Association Cortex Association cortex is the cerebral cortex outside the primary areas (Figure 1). It is essential for mental functions that are more complex than detecting basic dimensions of sensory stimulation, for which primary sensory areas appear to be necessary.he surface area of the human cerebral cortex (and monkey's, dog's, and horse's as well) is further enlarged by the sulci and gyri shown by the curving lines on the cerebral hemispheres. Figure 1-2e. Primary and association cortical areas in human and rat.