Stimulus frequency dependence of blood oxygenation level-dependent functional magnetic resonance imaging signals in the somatosensory cortex of rats

Kida, Ikuhiro; Yamamoto, Toru

doi:10.1016/j.neures.2008.05.006

Cited by 9 publications

(7 citation statements)

References 33 publications

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“…2A). Unlike isoflurane, the dependence of the optimal stimulus-frequency on stimulus duration was not found under α-chloralose anesthetized rats (Kida and Yamamoto, 2008; Ureshi et al, 2004). This is because the optimal stimulus frequency for α-chloralose anesthesia was found to be 1 – 3 Hz and the reduction of cortical neural activity due to the neural adaptation is small at these low frequencies.…”

Section: Discussionmentioning

confidence: 94%

Frequency-dependent neural activity, CBF, and BOLD fMRI to somatosensory stimuli in isoflurane-anesthetized rats

Kim

Masamoto²,

Fukuda

et al. 2010

NeuroImage

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Inhalation anesthetics (e.g. isoflurane) are preferable for longitudinal fMRI experiments in the same animals. We previously implemented isoflurane anesthesia for rodent forepaw stimulation studies, and optimized the stimulus parameters with short stimuli (1-3 s long stimulation with ten electric pulses). These parameters, however, may not be applicable for long periods of stimulation because repetitive stimuli induce neural adaptation. Here we evaluated frequency-dependent responses (pulse width of 1.0 ms and current of 1.5 mA) for 30-s long stimulation under 1.3-1.5% isoflurane anesthesia. The cerebral blood flow (CBF) response (using laser Doppler flowmetry: CBF LDF ) and field potential (FP) changes were simultaneously measured for nine stimulus frequencies (1-24 Hz). CBF (using arterial spin labeling: CBF ASL ) and blood oxygenation level dependent (BOLD) fMRI responses were measured at 9.4 T for four stimulus frequencies (1.5-12 Hz). Higher stimulus frequencies (12-24 Hz) produced a larger FP per unit time initially, but decreased more rapidly later due to neural adaptation effects. On the other hand, lower stimulus frequencies (1-3 Hz) induced smaller, but sustained FP activities over the entire stimulus period. Similar frequency-dependencies were observed in CBF LDF , CBF ASL and BOLD responses. A linear relationship between FP and CBF LDF was observed for all stimulus frequencies. Stimulation frequency for the maximal cumulative neural and hemodynamic changes is dependent on stimulus duration; 8-12 Hz for short stimulus durations (< 10 s) and 6-8 Hz for 30-s stimulation. Our findings suggest that neural adaptation should be considered in determining the somatosensory stimulation frequency and duration under isoflurane anesthesia.

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Section: Discussionmentioning

confidence: 94%

Frequency-dependent neural activity, CBF, and BOLD fMRI to somatosensory stimuli in isoflurane-anesthetized rats

Kim

Masamoto²,

Fukuda

et al. 2010

NeuroImage

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“…To keep the acquisition time at a reasonable limit, SE MRI sequences need to be speeded up. This is usually achieved using the echo planar imaging (EPI) sampling scheme 10,[16][17][18][19] . However, EPI induces image distortions that increase with the magnitude of the magnetic field, and contaminates the BOLD signal with T2* effects (making the signal stronger but less specific).…”

Section: Discussionmentioning

confidence: 99%

Functional Magnetic Resonance Imaging (fMRI) with Auditory Stimulation in Songbirds

Ruijssevelt

Groof

Kant

et al. 2013

JoVE

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The neurobiology of birdsong, as a model for human speech, is a pronounced area of research in behavioral neuroscience. Whereas electrophysiology and molecular approaches allow the investigation of either different stimuli on few neurons, or one stimulus in large parts of the brain, blood oxygenation level dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) allows combining both advantages, i.e. compare the neural activation induced by different stimuli in the entire brain at once. fMRI in songbirds is challenging because of the small size of their brains and because their bones and especially their skull comprise numerous air cavities, inducing important susceptibility artifacts. Gradient-echo (GE) BOLD fMRI has been successfully applied to songbirds (1-5) (for a review, see (6)). These studies focused on the primary and secondary auditory brain areas, which are regions free of susceptibility artifacts. However, because processes of interest may occur beyond these regions, whole brain BOLD fMRI is required using an MRI sequence less susceptible to these artifacts. This can be achieved by using spin-echo (SE) BOLD fMRI (7,8) . In this article, we describe how to use this technique in zebra finches (Taeniopygia guttata), which are small songbirds with a bodyweight of 15-25 g extensively studied in behavioral neurosciences of birdsong. The main topic of fMRI studies on songbirds is song perception and song learning. The auditory nature of the stimuli combined with the weak BOLD sensitivity of SE (compared to GE) based fMRI sequences makes the implementation of this technique very challenging.

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“…To be able to image 15 slices, we used a TR of 2000 ms. To keep the acquisition time at a reasonable limit, SE MRI sequences need to be speeded up. This is usually achieved using the echo planar imaging (EPI) sampling Scheme 15, 16, 22, 23. However, EPI induces image distortions which increase with the magnitude of the magnetic field, and contaminates the BOLD signal with T 2 * effects (making the signal stronger but less specific).…”

Section: Discussionmentioning

confidence: 99%

Implementation of spin‐echo blood oxygen level‐dependent (BOLD) functional MRI in birds

et al. 2010

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The advent of high-field MRI systems has allowed the implementation of blood oxygen level-dependent functional MRI (BOLD fMRI) on small animals. An increased magnetic field improves the signal-to-noise ratio and thus allows an improvement in the spatial resolution. However, it also increases susceptibility artefacts in the commonly acquired gradient-echo images. This problem is particularly prominent in songbird MRI because of the presence of numerous air cavities in the skull of birds. These T(2)*-related image artefacts can be circumvented using spin-echo BOLD fMRI. In this article, we describe the implementation of spin-echo BOLD fMRI in zebra finches, a small songbird of 15-25 g, extensively studied in the behavioural neurosciences of birdsong. Because the main topics in this research domain are song perception and song learning, the protocol implemented used auditory stimuli. Despite the auditory nature of the stimuli and the weak contrast-to-noise ratio of spin-echo BOLD fMRI compared with gradient-echo BOLD fMRI, we succeeded in detecting statistically significant differences in BOLD responses triggered by different stimuli. This study shows that spin-echo BOLD fMRI is a viable approach for the investigation of auditory processing in the whole brain of small songbirds. It can also be applied to study auditory processing in other small animals, as well as other sensory modalities.

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Stimulus frequency dependence of blood oxygenation level-dependent functional magnetic resonance imaging signals in the somatosensory cortex of rats

Cited by 9 publications

References 33 publications

Frequency-dependent neural activity, CBF, and BOLD fMRI to somatosensory stimuli in isoflurane-anesthetized rats

Frequency-dependent neural activity, CBF, and BOLD fMRI to somatosensory stimuli in isoflurane-anesthetized rats

Functional Magnetic Resonance Imaging (fMRI) with Auditory Stimulation in Songbirds

Implementation of spin‐echo blood oxygen level‐dependent (BOLD) functional MRI in birds

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