The return of consciousness after traumatic brain injury (TBI) is associated with restoring complex cortical dynamics; however, it is unclear what interactions govern these complex dynamics. Here, we set out to uncover the mechanism underlying the return of consciousness by measuring local field potentials (LFP) using invasive electrophysiological recordings in patients recovering from TBI. We found that injury to the thalamus, and its efferent projections, on MRI were associated with repetitive and low complexity LFP signals from a highly structured phase space, resembling a low-dimensional ring attractor. But why do thalamic injuries in TBI patients result in a cortical attractor? We built a simplified thalamocortical model, which connotes that thalamic input facilitates the formation of cortical ensembles required for the return of cognitive function and the content of consciousness. These observations collectively support the view that thalamic input to the cortex enables rich cortical dynamics associated with consciousness.
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http://dx.doi.org/10.1038/s42003-021-02738-2 | DOI Listing |
iScience
January 2025
Vivian L. Smith Department of Neurosurgery, McGovern Medical School at UT Health Houston, Houston, TX 77030, United States of America.
Speech production engages a distributed network of cortical and subcortical brain regions. The supplementary motor area (SMA) has long been thought to be a key hub in coordinating across these regions to initiate voluntary movements, including speech. We analyzed direct intracranial recordings from 115 patients with epilepsy as they articulated a single word in a subset of trials from a picture-naming task.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, H3A 2B4, Canada.
Excitation-inhibition (E/I) imbalance is theorized as a key mechanism in the pathophysiology of epilepsy, with ample research focusing on elucidating its cellular manifestations. However, few studies investigate E/I imbalance at the macroscale, whole-brain level, and its microcircuit-level mechanisms and clinical significance remain incompletely understood. Here, the Hurst exponent, an index of the E/I ratio, is computed from resting-state fMRI time series, and microcircuit parameters are simulated using biophysical models.
View Article and Find Full Text PDFMethods Mol Biol
January 2025
Institute of Neurophysiology and NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany.
The bimolecular fluorescence complementation (BiFC) technique is a powerful tool for visualizing protein-protein interactions in vivo. It involves genetically fused nonfluorescent fragments of green fluorescent protein (GFP) or its variants to the target proteins of interest. When these proteins interact, the GFP fragments come together, resulting in the reconstitution of a functional fluorescent protein complex that can be observed using fluorescence microscopy.
View Article and Find Full Text PDFPLoS Biol
January 2025
Humanities and Social Sciences, California Institute of Technology, Pasadena, California, United States of America.
Pivotal to self-preservation is the ability to identify when we are safe and when we are in danger. Previous studies have focused on safety estimations based on the features of external threats and do not consider how the brain integrates other key factors, including estimates about our ability to protect ourselves. Here, we examine the neural systems underlying the online dynamic encoding of safety.
View Article and Find Full Text PDFBiological memory networks are thought to store information by experience-dependent changes in the synaptic connectivity between assemblies of neurons. Recent models suggest that these assemblies contain both excitatory and inhibitory neurons (E/I assemblies), resulting in co-tuning and precise balance of excitation and inhibition. To understand computational consequences of E/I assemblies under biologically realistic constraints we built a spiking network model based on experimental data from telencephalic area Dp of adult zebrafish, a precisely balanced recurrent network homologous to piriform cortex.
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