ACC Theta Improves Hippocampal Contextual Processing during Remote Recall

Wirt, Ryan A.; Hyman, James M.

doi:10.1016/j.celrep.2019.04.080

Cited by 27 publications

(14 citation statements)

References 131 publications

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“…In the current experiments, our control group had decreased ACC–hippocampus coherence during error trials, indicating a lack of communication between these areas and replicating the purest essence of neural synchrony hypothesis (i.e., synchrony supports information transfer enabling cognitive success). Similar theta range effects have been found in spatial working memory and long-term memory tasks before in rodents 53 , 54 , 95 , macaques 96 , and in humans 97 , 98 . Thus, it is quite remarkable that we found that in STZ animals coherence between the ACC and hippocampus was decreased on correct trials.…”

Section: Discussionsupporting

confidence: 78%

Altered theta rhythm and hippocampal-cortical interactions underlie working memory deficits in a hyperglycemia risk factor model of Alzheimer’s disease

et al. 2021

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Diabetes mellitus is a metabolic disease associated with dysregulated glucose and insulin levels and an increased risk of developing Alzheimer’s disease (AD) later in life. It is thought that chronic hyperglycemia leads to neuroinflammation and tau hyperphosphorylation in the hippocampus leading to cognitive decline, but effects on hippocampal network activity are unknown. A sustained hyperglycemic state was induced in otherwise healthy animals and subjects were then tested on a spatial delayed alternation task while recording from the hippocampus and anterior cingulate cortex (ACC). Hyperglycemic animals performed worse on long delay trials and had multiple electrophysiological differences throughout the task. We found increased delta power and decreased theta power in the hippocampus, which led to altered theta/delta ratios at the end of the delay period. Cross frequency coupling was significantly higher in multiple bands and delay period hippocampus-ACC theta coherence was elevated, revealing hypersynchrony. The highest coherence values appeared long delays on error trials for STZ animals, the opposite of what was observed in controls, where lower delay period coherence was associated with errors. Consistent with previous investigations, we found increases in phosphorylated tau in STZ animals’ hippocampus and cortex, which might account for the observed oscillatory and cognitive changes.

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Section: Discussionsupporting

confidence: 78%

Altered theta rhythm and hippocampal-cortical interactions underlie working memory deficits in a hyperglycemia risk factor model of Alzheimer’s disease

et al. 2021

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“…This notion is supported by our findings that ACC-CA1 cross-regional interaction, but not region-autonomous ACC activity, is enhanced during the remote session (Figures 2D, 3C, 3D, and S1B). Consistent with this, a recent study has found that non-aversive contextual re-exposure at the remote time point enhances ACC-CA1 crossregional interaction (Wirt and Hyman, 2019), suggesting that the recruitment of ACC-CA1 pathway at remote recall may be a general mechanism common to multiple forms of memory. Furthermore, although we cannot exclude the possibility that non-freezing periods engage cognitive processes in addition to recall, such as updating, extinction, and reconsolidation, we did observe a strong correlation between ACC-entrained CA1 synchronous firing during these periods and freezing levels (Figures 4D and 4E), suggesting an active role in recall.…”

Section: Discussionsupporting

confidence: 61%

Physiological Signature of Memory Age in the Prefrontal-Hippocampal Circuit

et al. 2019

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“…Additional evidence for the neocortex-to-hippocampus information flow was found in oscillatory and spiking activity patterns during the retrieval of old, consolidated memory. When rodents are re-exposed to a neutral (Wirt & Hyman, 2019) or aversive context (Makino, Polygalov, Bolaños, Benucci, & McHugh, 2019) 1 month later, theta oscillations in the ACC become strongly synchronized with those in the hippocampus. The analysis of the directionality of oscillatory coupling revealed that ACC theta oscillations lead hippocampal theta oscillations.…”

Section: The Hippocampus Instructs the Maturation Of Neocortical Memory Traces Through The Coordinated Reactivation Of Memory Traces In Tmentioning

confidence: 99%

Neurobiology of systems memory consolidation

Takehara‐Nishiuchi

2020

Eur J of Neuroscience

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Psychological theories posit that the hippocampus rapidly forms associations among ongoing events as they unfold. During a subsequent maturation process, so-called systems memory consolidation, these associations are gradually stabilized within distributed neocortical circuits through close interactions between the hippocampus and neocortex. In the past 50 years, a major effort in neurobiological research has been directed towards translating these descriptive accounts into tangible, biological processes in the brain. Until the early 2000s, most studies exclusively focused on examining whether the hippocampus becomes unnecessary for memory retrieval once the memory has been consolidated. With recent methodological advances, however, the field shifted attention to several other theoretical accounts and began to uncover the genetic, physiological and structural underpinnings of systems memory consolidation at an unprecedented level of precision. Here I review these neurobiological findings in the past 15 years within a framework of six essential predictions extracted from the psychological theories. Genetic approaches have made it possible to tag neurons that were activated during memory encoding and investigate their physiological and genetic profiles as well as reactivation patterns during subsequent retrieval. In parallel, electrophysiological and imaging approaches detected signs of the gradual refinement of memory representations and its underlying hippocampalneocortical dialogue in millisecond-resolved neural firing patterns, the inter-region coupling of neural activity, across-day stability of neural ensemble activity and functional connectome. This summary represents substantial progress in our understanding of neurobiological mechanisms of systems memory consolidation whilst also identifying several essential remaining questions for future investigations.

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ACC Theta Improves Hippocampal Contextual Processing during Remote Recall

Abstract: Highlights d ACC leads CA1 during remote recall d ACC theta modulates CA1 spiking and gamma power during remote recall d ACC and CA1 ensemble context information increases over consolidation d Consolidation increases the strength and spread of ACC theta effects on CA1 networks

Cited by 27 publications

References 131 publications

Altered theta rhythm and hippocampal-cortical interactions underlie working memory deficits in a hyperglycemia risk factor model of Alzheimer’s disease

Altered theta rhythm and hippocampal-cortical interactions underlie working memory deficits in a hyperglycemia risk factor model of Alzheimer’s disease

Physiological Signature of Memory Age in the Prefrontal-Hippocampal Circuit

Neurobiology of systems memory consolidation

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