ABSTRACT
The brain development described originates, like the small brain described above, from a primary neural network. Sigmund Freud based many of his ideas on J. H. Jackson's model of the brain-a hierarchical structure of functions in which each higher level presents anew and expands with a more complex organization the functions present in the lower levels. As highlighted by A. N. Schore, the narrowing of the distance between psychoanalysis and the neurosciences means that a more detailed study needs to be carried out on the important link that Freud imagined between Jackson's hierarchical structure and psychic organization. The leech is a metameric creature, i.e. it is made up of a series of repeated body segments and ganglia-a kind of organization adopted by evolution in order to render a species more complex. The reticulum represents the general structure of the brain, a type of neural organization that distinguishes the development of the brain of all mammals.
