scholarly journals Coordinated hippocampal-thalamic-cortical communication crucial for engram dynamics underneath systems consolidation

2020 ◽  
Author(s):  
Douglas Feitosa Tomé ◽  
Sadra Sadeh ◽  
Claudia Clopath
Keyword(s):  
Synaptic Plasticity ◽  
Brain Regions ◽  
Inhibitory Input ◽  
Hippocampal Damage ◽  
Synaptic Coupling ◽  
Cell Dynamics ◽  
Mediodorsal Thalamus ◽  
Systems Consolidation ◽  
Cortical Regions

AbstractSystems consolidation refers to the reorganization of memory over time across brain regions. Despite recent advancements in unravelling engrams and circuits essential for this process, the exact mechanisms behind engram cell dynamics and the role of associated pathways remain poorly understood. Here, we propose a computational model to address this knowledge gap that consists of a multi-region spiking recurrent neural network subject to biologically-plausible synaptic plasticity mechanisms. By coordinating the timescales of synaptic plasticity throughout the network and incorporating a hippocampus-thalamus-cortex circuit, our model is able to couple engram reactivations across these brain regions and thereby reproduce key dynamics of cortical and hippocampal engram cells along with their interdependencies. Decoupling hippocampal-thalamic-cortical activity disrupts engram dynamics and systems consolidation. Our modeling work also yields several testable predictions: engram cells in mediodorsal thalamus are activated in response to partial cues in recent and remote recall and are crucial for systems consolidation; hippocampal and thalamic engram cells are essential for coupling engram reactivations between subcortical and cortical regions; inhibitory engram cells have region-specific dynamics with coupled reactivations; inhibitory input to mediodorsal thalamus is critical for systems consolidation; and thalamocortical synaptic coupling is predictive of cortical engram dynamics and the retrograde amnesia pattern induced by hippocampal damage. Overall, our results suggest that systems consolidation emerges from concerted interactions among engram cells in distributed brain regions enabled by coordinated synaptic plasticity timescales in multisynaptic subcortical-cortical circuits.

scholarly journals Region-specific complexity of the intracranial EEG in the sleeping human brain

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Elzbieta Olejarczyk ◽  
Jean Gotman ◽  
Birgit Frauscher
Keyword(s):  
Sleep Stage ◽  
Brain Regions ◽  
Sleep Stages ◽  
Precentral Gyrus ◽  
Self Similarity ◽  
Intracranial Eeg ◽  
Brain Signals ◽  
Cortical Regions ◽  
The Brain

AbstractAs the brain is a complex system with occurrence of self-similarity at different levels, a dedicated analysis of the complexity of brain signals is of interest to elucidate the functional role of various brain regions across the various stages of vigilance. We exploited intracranial electroencephalogram data from 38 cortical regions using the Higuchi fractal dimension (HFD) as measure to assess brain complexity, on a dataset of 1772 electrode locations. HFD values depended on sleep stage and topography. HFD increased with higher levels of vigilance, being highest during wakefulness in the frontal lobe. HFD did not change from wake to stage N2 in temporo-occipital regions. The transverse temporal gyrus was the only area in which the HFD did not differ between any two vigilance stages. Interestingly, HFD of wakefulness and stage R were different mainly in the precentral gyrus, possibly reflecting motor inhibition in stage R. The fusiform and parahippocampal gyri were the only areas showing no difference between wakefulness and N2. Stages R and N2 were similar only for the postcentral gyrus. Topographical analysis of brain complexity revealed that sleep stages are clearly differentiated in fronto-central brain regions, but that temporo-occipital regions sleep differently.

Role of Nicotinic and Muscarinic Receptors on Synaptic Plasticity and Neurological Diseases

2016 ◽  
Vol 22 (14) ◽  
pp. 2004-2014 ◽  
Author(s):  
Marco Fuenzalida ◽  
Miguel Ángel Pérez ◽  
Hugo R. Arias
Keyword(s):  
Synaptic Plasticity ◽  
Muscarinic Receptors ◽  
Neurological Diseases

scholarly journals Dysregulation of Astrocyte–Neuronal Communication in Alzheimer’s Disease

2021 ◽  
Vol 22 (15) ◽  
pp. 7887
Author(s):  
Carmen Nanclares ◽  
Andres Mateo Baraibar ◽  
Alfonso Araque ◽  
Paulo Kofuji
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Synaptic Plasticity ◽  
Neuronal Excitability ◽  
Active Role ◽  
Ionic Homeostasis ◽  
Neuronal Communication ◽  
Structural Support

Recent studies implicate astrocytes in Alzheimer’s disease (AD); however, their role in pathogenesis is poorly understood. Astrocytes have well-established functions in supportive functions such as extracellular ionic homeostasis, structural support, and neurovascular coupling. However, emerging research on astrocytic function in the healthy brain also indicates their role in regulating synaptic plasticity and neuronal excitability via the release of neuroactive substances named gliotransmitters. Here, we review how this “active” role of astrocytes at synapses could contribute to synaptic and neuronal network dysfunction and cognitive impairment in AD.

scholarly journals Monitoring and Modulating Inflammation-Associated Alterations in Synaptic Plasticity: Role of Brain Stimulation and the Blood–Brain Interface

Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 359
Author(s):  
Maximilian Lenz ◽  
Amelie Eichler ◽  
Andreas Vlachos
Keyword(s):  
Synaptic Plasticity ◽  
Brain Stimulation ◽  
Vascular Function ◽  
Neuropsychiatric Symptoms ◽  
Systemic Infection ◽  
Brain Functions ◽  
Blood Brain ◽  
Brain Interface ◽  
The Central Nervous System

Inflammation of the central nervous system can be triggered by endogenous and exogenous stimuli such as local or systemic infection, trauma, and stroke. In addition to neurodegeneration and cell death, alterations in physiological brain functions are often associated with neuroinflammation. Robust experimental evidence has demonstrated that inflammatory cytokines affect the ability of neurons to express plasticity. It has been well-established that inflammation-associated alterations in synaptic plasticity contribute to the development of neuropsychiatric symptoms. Nevertheless, diagnostic approaches and interventional strategies to restore inflammatory deficits in synaptic plasticity are limited. Here, we review recent findings on inflammation-associated alterations in synaptic plasticity and the potential role of the blood–brain interface, i.e., the blood–brain barrier, in modulating synaptic plasticity. Based on recent findings indicating that brain stimulation promotes plasticity and modulates vascular function, we argue that clinically employed non-invasive brain stimulation techniques, such as transcranial magnetic stimulation, could be used for monitoring and modulating inflammation-induced alterations in synaptic plasticity.

The role of elevated autophagy on the synaptic plasticity impairment caused by CdSe/ZnS quantum dots

Biomaterials ◽  
2013 ◽  
Vol 34 (38) ◽  
pp. 10172-10181 ◽  
Author(s):  
Liang Chen ◽  
Yanyan Miao ◽  
Lin Chen ◽  
Peipei Jin ◽  
Yingying Zha ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Synaptic Plasticity

scholarly journals Learning Speech Production and Perception through Sensorimotor Interactions

2020 ◽  
Author(s):  
Shihab Shamma ◽  
Prachi Patel ◽  
Shoutik Mukherjee ◽  
Guilhem Marion ◽  
Bahar Khalighinejad ◽  
...  
Keyword(s):  
Vocal Tract ◽  
Human Subjects ◽  
Motor Task ◽  
Neural Processes ◽  
Mathematical Simulations ◽  
Predictive Role ◽  
Sensorimotor Interactions ◽  
Forward Projection ◽  
Cortical Regions

Abstract Action and Perception are closely linked in many behaviors necessitating a close coordination between sensory and motor neural processes so as to achieve a well-integrated smoothly evolving task performance. To investigate the detailed nature of these sensorimotor interactions, and their role in learning and executing the skilled motor task of speaking, we analyzed ECoG recordings of responses in the high-γ band (70 Hz-150 Hz) in human subjects while they listened to, spoke, or silently articulated speech. We found elaborate spectrotemporally-modulated neural activity projecting in both forward (motor-to-sensory) and inverse directions between the higher-auditory and motor cortical regions engaged during speaking. Furthermore, mathematical simulations demonstrate a key role for the forward projection in learning to control the vocal tract, beyond its commonly-postulated predictive role during execution. These results therefore offer a broader view of the functional role of the ubiquitous forward projection as an important ingredient in learning, rather than just control, of skilled sensorimotor tasks.

scholarly journals Cochlear activity in silent cue-target intervals shows a theta-rhythmic pattern and is correlated to attentional alpha and theta modulations

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Moritz Herbert Albrecht Köhler ◽  
Gianpaolo Demarchi ◽  
Nathan Weisz
Keyword(s):  
Selective Attention ◽  
Brain Regions ◽  
Attentional Focus ◽  
Theta Activity ◽  
Superior Olivary Complex ◽  
Rhythmic Pattern ◽  
Auditory Input ◽  
Auditory Selective Attention ◽  
Beta Power ◽  
Cortical Regions

AbstractBackgroundA long-standing debate concerns where in the processing hierarchy of the central nervous system (CNS) selective attention takes effect. In the auditory system, cochlear processes can be influenced via direct and mediated (by the inferior colliculus) projections from the auditory cortex to the superior olivary complex (SOC). Studies illustrating attentional modulations of cochlear responses have so far been limited to sound-evoked responses. The aim of the present study is to investigate intermodal (audiovisual) selective attention in humans simultaneously at the cortical and cochlear level during a stimulus-free cue-target interval.ResultsWe found that cochlear activity in the silent cue-target intervals was modulated by a theta-rhythmic pattern (~ 6 Hz). While this pattern was present independently of attentional focus, cochlear theta activity was clearly enhanced when attending to the upcoming auditory input. On a cortical level, classical posterior alpha and beta power enhancements were found during auditory selective attention. Interestingly, participants with a stronger release of inhibition in auditory brain regions show a stronger attentional modulation of cochlear theta activity.ConclusionsThese results hint at a putative theta-rhythmic sampling of auditory input at the cochlear level. Furthermore, our results point to an interindividual variable engagement of efferent pathways in an attentional context that are linked to processes within and beyond processes in auditory cortical regions.

scholarly journals The Right Hemisphere Is Responsible for the Greatest Differences in Human Brain Response to High-Arousing Emotional versus Neutral Stimuli: A MEG Study

2021 ◽  
Vol 11 (8) ◽  
pp. 960
Author(s):  
Mina Kheirkhah ◽  
Philipp Baumbach ◽  
Lutz Leistritz ◽  
Otto W. Witte ◽  
Martin Walter ◽  
...  
Keyword(s):  
Human Brain ◽  
Right Hemisphere ◽  
Emotional Stimuli ◽  
Brain Response ◽  
Whole Brain ◽  
Brain Responses ◽  
Cortical Regions ◽  
The Right ◽  
Healthy Participants

Studies investigating human brain response to emotional stimuli—particularly high-arousing versus neutral stimuli—have obtained inconsistent results. The present study was the first to combine magnetoencephalography (MEG) with the bootstrapping method to examine the whole brain and identify the cortical regions involved in this differential response. Seventeen healthy participants (11 females, aged 19 to 33 years; mean age, 26.9 years) were presented with high-arousing emotional (pleasant and unpleasant) and neutral pictures, and their brain responses were measured using MEG. When random resampling bootstrapping was performed for each participant, the greatest differences between high-arousing emotional and neutral stimuli during M300 (270–320 ms) were found to occur in the right temporo-parietal region. This finding was observed in response to both pleasant and unpleasant stimuli. The results, which may be more robust than previous studies because of bootstrapping and examination of the whole brain, reinforce the essential role of the right hemisphere in emotion processing.

scholarly journals The G Protein-Coupled Glutamate Receptors as Novel Molecular Targets in Schizophrenia Treatment—A Narrative Review

2021 ◽  
Vol 10 (7) ◽  
pp. 1475
Author(s):  
Waldemar Kryszkowski ◽  
Tomasz Boczek
Keyword(s):  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Glutamate Release ◽  
Molecular Targets ◽  
Brain Regions ◽  
Psychotic Symptoms ◽  
Unknown Etiology ◽  
Metabotropic Glutamate ◽  
G Protein Coupled

Schizophrenia is a severe neuropsychiatric disease with an unknown etiology. The research into the neurobiology of this disease led to several models aimed at explaining the link between perturbations in brain function and the manifestation of psychotic symptoms. The glutamatergic hypothesis postulates that disrupted glutamate neurotransmission may mediate cognitive and psychosocial impairments by affecting the connections between the cortex and the thalamus. In this regard, the greatest attention has been given to ionotropic NMDA receptor hypofunction. However, converging data indicates metabotropic glutamate receptors as crucial for cognitive and psychomotor function. The distribution of these receptors in the brain regions related to schizophrenia and their regulatory role in glutamate release make them promising molecular targets for novel antipsychotics. This article reviews the progress in the research on the role of metabotropic glutamate receptors in schizophrenia etiopathology.

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