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Cureus Mar 2023While bilateral stimulation of the anterior thalamic nuclei remains the only approved deep brain stimulation (DBS) option for focal epilepsy, two additional thalamic... (Review)
Review
While bilateral stimulation of the anterior thalamic nuclei remains the only approved deep brain stimulation (DBS) option for focal epilepsy, two additional thalamic targets have been proposed. Earlier work indicated the potential of centromedian thalamic nucleus stimulation with recent findings highlighting the medial pulvinar nucleus. The latter has been shown to exhibit electrophysiological and imaging alterations in patients with partial status epilepticus and temporal lobe epilepsy. On this basis, recent studies have begun assessing the feasibility and efficacy of pulvinar stimulation, with encouraging results on the reduction of seizure frequency and severity. Building on existing neuroanatomical knowledge, indicating that the medial pulvinar is connected to the temporal lobe via the temporopulvinar bundle of Arnold, we hypothesize that this is one of the routes through which medial pulvinar stimulation affects temporal lobe structures. We suggest that further anatomic, imaging, and electrophysiologic studies are warranted to deepen our understanding of the subject and guide future clinical applications.
PubMed: 37025746
DOI: 10.7759/cureus.35772 -
Nature Neuroscience Apr 2016Several challenges to current views of thalamocortical processing are offered here. Glutamatergic pathways in thalamus and cortex are divided into two distinct classes:... (Review)
Review
Several challenges to current views of thalamocortical processing are offered here. Glutamatergic pathways in thalamus and cortex are divided into two distinct classes: driver and modulator. We suggest that driver inputs are the main conduits of information and that modulator inputs modify how driver inputs are processed. Different driver sources reveal two types of thalamic relays: first order relays receive subcortical driver input (for example, retinal input to the lateral geniculate nucleus), whereas higher order relays (for example, pulvinar) receive driver input from layer 5 of cortex and participate in cortico-thalamo-cortical (or transthalamic) circuits. These transthalamic circuits represent an unappreciated aspect of cortical functioning, which I discuss here. Direct corticocortical connections are often paralleled by transthalamic ones. Furthermore, driver inputs to thalamus, both first and higher order, typically arrive via branching axons, and the transthalamic branch often innervates subcortical motor centers, leading to the suggestion that these inputs to thalamus serve as efference copies.
Topics: Animals; Cerebral Cortex; Glutamic Acid; Humans; Nerve Net; Neural Pathways; Thalamus
PubMed: 27021938
DOI: 10.1038/nn.4269 -
Annals of Clinical and Translational... Jul 2023Deep brain stimulation (DBS) is a promising treatment for drug-refractory epilepsies (DRE) when targeting the anterior nuclei of thalamus (ANT). However, targeting other...
Deep brain stimulation (DBS) is a promising treatment for drug-refractory epilepsies (DRE) when targeting the anterior nuclei of thalamus (ANT). However, targeting other thalamic nuclei, such as the pulvinar, shows therapeutic promise. Our pioneering case study presents the application of ambulatory seizure monitoring using spectral fingerprinting (12.15-17.15 Hz) recorded through Medtronic Percept DBS implanted bilaterally in the medial pulvinar thalami. This technology offers unprecedented opportunities for real-time monitoring of seizure burden and thalamocortical network modulation for effective seizure reduction in patients with bilateral mesial temporal and temporal plus epilepsies that are not suitable for resection.
Topics: Humans; Pulvinar; Deep Brain Stimulation; Electrodes, Implanted; Epilepsy; Seizures
PubMed: 37231611
DOI: 10.1002/acn3.51815 -
Journal of Clinical Neuroscience :... Jul 2021To define both the severity and extent of structural alteration in certain thalamic nuclei by means of MR morphometry and to compare these findings with clinical...
OBJECTIVES
To define both the severity and extent of structural alteration in certain thalamic nuclei by means of MR morphometry and to compare these findings with clinical performance in different phenotypes of multiple sclerosis (MS).
METHODS
We comparatively measured the thalamus nuclei volumes of patients with remitting-relapsing (RRMS) and secondary-progressive (SPMS) phenotypes of multiple sclerosis and healthy control subjects (HC). The evaluation of neurological performance was based on the results of Expanded Disability Status Scale and Multiple Sclerosis Severity Scale. Cognitive and mental state was rated according to the results of Mini-Mental State Examination, Frontal Assessment Battery, Montreal Cognitive Assessment and Symbol Digit Modalities Test. Freesurfer 6.0 was used for thalamic nuclei volumes calculation.
RESULTS
The median volume decline in thalamic pulvinar nuclei in RRMS group on the left side (anterior nucleus - 186,6 mm, posterior nucleus - 149,4 mm, medial nucleus 852,4 mm) compared to HC (anterior nucleus - 229,2 mm, posterior nucleus - 187,5 mm, medical nucleus - 1081,3 mm). Same group, right side - anterior nucleus - 219,5 mm, posterior nucleus 187,1 mm, medial nucleus - 989,6 mm; HC group - anterior nucleus 261,1 mm, posterior nucleus 240,5 mm, medial nucleus - 1196,7 mm (p < 0,05). The highest correlation of the written section of SDMT was observed with the left ventral anterior nucleus (r = 0,71).
CONCLUSION
These findings indicate the credible correlation between clinical progression of neurological and cognitive impairment in MS patients with asymmetry left-sided thalamic nuclei atrophy and may be considered a potential predicting tool of MS progression.
Topics: Adult; Atrophy; Cognitive Dysfunction; Humans; Magnetic Resonance Imaging; Middle Aged; Multiple Sclerosis; Neuropsychological Tests; Thalamic Nuclei
PubMed: 34090763
DOI: 10.1016/j.jocn.2021.05.043 -
Applied Neuropsychology. Child 2015Attention-deficit hyperactivity disorder (ADHD) is a chronic disorder with symptoms of inattention and impulsivity that partially remit with age. A review of... (Review)
Review
Attention-deficit hyperactivity disorder (ADHD) is a chronic disorder with symptoms of inattention and impulsivity that partially remit with age. A review of longitudinal studies of children and adolescents with ADHD showed that the majority will have continued cognitive and functional impairments into adulthood. The thalamus likely plays a prominent role in ADHD symptomatology, based on evidence that the thalamus generates waking-state electroencephalography (EEG) rhythms along with extensive thalamic neural circuitry connections with cortical and subcortical areas. Research demonstrates a specific abnormality in the thalamic pulvinar nucleus in ADHD populations. The thalamus can also play a role in ADHD treatment, based on solid evidence that both animals and humans can learn to self-regulate EEG oscillations. Given the underarousal and sleep disturbance commonly seen in ADHD, along with data that indicate an increased dosage of ADHD medication may improve behavioral control at a cost of lowered cognitive functioning, further investigation of the role for self-regulation through EEG training is warranted.
Topics: Attention Deficit Disorder with Hyperactivity; Disease Management; Electroencephalography; Humans; Thalamus
PubMed: 25748775
DOI: 10.1080/21622965.2015.1005475 -
Frontiers in Systems Neuroscience 2015
PubMed: 25852498
DOI: 10.3389/fnsys.2015.00039 -
NeuroImage Nov 2022Brain iron homeostasis is necessary for healthy brain function. MRI and histological studies have shown altered brain iron levels in the brains of patients with multiple...
Brain iron homeostasis is necessary for healthy brain function. MRI and histological studies have shown altered brain iron levels in the brains of patients with multiple sclerosis (MS), particularly in the deep gray matter (DGM). Previous studies were able to only partially separate iron-modifying effects because of incomplete knowledge of iron-modifying processes and influencing factors. It is therefore unclear to what extent and at which stages of the disease different processes contribute to brain iron changes. We postulate that spatially covarying magnetic susceptibility networks determined with Independent Component Analysis (ICA) reflect, and allow for the study of, independent processes regulating iron levels. We applied ICA to quantitative susceptibility maps for 170 individuals aged 9-81 years without neurological disease ("Healthy Aging" (HA) cohort), and for a cohort of 120 patients with MS and 120 age- and sex-matched healthy controls (HC; together the "MS/HC" cohort). Two DGM-associated "susceptibility networks" identified in the HA cohort (the Dorsal Striatum and Globus Pallidus Interna Networks) were highly internally reproducible (i.e. "robust") across multiple ICA repetitions on cohort subsets. DGM areas overlapping both robust networks had higher susceptibility levels than DGM areas overlapping only a single robust network, suggesting that these networks were caused by independent processes of increasing iron concentration. Because MS is thought to accelerate brain aging, we hypothesized that associations between age and the two robust DGM-associated networks would be enhanced in patients with MS. However, only one of these networks was altered in patients with MS, and it had a null age association in patients with MS rather than a stronger association. Further analysis of the MS/HC cohort revealed three additional disease-related networks (the Pulvinar, Mesencephalon, and Caudate Networks) that were differentially altered between patients with MS and HCs and between MS subtypes. Exploratory regression analyses of the disease-related networks revealed differential associations with disease duration and T2 lesion volume. Finally, analysis of ROI-based disease effects in the MS/HC cohort revealed an effect of disease status only in the putamen ROI and exploratory regression analysis did not show associations between the caudate and pulvinar ROIs and disease duration or T2 lesion volume, showing the ICA-based approach was more sensitive to disease effects. These results suggest that the ICA network framework increases sensitivity for studying patterns of brain iron change, opening a new avenue for understanding brain iron physiology under normal and disease conditions.
Topics: Brain; Brain Diseases; Gray Matter; Humans; Iron; Magnetic Resonance Imaging; Multiple Sclerosis
PubMed: 35878723
DOI: 10.1016/j.neuroimage.2022.119503 -
The Journal of Comparative Neurology Feb 2019Pyramidal cells in cortical Layers 5 and 6 are the only cells in the cerebral cortex with axons that leave the cortex to influence the thalamus. Layer 6 cells provide... (Review)
Review
Pyramidal cells in cortical Layers 5 and 6 are the only cells in the cerebral cortex with axons that leave the cortex to influence the thalamus. Layer 6 cells provide modulatory feedback input to all thalamic nuclei. Layer 5 cells provide driving input to higher-order thalamic nuclei and do not innervate first-order nuclei, which get their driving inputs from subcortical sources. Higher-order nuclei innervated by Layer 5 cells thus seem to be involved with cortico-thalamo-cortical communication. The Layer 5 axons branch to also target additional subcortical structures that mediate interactions with the external environment. These corticofugal pathways represent the only means by which the cortex influences the rest of the neuraxis and thus are essential for proper cortical function and species survival. Here we review current understanding of the corticofugal pathways from Layers 5 and 6 and speculate on their functional contributions to neural processing and behavior.
Topics: Animals; Brain; Cerebral Cortex; Humans; Nerve Net; Pyramidal Cells; Thalamus
PubMed: 29524229
DOI: 10.1002/cne.24423 -
Plants (Basel, Switzerland) May 2020As sessile organisms, plants do not possess the nerves and muscles that facilitate movement in most animals. However, several plant species can move quickly in response... (Review)
Review
As sessile organisms, plants do not possess the nerves and muscles that facilitate movement in most animals. However, several plant species can move quickly in response to various stimuli (e.g., touch). One such plant species, L., possesses the motor organ pulvinus at the junction of the leaflet-rachilla, rachilla-petiole, and petiole-stem, and upon mechanical stimulation, this organ immediately closes the leaflets and moves the petiole. Previous electrophysiological studies have demonstrated that a long-distance and rapid electrical signal propagates through in response to mechanical stimulation. Furthermore, the spatial and temporal patterns of the action potential in the pulvinar motor cells were found to be closely correlated with rapid movements. In this review, we summarize findings from past research and discuss the mechanisms underlying long-distance signal transduction in . We also propose a model in which the action potential, followed by water flux (i.e., a loss of turgor pressure) in the pulvinar motor cells is a critical step to enable rapid movement.
PubMed: 32375332
DOI: 10.3390/plants9050587 -
Cerebral Cortex (New York, N.Y. : 1991) May 2020The neural basis of memory is highly distributed, but the thalamus is known to play a particularly critical role. However, exactly how the different thalamic nuclei...
The neural basis of memory is highly distributed, but the thalamus is known to play a particularly critical role. However, exactly how the different thalamic nuclei contribute to different kinds of memory is unclear. Moreover, whether thalamic connectivity with the medial temporal lobe (MTL), arguably the most fundamental memory structure, is critical for memory remains unknown. We explore these questions using an fMRI recognition memory paradigm that taps familiarity and recollection (i.e., the two types of memory that support recognition) for objects, faces, and scenes. We show that the mediodorsal thalamus (MDt) plays a material-general role in familiarity, while the anterior thalamus plays a material-general role in recollection. Material-specific regions were found for scene familiarity (ventral posteromedial and pulvinar thalamic nuclei) and face familiarity (left ventrolateral thalamus). Critically, increased functional connectivity between the MDt and the parahippocampal (PHC) and perirhinal cortices (PRC) of the MTL underpinned increases in reported familiarity confidence. These findings suggest that familiarity signals are generated through the dynamic interaction of functionally connected MTL-thalamic structures.
Topics: Adult; Anterior Thalamic Nuclei; Female; Functional Neuroimaging; Humans; Magnetic Resonance Imaging; Male; Mediodorsal Thalamic Nucleus; Mental Recall; Neural Pathways; Parahippocampal Gyrus; Perirhinal Cortex; Pulvinar; Recognition, Psychology; Temporal Lobe; Thalamus; Ventral Thalamic Nuclei; Young Adult
PubMed: 31989161
DOI: 10.1093/cercor/bhz345