Substance Use Disorder (SUD) is a complex condition with profound effects on brain function. Understanding the altered functional connectivity patterns in the brains of SUD patients is crucial for unraveling the neurological underpinnings of this disorder. This study employs Energy Landscape Analysis, an energy-based machine learning technique, to investigate whole brain Regions of Interest (ROI) functional connectivity differences between SUD patients and healthy controls. The challenge with Energy Landscape Analysis lies in selecting the appropriate ROI from the extensive brain atlas. In this study, seed-based connectivity was utilized to identify relevant ROIs, overcoming the limitation of analyzing only a limited number of ROIs. The dataset comprised 53 cocaine users and 52 age- and sex-matched healthy controls, with fMRI data preprocessed using the CONN toolbox. ROI-ROI seed-based pair connectivity was derived through first and second level analyses. The identified sub-ROIs were categorized into default CONN network affiliations and bundled into Superior Temporal Gyrus (STG), Inferior Temporal Gyrus, temporooccipital part (toITG), Visual Primary (VIS-P), Auditory (AUD), Cerebellum, Basal Ganglia (BSL), and Thalamus (THL). Significance testing revealed eight connectivity states among all above regions with p-values that satisfy Bonferroni correction between controls and patients. Notably, the connectivity states with the lowest p-values revealed a distinctive pattern: STG (auditory attention) toITG were disconnected from the rest of the networks. This finding underscores the importance of investigating specific network disruptions in SUD, shedding light on potential neural mechanisms underlying the disorder. In summary, our study utilizes Energy Landscape Analysis to explore whole brain ROI functional connectivity in SUD, revealing disrupted connectivity patterns that may have implications for understanding the neural basis of this disorder. These findings may ultimately inform targeted interventions and treatment strategies for individuals with SUD.
Substance Use Disorder (SUD) represents a pervasive global health crisis characterized by the compulsive and detrimental use of psychoactive substances. In this study, we explore the functional connectivity disparities between two age- and sex-matched groups comprising 53 individuals with Cocaine Use Disorder (CUD) and 52 Healthy Control (HC) subjects. We employed resting-state fMRI data, which were preprocessed using the CONN toolbox, ensuring high-quality data for subsequent analysis. The CONN toolbox has a default atlas of 164 ROIs based on the FSL-Harvard Oxford atlas and the automated Anatomical Labeling Atlas (AAL). The investigation extended into first level and second level-analysis features within the CONN toolbox to discern functional connectivity patterns between these two groups. At the group level analysis centered on contrasting CUD patients and HCs, we particularly focused on the Region-of-Interest (ROI)-ROI connectivity maps in this study. This study revealed some key findings: Firstly, we observed that HC subjects exhibited significantly stronger connectivity between the Superior Temporal Gyrus (STG) and regions of interest within the basal ganglia network (BSL), compared to individuals with CUD. Secondly, the HC group demonstrated heightened connectivity between regions of interest belonging to the visual network and the cerebellum, contrasting with the weaker connectivity observed in the CUD group. Lastly, there was a notable increase in connectivity between the Inferior Temporal Gyrus, temporooccipital part (toITG), and the cerebellum in individuals with CUD, further emphasizing the disruption in functional connectivity within this population. Understanding these functional connectivity differences may inform future interventions and diagnostic approaches in the context of cocaine use disorder.
Segmenting the human brain into networks has been a useful approach in analyzing functional connectivity. Brain network bundling can determine which regions are engaged and if they are working together. The thalamus (THL) and basal ganglia (BSL) regions in the subcortical network are linked to multiple cortical areas due to their roles in neural circuitry outlined in the cortico-basal ganglia-thalamo cortical map. Here we explore their coupling with the default mode network (DMN), frontoparietal network (FPN), salience network (SAN), attention network (ATN), sensorimotor network (SSM), visual network (VIS), and auditory network (AUD) using the energy landscape technique. Energy landscape analysis helps identify the statistical differences in functional behaviors between the healthy control and patient groups, which are obtained from the fMRI activity time courses of the 9 internetworks. In this work, we focused on studying 107 schizophrenic patients and 86 healthy controls and obtained the constructed activity patterns and disconnectivity graphs of each subject. The differences between two groups are compared. The results from bundling THL and BSL with the DMN, FPN, SAN, ATN, SSM, VIS, and AUD shows that these regions are more strongly coupled in controls than in patients. After performing energy calculations and heat map generations, we observed several lower energy band states that are common among all control and patient subjects. The potential implications of these common band states are discussed.
The study of brain activity changes caused by physiological or other conditions like aging is crucial not only to understand the brain dynamics but also to identify those changes and distinguish the subject groups. In this work, we are performing a sliding window technique on the Energy Landscape analysis to explore temporal signatures of the seven major restingstate networks, namely, default mode (DMN), frontal-parietal (FPN), salience (SAN), attention (ATN), sensory-motor (SMN), visual (VIS) and auditory (AUD) networks. The dataset used for this study consists of 23 young adult and 47 old adult subjects with normal cognitive function. To study the dynamic behavior of the brain, we have applied the sliding window technique on the time courses of the obtained fMRI data. With 90-second windows and 4-second shifts from a total of 180 second time course, we obtain 24 windows of temporal energy landscape information, which is presented as a matrix with the energies of all possible connectivity states vs the sequence of sliding windows. A heat map was displayed using this matrix to examine the energy transition of these states. We found that a few bands of connectivity states are consistently low energies among the different groups of subjects. One observation was that the states in these bands are only one or two hamming distances away from each other, which means these connectivity states with consistently low energy values are close in terms of the region of interest (ROIs) connectivity. Also, SAN and ATN were working synchronously for both young and old subjects in all these bands. In summary, we are using the sliding window technique with the Energy landscape analysis to find out the brain state dynamics for the old and young subjects.
It is estimated that by 2030, mental illness will cost global economy $16 trillion. To identify mental illness, we introduce electroencephalography (EEG) based connectivity biomarkers. EEG permits exploration of brain causal activities at high temporal resolution. Conventional EEG based brain connectivity studies are mostly describing connections among scalp electrode locations, which challenge the functional meaning interpretation of brain activities. In this work, we introduce a novel methodology to generate functional brain network biomarkers from source localized EEG for identifying human subjects that suffer from neurological disorders. We use sLORETA for source localization, post artifact removal, of EEG data followed by threshold binarization for marking activated and deactivated cortical estimates, and data-driven energy landscape analysis, which is rooted in statistical physics theory. This yields the brain subnetwork energy states. Furthermore, we demonstrate our novel method by a preliminary study where EEG data was recorded from 11 channels at 1000Hz from 22 schizophrenia patients and 27 healthy controls in response to transcranial magnetic stimulation administered on the left motor cortex. Sensorimotor network that is responsible for processing input and output of senses and motor activity comprises of precentral gyrus, postcentral gyrus, and paracentral gyrus was observed. In result, we found an energy state in the sensorimotor network, that significantly distinguished patients from controls (p-value<0.05) with Bonferroni correction. For future scope, we are observing other networks. Conclusively, we demonstrate a promising non-invasive low-cost data-driven method for brain network biomarker extraction at high spatiotemporal resolution for clinical applications.
Noninvasive electric stimulation-based treatments for neuropsychiatric disorders are of high interest in both research and clinical studies. Among them, transcranial magnetic stimulation (TMS) is widely accepted as a safe and effective method. Enhancing the performance of the apparatus requires stimulation of deeper brain regions which isn’t accessible with current coils due to the increased depth-spread tradeoff at deeper regions. In addition, focal rodent coils need to be developed to better understand brain stimulation mechanisms. Due to the smaller size of the rodent brain, a variety of challenges like the depth-spread tradeoff and high energy requirement arise when stimulating a functionally specific brain region. In this study, we have introduced tilted, wire-wrapped, multi-stacked coils for the purpose of enhancing brain stimulation for primates and non-primates. To improve the performance of the coils, we added different types of ferromagnetic cores to understand the efficacy of these cores on the distribution, decay rate, and the focality of the induced electric field. The analysis was performed using Finite Element Model (FEM) simulations, and the results were then verified using 3-d printed coils and experimental procedures. The performance of the coils was dependent on the relative permeability of the ferromagnetic core, demonstrating a general improvement in the focality and energy requirement of these TMS coils.
Brain connectivity biomarkers are powerful tools for not only identifying neuropsychiatric disorders in patients but also validating treatment effectiveness. In this work, we used energy landscape techniques to analyze resting state fMRI data collected from 107 healthy control (HC) and 86 Schizophrenia patients (SZ). Activity patterns and disconnectivity graphs were obtained from 264 ROIs and 180-second fMRI time course of each subject. Statistics of individual and subgroups’ inter-network and intra-network connections of Auditory Network (AUD), Attention Network (ATN), Default – Mode Network (DMN), Frontoparietal Network (FPN), Salience Network (SAN), Sensorimotor Network (SSM), and Visual Network (VIS) were analyzed. For inter-network results we found that the DMN and ATN of SZ are strongly coupled. But for HC, a stable brain states that the ATN, SAN, and FPN are coupled as a group and anti-correlated with the other coupled group of DMN, SSM, VIS, and AUD. For intra-networks we found that in FPN, controls have more flexibility to allow the Inferior Frontal Gyrus independently working together with the Superior Temporal Gyrus. In FPN we found that regions that process language and regions that process motor and planning can sometimes be decoupled in SZ. In SMN, some controls can accomplish a brain state to separate voluntary and autopilot activities. In VIS, controls have the ability to separate lower-level visual processing from working memory, motor planning, and guided coordination, whereas patients mixed some of them together, suggesting lack of self-awareness and self-constraint.
Computational neuroscience models can be used to understand neural dynamics in the brain and these dynamics change as the physiological and other conditions like aging. One such approach we have used in this work is Energy Landscape analysis based on resting-state fMRI data. The dataset consists of 70 subjects with normal cognitive function, of which 23 are young adults and 47 are old adults. In this analysis, disconnectivity graphs and activity patterns are generated and using connectivity statistics among seven prominent brain networks. To study brain dynamic behaviors, we perform sliding window studies on the dataset and observe local minima of each window evolving in time. By varying the window shift from multiple seconds to 1 second, we can obtain statistics and evaluate the speed and activity pattern holding time of individual and group subjects. We found that older subjects can hold the brain states for a longer time but then jump to other dominated brain state local minima with a large hamming distance, whereas young subjects change dominated local minima more frequently but with a small hamming distance of 1 or 2. In fact, when averaged over the full time course, old subjects have more stable brain states local minima compared to young subjects. For both young and old subjects, the default mode network (DMN) and visual network (VIS) are coupled but for young subjects the two networks are on and off together and strongly correlated. For old subjects, there is an extra dominated brain state local minimum that the DMN and attention network (ATN) are correlated and anti-correlated with (VIS) and sensory-motor networks (SMN). This state may suggest old subjects are more capable of focusing on brain internal models and not getting influenced by external visual and sensory factors than young subjects.
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