Self And The Phenomenon Of Life: A Biologist Examines Life From Molecules To Humanity

The Animal Self: Neurobehavioral Correlates 157

“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity

nervous system is necessary for the full expression of self. It is through
the mechanism of the brain that self assumes the capacity of conscious-
ness, first of the world, and finally of itself.
Sigmund Freud divided human self into id, ego and superego, cor-
responding, respectively, to animal impulse, the day-in-and-day-out self,
and the moral and idealized self.^28 Kandel suggested, and I agree, that
the three levels of self can be roughly correlated with the phylogenetic
stratifications of the brain: id is the function of the lowermost part —
the brain stem and the limbic system; above this are the cerebral hemi-
spheres which give rise to ego; whereas superego is the function of the
upper- and outer-most part of the hemisphere — a thin layer of gray
matter called cerebral cortex, especially the prefrontal cortex.^29 The pre-
frontal cortex occupies the highest level in the hierarchy of the nervous
system and its function is what most distinguishes humans from other
animals. It is involved in planning, foresight, self-control, self-restraint,
and deferred gratification. Figure 7.18 is a diagram of this scheme.

Fig. 7.18. Evolutionary stratification of the brain in the building of the human self.
The three layers conceived by Paul MacLean in the 1960s are, approximately: (A) the ar-
chipallium for survival; (B) the paleopallium for feeling and emotion; (C) the neopallium
for rational thinking. When translated into psychoanalytic terms, id corresponds to (A)
and (B); ego corresponds to (C), while superego resides in a special part of the cerebral
cortex equivalent to the prefrontal cortex (D). [See Note 39.]