scholarly journals Probabilistic mapping of thalamic nuclei and thalamocortical functional connectivity in idiopathic generalised epilepsy

2021 ◽  
Author(s):  
Yachin Chen ◽  
Nicholas Fallon ◽  
Barbara A. K. Kreilkamp ◽  
Christine Denby ◽  
Martyn Bracewell ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Thalamic Nuclei ◽  
Probabilistic Mapping ◽  
Idiopathic Generalised Epilepsy

scholarly journals Thalamic Functional Connectivity during Spatial Long-Term Memory and the Role of Sex

2020 ◽  
Vol 10 (12) ◽  
pp. 898
Author(s):  
Dylan S. Spets ◽  
Scott D. Slotnick
Keyword(s):  
Sex Differences ◽  
Functional Connectivity ◽  
Region Of Interest ◽  
Brain Regions ◽  
Long Term Memory ◽  
Thalamic Nuclei ◽  
Term Memory ◽  
Correlated Activity ◽  
Abstract Shapes

The thalamus has been implicated in many cognitive processes, including long-term memory. More specifically, the anterior (AT) and mediodorsal (MD) thalamic nuclei have been associated with long-term memory. Despite extensive mapping of the anatomical connections between these nuclei and other brain regions, little is known regarding their functional connectivity during long-term memory. The current study sought to determine which brain regions are functionally connected to AT and MD during spatial long-term memory and whether sex differences exist in the patterns of connectivity. During encoding, abstract shapes were presented to the left and right of fixation. During retrieval, shapes were presented at fixation, and participants made an “old-left” or “old-right” judgment. Activations functionally connected to AT and MD existed in regions with known anatomical connections to each nucleus as well as in a broader network of long-term memory regions. Sex differences were identified in a subset of these regions. A targeted region-of-interest analysis identified anti-correlated activity between MD and the hippocampus that was specific to females, which is consistent with findings in rodents. The current results suggest that AT and MD play key roles during spatial long-term memory and suggest that these functions may be sex specific.

scholarly journals Thalamic Arousal Network Disturbances in Temporal Lobe Epilepsy and Improvement After Surgery

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Hernán F J González ◽  
Srijata Chakravorti ◽  
Sarah E Goodale ◽  
Kanupriya Gupta ◽  
Daniel O Claassen ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epilepsy Surgery ◽  
Occipital Lobe ◽  
Visuospatial Attention ◽  
Partial Recovery ◽  
Thalamic Nuclei ◽  
Spearman's Rho ◽  
Spearman’S Rho

Abstract INTRODUCTION The effects of temporal lobe epilepsy (TLE) on subcortical arousal structures remain incompletely understood. Here we evaluate thalamic arousal network functional connectivity in TLE and examine changes after epilepsy surgery. METHODS We examined 26 adult TLE patients and 26 matched control participants and used resting-state functional magnetic resonance imaging (fMRI) to measure functional connectivity between the thalamus (entire thalamus and 19 bilateral thalamic nuclei) and both neocortex and brainstem ascending reticular activating system (ARAS) nuclei. Postoperative imaging was completed for 19 patients > 1 yr after surgery and compared to preoperative baseline. RESULTS Before surgery, TLE patients demonstrated abnormal thalamo-occipital functional connectivity, losing the normal negative fMRI correlation between the intralaminar central lateral (CL) nucleus and medial occipital lobe seen in controls (P < .001, paired t-test). Patients also had abnormal connectivity between ARAS and CL, lower ipsilateral intrathalamic connectivity, and smaller ipsilateral thalamic volume compared to controls (P < .05 for each, paired t-tests). Abnormal brainstem-thalamic connectivity was associated with impaired visuospatial attention (? = −0.50, P = .02, Spearman's rho), while lower intrathalamic connectivity and volume were related to higher frequency of consciousness-sparing seizures (P < .02, Spearman's rho). After epilepsy surgery, patients with improved seizures showed partial recovery of thalamo-occipital and brainstem-thalamic connectivity, with values more closely resembling controls (P < .01 for each, ANOVA). CONCLUSION Overall, TLE patients demonstrate impaired connectivity in thalamic arousal networks that may be involved in visuospatial attention, but these disturbances may partially recover after successful epilepsy surgery. Thalamic arousal network dysfunction may contribute to morbidity in TLE.

scholarly journals Dissociated mean and functional connectivity BOLD signals in visual cortex during eyes closed and fixation

2012 ◽  
Vol 108 (9) ◽  
pp. 2363-2372 ◽  
Author(s):  
Mark McAvoy ◽  
Linda Larson-Prior ◽  
Marek Ludwikow ◽  
Dongyang Zhang ◽  
Abraham Z. Snyder ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Functional Connectivity ◽  
Primary Visual Cortex ◽  
Blood Oxygen Level Dependent ◽  
Extrastriate Cortex ◽  
Connected Components ◽  
Bold Signal ◽  
Thalamic Nuclei ◽  
Eyes Closed ◽  
Visual Areas

We investigated the effects of resting state type on blood oxygen level-dependent (BOLD) signal and functional connectivity in two paradigms: participants either alternated between fixation and eyes closed or maintained fixation or eyes closed throughout each scan. The BOLD signal and functional connectivity of lower and higher tiers of the visual cortical hierarchy were found to be differentially modulated during eyes closed versus fixation. Fixation was associated with greater mean BOLD signals in primary visual cortex and lower mean BOLD signals in extrastriate visual areas than periods of eyes closed. In addition, analysis of thalamocortical functional connectivity during scans in which participants maintained fixation showed synchronized BOLD fluctuations between those thalamic nuclei whose mean BOLD signal was systematically modulated during alternating epochs of eyes closed and fixation, primary visual cortex and the attention network, while during eyes closed negatively correlated fluctuations were seen between the same thalamic nuclei and extrastriate visual areas. Finally, in all visual areas the amplitude of spontaneous BOLD fluctuations was greater during eyes closed than during fixation. The dissociation between early and late tiers of visual cortex, which characterizes both mean and functionally connected components of the BOLD signal, may depend on the reorganization of thalamocortical networks. Since dissociated changes in local blood flow also characterize transitions between different stages of sleep and wakefulness (Braun AR, Balkin TJ, Wesenten NJ, Gwadry F, Carson RE, Varga M, Baldwin P, Belenky G, Herscovitch P. Science 279: 91–95, 1998), our results suggest that dissociated endogenous neural activity in primary and extrastriate cortex may represent a general aspect of brain function.

scholarly journals Impact of anaesthesia on static and dynamic functional connectivity in mice

2021 ◽  
Author(s):  
Tomokazu Tsurugizawa ◽  
Daisuke Yoshimaru
Keyword(s):  
Functional Connectivity ◽  
Functional Mri ◽  
Resting State ◽  
Low Frequency ◽  
Resting State Fmri ◽  
Brain Network ◽  
List Type ◽  
Thalamic Nuclei ◽  
Dynamic Functional Connectivity ◽  
Subcortical Regions

AbstractA few studies have compared the static functional connectivity between awake and anaesthetized states in rodents by resting-state fMRI. However, impact of anaesthesia on static and dynamic fluctuations in functional connectivity has not been fully understood. Here, we developed a resting-state fMRI protocol to perform awake and anaesthetized functional MRI in the same mice. Static functional connectivity showed a widespread decrease under anaesthesia, such as when under isoflurane or a mixture of isoflurane and medetomidine. Several interhemispheric connections were key connections for anaesthetized condition from awake. Dynamic functional connectivity demonstrates the shift from frequent broad connections across the cortex, the hypothalamus, and the auditory-visual cortex to frequent local connections within the cortex only. Fractional amplitude of low frequency fluctuation in the thalamic nuclei decreased under both anaesthesia. These results indicate that typical anaesthetics for functional MRI alters the spatiotemporal profile of the dynamic brain network in subcortical regions, including the thalamic nuclei and limbic system.HighlightsResting-state fMRI was compared between awake and anaesthetized in the same mice.Anaesthesia induced a widespread decrease of static functional connectivity.Anaesthesia strengthened local connections within the cortex.fALFF in the thalamus was decreased by anaesthesia.

scholarly journals Thalamic arousal network disturbances in temporal lobe epilepsy and improvement after surgery

2019 ◽  
Vol 90 (10) ◽  
pp. 1109-1116 ◽  
Author(s):  
Hernán F J González ◽  
Srijata Chakravorti ◽  
Sarah E Goodale ◽  
Kanupriya Gupta ◽  
Daniel O Claassen ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epilepsy Surgery ◽  
Occipital Lobe ◽  
Visuospatial Attention ◽  
Partial Recovery ◽  
Thalamic Nuclei ◽  
Spearman's Rho ◽  
Spearman’S Rho

ObjectiveThe effects of temporal lobe epilepsy (TLE) on subcortical arousal structures remain incompletely understood. Here, we evaluate thalamic arousal network functional connectivity in TLE and examine changes after epilepsy surgery.MethodsWe examined 26 adult patients with TLE and 26 matched control participants and used resting-state functional MRI (fMRI) to measure functional connectivity between the thalamus (entire thalamus and 19 bilateral thalamic nuclei) and both neocortex and brainstem ascending reticular activating system (ARAS) nuclei. Postoperative imaging was completed for 19 patients >1 year after surgery and compared with preoperative baseline.ResultsBefore surgery, patients with TLE demonstrated abnormal thalamo-occipital functional connectivity, losing the normal negative fMRI correlation between the intralaminar central lateral (CL) nucleus and medial occipital lobe seen in controls (p < 0.001, paired t-test). Patients also had abnormal connectivity between ARAS and CL, lower ipsilateral intrathalamic connectivity, and smaller ipsilateral thalamic volume compared with controls (p < 0.05 for each, paired t-tests). Abnormal brainstem–thalamic connectivity was associated with impaired visuospatial attention (ρ = −0.50, p = 0.02, Spearman’s rho) while lower intrathalamic connectivity and volume were related to higher frequency of consciousness-sparing seizures (p < 0.02, Spearman’s rho). After epilepsy surgery, patients with improved seizures showed partial recovery of thalamo-occipital and brainstem–thalamic connectivity, with values more closely resembling controls (p < 0.01 for each, analysis of variance).ConclusionsOverall, patients with TLE demonstrate impaired connectivity in thalamic arousal networks that may be involved in visuospatial attention, but these disturbances may partially recover after successful epilepsy surgery. Thalamic arousal network dysfunction may contribute to morbidity in TLE.

scholarly journals Evaluation of functional connectivity in subdivisions of the thalamus in schizophrenia

2019 ◽  
Vol 214 (5) ◽  
pp. 288-296 ◽  
Author(s):  
Jinnan Gong ◽  
Cheng Luo ◽  
Xiangkui Li ◽  
Sisi Jiang ◽  
Budhachandra S. Khundrakpam ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Brain Connectivity ◽  
Anterior Cingulate ◽  
Data Driven ◽  
Thalamic Nuclei ◽  
Functional Connections ◽  
Duration Of Illness ◽  
Wide Range ◽  
Magnetic Resonance Imaging Mri ◽  
White Matter Tractography

BackgroundPrevious studies in schizophrenia revealed abnormalities in the cortico-cerebellar-thalamo-cortical circuit (CCTCC) pathway, suggesting the necessity for defining thalamic subdivisions in understanding alterations of brain connectivity.AimsTo parcellate the thalamus into several subdivisions using a data-driven method, and to evaluate the role of each subdivision in the alterations of CCTCC functional connectivity in patients with schizophrenia.MethodThere were 54 patients with schizophrenia and 42 healthy controls included in this study. First, the thalamic structural and functional connections computed, based on diffusion magnetic resonance imaging (MRI, white matter tractography) and resting-state functional MRI, were clustered to parcellate thalamus. Next, functional connectivity of each thalamus subdivision was investigated, and the alterations in thalamic functional connectivity for patients with schizophrenia were inspected.ResultsBased on the data-driven parcellation method, six thalamic subdivisions were defined. Loss of connectivity was observed between several thalamic subdivisions (superior-anterior, ventromedial and dorsolateral part of the thalamus) and the sensorimotor system, anterior cingulate cortex and cerebellum in patients with schizophrenia. A gradual pattern of dysconnectivity was observed across the thalamic subdivisions. Additionally, the altered connectivity negatively correlated with symptom scores and duration of illness in individuals with schizophrenia.ConclusionsThe findings of the study revealed a wide range of thalamic functional dysconnectivity in the CCTCC pathway, increasing our understanding of the relationship between the CCTCC pathway and symptoms associated with schizophrenia, and further indicating a potential alteration pattern in the thalamic nuclei in people with schizophrenia.Declaration of interestNone.

scholarly journals Mapping thalamocortical functional connectivity with large-scale brain networks in patients with first-episode psychosis

2021 ◽  
Author(s):  
Yoo Bin Kwak ◽  
Kang Ik Kevin Cho ◽  
Wu Jeong Hwang ◽  
Ahra Kim ◽  
Hyungyou Park ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Network Dynamics ◽  
First Episode Psychosis ◽  
Brain Network ◽  
First Episode ◽  
Functional Magnetic Resonance ◽  
Thalamic Nuclei ◽  
Functional Studies ◽  
Episode Psychosis

Abstract Abnormal thalamocortical networks involving specific thalamic nuclei have been implicated in schizophrenia pathophysiology. While comparable topography of anatomical and functional connectivity abnormalities has been reported in patients across illness stages, previous functional studies have been confined to anatomical pathways of thalamocortical networks. To address this issue, we incorporated large-scale brain network dynamics into examining thalamocortical functional connectivity. Forty patients with first-episode psychosis and forty healthy controls underwent T1-weighted and resting-state functional magnetic resonance imaging. Independent component analysis of voxelwise thalamic functional connectivity maps parcellated the cortex into thalamus-related networks, and thalamic subdivisions associated with these networks were delineated. Functional connectivity of (i) networks with the thalamus and (ii) thalamic subdivision seeds were examined. In patients, functional connectivity of the salience network with the thalamus was decreased and localized to the ventrolateral (VL) and ventroposterior (VP) thalamus, while that of a network comprising the cerebellum, temporal and parietal regions was increased and localized to the MD thalamus. In patients, thalamic subdivision encompassing the VL and VP thalamus demonstrated hypoconnectivity and that encompassing the MD and pulvinar regions demonstrated hyperconnectivity. Our results extend the implications of disrupted thalamocortical networks involving specific thalamic nuclei to dysfunctional large-scale brain network dynamics in schizophrenia pathophysiology.

scholarly journals Brain dynamics: the temporal variability of connectivity, and differences in schizophrenia and ADHD

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Edmund T. Rolls ◽  
Wei Cheng ◽  
Jianfeng Feng
Keyword(s):  
Functional Connectivity ◽  
Mental Disorders ◽  
Temporal Variability ◽  
Temporal Cortex ◽  
Brain Dynamics ◽  
First Episode ◽  
Thalamic Nuclei ◽  
Attractor Networks ◽  
Human Connectome Project ◽  
Health And Disease

AbstractWe describe advances in the understanding of brain dynamics that are important for understanding the operation of the cerebral cortex in health and disease. In data from 1017 participants from the Human Connectome Project, we show that early visual and connected areas have low temporal variability of their functional connectivity. We show that a low temporal variability of the connectivity of cortical areas is related to high mean functional connectivity between those areas, and provide an account of how these dynamics arise. We then investigate how these concepts help to understand brain dynamics in mental disorders. We find that in both first episode and long-term schizophrenia, reduced functional connectivity of early visual and related temporal cortex areas is associated with increased temporal variability of the functional connectivity, consistent with decreased stability of attractor networks related to sensory processing. In ADHD, we find these functional connectivities are increased and their temporal variability is decreased, and relate this to increased engagement with visual sensory input as manifest in high screen time usage in ADHD. We further show that these differences in the dynamics of the cortex in schizophrenia, and ADHD can be related to differences in the functional connectivity of the specific sensory vs. association thalamic nuclei. These discoveries help to advance our understanding of cortical operation in health, and in some mental disorders.

scholarly journals The functional connectivity of intralaminar thalamic nuclei in the human basal ganglia

2014 ◽  
Vol 36 (4) ◽  
pp. 1335-1347 ◽  
Author(s):  
Clara Rodriguez-Sabate ◽  
Catalina Llanos ◽  
Ingrid Morales ◽  
Roberto Garcia-Alvarez ◽  
Magdalena Sabate ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Functional Connectivity ◽  
Thalamic Nuclei ◽  
Intralaminar Thalamic Nuclei
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