The BOLD signal response for fluctuating stimulation images.

In the measurement of brain function by using fMRI, increasing of blood flow and decreasing of de-oxy-hemoglobin concentration as a cause of this increasing (BOLD: Blood Oxygenation Level-Dependent) are measured. And brain activity is evaluated as the function of BOLD signal. In the f-MRI measurement, MRI data under stimulation and resting are measured periodically, and these data are compared and analyzed.

Influence of moving sight by turning over frequency.

In late years, f-MRI (functional magnetic resonance imaging) are used for analysis of a visual function. In case of the study for a visual function, the checker flag pattern consists of white square and black square is usually used for sight stimulation. In sight stimulation using this pattern, a color of square (black and white) changes alternately at constant frequency.

Time-dependence evaluation of the primary visual cortex by 1H MR-spectroscopy using a stimulation control system.

Unlabelled: Proton magnetic resonance spectroscopy ((1)H MRS) is used to evaluate tumors and their remaining function under the assumption that event-related inspection and a method of data collection dependent on time are difficult. Therefore, this study examined the possibility that time depended on in MRS with a visual cortex. We conducted experiments using the following stimulations: REST: eyes are in a closed state,

Control: eyes are in an open state, and Continuous: consecutive stimulation and time dependence in the visual cortex.

Analysis of brain activation by visual and auditory stimulation after visual and auditory simultaneous stimulation using F-MRI.

It is said that the auditory spatial perception is strongly affected by visual cues, and when auditory and visual stimulation are given form different positions simultaneously, the source position of sound is mislead to the direction of visual stimulation. The purpose of this study is analyzing the brain response on f-MRI by simultaneous stimulation of auditory and visually sensors. f-MRI of some subjects were measured by using simultaneous stimulation, and the results of these experiments were analyzed and assessed.

[Response by visual stimulation with the BOLD effect and motion artifact: identification of the activating signal and motion artifact].

This study used functional magnetic resonance imaging (fMRI) to evaluate brain function. fMRI data were collected by a block paradigm, and brain function was evaluated. However, irrelevant artifacts caused by the BOLD effect frequently occur in analytical processing.

[With-time change of hemodynamics in fMRI: linearity consideration after stimulation ends from stimulation beginning].

The BOLD signal responses that occur after a few seconds at the beginning and the end of stimulus are due to hemodynamic delay. A temporary increase of deoxyhemoglobin just after the beginning of stimulus causes an initial dip in the hemodynamic signal (response). After the initial dip, an increase of BOLD signal causes an overshoot.

[Evaluation of time resolution of the primary motor cortex by a single paradigm using a stimulation system].

Many researchers are investigating brain function by using a block paradigm in fMRI measurement. However, time resolution has been limited because the block paradigm employed data collection by consecutive image acquisition after stimulation began. Because of this problem, the evaluation of early brain activity was not adequate.

[Effect of BOLD on sight stimulation and artifact of CSF: identification of activating signal and CSF artifact].

This study used functional magnetic resonance imaging (fMRI) for brain function evaluation. fMRI data were collected by a block paradigm, and brain function was evaluated. In the block paradigm, the BOLD effect causes a several-second delay in hemodynamics, and analytical processing is done in consideration of this time lag.

[Evaluation of time resolution of primary visual cortex using a single paradigm: sequence design employing a stimulation system].

The characteristics of fMRI include high-resolution, non-invasiveness, and ease of use, making it increasingly popular for brain imaging. However, imaging by the block paradigm is limited in time resolution from stimulus presentation to the subject to image acquisition. Therefore, it is not necessarily adequate for the evaluation of early (initial) brain activity.