Characteristics of fMRI responses to visual stimulation in anesthetized vs. awake mice

AbstractThe functional characteristics of the mouse visual system have not previously been well explored using fMRI. In this research, we examined 9.4 T BOLD fMRI responses to visual stimuli of varying pulse durations (1 – 50 ms) and temporal frequencies (1 – 10 Hz) under ketamine and xylazine anesthesia, and compared fMRI responses of anesthetized and awake mice. Under anesthesia, significant positive BOLD responses were detected bilaterally in the major structures of the visual pathways, including the dorsal lateral geniculate nuclei, superior colliculus, lateral posterior nucleus of thalamus, primary visual area, and higher-order visual area. BOLD responses increased slightly with pulse duration, were maximal at 3 – 5 Hz stimulation, and significantly decreased at 10 Hz, which were all consistent with previous neurophysiological findings. When the mice were awake, the BOLD fMRI response was faster in all active regions and stronger in the subcortical areas compared with the anesthesia condition. In the V1, the BOLD response was biphasic for 5 Hz stimulation and negative for 10 Hz stimulation under wakefulness, whereas prolonged positive BOLD responses were observed at both frequencies under anesthesia. Unexpected activation was detected in the extrastriate postrhinal area and non-visual subiculum complex under anesthesia, but not under wakefulness. Widespread positive BOLD activity under anesthesia likely results from the disinhibition and sensitization of excitatory neurons induced by ketamine. Overall, fMRI can be a viable tool for mapping brain-wide functional networks.

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Differential effects of aquaporin-4 channel inhibition on BOLD fMRI and Diffusion fMRI responses in rat visual cortex

10.1101/2020.01.24.917849 ◽

2020 ◽

Author(s):

Yuji Komaki ◽

Clément Debacker ◽

Boucif Djemai ◽

Luisa Ciobanu ◽

Tomokazu Tsurugizawa ◽

...

Keyword(s):

Visual Cortex ◽

Channel Blocker ◽

Visual Stimulation ◽

Aquaporin 4 ◽

Coupling Mechanism ◽

Bold Fmri ◽

Channel Inhibition ◽

Electrophysiological Responses ◽

Fmri Response ◽

And Diffusion

AbstractThe contribution of astrocytes to the BOLD fMRI and DfMRI responses in visual cortex of mice following visual stimulation were investigated an aquaporin 4 (AQP4) channel blocker, TGN-020, acting as an astrocyte function perturbator. Under TGN-020 injection the amplitude of the BOLD fMRI response became significantly higher. In contrast no significant changes in the DfMRI responses and the electrophysiological responses were observed. Those results further confirm the implications of astrocytes in the neurovascular coupling mechanism underlying BOLD fMRI, while DfMRI relies on other, not astrocyte-mediated mechanisms.

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Low-level carbon monoxide exposure affects BOLD fMRI response

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x19887358 ◽

2019 ◽

Vol 40 (11) ◽

pp. 2215-2224

Author(s):

Caroline Bendell ◽

Shakeeb H Moosavi ◽

Mari Herigstad

Keyword(s):

Carbon Monoxide ◽

Visual Stimulation ◽

Blood Oxygen Level Dependent ◽

Blood Oxygen Level ◽

Bold Fmri ◽

Low Level ◽

Fmri Response ◽

Underlying Mechanisms ◽

Air Control ◽

The Impact

Blood oxygen level dependent (BOLD) fMRI is a common technique for measuring brain activation that could be affected by low-level carbon monoxide (CO) exposure from, e.g. smoking. This study aimed to probe the vulnerability of BOLD fMRI to CO and determine whether it may constitute a significant neuroimaging confound. Low-level (6 ppm exhaled) CO effects on BOLD response were assessed in 12 healthy never-smokers on two separate experimental days (CO and air control). fMRI tasks were breath-holds (hypercapnia), visual stimulation and fingertapping. BOLD fMRI response was lower during breath holds, visual stimulation and fingertapping in the CO protocol compared to the air control protocol. Behavioural and physiological measures remained unchanged. We conclude that BOLD fMRI might be vulnerable to changes in baseline CO, and suggest exercising caution when imaging populations exposed to elevated CO levels. Further work is required to fully elucidate the impact on CO on fMRI and its underlying mechanisms.

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Reduction in BOLD fMRI response to primary visual stimulation following alcohol ingestion

Psychiatry Research Neuroimaging ◽

10.1016/s0925-4927(98)00022-5 ◽

1998 ◽

Vol 82 (3) ◽

pp. 135-146 ◽

Cited By ~ 81

Author(s):

Jonathan M Levin ◽

Marjorie H Ross ◽

Jack H Mendelson ◽

Marc J Kaufman ◽

Nicholas Lange ◽

...

Keyword(s):

Visual Stimulation ◽

Alcohol Ingestion ◽

Bold Fmri ◽

Fmri Response

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Neurochemical and BOLD Responses during Neuronal Activation Measured in the Human Visual Cortex at 7 Tesla

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2014.233 ◽

2015 ◽

Vol 35 (4) ◽

pp. 601-610 ◽

Cited By ~ 78

Author(s):

Petr Bednařík ◽

Ivan Tkáč ◽

Federico Giove ◽

Mauro DiNuzzo ◽

Dinesh K Deelchand ◽

...

Keyword(s):

Magnetic Resonance ◽

Visual Stimulation ◽

Blood Oxygenation ◽

7 Tesla ◽

Single Subject ◽

Resonance Spectroscopy ◽

Functional Magnetic Resonance ◽

Bold Fmri ◽

Bold Responses ◽

Concentration Changes

Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level—dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at characterizing the relationship between metabolite concentrations and BOLD-fMRI signals during a block-designed paradigm of visual stimulation. Functional magnetic resonance spectroscopy (fMRS) and fMRI data were acquired from 12 volunteers. A short echo-time semi-LASER localization sequence optimized for 7 Tesla was used to achieve full signal-intensity MRS data. The group analysis confirmed that during stimulation lactate and glutamate increased by 0.26±0.06 μmol/g (∼30%) and 0.28±0.03 μmol/g (∼3%), respectively, while aspartate and glucose decreased by 0.20±0.04 μmol/g (∼5%) and 0.19±0.03 μmol/g (∼16%), respectively. The single-subject analysis revealed that BOLD-fMRI signals were positively correlated with glutamate and lactate concentration changes. The results show a linear relationship between metabolic and BOLD responses in the presence of strong excitatory sensory inputs, and support the notion that increased functional energy demands are sustained by oxidative metabolism. In addition, BOLD signals were inversely correlated with baseline γ-aminobutyric acid concentration. Finally, we discussed the critical importance of taking into account linewidth effects on metabolite quantification in fMRS paradigms.

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Projection status of calbindin- and parvalbumin-immunoreactive neurons in the superficial layers of the rat's superior colliculus

Visual Neuroscience ◽

10.1017/s095252380001141x ◽

1997 ◽

Vol 14 (2) ◽

pp. 277-286 ◽

Cited By ~ 28

Author(s):

Richard D. Lane ◽

Dawn M. Allan ◽

Carol A. Bennett-Clarke ◽

David L. Howell ◽

Robert W. Rhoades

Keyword(s):

Superior Colliculus ◽

Calcium Binding ◽

Neuronal Population ◽

Dorsal Lateral Geniculate Nucleus ◽

Projection Neurons ◽

Retrograde Labeling ◽

Thalamic Projections ◽

Lateral Posterior ◽

Lateral Posterior Nucleus ◽

Dorsal Lateral Geniculate

AbstractImmunocytochemistry and retrograde labeling were used to define the thalamic projections of calbindin- and parvalbumin-containing cells in superficial layers of the rat's superior colliculus (SC). Quantitative analysis revealed that 90.8 ± 2.2% (mean ± standard deviation) of the calbindin-immunoreactive neurons in the stratum griseum superficiale (SGS) projected to the dorsal lateral geniculate nucleus (LGNd) and that 91.3 ± 4.3% of calbindin-immunoreactive neurons in the stratum opticum (SO) projected to the lateral posterior nucleus (LP). In contrast, only 17.3 ± 2.5% of parvalbumin-immunoreactive neurons in the SGS were found to project to the LGNd and 16.5 ± 3.1% of the parvalbumin-immunoreactive SO cells were retrogradely labeled after LP injections. Few of the parvalbumin-immunoreactive neurons in either the SGS (7.2 ± 2.5%) or the SO (9.2 ± 2.5%) were GABA positive. The retrograde-labeling results suggest that parvalbumin-immunoreactive neurons in the rat's SO and SGS may either be primarily interneurons or have descending projections, while calbindin-containing cells are primarily thalamic projection neurons. These results are consistent with data from other rodents, but almost exactly the opposite of data that have been reported for the cat for these same populations of SC projection neurons. Such interspecies differences raise questions regarding the functional importance of expressing one calcium-binding protein versus another in a specific neuronal population.

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Temporal Dynamics of Shape Analysis in Macaque Visual Area V2

Journal of Neurophysiology ◽

10.1152/jn.00822.2003 ◽

2004 ◽

Vol 92 (5) ◽

pp. 3030-3042 ◽

Cited By ~ 47

Author(s):

Jay Hegdé ◽

David C. Van Essen

Keyword(s):

Cortical Neurons ◽

Time Course ◽

Temporal Dynamics ◽

Visual Stimulation ◽

Signal To Noise Ratio ◽

Stimulus Onset ◽

Visual Area ◽

Response Modulation ◽

Population Response ◽

Area V2

The firing rate of visual cortical neurons typically changes substantially during a sustained visual stimulus. To assess whether, and to what extent, the information about shape conveyed by neurons in visual area V2 changes over the course of the response, we recorded the responses of V2 neurons in awake, fixating monkeys while presenting a diverse set of static shape stimuli within the classical receptive field. We analyzed the time course of various measures of responsiveness and stimulus-related response modulation at the level of individual cells and of the population. For a majority of V2 cells, the response modulation was maximal during the initial transient response (40–80 ms after stimulus onset). During the same period, the population response was relatively correlated, in that V2 cells tended to respond similarly to specific subsets of stimuli. Over the ensuing 80–100 ms, the signal-to-noise ratio of individual cells generally declined, but to a lesser degree than the evoked-response rate during the corresponding time bins, and the response profiles became decorrelated for many individual cells. Concomitantly, the population response became substantially decorrelated. Our results indicate that the information about stimulus shape evolves dynamically and relatively rapidly in V2 during static visual stimulation in ways that may contribute to form discrimination.

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Pushing behavior and hemiparesis: which is critical for functional recovery in pusher patients ? Case report

Arquivos de Neuro-Psiquiatria ◽

10.1590/s0004-282x2007000300035 ◽

2007 ◽

Vol 65 (2b) ◽

pp. 536-539 ◽

Cited By ~ 9

Author(s):

Taiza E.G. Santos-Pontelli ◽

Octávio M. Pontes-Neto ◽

José Fernando Colafêmina ◽

Dráulio B. de Araújo ◽

Antônio Carlos Santos ◽

...

Keyword(s):

Case Report ◽

Barthel Index ◽

Functional Improvement ◽

Chronic Hypertension ◽

Acute Hemorrhage ◽

Lateral Posterior ◽

History Of ◽

Lateral Posterior Nucleus ◽

Neuroimaging Study ◽

The Right

We report a sequential neuroimaging study in a 48-years-old man with a history of chronic hypertension and lacunar strokes involving the ventral lateral posterior nucleus of the thalamus. The patient developed mild hemiparesis and severe contraversive pushing behavior after an acute hemorrhage affecting the right thalamus. Following standard motor physiotherapy, the pusher behavior completely resolved 3 months after the onset and, at that time, he had a Barthel Index of 85, although mild left hemiparesis was still present. This case report illustrates that pushing behavior itself may be severely incapacitating, may occur with only mild hemiparesis and affected patients may have dramatic functional improvement (Barthel Index 0 to 85) after resolution pushing behavior without recovery of hemiparesis.

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Voxel-Wise Linearity Analysis of Increments and Decrements in BOLD Responses in Human Visual Cortex Using a Contrast Adaptation Paradigm

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.541314 ◽

2021 ◽

Vol 15 ◽

Author(s):

Yun Lin ◽

Xi Zhou ◽

Yuji Naya ◽

Justin L. Gardner ◽

Pei Sun

Keyword(s):

Visual Cortex ◽

Primary Visual Cortex ◽

Bold Signal ◽

Transient Responses ◽

Bold Fmri ◽

Human Visual Cortex ◽

Contrast Adaptation ◽

Bold Responses

The linearity of BOLD responses is a fundamental presumption in most analysis procedures for BOLD fMRI studies. Previous studies have examined the linearity of BOLD signal increments, but less is known about the linearity of BOLD signal decrements. The present study assessed the linearity of both BOLD signal increments and decrements in the human primary visual cortex using a contrast adaptation paradigm. Results showed that both BOLD signal increments and decrements kept linearity to long stimuli (e.g., 3 s, 6 s), yet, deviated from linearity to transient stimuli (e.g., 1 s). Furthermore, a voxel-wise analysis showed that the deviation patterns were different for BOLD signal increments and decrements: while the BOLD signal increments demonstrated a consistent overestimation pattern, the patterns for BOLD signal decrements varied from overestimation to underestimation. Our results suggested that corrections to deviations from linearity of transient responses should consider the different effects of BOLD signal increments and decrements.

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