Limitations of temporal resolution in functional MRI

Magn Reson Med. 1997 Apr;37(4):631-6. doi: 10.1002/mrm.1910370427.

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 if 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Brain / anatomy & histology*
  • Brain / physiology
  • Cerebrovascular Circulation
  • Hemodynamics / physiology
  • Humans
  • Image Processing, Computer-Assisted / methods*
  • Magnetic Resonance Imaging* / methods
  • Magnetic Resonance Imaging* / standards
  • Motor Cortex / physiology
  • Psychomotor Performance
  • Visual Cortex / physiology