<p>The next layer, the paleomammalian brain, better known as the limbic system, is primed and ready to be further developed by early life experiences. This area is largely responsible for the functions of memory, learning, and emotion. This second layer is responsible for basic autonomic functioning, as well as reflexes, and basic survival (DeRidder, 2014). The proliferation of the limbic system created higher frequencies, such as theta and alpha. The limbic structures include the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus. These limbic structures are wrapped in the cerebral cortex, which is the outermost and third layer of the brain.&nbsp;&nbsp;</p><p>From an evolutionary perspective, the reptilian brain is fully functional at birth and the second layer—the limbic system—is prepared for the organizational experiences of early life. The neuronal development of the brain’s first and second layers are virtually complete at birth; the branching of dendrites that occurs thereafter is dubbed “wiring,” since the growth of neurons and dendrites resembles wires (Seung, 2012). The wiring and creation of oligodendrocytes (glia cells responsible for myelination) now occurs from the limbic structures into the cortex. The self-reliance of the brain circuits has increased as we have evolved, and have moved to higher levels in the brain, ones that have less and less contact with sensory inputs.</p><p>Most of our significant early emotional and intellectual experiences, those that shape our later perceptions and reactions, occur when the limbic and reptilian structures are in dominance (Cozolino, 2002, p. 9). That is to say, many of our social-emotional reactions and behaviors are literally programmed beneath the surface of our consciousness. Indeed, empirical evidence suggests that processing emotion can occur without conscious awareness (Balconi &amp; Lucchiari, 2008; Bunce, Bernat, Wong, &amp; Shevrin, 1999; LeDoux, 1998a).&nbsp;</p>