Help in understanding effect size in fMRI

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In summary, a student of a Master's degree in Neuroscience is seeking help understanding the results of an article on emotional face presentations in a cortically blind field. They are specifically struggling with the concept of a negative effect size in fMRI and are seeking an explanation for the "unseen CS-" and its strong negativity in the amygdala. Thanks is given to anyone who can provide assistance, as both the student and @DiracPool are confused by the explanation. It is noted that interpretation of fMRI results can be subjective and requires a solid understanding of specific aspects of brain responses.
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dentons
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Hello everyone, I'm a student of a Master's degree in Neuroscience and I'm preparing a journal club presentation on an article called "Differential extrageniculostriate and amygdala responses to presentation of emotional faces in a cortically blind field". I'm struggling to understand some of the results, in particular what a negative effect size means in fMRI. Is there someone that can explain that to me? I'm referring in particular to this picture of the paper https://d1gqps90bl2jsp.cloudfront.net/content/brain/124/6/1241/F4.large.jpg?width=800&height=600&carousel=1 the one attached).
What can I say about the "unseen CS-"? Why is it so negative? Does it mean that the amygdala has a very low degree of activation?
Thanks to anyone that can help me :)
 

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This appears to be something @DiracPool could help with. I'm confused with your explanation as well. fMRI mesures blood flow in the brain which indirectly shows which brain tissues are active. Interpretation is, IMO, sometimes a bit subjective. Each area seems to require the reader to be in the know how the ground rules are applied. My opinion only. In particular you have to have a solid grip on the particular known aspects of certain kinds of responses.
 

FAQ: Help in understanding effect size in fMRI

1. What is effect size in fMRI?

Effect size in fMRI refers to the magnitude of the difference between two groups or conditions in a study, as measured by the strength of the brain activity. It is an important statistic in fMRI research as it helps to determine the significance and practical importance of the findings.

2. How is effect size calculated in fMRI?

Effect size in fMRI is typically calculated using Cohen’s d, which is the difference between the means of two groups divided by the standard deviation. Other measures such as Pearson’s correlation coefficient or odds ratios can also be used to calculate effect size in fMRI.

3. What is a large effect size in fMRI?

A large effect size in fMRI is typically considered to be around 0.8 or higher. This indicates a strong and significant difference between the two groups or conditions being compared. However, the interpretation of effect size also depends on the specific research context and should be considered in conjunction with other statistical measures.

4. Why is effect size important in fMRI research?

Effect size is important in fMRI research as it provides a more meaningful and accurate measure of the differences between groups or conditions compared to p-values or statistical significance alone. It also allows for the comparison of effect sizes across different studies, which can help to build a more robust understanding of the findings.

5. How can understanding effect size improve fMRI studies?

Understanding effect size in fMRI can improve studies by providing more accurate and reliable results. It also allows for the evaluation of the practical significance of the findings, which can inform future research and potentially lead to more effective interventions or treatments. Additionally, reporting effect sizes can enhance the transparency and reproducibility of fMRI studies.

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