Biomedical Engineering Reference
In-Depth Information
Chapter 11
Using fMRI for Elucidating Dynamic Interactions
Yul-Wan Sung and Seiji Ogawa
Abstract
For elucidation of information processing mechanism of the human brain, it is important to know
dynamic characteristics of functional areas involved in stimulus processing and the functional network
consists of those areas. Although it is very difficult to trace the dynamics of neuronal activities with slowly
responding signals of functional MRI (fMRI), there is a possibility that some aspects of the dynamics can
be probed up to a time scale of tens to hundreds milliseconds by fMRI. Here, we describe some evidences
for such possibility in the visual information processing.
Key words:
fMRI, Paired stimulus paradigm, interaction, inter stimulus interval (ISI), suppression.
1. Introduction
FMRI is the most useful method among non-invasive tools for
mapping of brain function. The mapping study has been used to
localize areas activated for processing the information generated
in the brain by a stimulus. But to elucidate the functional roles
of the areas involved in processing the stimulus, it is necessary to
know the details of their functional characteristics and the tempo-
ral dynamics of the interaction among these areas in the network.
Although fMRI is a highly effective method to spatially localize
functional areas related to a given stimulus, it is very difficult to
trace the dynamics of neuronal activities with the slow fMRI sig-
nal. However, there are cases where the dynamic effect can be
detected up to a time scale of tens to hundreds ms by fMRI if
neuronal activities interact with each other in a functional unit or
between functional units. Here, we will show the potential of the
conventional (or slow) fMRI by elucidating such dynamic inter-
actions in the visual information processing of the human brain.
