scholarly journals Increased sensitivity to strong perturbations in a whole-brain model of LSD

2021 ◽  
Author(s):  
Beatrice M. Jobst ◽  
Selen Atasoy ◽  
Adrián Ponce-Alvarez ◽  
Ana Sanjuán ◽  
Leor Roseman ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
External Perturbation ◽  
Brain Regions ◽  
Lysergic Acid ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Whole Brain ◽  
Response Diversity ◽  
Brain States ◽  
The Brain

AbstractLysergic acid diethylamide (LSD) is a potent psychedelic drug, which has seen a revival in clinical and pharmacological research within recent years. Human neuroimaging studies have shown fundamental changes in brain-wide functional connectivity and an expansion of dynamical brain states, thus raising the question about a mechanistic explanation of the dynamics underlying these alterations. Here, we applied a novel perturbational approach based on a whole-brain computational model, which opens up the possibility to externally perturb different brain regions in silico and investigate differences in dynamical stability of different brain states, i.e. the dynamical response of a certain brain region to an external perturbation. After adjusting the whole-brain model parameters to reflect the dynamics of functional magnetic resonance imaging (fMRI) BOLD signals recorded under the influence of LSD or placebo, perturbations of different brain areas were simulated by either promoting or disrupting synchronization in the regarding brain region. After perturbation offset, we quantified the recovery characteristics of the brain area to its basal dynamical state with the Perturbational Integration Latency Index (PILI) and used this measure to distinguish between the two brain states. We found significant changes in dynamical complexity with consistently higher PILI values after LSD intake on a global level, which indicates a shift of the brain’s global working point further away from a stable equilibrium as compared to normal conditions. On a local level, we found that the largest differences were measured within the limbic network, the visual network and the default mode network. Additionally, we found a higher variability of PILI values across different brain regions after LSD intake, indicating higher response diversity under LSD after an external perturbation. Our results provide important new insights into the brain-wide dynamical changes underlying the psychedelic state - here provoked by LSD intake - and underline possible future clinical applications of psychedelic drugs in particular psychiatric disorders.HighlightsNovel offline perturbational method applied on functional magnetic resonance imaging (fMRI) data under the effect of lysergic acid diethylamide (LSD)Shift of brain’s global working point to more complex dynamics after LSD intakeConsistently longer recovery time after model perturbation under LSD influenceStrongest effects in resting state networks relevant for psychedelic experienceHigher response diversity across brain regions under LSD influence after an external in silico perturbation

scholarly journals Regional brain activation/deactivation during word generation in schizophrenia: fMRI study

2011 ◽  
Vol 198 (3) ◽  
pp. 213-222 ◽  
Author(s):  
John P. John ◽  
Harsha N. Halahalli ◽  
Mandapati K. Vasudev ◽  
Peruvumba N. Jayakumar ◽  
Sanjeev Jain
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Brain Regions ◽  
Repetition Condition ◽  
Healthy Individuals ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Word Generation ◽  
The Brain

BackgroundExamination of the brain regions that show aberrant activations and/or deactivations during semantic word generation could pave the way for a better understanding of the neurobiology of cognitive dysfunction in schizophrenia.AimsTo examine the pattern of functional magnetic resonance imaging blood oxygen level dependent activations and deactivations during semantic word generation in schizophrenia.MethodFunctional magnetic resonance imaging was performed on 24 participants with schizophrenia and 24 matched healthy controls during an overt, paced, ‘semantic category word generation’ condition and a baseline ‘word repetition’ condition that modelled all the lead-in/associated processes involved in the performance of the generation task.ResultsThe brain regions activated during word generation in healthy individuals were replicated with minimal redundancies in participants with schizophrenia. The individuals with schizophrenia showed additional activations of temporo-parieto-occipital cortical regions as well as subcortical regions, despite significantly poorer behavioural performance than the healthy participants. Importantly, the extensive deactivations in other brain regions during word generation in healthy individuals could not be replicated in those with schizophrenia.ConclusionsMore widespread activations and deficient deactivations in the poorly performing participants with schizophrenia may reflect an inability to inhibit competing cognitive processes, which in turn could constitute the core information-processing deficit underlying impaired word generation in schizophrenia.

scholarly journals Functional magnetic resonance imaging in schizophrenia

2010 ◽  
Vol 12 (3) ◽  
pp. 333-343 ◽  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Neural Substrates ◽  
Brain Regions ◽  
Affective Neuroscience ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Behavioral Deficits ◽  
The Brain

The integration of functional magnetic resonance imaging (fMRI) with cognitive and affective neuroscience paradigms enables examination of the brain systems underlying the behavioral deficits manifested in schizophrenia; there have been a remarkable increase in the number of studies that apply fMRI in neurobiological studies of this disease. This article summarizes features of fMRI methodology and highlights its application in neurobehavioral studies in schizophrenia. Such work has helped elucidate potential neural substrates of deficits in cognition and affect by providing measures of activation to neurobehavioral probes and connectivity among brain regions. Studies have demonstrated abnormalities at early stages of sensory processing that may influence downstream abnormalities in more complex evaluative processing. The methodology can help bridge integration with neuropharmacologic and genomic investigations.

The Brain Circuits and Dynamics of Curiosity-Driven Behavior in Naturally Curious Marmosets

2021 ◽  
Author(s):  
Xiaoguang Tian ◽  
Afonso C Silva ◽  
Cirong Liu
Keyword(s):  
Behavioral Responses ◽  
Brain Regions ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Cortical Areas ◽  
Brain Circuits ◽  
New Information ◽  
Brain States ◽  
Main Barrier ◽  
The Brain

Abstract Curiosity is a fundamental nature of animals for adapting to changing environments, but its underlying brain circuits and mechanisms remain poorly understood. One main barrier is that existing studies use rewards to train animals and motivate their engagement in behavioral tasks. As such, the rewards become significant confounders in interpreting curiosity. Here, we overcame this problem by studying research-naïve and naturally curious marmosets that can proactively and persistently participate in a visual choice task without external rewards. When performing the task, the marmosets manifested a strong innate preference towards acquiring new information, associated with faster behavioral responses. Longitudinally functional magnetic resonance imaging revealed behavior-relevant brain states that reflected choice preferences and engaged several brain regions, including the cerebellum, the hippocampus, and cortical areas 19DI, 25, and 46D, with the cerebellum being the most prominent. These results unveil the essential brain circuits and dynamics underlying curiosity-driven activity.

scholarly journals Perceiving actions before they happen: psychological dimensions scaffold neural action prediction

2020 ◽  
Author(s):  
Mark A Thornton ◽  
Diana I Tamir
Keyword(s):  
Magnetic Resonance Imaging ◽  
Functional Neuroimaging ◽  
Social World ◽  
Action Space ◽  
Action Prediction ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
The Social ◽  
Psychological Dimensions ◽  
The Brain

Abstract The social world buzzes with action. People constantly walk, talk, eat, work, play, snooze and so on. To interact with others successfully, we need to both understand their current actions and predict their future actions. Here we used functional neuroimaging to test the hypothesis that people do both at the same time: when the brain perceives an action, it simultaneously encodes likely future actions. Specifically, we hypothesized that the brain represents perceived actions using a map that encodes which actions will occur next: the six-dimensional Abstraction, Creation, Tradition, Food(-relevance), Animacy and Spiritualism Taxonomy (ACT-FAST) action space. Within this space, the closer two actions are, the more likely they are to precede or follow each other. To test this hypothesis, participants watched a video featuring naturalistic sequences of actions while undergoing functional magnetic resonance imaging (fMRI) scanning. We first use a decoding model to demonstrate that the brain uses ACT-FAST to represent current actions. We then successfully predicted as-yet unseen actions, up to three actions into the future, based on their proximity to the current action’s coordinates in ACT-FAST space. This finding suggests that the brain represents actions using a six-dimensional action space that gives people an automatic glimpse of future actions.

scholarly journals Globally conditioned Granger causality in brain–brain and brain–heart interactions: a combined heart rate variability/ultra-high-field (7 T) functional magnetic resonance imaging study

2016 ◽  
Vol 374 (2067) ◽  
pp. 20150185 ◽  
Author(s):  
Andrea Duggento ◽  
Marta Bianciardi ◽  
Luca Passamonti ◽  
Lawrence L. Wald ◽  
Maria Guerrisi ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Resting State ◽  
High Field ◽  
Brain Activity ◽  
Brain Regions ◽  
Sympathovagal Balance ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Ultra High Field ◽  
Conditioned Approach

The causal, directed interactions between brain regions at rest (brain–brain networks) and between resting-state brain activity and autonomic nervous system (ANS) outflow (brain–heart links) have not been completely elucidated. We collected 7 T resting-state functional magnetic resonance imaging (fMRI) data with simultaneous respiration and heartbeat recordings in nine healthy volunteers to investigate (i) the causal interactions between cortical and subcortical brain regions at rest and (ii) the causal interactions between resting-state brain activity and the ANS as quantified through a probabilistic, point-process-based heartbeat model which generates dynamical estimates for sympathetic and parasympathetic activity as well as sympathovagal balance. Given the high amount of information shared between brain-derived signals, we compared the results of traditional bivariate Granger causality (GC) with a globally conditioned approach which evaluated the additional influence of each brain region on the causal target while factoring out effects concomitantly mediated by other brain regions. The bivariate approach resulted in a large number of possibly spurious causal brain–brain links, while, using the globally conditioned approach, we demonstrated the existence of significant selective causal links between cortical/subcortical brain regions and sympathetic and parasympathetic modulation as well as sympathovagal balance. In particular, we demonstrated a causal role of the amygdala, hypothalamus, brainstem and, among others, medial, middle and superior frontal gyri, superior temporal pole, paracentral lobule and cerebellar regions in modulating the so-called central autonomic network (CAN). In summary, we show that, provided proper conditioning is employed to eliminate spurious causalities, ultra-high-field functional imaging coupled with physiological signal acquisition and GC analysis is able to quantify directed brain–brain and brain–heart interactions reflecting central modulation of ANS outflow.

scholarly journals Applying 3DPCANet and Functional Magnetic Resonance Imaging to Aided Diagnosis of Alzheimer’s Disease

2021 ◽  
Author(s):  
Yu Wang ◽  
Hongfei Jia ◽  
Yifan Duan ◽  
Hongbing Xiao
Keyword(s):  
Magnetic Resonance Imaging ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Brain Regions ◽  
Support Vector ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Public Data

Abstract Alzheimer's disease (AD) is a progressive neurodegenerative disease, which changes the structure of brain regions by some hidden causes. In this paper for assisting doctors to make correct judgments, an improved 3DPCANet method is proposed to classify AD by combining the mean (mALFF) of the whole brain. The main idea includes that firstly, the functional magnetic resonance imaging (fMRI) data is pre-processed, and mALFF is calculated to get the corresponding matrix. Then the features of mALFF images are extracted via the improved 3DPCANet network. Finally, AD patients with different stages are classified using support vector machine (SVM). Experiments results based on public data from the Alzheimer’s disease neuroimaging initiative (ADNI) show that the proposed approach has better performance compared with state-of-the-art methods. The accuracies of AD vs. significant memory concern (SMC), SMC vs. late mild cognitive impairment (LMCI), and normal control (NC) vs. SMC reach respectively 92.42%, 91.80%, and 89.50%, which testifies the feasibility and effectiveness of the proposed method.

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