Design And Evaluation Of A Caloric Stimulation Device For F MRI-study

On account of good temporal and spatial resolution, functional magnetic resonance imaging(fMRI) technology is more and more widely used on research of human brain. In fMRI studies of brain function, researchers need to use a wide variety of stimulation devices to give subjects different sensory stimulation, such as vision, auditory, olfactory, gustatory, tactile and so on. Currently, most fMRI studies are based on visual and auditory stimulation task, much fewer fMRI studies are based on tactile stimulation task. One of the reasons is lack of the tactile stimulation device, so giving subjects accurate tactile stimulation automatically in MRI environment is very hard. The other reason is that tactile sense of human is a complicated sense, it includes touch, temperature and pain senses. When the touch and pain stimulation tasks is given to subjects, the stimulation device easily generate irrelevant stimulus that may result in the research failure. Taking into account the feasibility of the experiments, we mainly develop a computer-controlled caloric stimulation device for fMRI studies and evaluate it in a temperature fMRI experiment. The main achievements are as follows.By connecting some traditional stimulation devices design methods with our experimental aims, we analyzed and summarized the features of caloric stimulation device, such as one stimulation task, computer-controlled, synchronization with imaging and MRI-compatible. And conclude the basic experimental design principles of fMRI caloric stimulation device, which is consist of PC software platform, control module, thermal stimulation generation module and a small peltier-pod.According to the above design principle, we have designed and verified a computer-controlled caloric stimulation device for delivering caloric stimulation in fMRI environment. The device ‘s microcontroller modules is designed by MSP430 micro control chip which can receive the stimulation sequence written in LabVIEW, and then the microcontroller transfers the stimulation sequence to a digital PID temperature control module to exactly realize the caloric stimulation via a small peltier-pod. The stimulation can carry out some temperature stimulation tasks.With this device, we performed the caloric stimulation fMRI experiment with cold(16℃), heat(40℃) and warm(32℃), whose results verify that the device reliably presents caloric stimulation to 5 test subjects.