Post-learning hippocampal dynamics promote preferential retention of rewarding events

Reward motivation is known to modulate memory encoding, and this effect depends on interactions between the substantia nigra/ventral tegmental area complex (SN/VTA) and the hippocampus. It is unknown, however, whether these interactions influence offline neural activity in the human brain that is thought to promote memory consolidation. Here we used fMRI to test the effect of reward motivation on post-learning neural dynamics and subsequent memory for objects that were learned in high- and low-reward motivation contexts. We found that post-learning increases in resting-state functional connectivity between the SN/VTA and hippocampus predicted preferential retention of objects that were learned in high-reward contexts. In addition, multivariate pattern classification revealed that hippocampal representations of high-reward contexts were preferentially reactivated during post-learning rest, and the number of hippocampal reactivations was predictive of preferential retention of items learned in high-reward contexts. These findings indicate that reward motivation alters offline post-learning dynamics between the SN/VTA and hippocampus, providing novel evidence for a potential mechanism by which reward could influence memory consolidatio

Neural reactivation in parietal cortex enhances memory for episodically linked information.

Remembering is a complex process that involves recalling specific details, such as who you were with when you celebrated your last birthday, as well as contextual information, such as the place where you celebrated. It is well established that the act of remembering enhances long-term retention of the retrieved information, but the neural and cognitive mechanisms that drive memory enhancement are not yet understood. One possibility is that the process of remembering results in reactivation of the broader episodic context. Consistent with this idea, in two experiments, we found that multiple retrieval attempts enhanced long-term retention of both the retrieved object and the nontarget object that shared scene context, compared with a restudy control. Using representational similarity analysis of fMRI data in experiment 2, we found that retrieval resulted in greater neural reactivation of both the target objects and contextually linked objects compared with restudy. Furthermore, this reactivation occurred in a network of medial and lateral parietal lobe regions that have been linked to episodic recollection. The results demonstrate that retrieving a memory can enhance retention of information that is linked in the broader event context and the hippocampus and a posterior medial network of parietal cortical areas (also known as the Default Network) play complementary roles in supporting the reactivation of episodically linked information during retrieval

Associations of Cumulative Sun Exposure and Phenotypic Characteristics with Histologic Solar Elastosis

Solar elastosis adjacent to melanomas in histologic sections is regarded as an indicator of sun exposure although the associations of ultraviolet (UV) exposure and phenotype with solar elastosis are yet to be fully explored

The Influence of Emotion on the Neural Correlates of Episodic Memory: Linking Encoding, Consolidation, and Retrieval Processes

<p>Emotion is known to influence multiple aspects of memory formation, which may include the initial encoding of the memory trace, its consolidation over time, and the efficacy of its retrieval. However, prior investigations have tended to treat emotional modulation of episodic memory as a unitary construct, thus conflating the contributions of these different stages to emotion-mediated memory enhancements. The present thesis aims to disentangle the component processes of emotional memory formation and retrieval through a series of studies using cognitive behavioral and functional magnetic resonance imaging (fMRI) methods. In the first 2 studies, neural activity was evaluated during the initial viewing of emotionally arousing and neutral scenes and, in the 3rd study, neural activity during this initial viewing period was compared to that during a recognition memory task. The findings are compatible with the proposal that two distinct networks support successful emotional memory formation: an amygdala-medial temporal lobe (MTL) network that modulates the consolidation of memories over time and a prefrontal-MTL network that translates emotion effects on controlled elaboration into superior memory encoding. The superlative quality of emotional memories is furthermore marked by heightened similarity between neural states at encoding and retrieval, suggesting another line of evidence through which emotion effects can be observed. Taken together, the results presented here highlight the heterogeneity of processes that confer mnemonic advantages to emotionally significant information.</p>Dissertatio

Patterns of episodic content and specificity predicting subjective memory vividness

The ability to remember and internally represent events is often accompanied by a subjective sense of “vividness”. Vividness measures are frequently used to evaluate the experience of remembering and imagining events, yet little research has considered the objective attributes of event memories that underlie this subjective judgment, and individual differences in this mapping. Here, we tested how the content and specificity of event memories support subjectively vivid recollection. Over three experiments, participants encoded events containing a theme word and three distinct elements — a person, a place, and an object. In a memory test, memory for event elements was assessed at two levels of specificity — semantic gist (names) and perceptual details (lure discrimination). We found a strong correspondence between memory vividness and memory for gist information that did not vary by which elements were contained in memory. There was a smaller, additive benefit of remembering specific perceptual details on vividness, which, in one study, was driven by memory for place details. Moreover, we found individual differences in the relationship between memory vividness and objective memory attributes primarily along the specificity dimension, such that one cluster of participants used perceptual detail to inform memory vividness whereas another cluster were more driven by gist information. Therefore, while gist memory appears to drive vividness on average, there were idiosyncrasies in this pattern across participants. When assessing subjective ratings of memory and imagination, research should consider how these ratings map onto objective memory attributes in the context of their study design and population