Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2003 Mar;18(3):186-93.
doi: 10.1002/hbm.10092.

Comparison of block and event-related fMRI designs in evaluating the word-frequency effect

Michael W L Chee  1 , Vinod Venkatraman, Christopher Westphal, Soon Chun Siong
Affiliations
Comparative Study

Comparison of block and event-related fMRI designs in evaluating the word-frequency effect

Michael W L Chee et al. Hum Brain Mapp. 2003 Mar.

Abstract

Printed word frequency can modulate retrieval effort in a task requiring associative semantic judgment. Event-related fMRI, while avoiding stimulus order predictability, is in theory statistically less powerful than block designs. We compared one event-related and two block designs that evaluated the same semantic judgment task and found that similar brain regions demonstrated the word frequency effect. Although the responses were lower in amplitude, event-related fMRI was able to detect the word frequency effect to a comparable degree compared to the block designs. The detection of a frequency effect with the event-related design also suggests that stimulus-order predictability may not be as serious a concern in block designs as might be supposed.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Exemplars of the stimuli used in the semantic judgment tasks (high and low frequency) and control tasks for Experiment 1 (block design with size judgment).
Figure 2
Figure 2
Axial brain slices showing areas activated in the low‐ and high‐frequency conditions as well as in the contrast between these two conditions in the block and event‐related experiments. Group level data is depicted (n = 12 for the block design using size judgment as a control, n = 8 for the block design using fixation as control, and n = 12 for the event‐related design).
Figure 3
Figure 3
Percent signal change graphs depicting group‐averaged responses to low‐ and high‐frequency stimuli obtained from the left prefrontal ROI in the event‐related and block designs. Error bars depict 1 SE.
See this image and copyright information in PMC

References

    1. Aguirre GK, D'Esposito M (1999): Experimental design for brain fMRI In: Bandettini PA, editor. Functional MRI. Berlin: Springer‐Verlag; 369–380.
    1. Aguirre GK, Zarahn E, D'Esposito M (1997): Empirical analyses of BOLD fMRI statistics. II. Spatially smoothed data collected under null‐hypothesis and experimental conditions. Neuroimage 5: 199–212. - PubMed
    1. Bandettini PA, Cox RW (2000): Event‐related fMRI contrast when using constant interstimulus interval: theory and experiment. Magn Reson Med 43: 540–548. - PubMed
    1. Beauchamp MS, Lee KE, Haxby JV, Martin A (2002): Parallel visual motion processing streams for manipulable objects and human movements. Neuron 34: 149–159. - PubMed
    1. Binder J, Frost J, Hammeke T, Bellgowan P, Rao S, Cox R (1999): Conceptual processing during the conscious resting state: a functional MRI study. J Cogn Neurosci 11: 80–95. - PubMed

Publication types