|Resting State Fluctuations: Human & Animal|
A Resting State Network in the Basal Ganglia
Simon Robinson1, Nicola Soldati1, Gianpaolo Basso1, Uta Sailer2, Jorge Jovicich1, Lorenzo Bruzzone, Ilse Kryspin Exner2, Herbert Bauer2, Ewald Moser3
1University of Trento, Trento, Italy; 2University of Vienna, Vienna, Austria; 3Medical University of Vienna, Vienna, Austria
Approximately 10 Resting State Networks (RSNs) of the human brain have been discovered over the past decade, changing our understanding of brain function. Using high temporal resolution EPI, a large number of subjects and group Independent Component Analysis, we uncover a previously unreported network in the basal ganglia; reproducible across subjects and runs. Using a novel analysis of component time course features, we demonstrate that this network clusters with other RSNs rather than physiological artifacts. This finding opens the way for research into possible disturbances of network in basal ganglia pathologies such as Parkinsonís disease.
Spontaneous Activity in the Visual Cortex Persists
During Visual Stimulation: A 7T Study
Marta Bianciardi1, Masaki Fukunaga, Peter van Gelderen, Silvina Horovitz, Jacco de Zwart, Jeff Duyn
1National Institutes of Health, Bethesda, USA
The aim of the present study is to investigate whether spontaneous fluctuations in the visual cortex are modulated by visual stimulation. With regard to spontaneous activity in other cerebral regions, previous works showed that both the default mode and the sensory-motor network continue during a wide range of tasks, being respectively modulated/unperturbed by stimulation. The result of our study is that also during visual stimulation, spontaneous and evoked activity overlap in the visual cortex at a 1.25mm in plane resolution. Nevertheless, we show that spontaneous activity during fixation with/without stimulation is reduced with respect to the eyes closed condition.
Language Lateralization is Correlated
with Resting-State Connectivity Within the Inferior Frontal Gyri
Jolyn N A D'Andrea1, Bradley G. Goodyear1
1University of Calgary, Calgary, Canada
In general, language is lateralized to the inferior frontal gyrus (IFG) of the left hemisphere; however, individual differences in lateralization due to handedness, gender, or pathology, may be associated with individual differences in resting-state connectivity within the IFGs of the two hemispheres. Our results demonstrate, using fMRI, a linear relationship between the degree of lateralization of activity during a verb generation task and inter-hemispheric connectivity within the IFGs, suggesting subjects that are left lateralized for language have stronger inter-hemispheric connections. Connectivity may be a potential alternative for understanding language dysfunction in patients who cannot perform language tasks well.
Investigating Motor Plasticity Using Resting State
FMRI and SEM
Liangsuo Ma1, Binquan Wang, Donald A. Robin, Peter Fox, Jinhu Xiong1
1University of Iowa, Iowa City, USA
We explored changes in regional activity and inter-regional connectivity in the motor system resting state network (RSN). Subjects were trained to perform a finger movement task for 4 weeks. Three sets of resting state fMRI images were acquired every two weeks. Structural equation modeling (SEM) was used quantify the inter-regional connectivity. We constructed and tested one SEM model. We observed significant changes in both regional activities and inter-regional connectivity in the motor system RSN. The changes in regional activity may reflect altered processing load during different phases of motor learning. Resting state inter-regional connectivity is likely associated with memory consolidation.
Spatial Extent of Task-Induced FMRI-BOLD Response
After Hemodynamic Scaling Using Resting State Fluctuations
Sridhar S. Kannurpatti1, Bharat B. Biswal1
1UMDNJ-New Jersey Medical School, Newark, New Jersey, USA
Variation in activation-induced fMRI-BOLD response across subjects can depend on their vascular sensitivity. Scaling of fMRI-BOLD response from the vascular sensitivity information contained in the task response signal itself or during resting conditions would be ideal to avoid scaling bias and subject compliance issues during the performance of a hypercapnic task traditionally used for hemodynamic scaling. We test the hypothesis that resting state physiological fluctuation amplitude (RSFA) indicates cerebral vascular reactivity in response to CO2 variation or hypercapnia and can be used as a hemodynamic scaling parameter to minimize intra and inter-subject variations in neural activation-induced fMRI response.
Caffeine Reduces Resting-State Functional
Connectivity in the Motor Cortex
Anna Leigh Rack-Gomer1, Joy Liau1, Joanna Perthen1, Thomas T. Liu1
1University of California San Diego, La Jolla, California , USA
Functional connectivity maps based on the spatial correlation of resting-state fluctuations in the blood oxygenation level-dependent (BOLD) signal are finding increasing use in applications such as the localization of functional regions, disease diagnosis, and enhanced understanding of information processing strategies employed by the brain. However, the basic mechanisms underlying the correlation in low-frequency BOLD fluctuations are not entirely understood. In this study we show that caffeine-induced vasoconstriction leads to a significant decrease in resting-state functional connectivity.
Comparison of Spontaneous
Electrophysiological and FMRI Fluctuations During Rest in Rat Brain
Young Ro Kim1, Bharat B. Biswal, Bruce R. Rosen
1Athinoula Martinos Center for Biomedical Imaging/ Massachusetts General Hospital, Charlestown, Massachusetts, USA
Resting state fMRI has been used to demonstrate that the spontaneous hemodynamic resting state fluctuations (RSF) are spatially synchronous among the functionally related brain regions (e.g., bilateral sensorimotor cortex). This finding has been interpreted as evidence of neural connectivity between discrete brain regions. Despite these advances, the relevance of RSF to overall neural activity and functional connectivity remains unclear. In this study, we plan to use electrophysiological measurements to detect the presence of resting state electro-cellular activity, so as to provide a basis for understanding whether these resting state fluctuations are derived from synchronous neuronal modulation.
Electrophysiological Investigation of the Basis of
the Resting-State FMRI Signal
Hanbing Lu1, Yantao Zuo1, Hong Gu1, James S. Waltz2, Wang Zhan1, Clara A. Scholl1, William Rea1, Yihong Yang1, Elliot A. Stein1
1NIH, Baltimore, Maryland, USA; 2University of Maryland School of Medicine, Baltimore, Maryland, USA
The neural mechanism of synchronized low frequency spontaneous fluctuations of the fMRI signal remains largely unknown. In the present study, electrophysiological recordings and resting-state fMRI measurements were conducted in Š-chloralose anesthetized rats. Region-specific, anesthetic dose-dependent resting-state functional connectivity was detected in bilateral primary somatosensory cortex (S1FL) of the resting brain. Cortical electroencephalographic (EEG) signal was recorded from bilateral S1FL; a visual cortex locus served as a control site. Results demonstrate that the power coherence in low frequency bands, particularly the delta band, correlates with the resting-state fMRI signal.
Effect of Propofol on Thalamocortical Connection: A
High-Field MR Study of Functional Connectivity on Rats
Ye Tu1, 2, Tian Yu1, Xiao-Yun Fu1, 2, Peng Xie1, 2, Su Lui2, Ti-Jiang Zhang2, Xiao-Qi Huang2, Hua-Fu Chen3, Qi-Yong Gong2
1Zunyi Medical College, Zunyi, People's Republic of China; 2Huaxi MR Research Center(HMRRC), Huaxi Hospital, Sichuan University, Chengdu, People's Republic of China; 3School of Science and Technology, University of Electronic Science and Technology, Chengdu, People's Republic of China
The mechanism of anesthesia, a state of profound central nervous system suppression is still poorly understood. One interesting question concerns the alteration of neural network under anesthesia.We examined the functional connectivity of the thalamus on rats at different concentration of propofol. Our functional connectivity analysis revealed propofol induced anesthesia disrupted functional interactions within thalamocortical neural networks. Combining regional cerebral blood flow (rCBF) with functional connectivity in future study will provide further insight into the mechanism of anesthesia.
Tightly Coupled Spontaneous EEG and CBF Signals in
the Anesthetized Rat Brain
Xiao Liu1, 2, Xiao-Hong Zhu1, Yi Zhang1, Wei Chen1
1University of Minnesota, Minneapolis, Minnesota, USA
The present study is to study the neurovascular coupling in the anesthetized rat brain by examining the simultaneously-recorded EEG and CBF signals. Strong temporal correlation was found between them, indicating a tight neurovascular coupling between CBF fluctuation and spontaneous neuronal activity in the resting brain. We also found strong temporal correlations between the left- and right-hemispheric somatosensory cortices for both EEG and CBF signals, which could be linked to the resting-state coherent BOLD fluctuations recently observed in human and animal brains. Therefore, our results may provide supports for the neural origin of the resting coherent BOLD fluctuations phenomenon.