The exceptions are associated with symbolic models (which are based on logic). The animals cannot make any symbolic models. As we know, the basic function of any brain (human or animal) is to make and operate image-models. Let's continue with the basic differences between the human and animal brain. THE HUMAN BRAIN (Introduction) The basic difference between the animal brain and human brain is the capacity of the human brain to make and operate symbolic models. The animals are not able in any way or form to make and operate symbolic models. We already analyzed how a human or animal brain interacts with an image to make an image-model. For the symbolic models the interaction is different. A symbolic model, as we know, uses as elements letters, words or numbers. When a human brain interacts with such elements, the M-models will contain such elements as specialized YM-models. Such YM-models contain all the shapes of the letters, for instance. It is not necessary to discover the elements, because they are there in an explicit way. All the symbolic elements are contained in a symbolic model called General Communication Language (GCL). There is a spoken language and a written language, as directly interacting symbolic models. This is true only for cultural zones which use alphabets. There is a specific application which treats this problem. For a given written text, we have all the elements and all the relations between the elements, in an explicit way, as words. Usually, the elements are the nouns and the relations between them are the verbs. Any sentence is a symbolic model, for instance. Example: the sentence: "I go home" has two elements "I" and "home" and a relation between the elements as "go". The stability of the symbolic models is based on logic. When a symbolic model is stable we call it a logical model. A logical (stable) model can be understood by anybody who can make and operate symbolic models. Sometimes there is a correspondence between image-models and symbolic-models as in the following example. Example: Let's analyze the sentence "An apple falls from an apple-tree". We have two elements and a relation between them. On the other hand, we can make an image-model that describes the same situation: an apple falls from an apple-tree. So, the logic could have been born in the process of translation from an image model to a symbolic model (when the translation is possible). As an image- model is stable based on laws of harmony, a symbolic model is stable based on the laws of logic. Here we have in an implicit way the definitions of harmony and logic, as the rules and methods to ensure the stability of an image-model (harmony) or a symbolic-model (logic). An implicit definition means that we are able to recognize the effect of harmony or logic in a structure of data. THE HUMAN BRAIN VERSUS ANIMAL BRAIN MDT is a theory that treats the human and animal brain in the same framework.