Limitations of temporal resolution in functional MRI

Seong Gi Kim, Wolfgang Richter, Kamil Ugurbil

Research output: Contribution to journalArticlepeer-review

181 Scopus citations

Abstract

In fMRI, images can be collected in a very short time; therefore, high temporal resolution is possible in principle. However, the temporal resolution is limited by a blurred intrinsic hemodynamic response and a finite signal-to-noise ratio. To determine the upper limit of temporal resolution in a single area during repeated tasks, motor cortex activity was investigated during visually instructed finger movements. Without averaging, a sequence of four single-finger movements with an execution time of approximately 2 s can be resolved when the delay time between consecutive sequences is at least 3 s. The hemodynamic response time is constant for each subject, but not among different subjects. The temporal resolution can be better when the signal from spatially distinct regions is examined. For a series of experiments involving a visually instructed delayed cued finger movement task with a well-defined, independently determined, variable delay time, time courses in the motor area are distinct from each other in two experiments it the difference in delay time is as little as 2 s. The activation in the visual area due to the presentation of the task serves here as an internal time reference. By comparing a set of fMRI time courses in multiple distinct areas, serial neural processing may be investigated.

Original languageEnglish (US)
Pages (from-to)631-636
Number of pages6
JournalMagnetic resonance in medicine
Volume37
Issue number4
DOIs
StatePublished - Apr 1997

Keywords

  • fMRI
  • functional mapping
  • neuro-imaging
  • serial neural processing

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