144 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”It is believed to be important for primitive drives and motivation, and for
this reason has been referred to as the “visceral brain.”
The autonomic nervous system, which consists of a chain of gan-
glia (carrying messages originating in the hypothalamus) alongside the
spinal cord, is responsible for energy consumption during emergency
(sympathetic) and for energy conservation at rest (parasympathetic).
The autonomic nervous system will be elaborated in Chapter 9 in con-
nection with emotion.
7.4 Synaptic Plasticity: The Key to Learning
Synaptic-based neuronal circuitry is the foundation of the Hebbian the-
ory of learning. Hebb, in the 1940s, suggested that repeated firing of one
neuron increases the synaptic efficacy with the next.^6 Perhaps the strongest
evidence in support of synaptic learning is the phenomenon of long-term
potentiation, a topic to be taken up in Chapter 10: Self and Memory.
Fig. 7.11. The limbic system (shaded areas) of the human brain (medial view of the
right hemisphere with the head pointing left). The following limbic structures form a
ring around the brain stem: ventromedial prefrontal cortex, cingulate cortex, entorhinal
cortex, hippocampus, and amygdala (deep in the brain). Other structures are labeled for
landmark identification.