Foveal Representation In V1 And V2 Of Macaque Monkey

How brain processes the visual information is always an important question for brain and cognition science.Fovea is the key for primate to obtain the visual information.Fovea is a small pit composed of closely packed cones located in the retina.It receives input from the central visual field.The density of cones in fovea is extremely high,and no rods exists in the very central region(0?1.7 degree).We have known for a long time that much more brain area is devoted to fovea representation if giving the same size of visual field,and cortical magnification factor was used for denoting such relationship.However,few studies have explored the very central fovea.In this paper,we used intrinsic signal optical imaging to study the foveal representation in monkey V1 and V2.The contents of this thesis mainly include two parts:(1)Building the optical imaging system for experiment and writing some programs for analyzing image data offline.The optical imaging system includes stimulation system that gives the vision stimuli on the monitor,collection system that collects the image data and other parts like the illumination system and a platform for animal.The stimulation system and collection system can be synchronized through serial ports.Then the right configuration is set and all parts can work together.The programs are mainly about the data preprocessing,single condition and difference maps and extracting activation regions.(2)We firstly used a staircase strategy to find the fixation point corresponding to fovea,then the arc and polarline stimuli are given.After extracting activation regions on the cortex,we calculated the magnification factor in fovea by two different ways.We put forward that the magnification factor in fovea can be as high as 16mm/deg.At last,we find some interesting phenomenon and discuss in part 5.We found that in the central fovea there exists large overlap between two activation regions on cortex representing two separated stimuli in visual field.