scholarly journals Aberrant prefrontal beta oscillations predict episodic memory encoding deficits in schizophrenia

2016 ◽  
Author(s):  
Federica Meconi ◽  
Sarah Anderl-Straub ◽  
Heidelore Raum ◽  
Michael Landgrebe ◽  
Berthold Langguth ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Verbal Memory ◽  
Semantic Processing ◽  
Memory Performance ◽  
Oscillatory Activity ◽  
Healthy Controls ◽  
Memory Encoding ◽  
Brain Oscillations ◽  
Beta Power ◽  
Pattern Similarity

AbstractVerbal episodic memory is one of the core cognitive functions affected in patients suffering from schizophrenia (SZ). Although this verbal memory impairment in SZ is a well-known finding, our understanding about its underlying neurophysiological mechanisms is rather scarce. Here we address this issue by recording brain oscillations during a memory task in a sample of healthy controls and patients suffering from SZ. Brain oscillations represent spectral fingerprints of specific neurocognitive operations and are therefore a promising tool to identify neurocognitive mechanisms that are affected by SZ. Healthy controls showed a prominent suppression of left prefrontal beta oscillatory activity during successful memory formation, which replicates several previous oscillatory memory studies. In contrast, patients failed to exhibit such left prefrontal beta power suppression. Utilizing a new topographical pattern similarity approach, we further demonstrate that the degree of similarity between a patient's beta power decrease to that of the controls reliably predicted memory performance. This relationship between beta power decreases and memory was such that the patients' memory performance improved as they showed a more similar topographical beta desynchronization pattern compared to that of healthy controls. These findings suggest that left prefrontal beta power suppression (or lack thereof) during memory encoding is a possible biomarker for the observed encoding impairments in SZ in verbal memory. This lack of left prefrontal beta power decreases might indicate a specific semantic processing deficit of verbal material in patients with schizophrenia.

scholarly journals Neural basis of episodic memory in the intermediate term after medial temporal lobe resection

2019 ◽  
Vol 131 (3) ◽  
pp. 790-798 ◽  
Author(s):  
Woorim Jeong ◽  
Hyeongrae Lee ◽  
June Sic Kim ◽  
Chun Kee Chung
Keyword(s):  
Episodic Memory ◽  
Temporal Lobe ◽  
Verbal Memory ◽  
Visual Memory ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Memory Function ◽  
Memory Encoding ◽  
Neural Basis ◽  
Surgery Group

OBJECTIVEHow the brain supports intermediate-term preservation of memory in patients who have undergone unilateral medial temporal lobe resection (MTLR) has not yet been demonstrated. To understand the neural basis of episodic memory in the intermediate term after surgery for temporal lobe epilepsy (TLE), the authors investigated the relationship between the activation of the hippocampus (HIP) during successful memory encoding and individual memory capacity in patients who had undergone MTLR. They also compared hippocampal activation with other parameters, including structural volumes of the HIP, duration of illness, and age at seizure onset.METHODSThirty-five adult patients who had undergone unilateral MTLR at least 1 year before recruiting and who had a favorable seizure outcome were enrolled (17 left MTLR, 18 right MTLR; mean follow-up 6.31 ± 2.72 years). All patients underwent a standardized neuropsychological examination of memory function and functional MRI scanning with a memory-encoding paradigm of words and figures. Activations of the HIP during successful memory encoding were calculated and compared with standard neuropsychological memory scores, hippocampal volumes, and other clinical variables.RESULTSGreater activation in the HIP contralateral to the side of the resection was related to higher postoperative memory scores and greater postoperative memory improvement than the preoperative baseline in both patient groups. Specifically, postoperative verbal memory performance was positively correlated with contralateral right hippocampal activation during word encoding in the left-sided surgery group. In contrast, postoperative visual memory performance was positively correlated with contralateral left hippocampal activation during figure encoding in the right-sided surgery group. Activation of the ipsilateral remnant HIP was not correlated with any memory scores or volumes of the HIP; however, it had a negative correlation with the seizure-onset age and positive correlation with the duration of illness in both patient groups.CONCLUSIONSFor the first time, a neural basis that supports effective intermediate-term episodic memory after unilateral MTLR has been characterized. The results provide evidence that engagement of the HIP contralateral rather than ipsilateral to the side of resection is responsible for effective memory function in the intermediate term (> 1 year) after surgery in patients who have undergone left MTLR and right MTLR. Engagement of the material-specific contralesional HIP, verbal memory in the left-sided surgery group, and visual memory in the right-sided surgery group were observed.

scholarly journals Tonic resting-state hubness supports high-frequency activity defined verbal-memory encoding network in epilepsy

2019 ◽  
Author(s):  
Chaitanya Ganne ◽  
Walter Hinds ◽  
James Kragel ◽  
Xiaosong He ◽  
Noah Sideman ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Verbal Memory ◽  
Resting State ◽  
High Frequency ◽  
Cognitive Networks ◽  
Gamma Activity ◽  
List Type ◽  
Healthy Controls ◽  
Memory Encoding ◽  
Memory Network

AbstractHigh-frequency gamma activity of verbal-memory encoding using invasive-electroencephalogram coupled has laid the foundation for numerous studies testing the integrity of memory in diseased populations. Yet, the functional connectivity characteristics of networks subserving these HFA-memory linkages remains uncertain. By integrating this electrophysiological biomarker of memory encoding from IEEG with resting-state BOLD fluctuations, we estimated the segregation and hubness of HFA-memory regions in drug-resistant epilepsy patients and matched healthy controls. HFA-memory regions express distinctly different hubness compared to neighboring regions in health and in epilepsy, and this hubness was more relevant than segregation in predicting verbal memory encoding. The HFA-memory network comprised regions from both the cognitive control and primary processing networks, validating that effective verbal-memory encoding requires multiple functions, and is not dominated by a central cognitive core. Our results demonstrate a tonic intrinsic set of functional connectivity, which provides the necessary conditions for effective, phasic, task-dependent memory encoding.HighlightsHigh frequency memory activity in IEEG corresponds to specific BOLD changes in resting-state data.HFA-memory regions had lower hubness relative to control brain nodes in both epilepsy patients and healthy controls.HFA-memory network displayed hubness and participation (interaction) values distinct from other cognitive networks.HFA-memory network shared regional membership and interacted with other cognitive networks for successful memory encoding.HFA-memory network hubness predicted both concurrent task (phasic) and baseline (tonic) verbal-memory encoding success.

scholarly journals Lifespan trajectories and relationships to memory of the macro- and microstructure of the anterior and posterior hippocampus – a longitudinal multi-modal imaging study

2019 ◽  
Author(s):  
Espen Langnes ◽  
Markus H. Sneve ◽  
Donatas Sederevicius ◽  
Inge K. Amlien ◽  
Kristine B Walhovd ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Verbal Memory ◽  
Structural Changes ◽  
Diffusion Tensor ◽  
Hippocampal Formation ◽  
Memory Performance ◽  
Memory Function ◽  
Imaging Study ◽  
Future Research ◽  
Microstructural Development

AbstractThere is evidence for a hippocampal long axis anterior-posterior (AP) differentiation in memory processing, which may have implications for the changes in episodic memory performance typically seen across development and aging. The hippocampal formation shows substantial structural changes with age, but the lifespan trajectories of hippocampal sub-regions along the AP axis are not established. The aim of the present study was to test whether the micro- and macro-structural age-trajectories of the anterior (aHC) and posterior (pHC) hippocampus are different. In a single-center longitudinal study, 1790 cognitively healthy participants, 4.1-93.4 years of age, underwent a total of 3367 MRI examinations and 3033 memory tests sessions over 1-6 time points, spanning an interval up to 11.1 years. T1-weighted scans were used to estimate the volume of aHC and pHC, and diffusion tensor imaging to measure mean diffusion (MD) within each region. We found that the macro- and microstructural lifespan-trajectories of aHC and pHC were clearly distinguishable, with partly common and partly unique variance shared with age. aHC showed a protracted period of microstructural development, while pHC microstructural development as indexed by MD was more or less completed in early childhood. In contrast, pHC showed larger unique aging-related changes. A similar aHC – pHC difference was observed for volume, although not as evident as for microstructure. All sub-regions showed age-dependent relationships to episodic memory function. For aHC micro- and macrostructure, the relationships to verbal memory performance varied significantly with age, being stronger among the older participants. Future research should disentangle the relationship between these structural properties and different memory processes – encoding vs. retrieval in particular – across the lifespan.

scholarly journals The genomic underpinnings of oscillatory biomarkers supporting successful memory encoding in humans

2019 ◽  
Author(s):  
Stefano Berto ◽  
Miles Fontenot ◽  
Sarah Seger ◽  
Fatma Ayhan ◽  
Emre Caglayan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Memory Performance ◽  
Temporal Cortex ◽  
Memory Task ◽  
Memory Formation ◽  
Inhibitory Neurons ◽  
Patient Specific ◽  
Memory Encoding ◽  
Brain Oscillations ◽  
Resected Tissue

AbstractIn humans, brain oscillations are thought to support critical features of memory formation such as coordination of activity across regions, consolidation, and temporal ordering of events. However, understanding the molecular mechanisms underlining this activity in humans remains a major challenge. Here, we measured memory-sensitive oscillations using direct intracranial electroencephalography recordings from the temporal cortex of patients performing an episodic memory task. By then employing transcriptomics on the resected tissue from the same patients, we linked gene expression with brain oscillations, identifying genes correlated with oscillatory signatures of memory formation across six frequency bands. A co-expression analysis isolated biomarker-specific modules associated with neuropsychiatric disorders as well as ion channel activity. Using single-nuclei transcriptomic data from this resected tissue, we further revealed that biomarker-specific modules are enriched for both excitatory and inhibitory neurons. This unprecedented dataset of patient-specific brain oscillations coupled to genomics unlocks new insights into the genetic mechanisms that support memory encoding. By linking brain expression of these genes to oscillatory patterns, our data help overcome limitations of phenotypic methods to uncover genetic links to memory performance.

Spatial Visualization Ability Mediates the Male Advantage in Spatial and Visual Episodic Memory

2016 ◽  
Vol 37 (3) ◽  
pp. 194-200 ◽  
Author(s):  
Karen L. Siedlecki
Keyword(s):  
Episodic Memory ◽  
Verbal Memory ◽  
Visual Memory ◽  
Memory Performance ◽  
Spatial Visualization ◽  
Mediation Analyses ◽  
Female Advantage ◽  
Male Advantage ◽  
The Relationship ◽  
Verbal Episodic Memory

Abstract. Individuals between the ages of 18 and 94 (N = 326) completed a battery of episodic memory tasks, as well as several measures of spatial visualization. A female advantage in verbal episodic memory and a male advantage in spatial and visual episodic memory were observed. Mediation analyses provided evidence that performance on spatial visualization tasks greatly influences the magnitude of the effect for sex differences among the different episodic memory constructs. In particular, the spatial visualization construct fully mediated the relationship between sex and episodic spatial memory performance. Further, when spatial visualization was included as a mediator in the model the relationship between sex and episodic verbal memory increased, and the relationship between sex and episodic visual memory reversed, such that women scored higher than men.

scholarly journals Complementary Role of Frontoparietal Activity and Cortical Pattern Similarity in Successful Episodic Memory Encoding

2012 ◽  
Vol 23 (7) ◽  
pp. 1562-1571 ◽  
Author(s):  
Gui Xue ◽  
Qi Dong ◽  
Chuansheng Chen ◽  
Zhong-Lin Lu ◽  
Jeanette A. Mumford ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Memory Encoding ◽  
Complementary Role ◽  
Pattern Similarity

The Involvement of the Thalamus in Semantic Retrieval: A Clinical Group Study

2013 ◽  
Vol 25 (6) ◽  
pp. 872-886 ◽  
Author(s):  
Giulio Pergola ◽  
Christian Bellebaum ◽  
Britta Gehlhaar ◽  
Benno Koch ◽  
Michael Schwarz ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Memory Performance ◽  
Striking Difference ◽  
Clinical Group ◽  
Healthy Controls ◽  
Semantic Retrieval ◽  
Retrieval Task ◽  
Phonological Representations

There is increasing attention about the role of the thalamus in high cognitive functions, including memory. Although the bulk of the evidence refers to episodic memory, it was recently proposed that the mediodorsal (MD) and the centromedian–parafascicular (CM–Pf) nuclei of the thalamus may process general operations supporting memory performance, not only episodic memory. This perspective agrees with other recent fMRI findings on semantic retrieval in healthy participants. It can therefore be hypothesized that lesions to the MD and the CM–Pf impair semantic retrieval. In this study, 10 patients with focal ischemic lesions in the medial thalamus and 10 healthy controls matched for age, education, and verbal IQ performed a verbal semantic retrieval task. Patients were assigned to a target clinical group and a control clinical group based on lesion localization. Patients did not suffer from aphasia and performed in the range of controls in a categorization and a semantic association task. However, target patients performed poorer than healthy controls on semantic retrieval. The deficit was not because of higher distractibility but of an increased rate of false recall and, in some patients, of a considerably increased rate of misses. The latter deficit yielded a striking difference between the target and the control clinical groups and is consistent with anomia. Follow-up high-resolution structural scanning session in a subsample of patients revealed that lesions in the CM–Pf and MD were primarily associated with semantic retrieval deficits. We conclude that integrity of the MD and the CM–Pf is required for semantic retrieval, possibly because of their role in the activation of phonological representations.

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