Estimation of Retinotopic Map of Awake Mouse Brain Based upon Retino-Cortical Response Model.

ABSTRACT

We proposed a novel retino-cortical response model on which the fine retinotopic map of the primary visual cortex was estimated from the intrinsic optical signal (IOS) induced by visual stimulation in an awake mouse. Our method was developed to overcome practical restrictions of measurement time and disturbances such as eye movement and brain background activity instead of synchronous averaging. In our model, it was assumed that the response of the cortical region was given by integrating the product of the image projected on a spherical retina and the retino-cortical sensitive function. In addition, in order to estimate parameters of the sensitive function, Monte Carlo-based numerical integration and nonlinear least square algorithm were employed. By applying this method to the actual IOS data, we estimated a biologically plausible spatial distribution of the sensitivity function parameters and a retinotopic map. Similar to our pervious study, higher-order brain regions such as the secondary visual cortex were also visualized. These results suggested usefulness of our proposed method based on the novel retino-cortical response model.Clinical Relevance- The method for evaluating visual functions under restoration was proposed and its validity was examined in animal experiments.