Hippocampal BOLD response during category learning predicts subsequent performance on transfer generalization

Abstract

To test a prediction of our previous computational model of cortico-hippocampal interaction (Gluck and Myers [1993, 2001]) for characterizing individual differences in category learning, we studied young healthy subjects using an fMRI-adapted category-learning task that has two phases, an initial phase in which associations are learned through trial-and-error feedback followed by a generalization phase in which previously learned rules can be applied to novel associations (Myers et al. [2003]). As expected by our model, we found a negative correlation between learning-related hippocampal responses and accuracy during transfer, demonstrating that hippocampal adaptation during learning is associated with better behavioral scores during transfer generalization. In addition, we found an inverse relationship between Blood Oxygenation Level Dependent (BOLD) activity in the striatum and that in the hippocampal formation and the orbitofrontal cortex during the initial learning phase. Conversely, activity in the dorsolateral prefrontal cortex, orbitofrontal cortex and parietal lobes dominated over that of the hippocampal formation during the generalization phase. These findings provide evidence in support of theories of the neural substrates of category learning which argue that the hippocampal region plays a critical role during learning for appropriately encoding and representing newly learned information so that that this learning can be successfully applied and generalized to subsequent novel task demands.

Increased generalization of learned associations is related to re-experiencing symptoms in veterans with symptoms of post-traumatic stress

“…If so, etiologies where the latter subregions are preferentially disrupted might produce increased generalization, while preferential disruption of the former subregions might reduce generalization. Consistent with this possibility, a recent neuroimaging study of this task in healthy adults showed an inverse relationship between learning-related hippocampal activity and subsequent generalization (Fera et al, 2013). Further imaging studies in individuals with PTSD would be useful to determine whether reduced hippocampal volume and/or activity similarly correlate with generalization and/or re-experiencing symptoms.…”

Hippocampal contributions to value-based learning: Converging evidence from fMRI and amnesia

“…This comparison was first implemented in FSL at the second level by coding early and late runs as 1 and −1, respectively. Although some literature suggests greater contribution of the hippocampus early in learning (and vice versa for the striatum; Dickerson et al, 2011;Fera et al, 2014;Poldrack et al, 2001;Poldrack & Packard, 2003;Shohamy et al, 2008), other work does not support this notion (see Delgado, Miller, Inati, & Phelps, 2005;Shohamy et al, 2008). Accordingly, we did not make specific predictions about the nature of changes across learning but perform such analyses only to align our work with that of others in the literature.…”

Deficits in hippocampal‐dependent transfer generalization learning accompany synaptic dysfunction in a mouse model of amyloidosis

“…Previous work shows that assessments of transfer generalization learning can detect subtle deficits in hippocampal function in humans (Myers et al, ; Gluck et al, ; Fera et al, ). The results described here demonstrate that performance in a formally identical task designed for use in mice (Montgomery et al, ) clearly depends upon an intact hippocampus.…”