How do we learn new categories and generalize category labels to new examples? Our lab uses long-standing models of categorization to better understand the role of abstraction vs. memory for individual examples in generalization, including linking model predictions to brain data. We have shown that the hippocampus, a region traditionally thought to support memory for individual episodes, can also form abstract category representations that integrate across related experiences. We have also used functional connectivity analyses to show how the hippocampus may form multiple types of memory representations by interacting with different parts of cortex that are known to be differentially involved in memory specificity vs. generalization. Most recently, we have begun to test whether older adults show deficits in concept learning and generalization that mirror deficits in memory specificity or whether generalization has a unique age-related trajectory.
Bowman, C.R. & Zeithamova, D. (2018). Abstract memory representations in the ventromedial prefrontal cortex and hippocampus support concept generalization. Journal of Neuroscience, 38(10), 2605-2614.
Frank, L.E.*, Bowman, C.R.*, & Zeithamova, D. (2019). Differential functional connectivity along the long axis of the hippocampus aligns with differential role in memory specificity and generalization. Journal of Cognitive Neuroscience, 31(12), 1-18.
Bowman, C.R. & Zeithamova, D. (2020). Training set coherence and set size effects on concept generalization and recognition. Journal of Experimental Psychology: Learning Memory & Cognition, 46(8), 1442-1464.
Bowman, C.R., Ashby, S.R., & Zeithamova, D. (2020). Age effects on category learning and their relationship to deficits in memory specificity. PsyArXiv. [Preprint].
Maintaining accurate memory involves discriminating between old and new information, which can be challenging when new and old information are highly similar. Our work has examined the process of discriminating between similar old and new information, including examination of age differences in this process. We have identified several key processes that contribute to mnemonic discrimination: retrieval of specific visual details supported by visual processing regions of the brain and top-down control of retrieval supported by portions of the prefrontal cortex. In particular, functional connectivity between the prefrontal cortex and hippocampus appears to aid in preventing individuals from erroneously endorsing new items as old. Older adults have particular difficulty with memory discrimination, which we have linked to deficits in retrieval of visual details in the visual cortex and hippocampus.
Bowman, C.R. & Dennis, N.A. (2015). Age differences in the neural correlates of novelty processing: The effects of item-relatedness. Brain Research, 1612, 2-15.
Bowman, C.R., & Dennis, N.A. (2016). The neural basis of recollection rejection: increases in hippocampal-prefrontal connectivity in the absence of a shared recall-to-reject and target recollection network. Journal of Cognitive Neuroscience, 28(8), 1194-1209.
Bowman, C.R.*, Shalome, S.L.*, & Dennis, N.A. (2017). Modulation of target recollection and recollection rejection networks due to retrieval facilitation and interference. Learning & Memory, 24(11), 607-611.
Bowman, C.R., Chamberlain, J.C., & Dennis, N.A. (2019). Sensory representations supporting memory specificity: Age effects on behavioral and neural discriminability. Journal of Neuroscience, 39(12), 2265-2275.
Older adults not only forget more information than young adults, but also have more false memories. We have contributed to work investigating the neural underpinning of false memories in young adults and their age-related increase in older adults. We showed that true and false memories in young adults have a shared reconstructive basis supported by the medial temporal lobe, but were dissociated by patterns of functional connectivity. Increases in false memories in older adults were accompanied by increases in activation in semantic processing regions such as lateral temporal cortices, which is consistent with the idea that older adults often make memory decisions based on overall conceptual information or ‘gist’ rather than specific details of past experience.
Dennis, N.A., Bowman, C.R. & Vandekar, S.N. (2012) True and phantom recollection: an fMRI investigation of similar and distinct neural correlates and connectivity. Neuroimage, 59, 2982-2993.