A considerable number of complex cells receive converging input from both eyes, the remainder being monocular. the determination of the outline of an object. These cells via the combined input from simple cells, are probably involved in the earliest stages of actual form perception, i.e. However, these cells are more flexible and will respond and analyze a stimulus regardless of its particular orientation.
Complex cells are also concerned with orientation of the stimulus. Each complex cell receives input from several simple cells. Sinple cells relay this processed information to the far more numerous complex cells which are found predominantly in layers II and III and V, which interact and communicate with one another including with layer IV which receives thalamic input. However, for a simple cell to fire, a stimulus must assume a specific orientation and position. In addition, simple cells are responsive to the particular position and orientation a stimulus may take. In fact, almost 95% of the neurons in area 17 are responsive to stimuli moving only in one direction, but not the direction of movement. Some are sensitive to stimuli moving in one direction, whereas others may respond to stimuli moving in any direction. They are found predominantly within area 17 and in layer IVa,b,c. To briefly summarize, simple cells appear to be involved in the initial analysis of incoming visual cortical input, and are most sensitive to slowly moving stimuli. These include simple, complex, and (higher & lower order) hypercomplex cells which are distributed disproportionately throughout areas 17,18, 19. The visual cortex is made up of a variety of cell types each of which is concerned with the analysis of different visual features (Ferster, et al., 1996 Hubel & Wiesel, 1959, 1962, 1968 Kaas & Krubitzer 1991 Sereno et al. SIMPLE, COMPLEX, LOWER- & HIGHER ORDER HYPERCOMPLEX FEATURE DETECTORS
Functional Neuroanatomy Of The Visual Association Areas 18 And 19
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