scholarly journals Brain Connectivity Alterations During Sleep by Closed-Loop Transcranial Neurostimulation Predict Meta-memory Sensitivity

2021 ◽  
pp. 1-41
Author(s):  
Ryan J. Hubbard ◽  
Iman Zadeh ◽  
Aaron P. Jones ◽  
Bradley Robert ◽  
Natalie B. Bryant ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Brain Stimulation ◽  
Closed Loop ◽  
Brain Connectivity ◽  
Memory Performance ◽  
Machine Learning Techniques ◽  
Beta Band ◽  
Graph Theoretic ◽  
Specific Memory ◽  
Up States

Abstract Meta-memory involves the ability to correctly judge the accuracy of our memories. The retrieval of memories can be improved using transcranial electrical brain stimulation (tES) during sleep, but evidence for improvements to meta-memory sensitivity is limited. Applying tES can enhance sleepdependent memory consolidation, which along with meta-memory requires the coordination of activity across distributed neural systems, suggesting that examining functional connectivity is important for understanding these processes. Nevertheless, little research has examined how functional connectivity modulations relate to overnight changes in meta-memory sensitivity. Here, we developed a closed-loop short-duration tES method, time-locked to up-states of ongoing slow-wave oscillations, to cue specific memory replays in humans. We measured electroencephalographic (EEG) coherence changes following stimulation pulses, and characterized network alterations with graph theoretic metrics. Using machine learning techniques, we show that pulsed tES elicited network changes in multiple frequency bands, including increased connectivity in the Theta band and increased efficiency in the Spindle band. Additionally, stimulation-induced changes in Beta band path length were predictive of overnight changes in meta-memory sensitivity. These findings add new insights into the growing literature investigating increases in memory performance through brain stimulation during sleep, and highlight the importance of examining functional connectivity to explain its effects.

scholarly journals Prefrontal–hippocampal functional connectivity encodes recognition memory and is impaired in intellectual disability

2020 ◽  
Vol 117 (21) ◽  
pp. 11788-11798 ◽  
Author(s):  
Maria Alemany-González ◽  
Thomas Gener ◽  
Pau Nebot ◽  
Marta Vilademunt ◽  
Mara Dierssen ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Functional Connectivity ◽  
Brain Connectivity ◽  
Memory Performance ◽  
Chronic Administration ◽  
Gamma Oscillations ◽  
Brain Regions ◽  
Tea Extract ◽  
Lower Intelligence ◽  
Cross Frequency Coupling

Down syndrome (DS) is the most common form of intellectual disability. The cognitive alterations in DS are thought to depend on brain regions critical for learning and memory such as the prefrontal cortex (PFC) and the hippocampus (HPC). Neuroimaging studies suggest that increased brain connectivity correlates with lower intelligence quotients (IQ) in individuals with DS; however, its contribution to cognitive impairment is unresolved. We recorded neural activity in the PFC and HPC of the trisomic Ts65Dn mouse model of DS during quiet wakefulness, natural sleep, and the performance of a memory test. During rest, trisomic mice showed increased theta oscillations and cross-frequency coupling in the PFC and HPC while prefrontal–hippocampal synchronization was strengthened, suggesting hypersynchronous local and cross-regional processing. During sleep, slow waves were reduced, and gamma oscillations amplified in Ts65Dn mice, likely reflecting prolonged light sleep. Moreover, hippocampal sharp-wave ripples were disrupted, which may have further contributed to deficient memory consolidation. Memory performance in euploid mice correlated strongly with functional connectivity measures that indicated a hippocampal control over memory acquisition and retrieval at theta and gamma frequencies, respectively. By contrast, trisomic mice exhibited poor memory abilities and disordered prefrontal–hippocampal functional connectivity. Memory performance and key neurophysiological alterations were rescued after 1 month of chronic administration of a green tea extract containing epigallocatequin-3-gallate (EGCG), which improves executive function in young adults with DS and Ts65Dn mice. Our findings suggest that abnormal prefrontal–hippocampal circuit dynamics are candidate neural mechanisms for memory impairment in DS.

scholarly journals Bilateral double beta peaks in a PD patient with STN electrodes

2020 ◽  
Vol 163 (1) ◽  
pp. 205-209 ◽  
Author(s):  
Thomas Koeglsperger ◽  
Jan H. Mehrkens ◽  
Kai Bötzel
Keyword(s):  
Physical Activity ◽  
Deep Brain Stimulation ◽  
Local Field ◽  
Brain Stimulation ◽  
Closed Loop ◽  
Local Field Potentials ◽  
Beta Activity ◽  
Field Potentials ◽  
Beta Band ◽  
Deep Brain

AbstractSubthalamic local field potentials in the beta band are considered as potential biomarkers for closed-loop deep brain stimulation. To investigate the subthalamic beta band peak amplitudes in a Parkinson’s disease patient over an extended period of time by using a novel and commercially available neurostimulator with permanent sensing capability. We recorded local field potentials of the subthalamic nucleus using the Medtronic Percept™ implantable neurostimulator at rest and during physical activity (gait) with and in response to deep brain stimulation. We found a double-peaked beta activity on both sides. Increasing stimulation and physical activity resulted in a decreased beta band amplitude, but was accompanied by the appearance of a second, and previously unrecognized peak at 13 Hz in the right hemisphere. Our results will support the investigation of distinct different peaks in the beta band and their relevance and usefulness as closed-loop biomarkers.

scholarly journals Task-induced functional brain connectivity mediates the relationship between striatal D2/3 receptors and working memory

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Matthew M Nour ◽  
Tarik Dahoun ◽  
Robert A McCutcheon ◽  
Rick A Adams ◽  
Matthew B Wall ◽  
...  
Keyword(s):  
Working Memory ◽  
Functional Connectivity ◽  
Task Performance ◽  
Memory Load ◽  
Brain Connectivity ◽  
Memory Performance ◽  
Age Related ◽  
Positron Emission ◽  
The Relationship ◽  
And Task

Working memory performance is thought to depend on both striatal dopamine 2/3 receptors (D2/3Rs) and task-induced functional organisation in key cortical brain networks. Here, we combine functional magnetic resonance imaging and D2/3R positron emission tomography in 51 healthy volunteers, to investigate the relationship between working memory performance, task-induced default mode network (DMN) functional connectivity changes, and striatal D2/3R availability. Increasing working memory load was associated with reduced DMN functional connectivity, which was itself associated with poorer task performance. Crucially, the magnitude of the DMN connectivity reduction correlated with striatal D2/3R availability, particularly in the caudate, and this relationship mediated the relationship between striatal D2/3R availability and task performance. These results inform our understanding of natural variation in working memory performance, and have implications for understanding age-related cognitive decline and cognitive impairments in neuropsychiatric disorders where dopamine signalling is altered.

Alterations in Intra- and Interregional Intrinsic Brain Connectivity Are Differentially Associated with Memory Performance in Amnestic Mild Cognitive Impairment

2018 ◽  
Vol 46 (3-4) ◽  
pp. 229-242 ◽  
Author(s):  
Dong Woo Kang ◽  
Hyun Kook Lim ◽  
Soo-Hyun Joo ◽  
Na Rae Lee ◽  
Chang-Uk Lee
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Functional Connectivity ◽  
Brain Connectivity ◽  
Memory Performance ◽  
Amnestic Mild Cognitive Impairment ◽  
Connectivity Pattern ◽  
Inferior Temporal Gyrus ◽  
Amci Group ◽  
With Memory

Background: Previous research has separated spatial patterns of intra- and interregional intrinsic brain connectivity, as evaluated by regional homogeneity (ReHo) and functional connectivity (FC), respectively, in prodromal Alzheimer’s disease (AD). Moreover, the intra- and interregional intrinsic brain connectivities have been demonstrated to have a significant relationship with each other. Objective: To explore FCs from brain regions which display a difference in ReHo between an amnestic mild cognitive impairment (aMCI) group and healthy controls (HC) and to examine the relationship of intra- and interregional intrinsic brain connectivity to cognitive function in both groups. Methods: Thirty-four subjects with aMCI and 38 HC underwent 3T MRI scanning and a battery of neuropsychological tests. Results: The aMCI group exhibited significantly higher ReHo in the left putamen and lower ReHo in the left inferior temporal gyrus than the HC. Furthermore, both groups showed a distinctive functional connectivity pattern seeded from 2 regions of interest which exhibited significant ReHo differences between the groups. In the HC group, only ReHo exhibited significant associations with memory performance, but in the aMCI group, only FC seeded from the left inferior temporal gyrus showed significant correlations with memory performance. Conclusions: By approaching both intra- and interregional intrinsic brain activities in the early stages of AD, the findings of this research provide insights into the early pathogenesis of AD as related to memory performance.

Influence of Primary Auditory Cortex in the Characterization of Autism Spectrum in Young Adults using Brain Connectivity Parameters and Deep Belief Networks: An fMRI Study

2020 ◽  
Vol 16 (9) ◽  
pp. 1059-1073
Author(s):  
Vidhusha Srinivasan ◽  
N. Udayakumar ◽  
Kavitha Anandan
Keyword(s):  
Functional Connectivity ◽  
Auditory Cortex ◽  
Language Processing ◽  
Brain Connectivity ◽  
Primary Auditory Cortex ◽  
Autism Spectrum ◽  
Belief Networks ◽  
Deep Belief Networks ◽  
High Functioning ◽  
Low Functioning

Background: The spectrum of autism encompasses High Functioning Autism (HFA) and Low Functioning Autism (LFA). Brain mapping studies have revealed that autism individuals have overlaps in brain behavioural characteristics. Generally, high functioning individuals are known to exhibit higher intelligence and better language processing abilities. However, specific mechanisms associated with their functional capabilities are still under research. Objective: This work addresses the overlapping phenomenon present in autism spectrum through functional connectivity patterns along with brain connectivity parameters and distinguishes the classes using deep belief networks. Methods: The task-based functional Magnetic Resonance Images (fMRI) of both high and low functioning autistic groups were acquired from ABIDE database, for 58 low functioning against 43 high functioning individuals while they were involved in a defined language processing task. The language processing regions of the brain, along with Default Mode Network (DMN) have been considered for the analysis. The functional connectivity maps have been plotted through graph theory procedures. Brain connectivity parameters such as Granger Causality (GC) and Phase Slope Index (PSI) have been calculated for the individual groups. These parameters have been fed to Deep Belief Networks (DBN) to classify the subjects under consideration as either LFA or HFA. Results: Results showed increased functional connectivity in high functioning subjects. It was found that the additional interaction of the Primary Auditory Cortex lying in the temporal lobe, with other regions of interest complimented their enhanced connectivity. Results were validated using DBN measuring the classification accuracy of 85.85% for high functioning and 81.71% for the low functioning group. Conclusion: Since it is known that autism involves enhanced, but imbalanced components of intelligence, the reason behind the supremacy of high functioning group in language processing and region responsible for enhanced connectivity has been recognized. Therefore, this work that suggests the effect of Primary Auditory Cortex in characterizing the dominance of language processing in high functioning young adults seems to be highly significant in discriminating different groups in autism spectrum.

scholarly journals Early stages of tau pathology and its associations with functional connectivity, atrophy and memory

Brain ◽  
2021 ◽  
Author(s):  
David Berron ◽  
Jacob W Vogel ◽  
Philip S Insel ◽  
Joana B Pereira ◽  
Long Xie ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Entorhinal Cortex ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory Impairment ◽  
Memory Performance ◽  
Hippocampal Atrophy ◽  
Tau Pathology ◽  
Β Amyloid ◽  
With Memory

Abstract In Alzheimer’s disease, postmortem studies have shown that the first cortical site where neurofibrillary tangles appear is the transentorhinal region, a subregion within the medial temporal lobe that largely overlaps with area 35, and the entorhinal cortex. Here we used tau-PET imaging to investigate the sequence of tau pathology progression within the human medial temporal lobe and across regions in the posterior-medial system. Our objective was to study how medial temporal tau is related to functional connectivity, regional atrophy, and memory performance. We included 215 β-amyloid negative cognitively unimpaired, 81 β-amyloid positive cognitively unimpaired and 87 β-amyloid positive individuals with mild cognitive impairment, who each underwent [18]F-RO948 tau and [18]F-flutemetamol amyloid PET imaging, structural T1-MRI and memory assessments as part of the Swedish BioFINDER-2 study. First, event-based modelling revealed that the entorhinal cortex and area 35 show the earliest signs of tau accumulation followed by the anterior and posterior hippocampus, area 36 and the parahippocampal cortex. In later stages, tau accumulation became abnormal in neocortical temporal and finally parietal brain regions. Second, in cognitively unimpaired individuals, increased tau load was related to local atrophy in the entorhinal cortex, area 35 and the anterior hippocampus and tau load in several anterior medial temporal lobe subregions was associated with distant atrophy of the posterior hippocampus. Tau load, but not atrophy, in these regions was associated with lower memory performance. Further, tau-related reductions in functional connectivity in critical networks between the medial temporal lobe and regions in the posterior-medial system were associated with this early memory impairment. Finally, in patients with mild cognitive impairment, the association of tau load in the hippocampus with memory performance was partially mediated by posterior hippocampal atrophy. In summary, our findings highlight the progression of tau pathology across medial temporal lobe subregions and its disease-stage specific association with memory performance. While tau pathology might affect memory performance in cognitively unimpaired individuals via reduced functional connectivity in critical medial temporal lobe-cortical networks, memory impairment in mild cognitively impaired patients is associated with posterior hippocampal atrophy.

Closed-loop programming using external responses for deep brain stimulation in Parkinson's disease

2021 ◽  
Vol 84 ◽  
pp. 47-51
Author(s):  
Fuyuko Sasaki ◽  
Genko Oyama ◽  
Satoko Sekimoto ◽  
Maierdanjiang Nuermaimaiti ◽  
Hirokazu Iwamuro ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Closed Loop ◽  
Deep Brain
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