BIOLOGY : MECHANISM OF THE BRAIN The outside is always an inside Neuronal assemblies Neurons in primitive animals like hydra have nerve nets. These respond by coordinated action from sensory stimuli like food particles to engulf them .In higher animals these nerve nets multiplied in number for unrelated purposes as ganglions. The problem occurs in coordination of the various nerve nets as they frequently have common inter neurons serving different purposes. In higher animals brain has a hierarchy of nerve nets. The hierarchical nets receive images from lower nets . Thus in visual cortex lower centres detect lines while higher centres synthesise oriented lines to shapes. This occurs due to mutual inhibition of the two nerve nets ,the higher net using memory of forms to inhibit lower network oriented lines. In mammals the highest multimodal nerve net is a map in cortex called hippocampus. The hippocampus has grid cells connected to afterent sensory inputs from pr...