Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

The relationship between global and local changes in PET scans.

K J Friston1, C D Frith, P F Liddle

  • 1MRC Cyclotron Unit, Hammersmith Hospital, London, U.K.

Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism
|July 1, 1990
PubMed
Summary

Normalization of cerebral activity in PET scans is crucial for localizing brain function. This study shows that cognitive activation effects are independent of global activity, enabling accurate analysis using covariance methods.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Caloric restriction reduces proteinuria in male rats with established nephropathy.

Physiological reports·2024
Same author

A generic curriculum development model for the biomedical physics component of the educational and training programmes of the non-physics healthcare professions.

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)·2021
Same author

Harmonisation of PET/CT contrast recovery performance for brain studies.

European journal of nuclear medicine and molecular imaging·2021
Same author

Quantification of [<sup>18</sup>F]afatinib using PET/CT in NSCLC patients: a feasibility study.

EJNMMI research·2020
Same author

Imaging disease activity of rheumatoid arthritis by macrophage targeting using second generation translocator protein positron emission tomography tracers.

PloS one·2019
Same author

Examining belief and confidence in schizophrenia - ADDENDUM.

Psychological medicine·2019

Area of Science:

  • Neuroimaging
  • Cognitive Neuroscience
  • Medical Physics

Background:

  • Positron Emission Tomography (PET) measures cerebral activity, such as regional cerebral blood flow (rCBF), to localize brain function.
  • Cerebral activity changes during activation paradigms have both global and local components.
  • Accurate localization requires removing global variance through normalization, but simple methods are insufficient.

Purpose of the Study:

  • To investigate the relationship between local and global cerebral activity during cognitive tasks.
  • To determine the appropriate normalization procedure for analyzing functional brain imaging data.
  • To validate a method for partitioning activation-induced changes into global and local effects.

Main Methods:

  • Analysis of PET data from 24 scans across six conditions in four subjects using a verbal fluency paradigm.

Related Experiment Videos

  • Evaluation of normalization procedures, including division by whole-brain mean.
  • Development and testing of models to partition activation effects into global and local components.

    • Main Results:

    • Simple normalization by dividing regional values by the whole-brain mean is inadequate due to non-proportional relationships.
    • A systematic deviation from proportionality between local and global activity was observed across brain regions.
    • Cognitive activation-induced increases in activity were found to be independent of global activity levels.

    Conclusions:

    • Normalization must be performed on a pixel-by-pixel basis, considering both local and global activity changes.
    • The independence of activation effects from global activity supports the use of analysis of covariance.
    • This approach allows for the accurate separation of activation-specific changes from global confounds in neuroimaging studies.