PMC:4620161 / 2116-4103 JSONTXT

{"project":"0_colil","denotations":[{"id":"26578853-11554800-357996","span":{"begin":1025,"end":1029},"obj":"11554800"},{"id":"26578853-14977420-357997","span":{"begin":1055,"end":1059},"obj":"14977420"},{"id":"26578853-18548064-357998","span":{"begin":1073,"end":1077},"obj":"18548064"},{"id":"26578853-22279224-357999","span":{"begin":1093,"end":1097},"obj":"22279224"},{"id":"26578853-23917518-358000","span":{"begin":1669,"end":1673},"obj":"23917518"},{"id":"26578853-15501093-358001","span":{"begin":1892,"end":1896},"obj":"15501093"},{"id":"26578853-15050587-358002","span":{"begin":1917,"end":1921},"obj":"15050587"},{"id":"26578853-17884583-358003","span":{"begin":1939,"end":1943},"obj":"17884583"},{"id":"26578853-22677309-358004","span":{"begin":1959,"end":1963},"obj":"22677309"}],"text":"When a region in the brain is activated, oxygen and glucose demands lead to blood vessel dilation, followed by increased blood to the tissue (neurons and astrocytes) under stress. The onset of a neuronal activity triggers a sequence of physiological events in the blood vessels of the surrounding area, typically characterized by the changes in cerebral blood flow as well as concentration fluctuations of deoxyhemoglobin and oxyhemoglobin. The blood oxygenation level dependent (BOLD) signal from the FMRI scanning mainly captures the concentration changes of deoxyhemoglobin; that is, the BOLD signal is a surrogate and signature of neuronal activations plus various sources of noise (e.g., physiological and random fluctuations). As an indirect measure of neuronal activity, the shape of the BOLD response may hold some crucial features about brain function. However, the cascade of events from neural activation to measurable MRI signal is complex and nonlinear under certain regimes (Friston et al., 1998b; Birn et al., 2001; Logothetis and Wandell, 2004; Logothetis, 2008; Magri et al., 2012): Even though the BOLD response is simply interpreted as changes in neuronal processing, the same neuronal activity may evoke different hemodynamic response (HDR) shape across trials, regions, conditions/tasks, subjects, and groups. For example, neurophysiological confounds such as neurovascular coupling or energy consumption changes could lead to different BOLD response features, potentially explaining the HDR variability in magnitude and shape across brain regions, cognitive conditions and populations (e.g., children with autism vs. controls, Reynell and Harris, 2013). Nevertheless, meaningful interpretation as well as detection power in FMRI data analysis may depend on the accurate modeling of the BOLD response both at the individual subject and group levels (e.g., Buxton et al., 2004; Handwerker et al., 2004; Stephen et al., 2007; Barbé et al., 2012; Badillo et al., 2013)."}

{"project":"TEST0","denotations":[{"id":"26578853-163-171-357996","span":{"begin":1025,"end":1029},"obj":"[\"11554800\"]"},{"id":"26578853-193-201-357997","span":{"begin":1055,"end":1059},"obj":"[\"14977420\"]"},{"id":"26578853-211-219-357998","span":{"begin":1073,"end":1077},"obj":"[\"18548064\"]"},{"id":"26578853-231-239-357999","span":{"begin":1093,"end":1097},"obj":"[\"22279224\"]"},{"id":"26578853-30-38-358000","span":{"begin":1669,"end":1673},"obj":"[\"23917518\"]"},{"id":"26578853-216-224-358001","span":{"begin":1892,"end":1896},"obj":"[\"15501093\"]"},{"id":"26578853-227-235-358002","span":{"begin":1917,"end":1921},"obj":"[\"15050587\"]"},{"id":"26578853-223-231-358003","span":{"begin":1939,"end":1943},"obj":"[\"17884583\"]"},{"id":"26578853-235-243-358004","span":{"begin":1959,"end":1963},"obj":"[\"22677309\"]"}],"text":"When a region in the brain is activated, oxygen and glucose demands lead to blood vessel dilation, followed by increased blood to the tissue (neurons and astrocytes) under stress. The onset of a neuronal activity triggers a sequence of physiological events in the blood vessels of the surrounding area, typically characterized by the changes in cerebral blood flow as well as concentration fluctuations of deoxyhemoglobin and oxyhemoglobin. The blood oxygenation level dependent (BOLD) signal from the FMRI scanning mainly captures the concentration changes of deoxyhemoglobin; that is, the BOLD signal is a surrogate and signature of neuronal activations plus various sources of noise (e.g., physiological and random fluctuations). As an indirect measure of neuronal activity, the shape of the BOLD response may hold some crucial features about brain function. However, the cascade of events from neural activation to measurable MRI signal is complex and nonlinear under certain regimes (Friston et al., 1998b; Birn et al., 2001; Logothetis and Wandell, 2004; Logothetis, 2008; Magri et al., 2012): Even though the BOLD response is simply interpreted as changes in neuronal processing, the same neuronal activity may evoke different hemodynamic response (HDR) shape across trials, regions, conditions/tasks, subjects, and groups. For example, neurophysiological confounds such as neurovascular coupling or energy consumption changes could lead to different BOLD response features, potentially explaining the HDR variability in magnitude and shape across brain regions, cognitive conditions and populations (e.g., children with autism vs. controls, Reynell and Harris, 2013). Nevertheless, meaningful interpretation as well as detection power in FMRI data analysis may depend on the accurate modeling of the BOLD response both at the individual subject and group levels (e.g., Buxton et al., 2004; Handwerker et al., 2004; Stephen et al., 2007; Barbé et al., 2012; Badillo et al., 2013)."}

{"project":"2_test","denotations":[{"id":"26578853-11554800-38284985","span":{"begin":1025,"end":1029},"obj":"11554800"},{"id":"26578853-14977420-38284986","span":{"begin":1055,"end":1059},"obj":"14977420"},{"id":"26578853-18548064-38284987","span":{"begin":1073,"end":1077},"obj":"18548064"},{"id":"26578853-22279224-38284988","span":{"begin":1093,"end":1097},"obj":"22279224"},{"id":"26578853-23917518-38284989","span":{"begin":1669,"end":1673},"obj":"23917518"},{"id":"26578853-15501093-38284990","span":{"begin":1892,"end":1896},"obj":"15501093"},{"id":"26578853-15050587-38284991","span":{"begin":1917,"end":1921},"obj":"15050587"},{"id":"26578853-17884583-38284992","span":{"begin":1939,"end":1943},"obj":"17884583"},{"id":"26578853-22677309-38284993","span":{"begin":1959,"end":1963},"obj":"22677309"}],"text":"When a region in the brain is activated, oxygen and glucose demands lead to blood vessel dilation, followed by increased blood to the tissue (neurons and astrocytes) under stress. The onset of a neuronal activity triggers a sequence of physiological events in the blood vessels of the surrounding area, typically characterized by the changes in cerebral blood flow as well as concentration fluctuations of deoxyhemoglobin and oxyhemoglobin. The blood oxygenation level dependent (BOLD) signal from the FMRI scanning mainly captures the concentration changes of deoxyhemoglobin; that is, the BOLD signal is a surrogate and signature of neuronal activations plus various sources of noise (e.g., physiological and random fluctuations). As an indirect measure of neuronal activity, the shape of the BOLD response may hold some crucial features about brain function. However, the cascade of events from neural activation to measurable MRI signal is complex and nonlinear under certain regimes (Friston et al., 1998b; Birn et al., 2001; Logothetis and Wandell, 2004; Logothetis, 2008; Magri et al., 2012): Even though the BOLD response is simply interpreted as changes in neuronal processing, the same neuronal activity may evoke different hemodynamic response (HDR) shape across trials, regions, conditions/tasks, subjects, and groups. For example, neurophysiological confounds such as neurovascular coupling or energy consumption changes could lead to different BOLD response features, potentially explaining the HDR variability in magnitude and shape across brain regions, cognitive conditions and populations (e.g., children with autism vs. controls, Reynell and Harris, 2013). Nevertheless, meaningful interpretation as well as detection power in FMRI data analysis may depend on the accurate modeling of the BOLD response both at the individual subject and group levels (e.g., Buxton et al., 2004; Handwerker et al., 2004; Stephen et al., 2007; Barbé et al., 2012; Badillo et al., 2013)."}