The relationship between level of processing and hippocampal-cortical functional connectivity during episodic memory formation in humans

Events that conform to our expectations, i.e, are congruent with our world knowledge or schemas, are better remembered than unrelated events. Yet events that conflict with schemas can also be remembered better. We examined this apparent paradox in four experiments, in which schemas were established by training ordinal relationships between randomly-paired objects, while episodic memory was tested for the number of objects on each trial. Better memory was found for both congruent and incongruent trials, relative to unrelated trials, producing memory performance that was a “U-shaped” function of congruency. Furthermore, the incongruency advantage, but not congruency advantage, emerged even if the information probed by the memory test was irrelevant to the schema, while the congruency advantage, but not incongruency advantage, also emerged after initial encoding. Schemas therefore augment episodic memory in multiple ways, depending on the match between novel and existing information.

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Glutamate connectivity associations converge upon the salience network in schizophrenia and healthy controls

Translational Psychiatry ◽

10.1038/s41398-021-01455-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Robert A. McCutcheon ◽

Toby Pillinger ◽

Maria Rogdaki ◽

Juan Bustillo ◽

Oliver D. Howes

Keyword(s):

Functional Connectivity ◽

Frontal Cortex ◽

Network Connectivity ◽

Resonance Spectroscopy ◽

Salience Network ◽

Healthy Controls ◽

1H Mrs ◽

Before And After ◽

Functional Brain Networks ◽

The Relationship

AbstractAlterations in cortical inter-areal functional connectivity, and aberrant glutamatergic signalling are implicated in the pathophysiology of schizophrenia but the relationship between the two is unclear. We used multimodal imaging to identify areas of convergence between the two systems. Two separate cohorts were examined, comprising 195 participants in total. All participants received resting state functional MRI to characterise functional brain networks and proton magnetic resonance spectroscopy (1H-MRS) to measure glutamate concentrations in the frontal cortex. Study A investigated the relationship between frontal cortex glutamate concentrations and network connectivity in individuals with schizophrenia and healthy controls. Study B also used 1H-MRS, and scanned individuals with schizophrenia and healthy controls before and after a challenge with the glutamatergic modulator riluzole, to investigate the relationship between changes in glutamate concentrations and changes in network connectivity. In both studies the network based statistic was used to probe associations between glutamate and connectivity, and glutamate associated networks were then characterised in terms of their overlap with canonical functional networks. Study A involved 76 individuals with schizophrenia and 82 controls, and identified a functional network negatively associated with glutamate concentrations that was concentrated within the salience network (p < 0.05) and did not differ significantly between patients and controls (p > 0.85). Study B involved 19 individuals with schizophrenia and 17 controls and found that increases in glutamate concentrations induced by riluzole were linked to increases in connectivity localised to the salience network (p < 0.05), and the relationship did not differ between patients and controls (p > 0.4). Frontal cortex glutamate concentrations are associated with inter-areal functional connectivity of a network that localises to the salience network. Changes in network connectivity in response to glutamate modulation show an opposite effect compared to the relationship observed at baseline, which may complicate pharmacological attempts to simultaneously correct glutamatergic and connectivity aberrations.

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Alpha/beta power decreases during episodic memory formation predict the magnitude of alpha/beta power decreases during subsequent retrieval

Neuropsychologia ◽

10.1016/j.neuropsychologia.2021.107755 ◽

2021 ◽

Vol 153 ◽

pp. 107755

Author(s):

Benjamin J. Griffiths ◽

María Carmen Martín-Buro ◽

Bernhard P. Staresina ◽

Simon Hanslmayr ◽

Tobias Staudigl

Keyword(s):

Episodic Memory ◽

Memory Formation ◽

Beta Power ◽

Alpha Beta

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Heritability and interindividual variability of regional structure-function coupling

Nature Communications ◽

10.1038/s41467-021-25184-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Zijin Gu ◽

Keith Wakefield Jamison ◽

Mert Rory Sabuncu ◽

Amy Kuceyeski

Keyword(s):

Functional Connectivity ◽

Structure Function ◽

Regional Differences ◽

Regional Scale ◽

Brain Regions ◽

Diffusion Weighted Mri ◽

Regional Structure ◽

Human Connectome Project ◽

Structural Connections ◽

The Relationship

AbstractWhite matter structural connections are likely to support flow of functional activation or functional connectivity. While the relationship between structural and functional connectivity profiles, here called SC-FC coupling, has been studied on a whole-brain, global level, few studies have investigated this relationship at a regional scale. Here we quantify regional SC-FC coupling in healthy young adults using diffusion-weighted MRI and resting-state functional MRI data from the Human Connectome Project and study how SC-FC coupling may be heritable and varies between individuals. We show that regional SC-FC coupling strength varies widely across brain regions, but was strongest in highly structurally connected visual and subcortical areas. We also show interindividual regional differences based on age, sex and composite cognitive scores, and that SC-FC coupling was highly heritable within certain networks. These results suggest regional structure-function coupling is an idiosyncratic feature of brain organisation that may be influenced by genetic factors.

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Differential neural structures, intrinsic functional connectivity, and episodic memory in subjective cognitive decline and healthy controls

Neurobiology of Aging ◽

10.1016/j.neurobiolaging.2021.04.016 ◽

2021 ◽

Author(s):

N. Nellessen ◽

O.A. Onur ◽

N. Richter ◽

H.I.L. Jacobs ◽

K.N.H. Dillen ◽

...

Keyword(s):

Functional Connectivity ◽

Episodic Memory ◽

Cognitive Decline ◽

Subjective Cognitive Decline ◽

Healthy Controls ◽

Intrinsic Functional Connectivity

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Cognitive processes supporting episodic memory formation in childhood: The role of source memory, binding, and executive functioning

Developmental Review ◽

10.1016/j.dr.2011.02.001 ◽

2010 ◽

Vol 30 (4) ◽

pp. 384-402 ◽

Cited By ~ 42

Author(s):

Vinaya Raj ◽

Martha Ann Bell

Keyword(s):

Executive Functioning ◽

Episodic Memory ◽

Cognitive Processes ◽

Source Memory ◽

Memory Formation ◽

Memory Binding

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Hippocampus volume and episodic memory in schizophrenia

Journal of the International Neuropsychological Society ◽

10.1017/s1355617709090225 ◽

2009 ◽

Vol 15 (2) ◽

pp. 182-195 ◽

Cited By ~ 32

Author(s):

ROBERT J. THOMA ◽

MOLLIE MONNIG ◽

FAITH M. HANLON ◽

GREGORY A. MILLER ◽

HELEN PETROPOULOS ◽

...

Keyword(s):

Episodic Memory ◽

Verbal Memory ◽

Visual Memory ◽

Chronic Schizophrenia ◽

Magnetic Resonance Images ◽

Schizophrenia Group ◽

Positive Correlations ◽

The Relationship ◽

Hippocampus Volume ◽

Volumetric Measures

AbstractPrevious studies of schizophrenia have suggested a linkage between neuropsychological (NP) deficits and hippocampus abnormality. The relationship between hippocampus volume and NP functioning was investigated in 24 patients with chronic schizophrenia and 24 matched healthy controls. Overall intracranial, white and gray matter, and anterior (AH) and posterior (PH) hippocampus volumes were assessed from magnetic resonance images (MRI). NP domains of IQ, attention, and executive function were also evaluated with respect to volumetric measures. It was hypothesized that AH and PH volumes and episodic memory scores would be positively associated in controls and that the schizophrenia group would depart from this normative pattern. NP functioning was impaired overall and AH volume was smaller in the schizophrenia group. In the controls, the hippocampus–memory relationships involved AH and PH, and correlations were significant for verbal memory measures. In the schizophrenia group, positive correlations were constrained to PH. Negative correlations emerged between AH and verbal and visual memory measures. For both groups, cortical volume negatively correlated with age, but a negative correlation between age and hippocampus volume was found only in the schizophrenia group. In this sample of adults with schizophrenia, atypical relationships between regional hippocampus volumes and episodic memory ability were found, as was an atypical negative association between hippocampus volume and age. (JINS, 2009, 15, 182–195.)

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Effects of amnesia on processing in the hippocampus and default mode network during a naturalistic memory task: a case study

10.31234/osf.io/e9n8c ◽

2018 ◽

Author(s):

Christiane Oedekoven ◽

James L. Keidel ◽

Stuart Anderson ◽

Angus Nisbet ◽

Chris Bird

Keyword(s):

Functional Connectivity ◽

Episodic Memory ◽

Memory Performance ◽

Memory Task ◽

Structural Mri ◽

Brain Regions ◽

Left Hippocampus ◽

Cortical Regions ◽

The Right ◽

Encoding And Retrieval

Despite their severely impaired episodic memory, individuals with amnesia are able to comprehend ongoing events. Online representations of a current event are thought to be supported by a network of regions centred on the posterior midline cortex (PMC). By contrast, episodic memory is widely believed to be supported by interactions between the hippocampus and these cortical regions. In this MRI study, we investigated the encoding and retrieval of lifelike events (video clips) in a patient with severe amnesia likely resulting from a stroke to the right thalamus, and a group of 20 age-matched controls. Structural MRI revealed grey matter reductions in left hippocampus and left thalamus in comparison to controls. We first characterised the regions activated in the controls while they watched and retrieved the videos. There were no differences in activation between the patient and controls in any of the regions. We then identified a widespread network of brain regions, including the hippocampus, that were functionally connected with the PMC in controls. However, in the patient there was a specific reduction in functional connectivity between the PMC and a region of left hippocampus when both watching and attempting to retrieve the videos. A follow up analysis revealed that in controls the functional connectivity between these regions when watching the videos was correlated with memory performance. Taken together, these findings support the view that the interactions between the PMC and the hippocampus enable the encoding and retrieval of multimodal representations of the contents of an event.

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