A study on asymmetry of spatial visual field by analysis of the fMRI BOLD response

The asymmetry of the left-right and upper-lower visual field is analyzed in this paper by a model approach based on the functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) response. The model consists of the convolution between a Gaussian function and the perfusion function of neural response to stimulus. The model parameters are estimated by a nonlinear optimal algorithm, and te asymmetry of the left-right and upper-lower visual field is investigated by the differences of the model parameters. The results from eight subjects show that reaction time is significant shorter and the response is significant stronger when the lower field is stimulated than that when the upper field is stimulated. For the left and right fields, the response is different. These results provide the fMRI BOLD response evidence of the asymmetry of spatial visual fields.