Oxygen Level and LFP in Task-Positive and Task-Negative Areas: Bridging BOLD fMRI and Electrophysiology

Bentley, William J.; Li, Jingfeng M.; Snyder, Abraham Z.; Raichle, Marcus E.; Snyder, Lawrence H.

doi:10.1093/cercor/bhu260

Cited by 44 publications

(57 citation statements)

References 88 publications

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“…To verify electrode placement, we first obtained visually evoked responses at each of these sites. As previously reported (43), both multiunit firing rate and oxygen level were elevated in V3, and both were suppressed in PCC (Fig. 1A).…”

Section: Resultssupporting

confidence: 89%

“…The amplitude and time course of stimulus-evoked responses in both task-positive and task-negative areas are similar for the two techniques (43), as is the finding of interregional correlations (Fig. 1).…”

Section: Oxygen Polarography Captures Interregional Oxygen Correlationsupporting

confidence: 69%

“…Other indirect support can be found in the fact that gamma-band power, a putative neural correlate of BOLD (but see ref. 43), is coherent within the default mode network only over a narrow frequency range (31). Still other studies find mixed results regarding the frequency content of BOLD correlation (37,42).…”

Section: Interregional Oxygen Correlation Is Independent Of Local Flumentioning

confidence: 91%

“…Electrodes were targeted to V3 and PCC, using anatomical MRI images and physiology (43). Briefly, each animal's brain was accessed via bilateral 15-mm (internal diameter) chronic custom recording chambers.…”

Section: Methodsmentioning

confidence: 99%

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Functional connectivity arises from a slow rhythmic mechanism

Bentley

Snyder

2015

Proc. Natl. Acad. Sci. U.S.A.

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The mechanism underlying temporal correlations among blood oxygen level-dependent signals is unclear. We used oxygen polarography to better characterize oxygen fluctuations and their correlation and to gain insight into the driving mechanism. The power spectrum of local oxygen fluctuations is inversely proportional to frequency raised to a power (1/f) raised to the beta, with an additional positive band-limited component centered at 0.06 Hz. In contrast, the power of the correlated oxygen signal is band limited from ∼0.01 Hz to 0.4 Hz with a peak at 0.06 Hz. These results suggest that there is a band-limited mechanism (or mechanisms) driving interregional oxygen correlation that is distinct from the mechanism(s) driving local (1/f) oxygen fluctuations. Candidates for driving interregional oxygen correlation include rhythmic or pseudo-oscillatory mechanisms.

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Section: Resultssupporting

confidence: 89%

Section: Oxygen Polarography Captures Interregional Oxygen Correlationsupporting

confidence: 69%

Section: Interregional Oxygen Correlation Is Independent Of Local Flumentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

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Functional connectivity arises from a slow rhythmic mechanism

Bentley

Snyder

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…This gamma-band activity is then suppressed as the DAN is activated and subjects engage with an external stimulus. In animals, it has proven difficult to reliably detect task-related deactivations in DMN structures inside the fMRI scanner, even in macaque monkeys (25)(26)(27). It is likely that animal subjects must expend considerable cognitive effort to complete the tasknegative control conditions inside the fMRI scanner and that this effort does not correspond well to quiet restfulness and as a result is not associated with DMN activation (27).…”

Section: Significancementioning

confidence: 99%

Basal forebrain contributes to default mode network regulation

Nair

Klaassen

Arató³

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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The default mode network (DMN) is a collection of cortical brain regions that is active during states of rest or quiet wakefulness in humans and other mammalian species. A pertinent characteristic of the DMN is a suppression of local field potential gamma activity during cognitive task performance as well as during engagement with external sensory stimuli. Conversely, gamma activity is elevated in the DMN during rest. Here, we document that the rat basal forebrain (BF) exhibits the same pattern of responses, namely pronounced gamma oscillations during quiet wakefulness in the home cage and suppression of this activity during active exploration of an unfamiliar environment. We show that gamma oscillations are localized to the BF and that gamma-band activity in the BF has a directional influence on a hub of the rat DMN, the anterior cingulate cortex, during DMNdominated brain states. The BF is well known as an ascending, activating, neuromodulatory system involved in wake-sleep regulation, memory formation, and regulation of sensory information processing. Our findings suggest a hitherto undocumented role of the BF as a subcortical node of the DMN, which we speculate may be important for switching between internally and externally directed brain states. We discuss potential BF projection circuits that could underlie its role in DMN regulation and highlight that certain BF nuclei may provide potential target regions for up-or down-regulation of DMN activity that might prove useful for treatment of DMN dysfunction in conditions such as epilepsy or major depressive disorder.gamma suppression | anterior cingulate cortex | granger causality A highly consistent finding across a wide range of functional imaging studies in humans is that a network of brain regions, referred to as the "default mode network" (DMN), increases its activity during passive mental states compared with the performance of cognitive tasks. This was initially shown in a metaanalysis of several PET studies (1), in which a distribution of brain regions broadly including the medial prefrontal, retrosplenial, and anterior cingulate cortex (ACC), as well as lateral parietal and temporal cortices, was shown to be activated when subjects were in a state of quiet restfulness. The DMN areas are thought to form a cohesive set of intrinsically coupled brain regions, such that fMRI activations in its component regions exhibit similar time courses, allowing them to be identified reliably using seed-region analysis (2-4). Activity in the DMN exhibits anticorrelation with a complementary, largely nonoverlapping, set of fronto-parietal brain areas known as the "dorsal attention network" (DAN) (5). It should be noted, however, that particular brain structures may harbor functionally heterogeneous elements and thus may contribute to multiple functions, as was shown for the ACC (6). During wakefulness, the human brain thus alternates between DAN-and DMN-dominated activation states, corresponding to effortful cognitive task performance on the one hand and quiet restful...

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Brain activity associated with taste stimulation: A mechanism for neuroplastic change?

2023

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Purpose Neuroplasticity may be enhanced by increasing brain activation and bloodflow in neural regions relevant to the target behavior. We administered precisely formulated and dosed taste stimuli to determine whether the associated brain activity patterns included areas that underlie swallowing control. Methods Five taste stimuli (unflavored, sour, sweet‐sour, lemon, and orange suspensions) were administered in timing‐regulated and temperature‐controlled 3 mL doses via a customized pump/tubing system to 21 healthy adults during functional magnetic resonance imaging (fMRI). Whole‐brain analyses of fMRI data assessed main effects of taste stimulation as well as differential effects of taste profile. Results Differences in brain activity associated with taste stimulation overall as well as specific stimulus type were observed in key taste and swallowing regions including the orbitofrontal cortex, insula, cingulate, and pre‐ and postcentral gyri. Overall, taste stimulation elicited increased activation in swallowing‐related brain regions compared to unflavored trials. Different patterns of blood oxygen level‐dependent (BOLD) signal were noted by taste profile. For most areas, sweet‐sour and sour trials elicited increases in BOLD compared to unflavored trials within that region, whereas lemon and orange trials yielded reductions in BOLD. This was despite identical concentrations of citric acid and sweetener in the lemon, orange, and sweet‐sour solutions. Conclusions These results suggest that neural activity in swallowing‐relevant regions can be amplified with taste stimuli and may be differentially affected by specific properties within very similar taste profiles. These findings provide critical foundational information for interpreting disparities in previous studies of taste effects on brain activity and swallowing function, defining optimal stimuli to increase brain activity in swallowing‐relevant regions, and harnessing taste to enhance neuroplasticity and recovery for persons with swallowing disorders.

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Oxygen Level and LFP in Task-Positive and Task-Negative Areas: Bridging BOLD fMRI and Electrophysiology

Cited by 44 publications

References 88 publications

Functional connectivity arises from a slow rhythmic mechanism

Functional connectivity arises from a slow rhythmic mechanism

Basal forebrain contributes to default mode network regulation

Brain activity associated with taste stimulation: A mechanism for neuroplastic change?

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