Why do some moments imprint themselves in memory while others vanish without a trace? This meta-analysis identifies a dissociation in large-scale brain networks during encoding: networks associated with impairing encoding are task-invariant, whereas those supporting it are task-specific. Drawing on 56 functional magnetic resonance imaging (fMRI) studies employing the subsequent memory paradigm,...
Neurofeedback (NF) has been proposed as a tool to support and expand access to meditation practice. Despite growing interest, no comprehensive review has examined neurofeedback for meditation-based interventions (NF-MED) across the full spectrum of practices. Here, we conducted a scoping systematic review according to PRISMA guidelines, mapping the NF-MED field across both clinical and...
Functional connectomes (FCs) derived from fMRI are unique to an individual and can be reliably distinguished from those of others. However, the neurobiological basis for this "fingerprint"-like uniqueness remains unclear. One hypothesis holds that FC fingerprinting reflects idiosyncratic conscious experiences, while an alternative suggests that stable, intrinsic brain functional network...
From an embodied cognition perspective, semantic processing is assumed to involve sensorimotor representations. The present study used functional magnetic resonance imaging to investigate whether comprehension of action intensity described in sentences is associated with neural representations shared with action execution, particularly those related to grip force. In the execution task,...
Much of a typical individual's mental life is characterized by spontaneous thoughts that occur independently of external stimuli. In prior studies, ongoing mental experiences and their neural correlates have been captured using thought probes presented at random intervals during functional magnetic resonance imaging (fMRI). However, this approach results in temporally imprecise estimates of...
Visual stimuli-induced "narrowband" gamma oscillations (30-70 Hz) are generated due to excitation-inhibition interactions and are linked to attention/binding. These oscillations attenuate with aging and neurodegeneration, potentially indicating declining inhibitory function. In contrast, meditation enhances endogenous stimulus-free gamma (power in a broad frequency range above 25 Hz). However,...
Conscious experience depends on the coordinated activity of neural processes that span multiple scales: from synapses to whole-brain dynamics. A recently introduced measure, dynamical independence (DI), identifies, characterises, and quantifies these multi-scale relationships using an information-theoretic dimensionality reduction approach. Here, we use DI to examine changes in the emergent...
Meditation, psychedelics, and brain connectivity: A randomized controlled resting-state fMRI study of N,N-dimethyltryptamine and harmine in a meditation retreat.
Abstract Mental transformations, such as mental rotation, rely on motor representations and engage neural processes similarly to physical actions. Neuroimaging studies reveal that mental rotation activates the occipito-parietal cortex and motor-related areas, with differences based on whether stimuli are bodily or non-bodily. These findings emphasize the role of frontoparietal networks in...
Abstract N,N-Dimethyltryptamine (DMT) is a serotonergic psychedelic, known to rapidly induce short-lasting alterations in conscious experience, characterized by a profound and immersive sense of physical transcendence alongside rich and vivid auditory distortions and visual imagery. Multimodal neuroimaging data paired with dynamic analysis techniques offer a valuable approach for identifying...
Psychedelics are serotonergic drugs that profoundly alter consciousness, yet their neural mechanisms are not fully understood. A popular theory, RElaxed Beliefs Under pSychedelics (REBUS), posits that psychedelics flatten the hierarchy of information flow in the brain. Here, we investigate hierarchy based on the imbalance between sending and receiving brain signals, as determined by directed...
Focused attention meditation (FA) is a foundational and widely studied practice that cultivates sustained concentration by focusing on a specific object, such as the breath, while disengaging from distractions. Numerous studies have investigated the neurophysiological mechanisms of FA, examining aspects such as spectral power, connectivity patterns, and neural entropy. However, despite this...
Mindfulness meditation is a systematic training in equanimity, sensory clarity, and concentration rooted in ancient contemplative traditions. Here, we synthesized cognitive-behavioral outcomes in long-term meditators (LTMs) resulting from diverse, prolonged meditation practices. Preliminary evidence suggests that LTMs exhibit increased cognitive-sensory integration and decoupling of affective...
Ketamine produces fast-acting antidepressant effects in treatment-resistant depression (TRD). Prior studies have shown altered functional dynamics between brain networks in major depression. We thus sought to determine whether functional brain network dynamics are modulated by ketamine therapy in TRD. Participants with TRD (n = 58, mean age = 40.7 years, female = 48.3%) completed resting-state...
Meditation training in older adults has been proposed as a non-pharmacological intervention to promote healthy aging and lower the risks of developing Alzheimer's disease (AD). Resting-state dynamic functional network connectivity (dFNC) highlighted two brain states, the "strongly connected" and "default mode network (DMN)-negatively connected" states, associated with protective factors for...
Analyses of functional connectivity (FC) in resting-state brain networks (RSNs) have generated many insights into cognition. However, the mechanistic underpinnings of FC and RSNs are still not well-understood. It remains debated whether resting-state activity is best characterized as reflecting noise-driven fluctuations around a single stable state, or instead, as a nonlinear dynamical system...
Imaging NeuroscienceDecember 19, 2024Jordan E. Pierce, Gagan S. Wig, Nicholas R. Harp et al.
Abstract The brain is organized into intrinsically connected functional networks that can be reliably identified during resting-state functional magnetic resonance imaging (fMRI). Healthy aging is marked by decreased network segregation, which is linked to worse cognitive functioning, but aging-related changes in emotion are less well characterized. Valence bias, which represents the tendency...
Abstract Recent meta-analytic evidence has underscored the significant role of the default mode network (DMN) in facilitating item word encoding. This study builds on this finding through a comprehensive meta-analysis of fMRI-based subsequent memory studies that use words as stimuli. The results highlight several key functions within the DMN. Firstly, the dorsomedial prefrontal cortex (dmPFC)...
Imaging NeuroscienceJuly 29, 2024Andrew D. Vigotsky, Rami Jabakhanji, Paulo Branco et al.
Abstract How does the human brain generate coherent, subjective perceptions—transforming yellow and oblong visual sensory information into the perception of an edible banana? This is a hard problem. According to the standard viewpoint, processing in groups of dedicated regions—identified as active “blobs” when using functional magnetic resonance imaging (fMRI)—gives rise to perception. Here, we...
Imaging Neuroscience2024Hubert Banville, Maurice Abou Jaoude, Sean U. N. Wood et al.7 citations
Abstract Electroencephalography (EEG) is an established method for quantifying large-scale neuronal dynamics which enables diverse real-world biomedical applications, including brain-computer interfaces, epilepsy monitoring, and sleep staging. Advances in sensor technology have freed EEG from traditional laboratory settings, making low-cost ambulatory or at-home assessments of brain function...
The stimulant ± 3,4-methylenedioxymethamphetamine (MDMA) has been shown to enhance the perceived pleasantness of touch. However, the underlying neural processes contributing to touch-related effects of MDMA are not well understood. Using a double-blind, randomized, within-subject design, this study used fMRI to examine hemodynamic changes following MDMA (1.5 mg/kg) vs. lactose placebo...
The thalamus is primarily known as a relay for sensory information; however, it also critically contributes to higher-order cortical processing and coordination. Thalamocortical hyperconnectivity is associated with hallucinatory phenomena that occur in various psychopathologies (e.g., psychosis, migraine aura) and altered states of consciousness (ASC; e.g., induced by psychedelic drugs)....