research attempts to define the nature of information processed in PHc.


Unitization of item and context information: Performance on tests of source memory is typically based on recollection of contextual information associated with an item. We conducted an event-related potential (ERP) study testing the hypothesis that unitization of item and source information increases the contribution of familiarity to source memory. Participants studied associations between words and background colors either in a highly unitized manner ("Imagine this item being red/green") or a less unitized manner ("Imagine this item associated with a stop sign/dollar bill"). ERPs were recorded while participants were given a source memory test in which they were shown each studied item and asked to make a confidence judgment about whether it was studied with a red or green background. ERP results revealed two topographically and temporally distinct neural correlates of source recognition, one that was associated with familiarity-based source memory in the unitized condition only and another that was associated with recollection-based source memory in both the unitized and nonunitized conditions. These findings converge with the ROC analyses, indicating that familiarity can contribute to source recognition when item and source information are unitized.

 

Publication List

Wang, F. & Diana, R.A. (2016). Temporal context processing within hippocampal subfields. NeuroImage, 134, 261-269. doi: 10.1016/j.neuroimage.2016.03.048

Tu, H.W. & Diana, R.A. (2016). Two are not better than one: Combining unitization and relational encoding strategies. Journal of Experimental Psychology: Learning, Memory, and Cognition, 42, 114-126. doi: 10.1037/xlm0000170

Diana, R.A., Yonelinas, A.P., & Ranganath, C. (2013). Parahippocampal cortex activation during context reinstatement predicts item recollection. Journal of Experimental Psychology: General. Advance online publication. doi: 10.1037/a0034029

Bastin, C., Diana, R.A., Simon, J., Collette, F., Yonelinas, A.P., & Salmon, E. (2013) Associative memory in aging: The effect of unitization on source memory. Psychology and Aging, 28, 275-283. doi: 10.1037/a0031566

Diana, R.A., Yonelinas, A.P., & Ranganath, C. (2013). Parahippocampal Cortex Activation During Context Reinstatement Predicts Item Recollection. Journal of Experimental Psychology: General, 2013, Aug 12.

Diana, R.A., Yonelinas, A.P., & Ranganath, C. (2012). Adaptation to cognitive context and item information in the medial temporal lobes. Neuropsychologia, 50, 3062-3069.


Diana, R.A., Ranganath, C. (2011). Recollection, familiarity and memory strength: Confusion about confounds. Trends in Cognitive Science, 15(8), 337-338.


Diana, R.A., Van den Boom, W., Yonelinas, A.P., & Ranganath, C. (2011). ERP correlates of source memory: Unitized source information increases familiarity-based retrieval. Brain Research, 1367, 278-286.


Diana, R.A., Yonelinas, A.P., Ranganath, C. (2010). Medial temporal lobe activity during source retrieval reflects information type, not memory strength. Journal of Cognitive Neuroscience, 22(8), 1808-1818.


Diana, R.A., Yonelinas, A.P., & Ranganath, C. (2008). The effects of unitization on familiarity-based source memory: Testing a behavioral prediction derived from neuroimaging data. Journal of Experimental Psychology: Learning, Memory, & Cognition, 34(4), 730-740.

 

Diana, R.A., Yonelinas, A.P., & Ranganath, C. (2008). High-resolution multi-voxel pattern analysis of category selectivity in the medial temporal lobes. Hippocampus, 18(6), 536-541.

Reder, L.M., Paynter, C., Diana, R.A., Ngiam, J., & Dickison, D. (2008). Experience is a double-edged sword: A computational model of the encoding/retrieval tradeoff with familiarity. In A.S. Benjamin & B. Ross (Eds), The Psychology of Learning and Motivation: Vol. 48. Skill and Strategy in Memory Use (pp. 217-306). London: Elsevier.

Diana, R.A., Yonelinas, A.P., & Ranganath, C. (2007). Imaging recollection and familiarity in the medial temporal lobe: A three-component model. Trends in Cognitive Science, 11(9), 379-386.


Diana, R.A. (2006). The low frequency encoding disadvantage: Reconciling word frequency effects in memory by considering processing demands at encoding (Doctoral dissertation). Available from ProQuest Dissertations and Theses database (UMI No. 3228004)

Diana, R.A. & Reder, L.M. (2006). The low frequency encoding disadvantage: Word frequency affects processing demands. Journal of Experimental Psychology: Learning, Memory, & Cognition, 32(4), 805-815.


Diana, R.A., Reder, L.M., Arndt, J., & Park, H. (2006). Models of recognition: A review of arguments in favor of a dual-process account. Psychonomic Bulletin & Review, 13(1), 1-21.


Diana, R.A. & Reder, L.M. (2005). The List Strength Effect: A contextual competition account. Memory & Cognition, 33(7), 1289-1302.


Diana, R.A., Vilberg, K.L., & Reder, L.M. (2005). Identifying the ERP correlate of a recognition memory search attempt. Cognitive Brain Research, 24(3), 674-684.


Diana, R.A., Peterson, M.J., & Reder, L.M. (2004). The role of spurious feature familiarity in recognition memory. Psychonomic Bulletin & Review, 11(1), 150-156.


Diana, R.A. & Reder, L.M. (2004). Visual and verbal metacognition: Are they really different? In D.T. Levin (Ed), Thinking and Seeing: Visual Metacognition in Adults and Children. Cambridge, MA: MIT Press.