scholarly journals Alterations in Neural Networks During Working Memory Encoding Related to Cognitive Impairment in Temporal Lobe Epilepsy

2022 ◽  
Vol 15 ◽  
Author(s):  
Liping Pan ◽  
Yakun Wu ◽  
Jie Bao ◽  
Dandan Guo ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Neural Networks ◽  
Working Memory ◽  
Cognitive Impairment ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Cognitive Deficits ◽  
Cognitive Outcomes ◽  
Functional Connectivity Strength ◽  
The Neural Networks ◽  
Connectivity Strength

Objective: The aim of the current study was to investigate the alterations in the neural networks of patients with temporal lobe epilepsy (TLE) during working memory (WM) encoding.Methods: Patients with TLE (n = 52) and healthy volunteers (n = 35) completed a WM task, during which 34-channel electroencephalogram signals were recorded. The neural networks during WM encoding were calculated in TLE patients with (TLE-WM) and without (TLE-N) WM deficits.Results: Functional connectivity strength decreased, and the theta network was altered in the TLE-WM group, although no significant differences in clinical features were observed between the TLE-N and TLE-WM groups.Conclusions: Not all patients with TLE present with cognitive impairments and alterations in the theta network were identified in TLE patients with functional cognitive deficits.Significance: The theta network may represent a sensitive measure of cognitive impairment and could predict cognitive outcomes among patients with TLE.

scholarly journals Disorganization of language and working memory systems in frontal versus temporal lobe epilepsy

2021 ◽  
Author(s):  
Lorenzo Caciagli ◽  
Casey Paquola ◽  
Xiaosong He ◽  
Christian Vollmar ◽  
Maria Centeno ◽  
...  
Keyword(s):  
Working Memory ◽  
Cognitive Impairment ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Large Scale ◽  
Memory Systems ◽  
Multiscale Approach ◽  
Continuous Transition ◽  
Default Mode ◽  
Task Effects

ABSTRACTCognitive impairment is a common comorbidity of epilepsy, and adversely impacts people with both frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE). While the underlying neural substrates in TLE have been extensively investigated, functional imaging studies in FLE are scarce. In this study, we profiled cognitive dysfunction in FLE, and directly compared FLE and TLE patients to establish commonalities and differences. We investigated 172 adult participants (56 with FLE, 64 with TLE, and 52 controls), using neuropsychological tests and four functional MRI tasks probing the neural correlates of expressive language (verbal fluency, verb generation) and working memory (verbal and visuo-spatial). Patient groups were comparable in disease duration and anti-epileptic drug load. We devised a multiscale approach to map the landscape of brain activation and deactivation during cognition, and track reorganization in FLE and TLE. Voxel-based analyses were complemented with profiling of task effects (i) across intrinsic functional systems, and (ii) along the principal functional connectivity gradient, which encodes a continuous transition from lower-level sensory to higher-order transmodal brain areas. We show that cognitive impairment in FLE is associated with reduced activation across attentional and executive systems, and reduced deactivation of the default mode system, indicative of a large-scale disorganization of task-related recruitment. Functional abnormalities in FLE were modulated by disease load. Patterns of dysfunction in FLE were broadly similar to those in TLE, but some traits were syndrome-specific: altered default-mode deactivation was more prominent in FLE, while impaired recruitment of posterior language areas during a task with semantic demands was more marked in TLE. Our study elucidates neural processes underlying language and working memory impairment in FLE, identifies shared and syndrome-specific alterations in the two most common focal epilepsies, and sheds light on system behavior that may be amenable to future remediation strategies.

Cognitive Impairment in Patients with Temporal Lobe Epilepsy

2018 ◽  
Vol 02 (02) ◽  
Author(s):  
Farhat Nouha ◽  
Daoud Sawsan ◽  
Sakka Salma ◽  
Hdiji Olfa ◽  
Haj Kacem Hanen ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe

scholarly journals Assessment of working memory in patients with mesial temporal lobe epilepsy associated with unilateral hippocampal sclerosis

2010 ◽  
Vol 18 (3) ◽  
pp. 223-228 ◽  
Author(s):  
Ivanda de Souza Silva Tudesco ◽  
Leonardo José Vaz ◽  
Marcele Araújo Silva Mantoan ◽  
Erich Belzunces ◽  
Maria Helena Noffs ◽  
...  
Keyword(s):  
Working Memory ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Hippocampal Sclerosis ◽  
Mesial Temporal Lobe Epilepsy ◽  
Mesial Temporal Lobe

scholarly journals Working Memory and Cross-Frequency Coupling of Neuronal Oscillations

2021 ◽  
Vol 12 ◽  
Author(s):  
Mohammed Abubaker ◽  
Wiam Al Qasem ◽  
Eugen Kvašňák
Keyword(s):  
Working Memory ◽  
Cognitive Impairment ◽  
Brain Stimulation ◽  
Large Body ◽  
Cognitive Outcomes ◽  
Essential Component ◽  
Non Invasive ◽  
Transcranial Alternating Current Stimulation ◽  
Frequency Coupling ◽  
Cross Frequency Coupling

Working memory (WM) is the active retention and processing of information over a few seconds and is considered an essential component of cognitive function. The reduced WM capacity is a common feature in many diseases, such as schizophrenia, attention deficit hyperactivity disorder (ADHD), mild cognitive impairment (MCI), and Alzheimer's disease (AD). The theta-gamma neural code is an essential component of memory representations in the multi-item WM. A large body of studies have examined the association between cross-frequency coupling (CFC) across the cerebral cortices and WM performance; electrophysiological data together with the behavioral results showed the associations between CFC and WM performance. The oscillatory entrainment (sensory, non-invasive electrical/magnetic, and invasive electrical) remains the key method to investigate the causal relationship between CFC and WM. The frequency-tuned non-invasive brain stimulation is a promising way to improve WM performance in healthy and non-healthy patients with cognitive impairment. The WM performance is sensitive to the phase and rhythm of externally applied stimulations. CFC-transcranial-alternating current stimulation (CFC-tACS) is a recent approach in neuroscience that could alter cognitive outcomes. The studies that investigated (1) the association between CFC and WM and (2) the brain stimulation protocols that enhanced WM through modulating CFC by the means of the non-invasive brain stimulation techniques have been included in this review. In principle, this review can guide the researchers to identify the most prominent form of CFC associated with WM processing (e.g., theta/gamma phase-amplitude coupling), and to define the previously published studies that manipulate endogenous CFC externally to improve WM. This in turn will pave the path for future studies aimed at investigating the CFC-tACS effect on WM. The CFC-tACS protocols need to be thoroughly studied before they can be considered as therapeutic tools in patients with WM deficits.

scholarly journals Atrophy and cognitive profiles in older adults with temporal lobe epilepsy are similar to mild cognitive impairment

Brain ◽  
2020 ◽  
Author(s):  
Erik Kaestner ◽  
Anny Reyes ◽  
Austin Chen ◽  
Jun Rao ◽  
Anna Christina Macari ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Late Onset ◽  
Amnestic Mild Cognitive Impairment

Abstract Epilepsy incidence and prevalence peaks in older adults yet systematic studies of brain ageing and cognition in older adults with epilepsy remain limited. Here, we characterize patterns of cortical atrophy and cognitive impairment in 73 older adults with temporal lobe epilepsy (>55 years) and compare these patterns to those observed in 70 healthy controls and 79 patients with amnestic mild cognitive impairment, the prodromal stage of Alzheimer’s disease. Patients with temporal lobe epilepsy were recruited from four tertiary epilepsy surgical centres; amnestic mild cognitive impairment and control subjects were obtained from the Alzheimer’s Disease Neuroimaging Initiative database. Whole brain and region of interest analyses were conducted between patient groups and controls, as well as between temporal lobe epilepsy patients with early-onset (age of onset <50 years) and late-onset (>50 years) seizures. Older adults with temporal lobe epilepsy demonstrated a similar pattern and magnitude of medial temporal lobe atrophy to amnestic mild cognitive impairment. Region of interest analyses revealed pronounced medial temporal lobe thinning in both patient groups in bilateral entorhinal, temporal pole, and fusiform regions (all P < 0.05). Patients with temporal lobe epilepsy demonstrated thinner left entorhinal cortex compared to amnestic mild cognitive impairment (P = 0.02). Patients with late-onset temporal lobe epilepsy had a more consistent pattern of cortical thinning than patients with early-onset epilepsy, demonstrating decreased cortical thickness extending into the bilateral fusiform (both P < 0.01). Both temporal lobe epilepsy and amnestic mild cognitive impairment groups showed significant memory and language impairment relative to healthy control subjects. However, despite similar performances in language and memory encoding, patients with amnestic mild cognitive impairment demonstrated poorer delayed memory performances relative to both early and late-onset temporal lobe epilepsy. Medial temporal lobe atrophy and cognitive impairment overlap between older adults with temporal lobe epilepsy and amnestic mild cognitive impairment highlights the risks of growing old with epilepsy. Concerns regarding accelerated ageing and Alzheimer’s disease co-morbidity in older adults with temporal lobe epilepsy suggests an urgent need for translational research aimed at identifying common mechanisms and/or targeting symptoms shared across a broad neurological disease spectrum.

scholarly journals Surgery for temporal lobe epilepsy in the elderly: Improving quality of life despite cognitive impairment

Seizure ◽  
2020 ◽  
Vol 79 ◽  
pp. 112-119 ◽  
Author(s):  
Daniel Delev ◽  
Julia Taube ◽  
Christoph Helmstaedter ◽  
Karlijn Hakvoort ◽  
Alexander Grote ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Cognitive Impairment ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
The Elderly ◽  
Epilepsy In The Elderly

scholarly journals Abnormal Resting-State Functional Connectivity Strength in Mild Cognitive Impairment and Its Conversion to Alzheimer’s Disease

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Yuxia Li ◽  
Xiaoni Wang ◽  
Yongqiu Li ◽  
Yu Sun ◽  
Can Sheng ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Functional Connectivity ◽  
Resting State ◽  
Angular Gyrus ◽  
Functional Connectivity Strength ◽  
Middle Occipital Gyrus ◽  
Left Angular Gyrus ◽  
Connectivity Strength

Individuals diagnosed with mild cognitive impairment (MCI) are at high risk of transition to Alzheimer’s disease (AD). However, little is known about functional characteristics of the conversion from MCI to AD. Resting-state functional magnetic resonance imaging was performed in 25 AD patients, 31 MCI patients, and 42 well-matched normal controls at baseline. Twenty-one of the 31 MCI patients converted to AD at approximately 24 months of follow-up. Functional connectivity strength (FCS) and seed-based functional connectivity analyses were used to assess the functional differences among the groups. Compared to controls, subjects with MCI and AD showed decreased FCS in the default-mode network and the occipital cortex. Importantly, the FCS of the left angular gyrus and middle occipital gyrus was significantly lower in MCI-converters as compared with MCI-nonconverters. Significantly decreased functional connectivity was found in MCI-converters compared to nonconverters between the left angular gyrus and bilateral inferior parietal lobules, dorsolateral prefrontal and lateral temporal cortices, and the left middle occipital gyrus and right middle occipital gyri. We demonstrated gradual but progressive functional changes during a median 2-year interval in patients converting from MCI to AD, which might serve as early indicators for the dysfunction and progression in the early stage of AD.

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