# Tag Info

12

As a slight modification of your statement: blood flow increases wherever activity in the brain increases. The type of fMRI that uses this principle is blood-oxygenation-level-dependent fMRI or BOLD fMRI. MRI in general detects signals by picking up proton signals from water molecules. This proton signal is basically caused by magnetizing the protons ...

9

The fMRI Data Center (www.fmridc.org) was one such repository. About ten years ago it was a requirement for publication in the Journal of Cognitive Neuroscience that you submit your full fMRI dataset to the fMRIDC. This requirement was only around for a few years, but they ended up having 120+ datasets before the grant funding ran out. The archive is ...

7

I'm only going to attempt to answer a small part of your question: how does glial activation affect the blood oxygen level-dependent (BOLD) response measured by fMRI? Schulz et al. (2012) were able to investigate the role of glial signaling on fMRI activity by simultaneously measuring neuronal responses with invasive optical imaging and fMRI. They found ...

6

Overall, while there are developing cognitive neuroscience theories of how hypnotic states are produced, there does not appear to be any known cognitive neuroscience basis for individual differences in hypnotic susceptibility based on a reasonable Google Scholar, Web of Science and Scopus search on the topic. There is at least some evidence to suggest that ...

5

Dario Ringach wrote in a letter titled Neuroscience: States of Mind: (inline references removed, see link for references) If the ability to perceive oriented stimuli is found to depend on the cortical state, we can then ask a number of important questions about cortical function. Is the time the cortex spends visiting particular states a function ...

5

Have you tried: connectomeviewer http://www.connectomeviewer.org/viewer brainnetviewer http://www.nitrc.org/projects/bnv/ which is a toolbox for the SPM software package http://www.fil.ion.ucl.ac.uk/spm/ Gephi http://gephi.org/ Trackvis http://trackvis.org/ Also Nico Dosenbach has some amazing picture of brain connectivity in this paper http://www.ncbi....

5

Yes, the effects of electromagnetic fields on the brain have been studied extensively, especially with respect to cellphone, WiFi, and other small devices that emit such fields. The results are typically mixed, but the overall consensus is that "it depends" - on the strength of the field, the environment, length of exposure, etc - and most modern consumer ...

5

Replicating fMRI signal was first used in the Tower of Hanoi task as seen in section 5.8 of "How to Build a Brain": There is strong evidence that dendritic processing, driven by neurotransmitter usage, underwrites the BOLD signal (Logothetis & Wandell, 2004). It is that BOLD signal that is actually measured by MRI machines. Consequently, MRI ...

5

I'm a TMS, but not an fMRI, researcher but I have experience using anatomical masks. I can guide you through the steps to make an anatomical mask, but unfortunately I don't have any code to offer you. First of all you need a set of x, y and z co-ordinates that specify where TOFC or LOC are. One way to find these is to find a paper that reports the x,y,z ...

5

Apparently, this can happen when your ROI is near the edge of the brain as reported here. The thread is pretty old though so this might have been fixed by today and there is another reason in your case.

5

I can see one case in which you still might analyze the data. This only works under three conditions: your paradigm has no variable durations of either stimulus presentations or breaks or others (or you can determine all the times retrospectively) AND all your fmri scans have timestamps in their header information (which I think is always the case, at ...

5

From meta-analyses that include musical emotion inductions, there is not much evidence that we can reliably distinguish between emotions in the brain, independent of the emotion induction procedure or meta-analytical method (1 2 3 4 5). We might be able to distinguish emotions with specificity and reliability within an individual, but this kind of work is ...

4

This might be better suited as a comment, but I'm not allowed to post such. I went through the nice list collected by Craig Bennett: nitrc.org: Data has been preprocessed, but there is no complete list of what has been done, and how the data has been collected. Maybe the information is hidden in the previous publications. Anyway, I would not use it for ...

4

In theory, yes, because there are now many theories, supported by evidence, which map different memory processes onto different regions and patterns of activity in the brain. In practice, there are many difficulties with doing this. First, it would depend on what stage or process you are thinking of (are you considering encoding? or retrieval?). Second, ...

4

The best way to learn is probably not by reading, but by doing. The SPM website contains a number of useful datasets with tutorials for various tasks. I also find PowerPoint slides from lectures and talks useful. There are a bunch of slides on the SPM website, but you can also find more on Google by limiting your results to type:pptx.

4

I know very little about fmri, but as @strongbad points out, surely it is Professor Thomas Nichols at Warwick. I'm not sure what the authoritative reference is, but Luo and Nichols (2003) might be worth a look. They state: We construct a histogram based on all non-tail data (10th to 90th percentile) and use the location of the minimum bin as the antimode ...

3

Like lea's comment indicated, FA is called "fractional" anisotropy simply because it's the degree of anisotropic diffusion, i.e., a ratio (Soares, Marques, Alves and Sousa, 2013). Fractional Anisotropy is a normalized measure of the fraction of the tensor's magnitude due to anisotropic diffusion, corresponding to the degree of anisotropic diffusion or ...

3

Focus and motives are very different cognitive processes. Essentially focus would be attention, while motivation is a complex neurocognitive process, such as hunger or thirst, which drives attentional orientation. I'm going to have to break this down a bit further because motivation is largely considered two processes 'wanting' and 'liking'. 'Wanting' is ...

3

I don't know any such group in Italy but there is a group in Liege, Belgium which is called Coma Science Group. It consists of scientists of various disciplines and their main interest is understanding disorders of consciousness. Also their work has a clinical orientation as well. From your description, I think it will be interesting to you. Their website is ...

3

I will focus on question #1: Analysis of MRI scans is typically done using voxels (Fig. 1). Voxels have a volume defined by three dimensions (length, width and depth). Voxel analysis. Source: Philips The slice thickness plus the 2D in-plane resolution (pixel size) yields the voxel size. The time to scan a slice can be regarded to be negligible. Making a ...

3

I cannot answer from fMRI's, but this theory conflicts with other anecdotal evidence from medicine. In sensory deprivation, or under psychotomimetic substances, you can be awake and unimpaired logically, and still have reality make as little sense as it does in a dream. (People on LSD are not less logical, in an abstract sense. If you can get them to care ...

3

Short answer Older image collection techniques like GRASS and FLASH are slower than EPI, but still fast enough to operate within the time span of the neurovascular delay. Background The speed of fMRI processing is an important limitation to what processes can be investigated with this technique. Figure 1 shows a number of physiological processes along ...

3

See https://www.reddit.com/r/neuro/comments/5y4pta/does_anyone_know_where_i_can_find_a_repository_of/ for a similar question. Websites that were posted there include http://www.humanconnectome.org/data/, http://neurovault.org, http://www.ppmi-info.org, https://openfmri.org/, http://fcon_1000.projects.nitrc.org/indi/abide/ and http://radiopaedia.org. Some ...

3

The coefficient is the measure of how strongly the given factor predicts the dependent variable, or in other words how much of the variance in the dependent variable can be explained by that factor. So the coefficient itself, and not the t-statistic of the coefficient, is a measure of what you're calling how well the model (or, more correctly, the regressor) ...

2

The simplest equation for getting a BOLD signal from neurotransmitter that I could find was in "Tracing Problem Solving in Real Time: fMRI Analysis of the Subject-paced Tower of Hanoi", which itself references many other publications where it was used: $$H(t)= m \times(t/s)^a\times e^{-(t/s)}$$ The parameters $s$, $a$ and $m$ don't have an explicit meaning....

2

The Nighres project has released some 7T MRI datasets and tools to run them. You can read the paper on the tools here, and download the datasets from NITRC here.

2

Below is a corrected version of the script. SPM seems to be quite finicky about the structure of the data passed to matlabbatch{...}.spm.spatial.realign.estwrite.daat{...}. %%job_realign.m SPM batch module. % SPM's spm_jobman function will eval this file, and automatically launch a % batch job if the parameters are valid. Cryptic errors out of spm_jobman ...

2

The information you seek is contained in the header of the image file. Matlab has open source tools for reading the header information. e.g., http://www.mathworks.com/matlabcentral/fileexchange/29344-read-medical-data-3d If you want an even more open source option, NiBabel is an open source python library for reading .nii files (header and image). I think ...

2

They used MRI to compare asymmetry in hemispheric volumes across the groups. Hemispheric volume is not something that is changing over time, and so it doesn't require the use of functional neuroimaging (e.g., fMRI). Instead, if we want to be accurate when measuring volume and making comparisons across groups, we need to have high spatial resolution of the ...

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